diff --git a/.github/workflows/build-nightly-apk.yml b/.github/workflows/build-nightly-apk.yml
index bca267be..c64dba12 100644
--- a/.github/workflows/build-nightly-apk.yml
+++ b/.github/workflows/build-nightly-apk.yml
@@ -51,10 +51,12 @@ jobs:
       androidHome: ${{ env.ANDROID_HOME }}
       androidSdkRoot: ${{ env.ANDROID_SDK_ROOT }}
     steps:
-      - name: Setup JDK 1.8
-        uses: actions/setup-java@v1
+      - name: Setup JDK 11
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          distribution: 'zulu'
+          java-version: '11'
+          cache: 'gradle'
       - name: Setup Android SDK
         uses: android-actions/setup-android@v2
       - name: Clean build artifacts
diff --git a/.github/workflows/build-release-aab-play.yml b/.github/workflows/build-release-aab-play.yml
index ec0a7069..5f3026e6 100644
--- a/.github/workflows/build-release-aab-play.yml
+++ b/.github/workflows/build-release-aab-play.yml
@@ -43,10 +43,12 @@ jobs:
       androidHome: ${{ env.ANDROID_HOME }}
       androidSdkRoot: ${{ env.ANDROID_SDK_ROOT }}
     steps:
-      - name: Setup JDK 1.8
-        uses: actions/setup-java@v1
+      - name: Setup JDK 11
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          distribution: 'zulu'
+          java-version: '11'
+          cache: 'gradle'
       - name: Setup Android SDK
         uses: android-actions/setup-android@v2
       - name: Clean build artifacts
diff --git a/.github/workflows/build-release-apk.yml b/.github/workflows/build-release-apk.yml
index 169704c1..4816ee73 100644
--- a/.github/workflows/build-release-apk.yml
+++ b/.github/workflows/build-release-apk.yml
@@ -43,10 +43,12 @@ jobs:
       androidHome: ${{ env.ANDROID_HOME }}
       androidSdkRoot: ${{ env.ANDROID_SDK_ROOT }}
     steps:
-      - name: Setup JDK 1.8
-        uses: actions/setup-java@v1
+      - name: Setup JDK 11
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          distribution: 'zulu'
+          java-version: '11'
+          cache: 'gradle'
       - name: Setup Android SDK
         uses: android-actions/setup-android@v2
       - name: Clean build artifacts
diff --git a/.gitignore b/.gitignore
index 07e9f679..375b15e2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -265,3 +265,4 @@ fabric.properties
 # End of https://www.toptal.com/developers/gitignore/api/android,androidstudio,gradle,java,kotlin
 
 signatures/
+.idea/*.xml
diff --git a/.idea/discord.xml b/.idea/discord.xml
deleted file mode 100644
index a04e4e5f..00000000
--- a/.idea/discord.xml
+++ /dev/null
@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="DiscordProjectSettings">
-    <option name="show" value="PROJECT_FILES" />
-  </component>
-  <component name="ProjectNotificationSettings">
-    <option name="askShowProject" value="false" />
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/kotlinc.xml b/.idea/kotlinc.xml
deleted file mode 100644
index 0dd4b354..00000000
--- a/.idea/kotlinc.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="Kotlin2JvmCompilerArguments">
-    <option name="jvmTarget" value="1.8" />
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/runConfigurations.xml b/.idea/runConfigurations.xml
deleted file mode 100644
index e497da99..00000000
--- a/.idea/runConfigurations.xml
+++ /dev/null
@@ -1,13 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="RunConfigurationProducerService">
-    <option name="ignoredProducers">
-      <set>
-        <option value="com.android.tools.idea.compose.preview.runconfiguration.ComposePreviewRunConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.AllInPackageGradleConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestClassGradleConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestMethodGradleConfigurationProducer" />
-      </set>
-    </option>
-  </component>
-</project>
\ No newline at end of file
diff --git a/app/build.gradle b/app/build.gradle
index c0af6190..62f4c95c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-kapt'
+apply plugin: 'kotlin-parcelize'
 apply plugin: 'com.google.gms.google-services'
 apply plugin: 'com.google.firebase.crashlytics'
 
@@ -35,6 +36,9 @@ android {
     buildTypes {
         debug {
             minifyEnabled = false
+            manifestPlaceholders = [
+                    buildTimestamp: 0
+            ]
         }
         release {
             minifyEnabled = true
@@ -120,25 +124,25 @@ dependencies {
     coreLibraryDesugaring "com.android.tools:desugar_jdk_libs:1.1.5"
 
     // Android Jetpack
-    implementation "androidx.appcompat:appcompat:1.2.0"
+    implementation "androidx.appcompat:appcompat:1.3.1"
     implementation "androidx.cardview:cardview:1.0.0"
-    implementation "androidx.constraintlayout:constraintlayout:2.0.4"
-    implementation "androidx.core:core-ktx:1.3.2"
-    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.3.0"
-    implementation "androidx.navigation:navigation-fragment-ktx:2.3.4"
-    implementation "androidx.recyclerview:recyclerview:1.1.0"
-    implementation "androidx.room:room-runtime:2.2.6"
-    implementation "androidx.work:work-runtime-ktx:2.5.0"
-    kapt "androidx.room:room-compiler:2.2.6"
+    implementation "androidx.constraintlayout:constraintlayout:2.1.0"
+    implementation "androidx.core:core-ktx:1.6.0"
+    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.3.1"
+    implementation "androidx.navigation:navigation-fragment-ktx:2.3.5"
+    implementation "androidx.recyclerview:recyclerview:1.2.1"
+    implementation "androidx.room:room-runtime:2.3.0"
+    implementation "androidx.work:work-runtime-ktx:2.6.0"
+    kapt "androidx.room:room-compiler:2.3.0"
 
     // Google design libs
-    implementation "com.google.android.material:material:1.3.0"
+    implementation "com.google.android.material:material:1.4.0"
     implementation "com.google.android:flexbox:2.0.1"
 
     // Play Services/Firebase
-    implementation "com.google.android.gms:play-services-wearable:17.0.0"
-    implementation "com.google.firebase:firebase-core:18.0.2"
-    implementation "com.google.firebase:firebase-crashlytics:17.4.0"
+    implementation "com.google.android.gms:play-services-wearable:17.1.0"
+    implementation "com.google.firebase:firebase-core:19.0.1"
+    implementation "com.google.firebase:firebase-crashlytics:18.2.1"
     implementation("com.google.firebase:firebase-messaging") { version { strictly "20.1.3" } }
 
     // OkHttp, Retrofit, Gson, Jsoup
@@ -153,7 +157,7 @@ dependencies {
 
     // Szkolny.eu libraries/forks
     implementation "eu.szkolny:android-snowfall:1ca9ea2da3"
-    implementation "eu.szkolny:agendacalendarview:5431f03098"
+    implementation "eu.szkolny:agendacalendarview:ac0f3dcf42"
     implementation "eu.szkolny:cafebar:5bf0c618de"
     implementation "eu.szkolny.fslogin:lib:2.0.0"
     implementation "eu.szkolny:material-about-library:1d5ebaf47c"
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index af4b653a..cbe7bd48 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -146,6 +146,7 @@
             android:configChanges="orientation|keyboardHidden"
             android:theme="@style/Base.Theme.AppCompat" />
         <activity android:name=".ui.modules.base.BuildInvalidActivity" />
+        <activity android:name=".ui.modules.settings.contributors.ContributorsActivity" />
 
         <!--  _____               _
              |  __ \             (_)
diff --git a/app/src/main/assets/pl-changelog.html b/app/src/main/assets/pl-changelog.html
index 27c85f0f..99883f04 100644
--- a/app/src/main/assets/pl-changelog.html
+++ b/app/src/main/assets/pl-changelog.html
@@ -1,13 +1,13 @@
-<h3>Wersja 4.8, 2021-05-26</h3>
+<h3>Wersja 4.9, 2021-09-11</h3>
 <ul>
-    <li>Dodano ikony dla powiadomień. @Luncenok</li>
-    <li>Terminarz: opcje konfiguracji, widok kompaktowy, grupowanie wydarzeń, znaczki nieprzeczytanych, nowe ikony i wiele innych usprawnień.</li>
-    <li>Wiadomości: usprawiono wyszukiwanie - zapisywanie szukanego tekstu po wejściu w wiadomość.</li>
-    <li>Wiadomości: dodano opcję konfiguracji podpisu przy wysyłaniu wiadomości.</li>
-    <li>Plan lekcji: dodano znacznik aktualnej pory dnia w planie lekcji.</li>
-    <li>Powiadomienia: dodano szczegółowy opis po rozwinięciu.</li>
-    <li>Wydarzenia: nowy rodzaj "lekcja online".</li>
-    <li>Naprawiono odbieranie nagrody w easter egg'u.</li>
+    <li>Vulcan: naprawiono brakujące lekcje w planie. @Antoni-Czaplicki</li>
+    <li>Vulcan: naprawiono wysyłanie wiadomości. @Antoni-Czaplicki</li>
+    <li>Vulcan: naprawiono brak frekwencji.</li>
+    <li>Naprawiono eksportowanie planu lekcji oraz pobieranie załączników. @doteq</li>
+    <li>Mobidziennik: naprawiono możliwość pobierania przyszłego planu lekcji.</li>
+    <li>Mobidziennik: poprawiono brak nowych linii w wysłanej wiadomości.</li>
+    <li>Dodano ekran "Twórcy aplikacji" w Ustawieniach. @Pengwius</li>
+    <li>Zmieniono domyślne tło nagłówka menu. 😋</li>
 </ul>
 <br>
 <br>
diff --git a/app/src/main/cpp/szkolny-signing.cpp b/app/src/main/cpp/szkolny-signing.cpp
index 9af553cb..9925362d 100644
--- a/app/src/main/cpp/szkolny-signing.cpp
+++ b/app/src/main/cpp/szkolny-signing.cpp
@@ -9,7 +9,7 @@
 
 /*secret password - removed for source code publication*/
 static toys AES_IV[16] = {
-	0x71, 0xcf, 0xdf, 0x13, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff  };
+	0x36, 0x60, 0xb0, 0x4b, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff  };
 
 unsigned char *agony(unsigned int laugh, unsigned char *box, unsigned char *heat);
 
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/App.kt b/app/src/main/java/pl/szczodrzynski/edziennik/App.kt
index a9186d94..71e6c7e6 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/App.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/App.kt
@@ -58,6 +58,7 @@ class App : MultiDexApplication(), Configuration.Provider, CoroutineScope {
         val profileId
             get() = profile.id
 
+        var enableChucker = false
         var debugMode = false
         var devMode = false
     }
@@ -115,9 +116,11 @@ class App : MultiDexApplication(), Configuration.Provider, CoroutineScope {
             HyperLog.initialize(this)
             HyperLog.setLogLevel(Log.VERBOSE)
             HyperLog.setLogFormat(DebugLogFormat(this))
-            val chuckerCollector = ChuckerCollector(this, true, RetentionManager.Period.ONE_HOUR)
-            val chuckerInterceptor = ChuckerInterceptor(this, chuckerCollector)
-            builder.addInterceptor(chuckerInterceptor)
+            if (enableChucker) {
+                val chuckerCollector = ChuckerCollector(this, true, RetentionManager.Period.ONE_HOUR)
+                val chuckerInterceptor = ChuckerInterceptor(this, chuckerCollector)
+                builder.addInterceptor(chuckerInterceptor)
+            }
         }
 
         http = builder.build()
@@ -172,6 +175,7 @@ class App : MultiDexApplication(), Configuration.Provider, CoroutineScope {
         App.profile = Profile(0, 0, 0, "")
         debugMode = BuildConfig.DEBUG
         devMode = config.debugMode || debugMode
+        enableChucker = config.enableChucker || devMode
 
         if (!profileLoadById(config.lastProfileId)) {
             db.profileDao().firstId?.let { profileLoadById(it) }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/Extensions.kt b/app/src/main/java/pl/szczodrzynski/edziennik/Extensions.kt
index 8d3b59d1..42eed408 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/Extensions.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/Extensions.kt
@@ -14,6 +14,7 @@ import android.graphics.Typeface
 import android.graphics.drawable.Drawable
 import android.os.Build
 import android.os.Bundle
+import android.os.Parcelable
 import android.text.*
 import android.text.style.CharacterStyle
 import android.text.style.ForegroundColorSpan
@@ -737,6 +738,7 @@ fun Bundle(vararg properties: Pair<String, Any?>): Bundle {
                 is Short -> putShort(property.first, property.second as Short)
                 is Double -> putDouble(property.first, property.second as Double)
                 is Boolean -> putBoolean(property.first, property.second as Boolean)
+                is Array<*> -> putParcelableArray(property.first, property.second as Array<out Parcelable>)
             }
         }
     }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt b/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt
index 160deb23..0274912f 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt
@@ -80,6 +80,11 @@ class Config(val db: AppDb) : CoroutineScope, AbstractConfig {
         get() { mDebugMode = mDebugMode ?: values.get("debugMode", false); return mDebugMode ?: false }
         set(value) { set("debugMode", value); mDebugMode = value }
 
+    private var mEnableChucker: Boolean? = null
+    var enableChucker: Boolean
+        get() { mEnableChucker = mEnableChucker ?: values.get("enableChucker", false); return mEnableChucker ?: false }
+        set(value) { set("enableChucker", value); mEnableChucker = value }
+
     private var mDevModePassword: String? = null
     var devModePassword: String?
         get() { mDevModePassword = mDevModePassword ?: values.get("devModePassword", null as String?); return mDevModePassword }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Constants.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Constants.kt
index f06ef354..cb0d5a06 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Constants.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Constants.kt
@@ -24,7 +24,7 @@ const val FAKE_LIBRUS_ACCOUNTS = "/synergia_accounts.php"
 
 val LIBRUS_USER_AGENT = "${SYSTEM_USER_AGENT}LibrusMobileApp"
 const val SYNERGIA_USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Gecko/20100101 Firefox/62.0"
-const val LIBRUS_CLIENT_ID = "0RbsDOkV9tyKEQYzlLv5hs3DM1ukrynFI4p6C1Yc"
+const val LIBRUS_CLIENT_ID = "VaItV6oRutdo8fnjJwysnTjVlvaswf52ZqmXsJGP"
 const val LIBRUS_REDIRECT_URL = "app://librus"
 const val LIBRUS_AUTHORIZE_URL = "https://portal.librus.pl/oauth2/authorize?client_id=$LIBRUS_CLIENT_ID&redirect_uri=$LIBRUS_REDIRECT_URL&response_type=code"
 const val LIBRUS_LOGIN_URL = "https://portal.librus.pl/rodzina/login/action"
@@ -43,7 +43,7 @@ const val LIBRUS_API_TOKEN_URL = "https://api.librus.pl/OAuth/Token"
 const val LIBRUS_API_TOKEN_JST_URL = "https://api.librus.pl/OAuth/TokenJST"
 const val LIBRUS_API_AUTHORIZATION = "Mjg6ODRmZGQzYTg3YjAzZDNlYTZmZmU3NzdiNThiMzMyYjE="
 const val LIBRUS_API_SECRET_JST = "18b7c1ee08216f636a1b1a2440e68398"
-const val LIBRUS_API_CLIENT_ID_JST = "49"
+const val LIBRUS_API_CLIENT_ID_JST = "59"
 //const val LIBRUS_API_CLIENT_ID_JST_REFRESH = "42"
 
 const val LIBRUS_JST_DEMO_CODE = "68656A21"
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Errors.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Errors.kt
index 5738064c..eefc1d31 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Errors.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Errors.kt
@@ -195,6 +195,7 @@ const val ERROR_VULCAN_HEBE_FIREBASE_ERROR                  = 362
 const val ERROR_VULCAN_HEBE_CERTIFICATE_GONE                = 363
 const val ERROR_VULCAN_HEBE_SERVER_ERROR                    = 364
 const val ERROR_VULCAN_HEBE_ENTITY_NOT_FOUND                = 365
+const val ERROR_VULCAN_HEBE_MISSING_SENDER_ENTRY            = 366
 const val ERROR_VULCAN_API_DEPRECATED                       = 390
 
 const val ERROR_LOGIN_EDUDZIENNIK_WEB_INVALID_LOGIN         = 501
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Regexes.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Regexes.kt
index 5d847e3f..2bbf1894 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Regexes.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Regexes.kt
@@ -117,6 +117,17 @@ object Regexes {
     }
 
 
+    val MOBIDZIENNIK_TIMETABLE_TOP by lazy {
+        """<div class="plansc_top">.+?</div></div>""".toRegex(DOT_MATCHES_ALL)
+    }
+    val MOBIDZIENNIK_TIMETABLE_CELL by lazy {
+        """<div class="plansc_cnt_w" style="(.+?)">.+?style="(.+?)".+?title="(.+?)".+?>\s+(.+?)\s+</div>""".toRegex(DOT_MATCHES_ALL)
+    }
+    val MOBIDZIENNIK_TIMETABLE_LEFT by lazy {
+        """<div class="plansc_godz">.+?</div></div>""".toRegex(DOT_MATCHES_ALL)
+    }
+
+
 
     val IDZIENNIK_LOGIN_HIDDEN_FIELDS by lazy {
         """<input type="hidden".+?name="([A-z0-9_]+)?".+?value="([A-z0-9_+-/=]+)?".+?>""".toRegex(DOT_MATCHES_ALL)
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/DataEdudziennik.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/DataEdudziennik.kt
index 40601249..49a9d4a0 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/DataEdudziennik.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/DataEdudziennik.kt
@@ -111,37 +111,6 @@ class DataEdudziennik(app: App, profile: Profile?, loginStore: LoginStore) : Dat
     val courseStudentEndpoint: String
         get() = "Course/$studentId/"
 
-    fun getSubject(longId: String, name: String): Subject {
-        val id = longId.crc32()
-        return subjectList.singleOrNull { it.id == id } ?: run {
-            val subject = Subject(profileId, id, name, name)
-            subjectList.put(id, subject)
-            subject
-        }
-    }
-
-    fun getTeacher(firstName: String, lastName: String, longId: String? = null): Teacher {
-        val name = "$firstName $lastName".fixName()
-        val id = name.crc32()
-        return teacherList.singleOrNull { it.id == id }?.also {
-            if (longId != null && it.loginId == null) it.loginId = longId
-        } ?: run {
-            val teacher = Teacher(profileId, id, firstName, lastName, longId)
-            teacherList.put(id, teacher)
-            teacher
-        }
-    }
-
-    fun getTeacherByFirstLast(nameFirstLast: String, longId: String? = null): Teacher {
-        val nameParts = nameFirstLast.split(" ")
-        return getTeacher(nameParts[0], nameParts[1], longId)
-    }
-
-    fun getTeacherByLastFirst(nameLastFirst: String, longId: String? = null): Teacher {
-        val nameParts = nameLastFirst.split(" ")
-        return getTeacher(nameParts[1], nameParts[0], longId)
-    }
-
     fun getEventType(longId: String, name: String): EventType {
         val id = longId.crc16().toLong()
         return eventTypes.singleOrNull { it.id == id } ?: run {
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebExams.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebExams.kt
index f6abf637..c700100c 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebExams.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebExams.kt
@@ -40,7 +40,7 @@ class EdudziennikWebExams(override val data: DataEdudziennik,
                 val subjectId = EDUDZIENNIK_SUBJECT_ID.find(subjectElement.attr("href"))?.get(1)
                         ?: return@forEach
                 val subjectName  = subjectElement.text().trim()
-                val subject = data.getSubject(subjectId, subjectName)
+                val subject = data.getSubject(subjectId.crc32(), subjectName)
 
                 val dateString = examElement.child(2).text().trim()
                 if (dateString.isBlank()) return@forEach
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebGrades.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebGrades.kt
index 459f13aa..6a247290 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebGrades.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebGrades.kt
@@ -53,7 +53,7 @@ class EdudziennikWebGrades(override val data: DataEdudziennik,
 
                 val subjectId = subjectElement.id().trim()
                 val subjectName = subjectElement.child(0).text().trim()
-                val subject = data.getSubject(subjectId, subjectName)
+                val subject = data.getSubject(subjectId.crc32(), subjectName)
 
                 val gradeType = when {
                     subjectElement.select("#sum").text().isNotBlank() -> TYPE_POINT_SUM
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebHomework.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebHomework.kt
index 169a5127..b843abe9 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebHomework.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebHomework.kt
@@ -41,7 +41,7 @@ class EdudziennikWebHomework(override val data: DataEdudziennik,
                     val subjectId = EDUDZIENNIK_SUBJECT_ID.find(subjectElement.attr("href"))?.get(1)
                             ?: return@forEach
                     val subjectName = subjectElement.text()
-                    val subject = data.getSubject(subjectId, subjectName)
+                    val subject = data.getSubject(subjectId.crc32(), subjectName)
 
                     val lessons = data.app.db.timetableDao().getAllForDateNow(profileId, date)
                     val startTime = lessons.firstOrNull { it.subjectId == subject.id }?.displayStartTime
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebStart.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebStart.kt
index 66cb7a59..3fdd6e0e 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebStart.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebStart.kt
@@ -73,7 +73,7 @@ class EdudziennikWebStart(override val data: DataEdudziennik,
         EDUDZIENNIK_SUBJECTS_START.findAll(text).forEach {
             val id = it[1].trim()
             val name = it[2].trim()
-            data.getSubject(id, name)
+            data.getSubject(id.crc32(), name)
         }
     }
 }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebTimetable.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebTimetable.kt
index 94db15ef..33feb75e 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebTimetable.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/edudziennik/data/web/EdudziennikWebTimetable.kt
@@ -5,6 +5,7 @@
 package pl.szczodrzynski.edziennik.data.api.edziennik.edudziennik.data.web
 
 import org.jsoup.Jsoup
+import pl.szczodrzynski.edziennik.crc32
 import pl.szczodrzynski.edziennik.data.api.Regexes.EDUDZIENNIK_SUBJECT_ID
 import pl.szczodrzynski.edziennik.data.api.Regexes.EDUDZIENNIK_TEACHER_ID
 import pl.szczodrzynski.edziennik.data.api.edziennik.edudziennik.DataEdudziennik
@@ -89,7 +90,7 @@ class EdudziennikWebTimetable(override val data: DataEdudziennik,
                         val subjectId = EDUDZIENNIK_SUBJECT_ID.find(subjectElement.attr("href"))?.get(1)
                                 ?: return@forEachIndexed
                         val subjectName = subjectElement.text().trim()
-                        val subject = data.getSubject(subjectId, subjectName)
+                        val subject = data.getSubject(subjectId.crc32(), subjectName)
 
                         /* Getting teacher */
 
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/MobidziennikFeatures.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/MobidziennikFeatures.kt
index 7396ac52..7b39e455 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/MobidziennikFeatures.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/MobidziennikFeatures.kt
@@ -18,6 +18,7 @@ const val ENDPOINT_MOBIDZIENNIK_WEB_ATTENDANCE          = 2050
 const val ENDPOINT_MOBIDZIENNIK_WEB_MANUALS             = 2100
 const val ENDPOINT_MOBIDZIENNIK_WEB_ACCOUNT_EMAIL       = 2200
 const val ENDPOINT_MOBIDZIENNIK_WEB_HOMEWORK            = 2300 // not used as an endpoint
+const val ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE           = 2400
 const val ENDPOINT_MOBIDZIENNIK_API2_MAIN               = 3000
 
 val MobidziennikFeatures = listOf(
@@ -38,6 +39,12 @@ val MobidziennikFeatures = listOf(
 
 
 
+        /**
+         * Timetable - web scraping - does nothing if the API_MAIN timetable is enough.
+         */
+        Feature(LOGIN_TYPE_MOBIDZIENNIK, FEATURE_TIMETABLE, listOf(
+                ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE to LOGIN_METHOD_MOBIDZIENNIK_WEB
+        ), listOf(LOGIN_METHOD_MOBIDZIENNIK_WEB, LOGIN_METHOD_MOBIDZIENNIK_WEB)),
         /**
          * Agenda - "API" + web scraping.
          */
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/MobidziennikData.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/MobidziennikData.kt
index 09e1e9fb..b82f6355 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/MobidziennikData.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/MobidziennikData.kt
@@ -84,6 +84,10 @@ class MobidziennikData(val data: DataMobidziennik, val onSuccess: () -> Unit) {
                 data.startProgress(R.string.edziennik_progress_endpoint_lucky_number)
                 MobidziennikWebManuals(data, lastSync, onSuccess)
             }*/
+            ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE-> {
+                data.startProgress(R.string.edziennik_progress_endpoint_timetable)
+                MobidziennikWebTimetable(data, lastSync, onSuccess)
+            }
             else -> onSuccess(endpointId)
         }
     }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebAttendance.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebAttendance.kt
index f23478b6..cbd797b1 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebAttendance.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebAttendance.kt
@@ -48,7 +48,7 @@ class MobidziennikWebAttendance(override val data: DataMobidziennik,
         //syncWeeks.clear()
         //syncWeeks += Date.fromY_m_d("2019-12-19")
 
-        syncWeeks.minBy { it.value }?.let {
+        syncWeeks.minByOrNull { it.value }?.let {
             data.toRemove.add(DataRemoveModel.Attendance.from(it))
         }
 
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebTimetable.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebTimetable.kt
new file mode 100644
index 00000000..6ceb3fd9
--- /dev/null
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/mobidziennik/data/web/MobidziennikWebTimetable.kt
@@ -0,0 +1,340 @@
+/*
+ * Copyright (c) Kuba Szczodrzyński 2021-9-8.
+ */
+
+package pl.szczodrzynski.edziennik.data.api.edziennik.mobidziennik.data.web
+
+import android.annotation.SuppressLint
+import org.jsoup.Jsoup
+import pl.szczodrzynski.edziennik.*
+import pl.szczodrzynski.edziennik.data.api.Regexes
+import pl.szczodrzynski.edziennik.data.api.edziennik.mobidziennik.DataMobidziennik
+import pl.szczodrzynski.edziennik.data.api.edziennik.mobidziennik.ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE
+import pl.szczodrzynski.edziennik.data.api.edziennik.mobidziennik.data.MobidziennikWeb
+import pl.szczodrzynski.edziennik.data.db.entity.Lesson
+import pl.szczodrzynski.edziennik.data.db.entity.Metadata
+import pl.szczodrzynski.edziennik.data.db.entity.SYNC_ALWAYS
+import pl.szczodrzynski.edziennik.utils.models.Date
+import pl.szczodrzynski.edziennik.utils.models.Time
+import pl.szczodrzynski.edziennik.utils.models.Week
+import kotlin.collections.set
+import kotlin.text.replace
+
+class MobidziennikWebTimetable(
+    override val data: DataMobidziennik,
+    override val lastSync: Long?,
+    val onSuccess: (endpointId: Int) -> Unit
+) : MobidziennikWeb(data, lastSync) {
+    companion object {
+        private const val TAG = "MobidziennikWebTimetable"
+    }
+
+    private val rangesH = mutableMapOf<ClosedFloatingPointRange<Float>, Date>()
+    private val hoursV = mutableMapOf<Int, Pair<Time, Int?>>()
+    private var startDate: Date
+
+    private fun parseCss(css: String): Map<String, String> {
+        return css.split(";").mapNotNull {
+            val spl = it.split(":")
+            if (spl.size != 2)
+                return@mapNotNull null
+            return@mapNotNull spl[0].trim() to spl[1].trim()
+        }.toMap()
+    }
+
+    private fun getRangeH(h: Float): Date? {
+        return rangesH.entries.firstOrNull {
+            h in it.key
+        }?.value
+    }
+
+    private fun stringToDate(date: String): Date? {
+        val items = date.split(" ")
+        val day = items.getOrNull(0)?.toIntOrNull() ?: return null
+        val year = items.getOrNull(2)?.toIntOrNull() ?: return null
+        val month = when (items.getOrNull(1)) {
+            "stycznia" -> 1
+            "lutego" -> 2
+            "marca" -> 3
+            "kwietnia" -> 4
+            "maja" -> 5
+            "czerwca" -> 6
+            "lipca" -> 7
+            "sierpnia" -> 8
+            "września" -> 9
+            "października" -> 10
+            "listopada" -> 11
+            "grudnia" -> 12
+            else -> return null
+        }
+        return Date(year, month, day)
+    }
+
+    init {
+        val currentWeekStart = Week.getWeekStart()
+        val nextWeekEnd = Week.getWeekEnd().stepForward(0, 0, 7)
+        if (Date.getToday().weekDay > 4) {
+            currentWeekStart.stepForward(0, 0, 7)
+        }
+        startDate = data.arguments?.getString("weekStart")?.let {
+            Date.fromY_m_d(it)
+        } ?: currentWeekStart
+
+        val syncFutureDate = startDate > nextWeekEnd
+        // TODO: 2021-09-09 make DataRemoveModel keep extra lessons
+        val syncExtraLessons = false && System.currentTimeMillis() - (lastSync ?: 0) > 2 * DAY * MS
+        if (!syncFutureDate && !syncExtraLessons) {
+            onSuccess(ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE)
+        }
+        else {
+            val types = when {
+                syncFutureDate -> mutableListOf("podstawowy")//, "pozalekcyjny")
+                syncExtraLessons -> mutableListOf("pozalekcyjny")
+                else -> mutableListOf()
+            }
+
+            syncTypes(types, startDate) {
+                // set as synced now only when not syncing future date
+                // (to avoid waiting 2 days for normal sync after future sync)
+                if (syncExtraLessons)
+                    data.setSyncNext(ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE, SYNC_ALWAYS)
+                onSuccess(ENDPOINT_MOBIDZIENNIK_WEB_TIMETABLE)
+            }
+        }
+    }
+
+    private fun syncTypes(types: MutableList<String>, startDate: Date, onSuccess: () -> Unit) {
+        if (types.isEmpty()) {
+            onSuccess()
+            return
+        }
+        val type = types.removeAt(0)
+        webGet(TAG, "/dziennik/planlekcji?typ=$type&tydzien=${startDate.stringY_m_d}") { html ->
+            MobidziennikLuckyNumberExtractor(data, html)
+            readRangesH(html)
+            readRangesV(html)
+            readLessons(html)
+            syncTypes(types, startDate, onSuccess)
+        }
+    }
+
+    private fun readRangesH(html: String) {
+        val htmlH = Regexes.MOBIDZIENNIK_TIMETABLE_TOP.find(html) ?: return
+        val docH = Jsoup.parse(htmlH.value)
+
+        var posH = 0f
+        for (el in docH.select("div > div")) {
+            val css = parseCss(el.attr("style"))
+            val width = css["width"]
+                ?.trimEnd('%')
+                ?.toFloatOrNull()
+                ?: continue
+            val value = stringToDate(el.attr("title"))
+                ?: continue
+
+            val range = posH.rangeTo(posH + width)
+            posH += width
+
+            rangesH[range] = value
+        }
+    }
+
+    private fun readRangesV(html: String) {
+        val htmlV = Regexes.MOBIDZIENNIK_TIMETABLE_LEFT.find(html) ?: return
+        val docV = Jsoup.parse(htmlV.value)
+
+        for (el in docV.select("div > div")) {
+            val css = parseCss(el.attr("style"))
+            val top = css["top"]
+                ?.trimEnd('%')
+                ?.toFloatOrNull()
+                ?: continue
+            val values = el.text().split(" ")
+
+            val time = values.getOrNull(0)?.let {
+                Time.fromH_m(it)
+            } ?: continue
+            val num = values.getOrNull(1)?.toIntOrNull()
+
+            hoursV[(top * 100).toInt()] = time to num
+        }
+    }
+
+    private val whitespaceRegex = "\\s+".toRegex()
+    private val classroomRegex = "\\((.*)\\)".toRegex()
+    private fun cleanup(str: String): List<String> {
+        return str
+            .replace(whitespaceRegex, " ")
+            .replace("\n", "")
+            .replace("&lt;small&gt;", "$")
+            .replace("&lt;/small&gt;", "$")
+            .replace("&lt;br /&gt;", "\n")
+            .replace("&lt;br/&gt;", "\n")
+            .replace("&lt;br&gt;", "\n")
+            .replace("<br />", "\n")
+            .replace("<br/>", "\n")
+            .replace("<br>", "\n")
+            .replace("<b>", "%")
+            .replace("</b>", "%")
+            .replace("<span>", "")
+            .replace("</span>", "")
+            .split("\n")
+            .map { it.trim() }
+    }
+
+    @SuppressLint("LongLogTag", "LogNotTimber")
+    private fun readLessons(html: String) {
+        val matches = Regexes.MOBIDZIENNIK_TIMETABLE_CELL.findAll(html)
+
+        val noLessonDays = mutableListOf<Date>()
+        for (i in 0..6) {
+            noLessonDays.add(startDate.clone().stepForward(0, 0, i))
+        }
+
+        for (match in matches) {
+            val css = parseCss("${match[1]};${match[2]}")
+            val left = css["left"]?.trimEnd('%')?.toFloatOrNull() ?: continue
+            val top = css["top"]?.trimEnd('%')?.toFloatOrNull() ?: continue
+            val width = css["width"]?.trimEnd('%')?.toFloatOrNull() ?: continue
+            val height = css["height"]?.trimEnd('%')?.toFloatOrNull() ?: continue
+
+            val posH = left + width / 2f
+            val topInt = (top * 100).toInt()
+            val bottomInt = ((top + height) * 100).toInt()
+
+            val lessonDate = getRangeH(posH) ?: continue
+            val (startTime, lessonNumber) = hoursV[topInt] ?: continue
+            val endTime = hoursV[bottomInt]?.first ?: continue
+
+            noLessonDays.remove(lessonDate)
+
+            var typeName: String? = null
+            var subjectName: String? = null
+            var teacherName: String? = null
+            var classroomName: String? = null
+            var teamName: String? = null
+            val items = (cleanup(match[3]) + cleanup(match[4])).toMutableList()
+
+            var length = 0
+            while (items.isNotEmpty() && length != items.size) {
+                length = items.size
+                val toRemove = mutableListOf<String?>()
+                items.forEachIndexed { i, item ->
+                    when {
+                        item.isEmpty() ->
+                            toRemove.add(item)
+                        item.contains(":") && item.contains(" - ") ->
+                            toRemove.add(item)
+
+                        item.startsWith("%") -> {
+                            subjectName = item.trim('%')
+                            // I have no idea what's going on here
+                            // ok now seriously.. the subject (long or short) item
+                            // may NOT be 0th, as the HH:MM - HH:MM item may be before
+                            // or even the typeName item. As these are always **before**,
+                            // they are removed in previous iterations, so the first not removed
+                            // item should be the long/short subjectName needing to be removed now.
+                            toRemove.add(items[toRemove.size])
+                            // ...and this has to be added later
+                            toRemove.add(item)
+                        }
+
+                        item.startsWith("&") -> {
+                            typeName = item.trim('&')
+                            toRemove.add(item)
+                        }
+                        typeName != null && (item.contains(typeName!!) || item.contains("</small>")) -> {
+                            toRemove.add(item)
+                        }
+
+                        item.contains("(") && item.contains(")") -> {
+                            classroomName = classroomRegex.find(item)?.get(1)
+                            items[i] = item.replace("($classroomName)", "").trim()
+                        }
+                        classroomName != null && item.contains(classroomName!!) -> {
+                            items[i] = item.replace("($classroomName)", "").trim()
+                        }
+
+                        item.contains("class=\"wyjatek tooltip\"") ->
+                            toRemove.add(item)
+                    }
+                }
+                items.removeAll(toRemove)
+            }
+
+            if (items.size == 2 && items[0].contains(" - ")) {
+                val parts = items[0].split(" - ")
+                teamName = parts[0]
+                teacherName = parts[1]
+            }
+            else if (items.size == 2 && typeName?.contains("odwołana") == true) {
+                teamName = items[0]
+            }
+            else if (items.size == 4) {
+                teamName = items[0]
+                teacherName = items[1]
+            }
+
+            val type = when (typeName) {
+                "zastępstwo" -> Lesson.TYPE_CHANGE
+                "lekcja odwołana", "odwołana" -> Lesson.TYPE_CANCELLED
+                else -> Lesson.TYPE_NORMAL
+            }
+            val subject = subjectName?.let { data.getSubject(null, it) }
+            val teacher = teacherName?.let { data.getTeacherByLastFirst(it) }
+            val team = teamName?.let { data.getTeam(
+                id = null,
+                name = it,
+                schoolCode = data.loginServerName ?: return@let null,
+                isTeamClass = false
+            ) }
+
+            Lesson(data.profileId, -1).also {
+                it.type = type
+                if (type == Lesson.TYPE_CANCELLED) {
+                    it.oldDate = lessonDate
+                    it.oldLessonNumber = lessonNumber
+                    it.oldStartTime = startTime
+                    it.oldEndTime = endTime
+                    it.oldSubjectId = subject?.id ?: -1
+                    it.oldTeamId = team?.id ?: -1
+                }
+                else {
+                    it.date = lessonDate
+                    it.lessonNumber = lessonNumber
+                    it.startTime = startTime
+                    it.endTime = endTime
+                    it.subjectId = subject?.id ?: -1
+                    it.teacherId = teacher?.id ?: -1
+                    it.teamId = team?.id ?: -1
+                    it.classroom = classroomName
+                }
+
+                it.id = it.buildId()
+
+                val seen = profile?.empty == false || lessonDate < Date.getToday()
+
+                if (it.type != Lesson.TYPE_NORMAL) {
+                    data.metadataList.add(
+                        Metadata(
+                            data.profileId,
+                            Metadata.TYPE_LESSON_CHANGE,
+                            it.id,
+                            seen,
+                            seen
+                        )
+                    )
+                }
+                data.lessonList += it
+            }
+        }
+
+        for (date in noLessonDays) {
+            data.lessonList += Lesson(data.profileId, date.value.toLong()).also {
+                it.type = Lesson.TYPE_NO_LESSONS
+                it.date = date
+            }
+        }
+    }
+}
+
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/DataPodlasie.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/DataPodlasie.kt
index d117c139..7962de7e 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/DataPodlasie.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/DataPodlasie.kt
@@ -81,39 +81,4 @@ class DataPodlasie(app: App, profile: Profile?, loginStore: LoginStore) : Data(a
 
     val loginShort: String?
         get() = studentLogin?.split('@')?.get(0)
-
-    fun getSubject(name: String): Subject {
-        val id = name.crc32()
-        return subjectList.singleOrNull { it.id == id } ?: run {
-            val subject = Subject(profileId, id, name, name)
-            subjectList.put(id, subject)
-            subject
-        }
-    }
-
-    fun getTeacher(firstName: String, lastName: String): Teacher {
-        val name = "$firstName $lastName".fixName()
-        return teacherList.singleOrNull { it.fullName == name } ?: run {
-            val id = name.crc32()
-            val teacher = Teacher(profileId, id, firstName, lastName)
-            teacherList.put(id, teacher)
-            teacher
-        }
-    }
-
-    fun getTeam(name: String? = null): Team {
-        if (name == "cała klasa" || name == null) return teamClass ?: run {
-            val id = className!!.crc32()
-            val teamCode = "$schoolShortName:$className"
-            val team = Team(profileId, id, className, Team.TYPE_CLASS, teamCode, -1)
-            teamList.put(id, team)
-            return team
-        } else {
-            val id = name.crc32()
-            val teamCode = "$schoolShortName:$name"
-            val team = Team(profileId, id, name, Team.TYPE_VIRTUAL, teamCode, -1)
-            teamList.put(id, team)
-            return team
-        }
-    }
 }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiFinalGrades.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiFinalGrades.kt
index 7c4575aa..bb4f696c 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiFinalGrades.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiFinalGrades.kt
@@ -36,7 +36,7 @@ class PodlasieApiFinalGrades(val data: DataPodlasie, val rows: List<JsonObject>)
             }
 
             val subjectName = grade.getString("SchoolSubject") ?: return@forEach
-            val subject = data.getSubject(subjectName)
+            val subject = data.getSubject(null, subjectName)
 
             val addedDate = if (profile.empty) profile.getSemesterStart(semester).inMillis
             else System.currentTimeMillis()
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiGrades.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiGrades.kt
index d5696567..c3946c76 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiGrades.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiGrades.kt
@@ -34,7 +34,7 @@ class PodlasieApiGrades(val data: DataPodlasie, val rows: List<JsonObject>) {
             val teacher = data.getTeacher(teacherFirstName, teacherLastName)
 
             val subjectName = grade.getString("SchoolSubject") ?: return@forEach
-            val subject = data.getSubject(subjectName)
+            val subject = data.getSubject(null, subjectName)
 
             val addedDate = grade.getString("ReceivedDate")?.let { Date.fromY_m_d(it).inMillis }
                     ?: System.currentTimeMillis()
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiMain.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiMain.kt
index 6fe77b5c..f108d35e 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiMain.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiMain.kt
@@ -22,7 +22,13 @@ class PodlasieApiMain(override val data: DataPodlasie,
 
     init {
         apiGet(TAG, PODLASIE_API_USER_ENDPOINT) { json ->
-            data.getTeam() // Save the class team when it doesn't exist.
+            // Save the class team when it doesn't exist.
+            data.getTeam(
+                id = null,
+                name = data.className ?: "",
+                schoolCode = data.schoolShortName ?: "",
+                isTeamClass = true
+            )
 
             json.getInt("LuckyNumber")?.let { PodlasieApiLuckyNumber(data, it) }
             json.getJsonArray("Teacher")?.asJsonObjectList()?.let { PodlasieApiTeachers(data, it) }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiTimetable.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiTimetable.kt
index a9a12d5d..13cff861 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiTimetable.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/podlasie/data/api/PodlasieApiTimetable.kt
@@ -43,14 +43,21 @@ class PodlasieApiTimetable(val data: DataPodlasie, rows: List<JsonObject>) {
             val startTime = lesson.getString("TimeFrom")?.let { Time.fromH_m_s(it) }
                     ?: return@forEach
             val endTime = lesson.getString("TimeTo")?.let { Time.fromH_m_s(it) } ?: return@forEach
-            val subject = lesson.getString("SchoolSubject")?.let { data.getSubject(it) }
+            val subject = lesson.getString("SchoolSubject")?.let { data.getSubject(null, it) }
                     ?: return@forEach
 
             val teacherFirstName = lesson.getString("TeacherFirstName") ?: return@forEach
             val teacherLastName = lesson.getString("TeacherLastName") ?: return@forEach
             val teacher = data.getTeacher(teacherFirstName, teacherLastName)
 
-            val team = lesson.getString("Group")?.let { data.getTeam(it) } ?: return@forEach
+            val team = lesson.getString("Group")?.let {
+                data.getTeam(
+                    id = null,
+                    name = it,
+                    schoolCode = data.schoolShortName ?: "",
+                    isTeamClass = it == "cała klasa"
+                )
+            } ?: return@forEach
             val classroom = lesson.getString("Room")
 
             Lesson(data.profileId, -1).also {
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/DataVulcan.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/DataVulcan.kt
index 55185745..e3516ad4 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/DataVulcan.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/DataVulcan.kt
@@ -222,6 +222,16 @@ class DataVulcan(app: App, profile: Profile?, loginStore: LoginStore) : Data(app
         get() { mHebeContext = mHebeContext ?: profile?.getStudentData("hebeContext", null); return mHebeContext }
         set(value) { profile?.putStudentData("hebeContext", value) ?: return; mHebeContext = value }
 
+    private var mSenderAddressHash: String? = null
+    var senderAddressHash: String?
+        get() { mSenderAddressHash = mSenderAddressHash ?: profile?.getStudentData("senderAddressHash", null); return mSenderAddressHash }
+        set(value) { profile?.putStudentData("senderAddressHash", value) ?: return; mSenderAddressHash = value }
+
+    private var mSenderAddressName: String? = null
+    var senderAddressName: String?
+        get() { mSenderAddressName = mSenderAddressName ?: profile?.getStudentData("senderAddressName", null); return mSenderAddressName }
+        set(value) { profile?.putStudentData("senderAddressName", value) ?: return; mSenderAddressName = value }
+
     val apiUrl: String?
         get() {
             val url = when (apiToken[symbol]?.substring(0, 3)) {
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeAttendance.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeAttendance.kt
index 9e41bb6d..b3ebafa4 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeAttendance.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeAttendance.kt
@@ -38,7 +38,7 @@ class VulcanHebeAttendance(
             lastSync = lastSync
         ) { list, _ ->
             list.forEach { attendance ->
-                val id = attendance.getLong("AuxPresenceId") ?: return@forEach
+                val id = attendance.getLong("Id") ?: return@forEach
                 val type = attendance.getJsonObject("PresenceType") ?: return@forEach
                 val baseType = getBaseType(type)
                 val typeName = type.getString("Name") ?: return@forEach
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeMain.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeMain.kt
index c017e3c9..5e2d31c0 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeMain.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeMain.kt
@@ -97,6 +97,10 @@ class VulcanHebeMain(
                 val studentSemesterId = period.getInt("Id") ?: return@forEach
                 val studentSemesterNumber = period.getInt("Number") ?: return@forEach
 
+                val senderEntry = student.getJsonObject("SenderEntry")
+                val senderAddressName = senderEntry.getString("Address")
+                val senderAddressHash = senderEntry.getString("AddressHash")
+
                 val hebeContext = student.getString("Context")
 
                 val isParent = login.getString("LoginRole").equals("opiekun", ignoreCase = true)
@@ -143,6 +147,8 @@ class VulcanHebeMain(
                     studentData["schoolSymbol"] = schoolSymbol
                     studentData["schoolShort"] = schoolShort
                     studentData["schoolName"] = schoolCode
+                    studentData["senderAddressName"] = senderAddressName
+                    studentData["senderAddressHash"] = senderAddressHash
                     studentData["hebeContext"] = hebeContext
                 }
                 dateSemester1Start?.let {
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeSendMessage.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeSendMessage.kt
index 8f5f5afa..c6a02ae7 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeSendMessage.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeSendMessage.kt
@@ -7,6 +7,7 @@ package pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.data.hebe
 import com.google.gson.JsonObject
 import org.greenrobot.eventbus.EventBus
 import pl.szczodrzynski.edziennik.*
+import pl.szczodrzynski.edziennik.data.api.ERROR_VULCAN_HEBE_MISSING_SENDER_ENTRY
 import pl.szczodrzynski.edziennik.data.api.VULCAN_HEBE_ENDPOINT_MESSAGES_SEND
 import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.DataVulcan
 import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.data.VulcanHebe
@@ -27,6 +28,22 @@ class VulcanHebeSendMessage(
     }
 
     init {
+        if (data.senderAddressName == null || data.senderAddressHash == null) {
+            VulcanHebeMain(data).getStudents(data.profile, null) {
+                if (data.senderAddressName == null || data.senderAddressHash == null) {
+                    data.error(TAG, ERROR_VULCAN_HEBE_MISSING_SENDER_ENTRY)
+                }
+                else {
+                    sendMessage()
+                }
+            }
+        }
+        else {
+            sendMessage()
+        }
+    }
+
+    private fun sendMessage() {
         val recipientsArray = JsonArray()
         recipients.forEach { teacher ->
             recipientsArray += JsonObject(
@@ -40,10 +57,10 @@ class VulcanHebeSendMessage(
         val senderName = (profile?.accountName ?: profile?.studentNameLong)
             ?.swapFirstLastName() ?: ""
         val sender = JsonObject(
-            "Address" to senderName,
+            "Address" to data.senderAddressName,
             "LoginId" to data.studentLoginId.toString(),
             "Initials" to senderName.getNameInitials(),
-            "AddressHash" to senderName.sha1Hex()
+            "AddressHash" to data.senderAddressHash
         )
 
         apiPost(
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTimetable.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTimetable.kt
index 03a28a9e..ffbb0289 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTimetable.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTimetable.kt
@@ -11,6 +11,7 @@ import pl.szczodrzynski.edziennik.data.api.VULCAN_HEBE_ENDPOINT_TIMETABLE_CHANGE
 import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.DataVulcan
 import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.ENDPOINT_VULCAN_HEBE_TIMETABLE
 import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.data.VulcanHebe
+import pl.szczodrzynski.edziennik.data.api.models.DataRemoveModel
 import pl.szczodrzynski.edziennik.data.db.entity.Lesson
 import pl.szczodrzynski.edziennik.data.db.entity.Lesson.Companion.TYPE_CANCELLED
 import pl.szczodrzynski.edziennik.data.db.entity.Lesson.Companion.TYPE_CHANGE
@@ -47,7 +48,7 @@ class VulcanHebeTimetable(
             ?: previousWeekStart
         val dateTo = dateFrom.clone().stepForward(0, 0, 13)
 
-        val lastSync = null
+        val lastSync = 0L
 
         apiGetList(
             TAG,
@@ -106,6 +107,8 @@ class VulcanHebeTimetable(
                     "Clearing lessons between ${dateFrom.stringY_m_d} and ${dateTo.stringY_m_d}"
                 )
 
+                data.toRemove.add(DataRemoveModel.Timetable.between(dateFrom, dateTo))
+
                 data.lessonList.addAll(lessonList)
 
                 data.setSyncNext(ENDPOINT_VULCAN_HEBE_TIMETABLE, SYNC_ALWAYS)
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/models/Data.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/models/Data.kt
index 8dda9543..2b7bdf1a 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/models/Data.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/models/Data.kt
@@ -2,6 +2,7 @@ package pl.szczodrzynski.edziennik.data.api.models
 
 import android.util.LongSparseArray
 import android.util.SparseArray
+import androidx.core.util.set
 import androidx.core.util.size
 import androidx.room.OnConflictStrategy
 import com.google.gson.JsonObject
@@ -376,4 +377,108 @@ abstract class Data(val app: App, val profile: Profile?, val loginStore: LoginSt
     fun startProgress(stringRes: Int) {
         callback.onStartProgress(stringRes)
     }
+
+    /*    _    _ _   _ _
+         | |  | | | (_) |
+         | |  | | |_ _| |___
+         | |  | | __| | / __|
+         | |__| | |_| | \__ \
+          \____/ \__|_|_|__*/
+    fun getSubject(id: Long?, name: String, shortName: String = name): Subject {
+        var subject = subjectList.singleOrNull { it.id == id }
+        if (subject == null)
+            subject = subjectList.singleOrNull { it.longName == name }
+        if (subject == null)
+            subject = subjectList.singleOrNull { it.shortName == name }
+
+        if (subject == null) {
+            subject = Subject(
+                profileId,
+                id ?: name.crc32(),
+                name,
+                shortName
+            )
+            subjectList[subject.id] = subject
+        }
+        return subject
+    }
+
+    fun getTeam(id: Long?, name: String, schoolCode: String, isTeamClass: Boolean = false): Team {
+        if (isTeamClass && teamClass != null)
+            return teamClass as Team
+        var team = teamList.singleOrNull { it.id == id }
+
+        val namePlain = name.replace(" ", "")
+        if (team == null)
+            team = teamList.singleOrNull { it.name.replace(" ", "") == namePlain }
+
+        if (team == null) {
+            team = Team(
+                profileId,
+                id ?: name.crc32(),
+                name,
+                if (isTeamClass) Team.TYPE_CLASS else Team.TYPE_VIRTUAL,
+                "$schoolCode:$name",
+                -1
+            )
+            teamList[team.id] = team
+        }
+        return team
+    }
+
+    fun getTeacher(firstName: String, lastName: String, loginId: String? = null): Teacher {
+        val teacher = teacherList.singleOrNull { it.fullName == "$firstName $lastName" }
+        return validateTeacher(teacher, firstName, lastName, loginId)
+    }
+
+    fun getTeacher(firstNameChar: Char, lastName: String, loginId: String? = null): Teacher {
+        val teacher = teacherList.singleOrNull { it.shortName == "$firstNameChar.$lastName" }
+        return validateTeacher(teacher, firstNameChar.toString(), lastName, loginId)
+    }
+
+    fun getTeacherByLastFirst(nameLastFirst: String, loginId: String? = null): Teacher {
+        val nameParts = nameLastFirst.split(" ")
+        return if (nameParts.size == 1)
+            getTeacher(nameParts[0], "", loginId)
+        else
+            getTeacher(nameParts[1], nameParts[0], loginId)
+    }
+
+    fun getTeacherByFirstLast(nameFirstLast: String, loginId: String? = null): Teacher {
+        val nameParts = nameFirstLast.split(" ")
+        return if (nameParts.size == 1)
+            getTeacher(nameParts[0], "", loginId)
+        else
+            getTeacher(nameParts[0], nameParts[1], loginId)
+    }
+
+    fun getTeacherByFDotLast(nameFDotLast: String, loginId: String? = null): Teacher {
+        val nameParts = nameFDotLast.split(".")
+        return if (nameParts.size == 1)
+            getTeacher(nameParts[0], "", loginId)
+        else
+            getTeacher(nameParts[0][0], nameParts[1], loginId)
+    }
+
+    fun getTeacherByFDotSpaceLast(nameFDotSpaceLast: String, loginId: String? = null): Teacher {
+        val nameParts = nameFDotSpaceLast.split(".")
+        return if (nameParts.size == 1)
+            getTeacher(nameParts[0], "", loginId)
+        else
+            getTeacher(nameParts[0][0], nameParts[1], loginId)
+    }
+
+    private fun validateTeacher(teacher: Teacher?, firstName: String, lastName: String, loginId: String?): Teacher {
+        val obj = teacher ?: Teacher(profileId, -1, firstName, lastName, loginId).apply {
+            id = fullName.crc32()
+            teacherList[id] = this
+        }
+        return obj.also {
+            if (loginId != null && it.loginId != null)
+                it.loginId = loginId
+            if (firstName.length > 1)
+                it.name = firstName
+            it.surname = lastName
+        }
+    }
 }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt
index 95d61224..da64cbc3 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt
@@ -22,10 +22,7 @@ import pl.szczodrzynski.edziennik.data.api.szkolny.interceptor.ApiCacheIntercept
 import pl.szczodrzynski.edziennik.data.api.szkolny.interceptor.SignatureInterceptor
 import pl.szczodrzynski.edziennik.data.api.szkolny.interceptor.Signing
 import pl.szczodrzynski.edziennik.data.api.szkolny.request.*
-import pl.szczodrzynski.edziennik.data.api.szkolny.response.ApiResponse
-import pl.szczodrzynski.edziennik.data.api.szkolny.response.RegisterAvailabilityStatus
-import pl.szczodrzynski.edziennik.data.api.szkolny.response.Update
-import pl.szczodrzynski.edziennik.data.api.szkolny.response.WebPushResponse
+import pl.szczodrzynski.edziennik.data.api.szkolny.response.*
 import pl.szczodrzynski.edziennik.data.db.entity.Event
 import pl.szczodrzynski.edziennik.data.db.entity.FeedbackMessage
 import pl.szczodrzynski.edziennik.data.db.entity.Notification
@@ -373,6 +370,15 @@ class SzkolnyApi(val app: App) : CoroutineScope {
         throw SzkolnyApiException(null)
     }
 
+    @Throws(Exception::class)
+    fun getContributors(): ContributorsResponse {
+        val response = api.contributors().execute()
+        if (response.isSuccessful && response.body() != null) {
+            return parseResponse(response)
+        }
+        throw SzkolnyApiException(null)
+    }
+
     @Throws(Exception::class)
     fun getFirebaseToken(registerName: String): String {
         val response = api.firebaseToken(registerName).execute()
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyService.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyService.kt
index c4198130..26a9a44e 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyService.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyService.kt
@@ -27,6 +27,9 @@ interface SzkolnyService {
     @POST("appUser")
     fun appUser(@Body request: AppUserRequest): Call<ApiResponse<Unit>>
 
+    @GET("contributors/android")
+    fun contributors(): Call<ApiResponse<ContributorsResponse>>
+
     @GET("updates/app")
     fun updates(@Query("channel") channel: String = "release"): Call<ApiResponse<List<Update>>>
 
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/Signing.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/Signing.kt
index a6095449..4c07bac8 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/Signing.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/Signing.kt
@@ -46,6 +46,6 @@ object Signing {
 
     /*fun provideKey(param1: String, param2: Long): ByteArray {*/
     fun pleaseStopRightNow(param1: String, param2: Long): ByteArray {
-        return "$param1.MTIzNDU2Nzg5MDZ/2nExVD===.$param2".sha256()
+        return "$param1.MTIzNDU2Nzg5MDkdkClKMQ===.$param2".sha256()
     }
 }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/response/ContributorsResponse.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/response/ContributorsResponse.kt
new file mode 100644
index 00000000..f824280a
--- /dev/null
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/response/ContributorsResponse.kt
@@ -0,0 +1,20 @@
+package pl.szczodrzynski.edziennik.data.api.szkolny.response
+
+import android.os.Parcelable
+import kotlinx.parcelize.Parcelize
+
+data class ContributorsResponse(
+    val contributors: List<Item>,
+    val translators: List<Item>
+) {
+
+    @Parcelize
+    data class Item(
+        val login: String,
+        val name: String?,
+        val avatarUrl: String,
+        val profileUrl: String,
+        val itemUrl: String,
+        val contributions: Int?
+    ) : Parcelable
+}
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/dialogs/timetable/GenerateBlockTimetableDialog.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/dialogs/timetable/GenerateBlockTimetableDialog.kt
index c93d5a6e..9eefffd0 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/dialogs/timetable/GenerateBlockTimetableDialog.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/dialogs/timetable/GenerateBlockTimetableDialog.kt
@@ -4,11 +4,14 @@
 
 package pl.szczodrzynski.edziennik.ui.dialogs.timetable
 
+import android.content.ContentResolver
+import android.content.ContentValues
 import android.content.Intent
 import android.graphics.*
 import android.net.Uri
 import android.os.Build
 import android.os.Environment
+import android.provider.MediaStore
 import android.util.Log
 import android.view.View
 import android.view.View.MeasureSpec
@@ -373,25 +376,31 @@ class GenerateBlockTimetableDialog(
 
             val today = Date.getToday().stringY_m_d
             val now = Time.getNow().stringH_M_S
+            val filename = "plan_lekcji_${app.profile.name}_${today}_${now}.png"
+            val resolver: ContentResolver = activity.applicationContext.contentResolver
+            val values = ContentValues()
+            values.put(MediaStore.MediaColumns.MIME_TYPE, "image/png")
 
-            val outputDir = Environment.getExternalStoragePublicDirectory("Szkolny.eu").apply { mkdirs() }
-            val outputFile = File(outputDir, "plan_lekcji_${app.profile.name}_${today}_${now}.png")
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                values.put(MediaStore.MediaColumns.DISPLAY_NAME, filename)
+                values.put(MediaStore.MediaColumns.RELATIVE_PATH, File(Environment.DIRECTORY_PICTURES, "Szkolny.eu").path)
+            } else {
+                val picturesDirectory = File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "Szkolny.eu")
+                picturesDirectory.mkdirs()
+                values.put(MediaStore.MediaColumns.DATA, File(picturesDirectory, filename).path)
+            }
 
             try {
-                val fos = FileOutputStream(outputFile)
-                bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos)
-                fos.close()
+                val uri = resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values) ?: return@withContext null
+                resolver.openOutputStream(uri).use {
+                    bitmap.compress(Bitmap.CompressFormat.PNG, 100, it)
+                }
+                uri
             } catch (e: Exception) {
                 Log.e("SAVE_IMAGE", e.message, e)
                 return@withContext null
             }
 
-            val uri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-                FileProvider.getUriForFile(activity, app.packageName + ".provider", outputFile)
-            } else {
-                Uri.parse("file://" + outputFile.absolutePath)
-            }
-            uri
         }
 
         progressDialog.dismiss()
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/agenda/AgendaFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/agenda/AgendaFragment.kt
index 8d228dcc..8607217a 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/agenda/AgendaFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/agenda/AgendaFragment.kt
@@ -21,6 +21,7 @@ import kotlinx.coroutines.*
 import pl.szczodrzynski.edziennik.App
 import pl.szczodrzynski.edziennik.MainActivity
 import pl.szczodrzynski.edziennik.R
+import pl.szczodrzynski.edziennik.data.db.entity.EventType
 import pl.szczodrzynski.edziennik.data.db.entity.Metadata
 import pl.szczodrzynski.edziennik.data.db.entity.Profile
 import pl.szczodrzynski.edziennik.databinding.FragmentAgendaCalendarBinding
@@ -136,9 +137,22 @@ class AgendaFragment : Fragment(), CoroutineScope {
         }
     }
 
+    private suspend fun checkEventTypes() {
+        withContext(Dispatchers.Default) {
+            val eventTypes = app.db.eventTypeDao().getAllNow(app.profileId).map {
+                it.id
+            }
+            val defaultEventTypes = EventType.getTypeColorMap().keys
+            if (!eventTypes.containsAll(defaultEventTypes)) {
+                app.db.eventTypeDao().addDefaultTypes(activity, app.profileId)
+            }
+        }
+    }
+
     private fun createDefaultAgendaView() { (b as? FragmentAgendaDefaultBinding)?.let { b -> launch {
         if (!isAdded)
             return@launch
+        checkEventTypes()
         delay(500)
 
         agendaDefault = AgendaFragmentDefault(activity, app, b)
@@ -146,6 +160,7 @@ class AgendaFragment : Fragment(), CoroutineScope {
     }}}
 
     private fun createCalendarAgendaView() { (b as? FragmentAgendaCalendarBinding)?.let { b -> launch {
+        checkEventTypes()
         delay(300)
 
         val dayList = mutableListOf<EventDay>()
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/base/lazypager/FragmentLazyPagerAdapter.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/base/lazypager/FragmentLazyPagerAdapter.kt
index d6205596..bc794073 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/base/lazypager/FragmentLazyPagerAdapter.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/base/lazypager/FragmentLazyPagerAdapter.kt
@@ -9,7 +9,7 @@ import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 
 class FragmentLazyPagerAdapter(
         fragmentManager: FragmentManager,
-        swipeRefreshLayout: SwipeRefreshLayout,
+        swipeRefreshLayout: SwipeRefreshLayout? = null,
         val fragments: List<Pair<LazyFragment, CharSequence>>
 ) : LazyPagerAdapter(fragmentManager, swipeRefreshLayout) {
     override fun getPage(position: Int) = fragments[position].first
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabPageFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabPageFragment.kt
index b1b84f9d..4d8205bf 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabPageFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabPageFragment.kt
@@ -5,10 +5,12 @@
 package pl.szczodrzynski.edziennik.ui.modules.debug
 
 import android.os.Bundle
+import android.os.Process
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.sqlite.db.SimpleSQLiteQuery
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
@@ -21,6 +23,7 @@ import pl.szczodrzynski.edziennik.ui.modules.base.lazypager.LazyFragment
 import pl.szczodrzynski.edziennik.utils.TextInputDropDown
 import pl.szczodrzynski.fslogin.decode
 import kotlin.coroutines.CoroutineContext
+import kotlin.system.exitProcess
 
 class LabPageFragment : LazyFragment(), CoroutineScope {
     companion object {
@@ -75,6 +78,37 @@ class LabPageFragment : LazyFragment(), CoroutineScope {
             app.db.eventDao().getRawNow("UPDATE events SET homeworkBody = NULL WHERE profileId = ${App.profileId}")
         }
 
+        b.chucker.isChecked = app.config.enableChucker
+
+        b.chucker.onChange { _, isChecked ->
+            app.config.enableChucker = isChecked
+            MaterialAlertDialogBuilder(activity)
+                .setTitle("Restart")
+                .setMessage("Wymagany restart aplikacji")
+                .setPositiveButton(R.string.ok) { _, _ ->
+                    Process.killProcess(Process.myPid())
+                    Runtime.getRuntime().exit(0)
+                    exitProcess(0)
+                }
+                .setCancelable(false)
+                .show()
+        }
+
+
+        b.disableDebug.onClick {
+            app.config.debugMode = false
+            MaterialAlertDialogBuilder(activity)
+                .setTitle("Restart")
+                .setMessage("Wymagany restart aplikacji")
+                .setPositiveButton(R.string.ok) { _, _ ->
+                    Process.killProcess(Process.myPid())
+                    Runtime.getRuntime().exit(0)
+                    exitProcess(0)
+                }
+                .setCancelable(false)
+                .show()
+        }
+
         b.unarchive.onClick {
             app.profile.archived = false
             app.profile.archiveId = null
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabProfileFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabProfileFragment.kt
index ee3ea2c6..f4b03f55 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabProfileFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/debug/LabProfileFragment.kt
@@ -166,7 +166,7 @@ class LabProfileFragment : LazyFragment(), CoroutineScope {
             json.add("App.profile", app.gson.toJsonTree(app.profile))
             json.add("App.profile.studentData", app.profile.studentData)
             json.add("App.profile.loginStore", loginStore?.data ?: JsonObject())
-            json.add("App.config", JsonParser().parse(app.gson.toJson(app.config.values)))
+            json.add("App.config", JsonParser().parse(app.gson.toJson(app.config.values.toSortedMap())))
         }
         adapter.items = LabJsonAdapter.expand(json, 0)
         adapter.notifyDataSetChanged()
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginFormFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginFormFragment.kt
index ea6bbe4d..3360e93b 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginFormFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginFormFragment.kt
@@ -85,6 +85,9 @@ class LoginFormFragment : Fragment(), CoroutineScope {
             if (credential is LoginInfo.FormField) {
                 val b = LoginFormFieldItemBinding.inflate(layoutInflater)
                 b.textLayout.hint = app.getString(credential.name)
+                if (credential.isNumber) {
+                    b.textEdit.inputType = InputType.TYPE_CLASS_NUMBER
+                }
                 if (credential.hideText) {
                     b.textEdit.inputType = InputType.TYPE_TEXT_VARIATION_PASSWORD
                     b.textLayout.endIconMode = TextInputLayout.END_ICON_PASSWORD_TOGGLE
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginInfo.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginInfo.kt
index 77036f19..8a5e60d1 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginInfo.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginInfo.kt
@@ -179,6 +179,7 @@ object LoginInfo {
                                     ERROR_LOGIN_VULCAN_INVALID_PIN_2_REMAINING to R.string.error_312_reason
                                 ),
                                 isRequired = true,
+                                isNumber = true,
                                 validationRegex = "[0-9]+",
                                 caseMode = FormField.CaseMode.LOWER_CASE
                             )
@@ -401,6 +402,7 @@ object LoginInfo {
         val validationRegex: String,
         val caseMode: CaseMode = CaseMode.UNCHANGED,
         val hideText: Boolean = false,
+        val isNumber: Boolean = false,
         val stripTextRegex: String? = null
     ) : BaseCredential(keyName, name, errorCodes) {
         enum class CaseMode { UNCHANGED, UPPER_CASE, LOWER_CASE }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginProgressFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginProgressFragment.kt
index 7550b08c..aaebbac0 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginProgressFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/login/LoginProgressFragment.kt
@@ -76,7 +76,7 @@ class LoginProgressFragment : Fragment(), CoroutineScope {
 
             val maxProfileId = max(
                     app.db.profileDao().lastId ?: 0,
-                    activity.profiles.maxBy { it.profile.id }?.profile?.id ?: 0
+                    activity.profiles.maxByOrNull { it.profile.id }?.profile?.id ?: 0
             )
             val loginType = args.getInt("loginType", -1)
             val loginMode = args.getInt("loginMode", 0)
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/messages/compose/MessagesComposeFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/messages/compose/MessagesComposeFragment.kt
index 091dabef..33744a98 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/messages/compose/MessagesComposeFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/messages/compose/MessagesComposeFragment.kt
@@ -503,10 +503,14 @@ class MessagesComposeFragment : Fragment(), CoroutineScope {
             text.toString()
         }
 
+        textHtml = textHtml
+            .replace("</b><b>", "")
+            .replace("</i><i>", "")
+            .replace("p style=\"margin-top:0; margin-bottom:0;\"", "p")
+
         if (app.profile.loginStoreType == LoginStore.LOGIN_TYPE_MOBIDZIENNIK) {
             textHtml = textHtml
-                    .replace("p style=\"margin-top:0; margin-bottom:0;\"", "span")
-                    .replace("</p>", "</span>")
+                    .replace("</p><br>", "</p>")
                     .replace("<b>", "<strong>")
                     .replace("</b>", "</strong>")
                     .replace("<i>", "<em>")
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsAboutCard.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsAboutCard.kt
index 5f55ec70..f4cc0023 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsAboutCard.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsAboutCard.kt
@@ -24,6 +24,7 @@ import pl.szczodrzynski.edziennik.ui.dialogs.changelog.ChangelogDialog
 import pl.szczodrzynski.edziennik.ui.modules.settings.SettingsCard
 import pl.szczodrzynski.edziennik.ui.modules.settings.SettingsLicenseActivity
 import pl.szczodrzynski.edziennik.ui.modules.settings.SettingsUtil
+import pl.szczodrzynski.edziennik.ui.modules.settings.contributors.ContributorsActivity
 import pl.szczodrzynski.edziennik.utils.Utils
 import kotlin.coroutines.CoroutineContext
 
@@ -90,6 +91,14 @@ class SettingsAboutCard(util: SettingsUtil) : SettingsCard(util), CoroutineScope
             it.subText = BuildConfig.VERSION_NAME + ", " + BuildConfig.BUILD_TYPE
         },
 
+        util.createActionItem(
+            text = R.string.settings_about_contributors_text,
+            subText = R.string.settings_about_contributors_subtext,
+            icon = CommunityMaterial.Icon.cmd_account_group_outline
+        ) {
+            activity.startActivity(Intent(activity, ContributorsActivity::class.java))
+        },
+
         util.createMoreItem(card, items = listOf(
             util.createActionItem(
                 text = R.string.settings_about_changelog_text,
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsThemeCard.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsThemeCard.kt
index a009279d..1018e92c 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsThemeCard.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/cards/SettingsThemeCard.kt
@@ -88,7 +88,7 @@ class SettingsThemeCard(util: SettingsUtil) : SettingsCard(util) {
             text = R.string.settings_theme_drawer_header_text,
             icon = CommunityMaterial.Icon2.cmd_image_outline
         ) {
-            if (app.config.ui.appBackground == null) {
+            if (app.config.ui.headerBackground == null) {
                 setHeaderBackground()
                 return@createActionItem
             }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsActivity.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsActivity.kt
new file mode 100644
index 00000000..676a5d58
--- /dev/null
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsActivity.kt
@@ -0,0 +1,83 @@
+package pl.szczodrzynski.edziennik.ui.modules.settings.contributors
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.isVisible
+import androidx.viewpager.widget.ViewPager
+import com.google.android.material.tabs.TabLayout
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import pl.szczodrzynski.edziennik.App
+import pl.szczodrzynski.edziennik.Bundle
+import pl.szczodrzynski.edziennik.R
+import pl.szczodrzynski.edziennik.data.api.szkolny.SzkolnyApi
+import pl.szczodrzynski.edziennik.data.api.szkolny.response.ContributorsResponse
+import pl.szczodrzynski.edziennik.databinding.ContributorsActivityBinding
+import pl.szczodrzynski.edziennik.ui.modules.base.lazypager.FragmentLazyPagerAdapter
+import pl.szczodrzynski.edziennik.ui.modules.error.ErrorSnackbar
+import kotlin.coroutines.CoroutineContext
+
+class ContributorsActivity : AppCompatActivity(), CoroutineScope {
+    companion object {
+        private const val TAG = "ContributorsActivity"
+        private var contributors: ContributorsResponse? = null
+    }
+
+    private lateinit var app: App
+    private lateinit var b: ContributorsActivityBinding
+
+    private var job = Job()
+    override val coroutineContext: CoroutineContext
+        get() = job + Dispatchers.Main
+
+    // local/private variables go here
+    private val errorSnackbar: ErrorSnackbar by lazy { ErrorSnackbar(this) }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        app = application as App
+        b = ContributorsActivityBinding.inflate(layoutInflater)
+        setContentView(b.root)
+
+        b.progressBar.isVisible = true
+        b.tabLayout.isVisible = false
+        b.viewPager.isVisible = false
+
+        launch {
+            contributors = contributors ?: SzkolnyApi(app).runCatching(errorSnackbar) {
+                getContributors()
+            } ?: return@launch
+
+            val pagerAdapter = FragmentLazyPagerAdapter(
+                supportFragmentManager,
+                fragments = listOf(
+                    ContributorsFragment().apply {
+                        arguments = Bundle(
+                            "items" to contributors!!.contributors.toTypedArray(),
+                            "quantityPluralRes" to R.plurals.contributions_quantity,
+                        )
+                    } to getString(R.string.contributors),
+
+                    ContributorsFragment().apply {
+                        arguments = Bundle(
+                            "items" to contributors!!.translators.toTypedArray(),
+                            "quantityPluralRes" to R.plurals.translations_quantity,
+                        )
+                    } to getString(R.string.translators),
+                )
+            )
+
+            b.viewPager.apply {
+                offscreenPageLimit = 1
+                adapter = pagerAdapter
+                b.tabLayout.setupWithViewPager(this)
+            }
+
+            b.progressBar.isVisible = false
+            b.tabLayout.isVisible = true
+            b.viewPager.isVisible = true
+        }
+    }
+}
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsAdapter.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsAdapter.kt
new file mode 100644
index 00000000..6cb189b9
--- /dev/null
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsAdapter.kt
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) Kuba Szczodrzyński 2021-9-7.
+ */
+
+package pl.szczodrzynski.edziennik.ui.modules.settings.contributors
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.annotation.PluralsRes
+import androidx.appcompat.app.AppCompatActivity
+import androidx.recyclerview.widget.RecyclerView
+import coil.load
+import coil.transform.CircleCropTransformation
+import pl.szczodrzynski.edziennik.R
+import pl.szczodrzynski.edziennik.data.api.szkolny.response.ContributorsResponse
+import pl.szczodrzynski.edziennik.databinding.ContributorsListItemBinding
+import pl.szczodrzynski.edziennik.plural
+import pl.szczodrzynski.edziennik.setText
+import pl.szczodrzynski.edziennik.utils.Utils
+
+class ContributorsAdapter(
+    val activity: AppCompatActivity,
+    val items: List<ContributorsResponse.Item>,
+    @PluralsRes
+    val quantityPluralRes: Int
+) : RecyclerView.Adapter<ContributorsAdapter.ViewHolder>() {
+    companion object {
+        private const val TAG = "ContributorsAdapter"
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        val inflater = LayoutInflater.from(parent.context)
+        val view = ContributorsListItemBinding.inflate(inflater, parent, false)
+        return ViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        val item = items[position]
+        val b = holder.b
+
+        b.text.text = item.name ?: item.login
+        b.subtext.setText(
+            R.string.contributors_subtext_format,
+            item.login,
+            activity.plural(
+                quantityPluralRes,
+                item.contributions ?: 0
+            )
+        )
+
+        b.image.load(item.avatarUrl) {
+            transformations(CircleCropTransformation())
+        }
+
+        b.root.setOnClickListener {
+            Utils.openUrl(activity, item.itemUrl)
+        }
+    }
+
+    override fun getItemCount() = items.size
+
+    class ViewHolder(val b: ContributorsListItemBinding) : RecyclerView.ViewHolder(b.root)
+}
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsFragment.kt
new file mode 100644
index 00000000..11741a85
--- /dev/null
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/settings/contributors/ContributorsFragment.kt
@@ -0,0 +1,47 @@
+package pl.szczodrzynski.edziennik.ui.modules.settings.contributors
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.recyclerview.widget.LinearLayoutManager
+import pl.szczodrzynski.edziennik.App
+import pl.szczodrzynski.edziennik.data.api.szkolny.response.ContributorsResponse
+import pl.szczodrzynski.edziennik.databinding.ContributorsListFragmentBinding
+import pl.szczodrzynski.edziennik.ui.modules.base.lazypager.LazyFragment
+import pl.szczodrzynski.edziennik.utils.SimpleDividerItemDecoration
+
+class ContributorsFragment : LazyFragment() {
+    companion object {
+        private const val TAG = "ContributorsFragment"
+    }
+
+    private lateinit var app: App
+    private lateinit var activity: ContributorsActivity
+    private lateinit var b: ContributorsListFragmentBinding
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        activity = (getActivity() as ContributorsActivity?) ?: return null
+        context ?: return null
+        app = activity.application as App
+        b = ContributorsListFragmentBinding.inflate(inflater)
+        return b.root
+    }
+
+    override fun onPageCreated(): Boolean {
+        val contributorsArray = requireArguments().getParcelableArray("items") as Array<ContributorsResponse.Item>
+        val contributors = contributorsArray.toList()
+        val quantityPluralRes = requireArguments().getInt("quantityPluralRes")
+
+        val adapter = ContributorsAdapter(activity, contributors, quantityPluralRes)
+        b.list.adapter = adapter
+        b.list.apply {
+            setHasFixedSize(true)
+            layoutManager = LinearLayoutManager(context)
+            addItemDecoration(SimpleDividerItemDecoration(context))
+            addOnScrollListener(onScrollListener)
+        }
+
+        return true
+    }
+}
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableDayFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableDayFragment.kt
index 3fc9ce83..00ce872e 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableDayFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableDayFragment.kt
@@ -151,7 +151,7 @@ class TimetableDayFragment : LazyFragment(), CoroutineScope {
         }
 
         b.scrollView.isVisible = true
-        b.dayFrame.removeView(b.dayView)
+        b.dayFrame.removeView(dayView)
         b.dayFrame.addView(dayView, 0)
 
         // Inflate a label view for each hour the day view will display
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableFragment.kt
index 970daeec..85332fe1 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/timetable/TimetableFragment.kt
@@ -120,8 +120,8 @@ class TimetableFragment : Fragment(), CoroutineScope {
             }
 
             val lessonRanges = app.db.lessonRangeDao().getAllNow(App.profileId)
-            startHour = lessonRanges.map { it.startTime.hour }.min() ?: DEFAULT_START_HOUR
-            endHour = lessonRanges.map { it.endTime.hour }.max()?.plus(1) ?: DEFAULT_END_HOUR
+            startHour = lessonRanges.map { it.startTime.hour }.minOrNull() ?: DEFAULT_START_HOUR
+            endHour = lessonRanges.map { it.endTime.hour }.maxOrNull()?.plus(1) ?: DEFAULT_END_HOUR
         }
         deferred.await()
         if (!isAdded)
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/views/AttachmentsView.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/views/AttachmentsView.kt
index 354a8921..c981a4ba 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/views/AttachmentsView.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/views/AttachmentsView.kt
@@ -37,9 +37,7 @@ class AttachmentsView @JvmOverloads constructor(
     }
 
     private val storageDir by lazy {
-        val storageDir = Environment.getExternalStoragePublicDirectory("Szkolny.eu")
-        storageDir.mkdirs()
-        storageDir
+        Utils.getStorageDir()
     }
 
     fun init(arguments: Bundle, owner: Any) {
@@ -82,6 +80,7 @@ class AttachmentsView @JvmOverloads constructor(
             list.adapter = adapter
             list.apply {
                 setHasFixedSize(false)
+                isNestedScrollingEnabled = false
                 layoutManager = LinearLayoutManager(context)
                 addItemDecoration(SimpleDividerItemDecoration(context))
             }
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/utils/Utils.java b/app/src/main/java/pl/szczodrzynski/edziennik/utils/Utils.java
index 910fc6f0..d4ffae05 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/utils/Utils.java
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/utils/Utils.java
@@ -776,7 +776,8 @@ public class Utils {
     public static File getStorageDir() {
         if (storageDir != null)
             return storageDir;
-        storageDir = Environment.getExternalStoragePublicDirectory("Szkolny.eu");
+        storageDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
+        storageDir = new File(storageDir, "Szkolny.eu");
         storageDir.mkdirs();
         return storageDir;
     }
diff --git a/app/src/main/res/drawable/header.png b/app/src/main/res/drawable/header.png
deleted file mode 100644
index 365f66e9..00000000
Binary files a/app/src/main/res/drawable/header.png and /dev/null differ
diff --git a/app/src/main/res/drawable/header.webp b/app/src/main/res/drawable/header.webp
new file mode 100644
index 00000000..d112e2f3
Binary files /dev/null and b/app/src/main/res/drawable/header.webp differ
diff --git a/app/src/main/res/layout/attendance_list_fragment.xml b/app/src/main/res/layout/attendance_list_fragment.xml
index 36f54733..bfcbf645 100644
--- a/app/src/main/res/layout/attendance_list_fragment.xml
+++ b/app/src/main/res/layout/attendance_list_fragment.xml
@@ -24,6 +24,7 @@
             android:layout_gravity="center"
             android:drawablePadding="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/attendances_no_data"
             android:textSize="24sp"
             android:visibility="gone"
diff --git a/app/src/main/res/layout/attendance_summary_fragment.xml b/app/src/main/res/layout/attendance_summary_fragment.xml
index e4d96e80..80b01ed4 100644
--- a/app/src/main/res/layout/attendance_summary_fragment.xml
+++ b/app/src/main/res/layout/attendance_summary_fragment.xml
@@ -152,6 +152,7 @@
                     android:layout_gravity="center"
                     android:drawablePadding="16dp"
                     android:fontFamily="sans-serif-light"
+                    android:gravity="center"
                     android:text="@string/attendances_no_data"
                     android:textSize="24sp"
                     android:visibility="gone"
diff --git a/app/src/main/res/layout/card_home_grades.xml b/app/src/main/res/layout/card_home_grades.xml
index faab735b..38ae61de 100644
--- a/app/src/main/res/layout/card_home_grades.xml
+++ b/app/src/main/res/layout/card_home_grades.xml
@@ -22,6 +22,7 @@
             android:layout_gravity="center_horizontal"
             android:layout_margin="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/card_grades_no_data"
             android:textSize="16sp" />
 
diff --git a/app/src/main/res/layout/card_home_template.xml b/app/src/main/res/layout/card_home_template.xml
index 8cea8889..1570c8b3 100644
--- a/app/src/main/res/layout/card_home_template.xml
+++ b/app/src/main/res/layout/card_home_template.xml
@@ -24,6 +24,7 @@
             android:layout_gravity="center_horizontal"
             android:layout_margin="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/card_grades_no_data"
             android:textSize="16sp" />
 
diff --git a/app/src/main/res/layout/contributors_activity.xml b/app/src/main/res/layout/contributors_activity.xml
new file mode 100644
index 00000000..b05e9c37
--- /dev/null
+++ b/app/src/main/res/layout/contributors_activity.xml
@@ -0,0 +1,100 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical">
+
+        <ProgressBar
+            android:id="@+id/progressBar"
+            android:layout_width="wrap_content"
+            android:layout_height="match_parent"
+            android:layout_gravity="center"
+            tools:visibility="gone" />
+
+        <androidx.coordinatorlayout.widget.CoordinatorLayout
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:fitsSystemWindows="true">
+
+            <com.google.android.material.appbar.AppBarLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:minHeight="?actionBarSize">
+
+                <com.google.android.material.appbar.CollapsingToolbarLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:minHeight="?actionBarSize"
+                    app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
+
+                    <LinearLayout
+                        android:layout_width="match_parent"
+                        android:layout_height="match_parent"
+                        android:orientation="vertical"
+                        android:paddingBottom="?actionBarSize"
+                        app:layout_collapseMode="parallax"
+                        app:layout_collapseParallaxMultiplier="0.7">
+
+                        <ImageView
+                            android:layout_width="wrap_content"
+                            android:layout_height="wrap_content"
+                            android:layout_gravity="center_horizontal"
+                            android:layout_marginTop="16dp"
+                            android:scaleType="center"
+                            android:scaleX="0.8"
+                            android:scaleY="0.8"
+                            android:src="@mipmap/ic_splash" />
+
+                        <TextView
+                            android:layout_width="match_parent"
+                            android:layout_height="wrap_content"
+                            android:layout_marginHorizontal="64dp"
+                            android:fontFamily="sans-serif-light"
+                            android:gravity="center"
+                            android:text="@string/app_name"
+                            android:textAppearance="@style/NavView.TextView.Large"
+                            android:textSize="28sp"
+                            android:textStyle="bold" />
+
+                        <TextView
+                            android:layout_width="match_parent"
+                            android:layout_height="wrap_content"
+                            android:layout_marginHorizontal="64dp"
+                            android:layout_marginBottom="48dp"
+                            android:fontFamily="sans-serif-light"
+                            android:gravity="center"
+                            android:text="@string/contributors_headline"
+                            android:textAppearance="@style/NavView.TextView.Medium" />
+                    </LinearLayout>
+
+                    <com.google.android.material.tabs.TabLayout
+                        android:id="@+id/tabLayout"
+                        android:layout_width="match_parent"
+                        android:layout_height="?actionBarSize"
+                        android:layout_gravity="bottom"
+                        android:background="?android:colorBackground"
+                        android:foreground="@color/colorSurface_2dp"
+                        android:minHeight="?actionBarSize"
+                        android:visibility="gone"
+                        app:tabIndicatorColor="?colorPrimary"
+                        app:tabMode="auto"
+                        app:tabSelectedTextColor="?colorPrimary"
+                        app:tabTextColor="?android:textColorPrimary"
+                        tools:visibility="visible" />
+                </com.google.android.material.appbar.CollapsingToolbarLayout>
+            </com.google.android.material.appbar.AppBarLayout>
+
+            <pl.szczodrzynski.edziennik.ui.modules.base.lazypager.LazyViewPager
+                android:id="@+id/viewPager"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:visibility="gone"
+                app:layout_behavior="@string/appbar_scrolling_view_behavior"
+                tools:visibility="visible" />
+        </androidx.coordinatorlayout.widget.CoordinatorLayout>
+    </LinearLayout>
+</layout>
diff --git a/app/src/main/res/layout/contributors_list_fragment.xml b/app/src/main/res/layout/contributors_list_fragment.xml
new file mode 100644
index 00000000..70d3d1c5
--- /dev/null
+++ b/app/src/main/res/layout/contributors_list_fragment.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/list"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:listitem="@layout/contributors_list_item" />
+</layout>
diff --git a/app/src/main/res/layout/contributors_list_item.xml b/app/src/main/res/layout/contributors_list_item.xml
new file mode 100644
index 00000000..5029203d
--- /dev/null
+++ b/app/src/main/res/layout/contributors_list_item.xml
@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:background="?selectableItemBackground"
+        android:gravity="center_vertical"
+        android:orientation="horizontal">
+
+        <ImageView
+            android:id="@+id/image"
+            android:layout_width="72dp"
+            android:layout_height="72dp"
+            android:padding="12dp"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:srcCompat="@drawable/ic_account_circle" />
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical"
+            android:orientation="vertical"
+            android:paddingHorizontal="8dp"
+            android:paddingVertical="16dp">
+
+            <TextView
+                android:id="@+id/text"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:ellipsize="end"
+                android:singleLine="true"
+                android:textAppearance="@style/NavView.TextView.Subtitle"
+                tools:text="der Librüsch" />
+
+            <TextView
+                android:id="@+id/subtext"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:ellipsize="end"
+                android:singleLine="true"
+                android:textAppearance="@style/NavView.TextView.Helper"
+                tools:text="[at]librüsch - ∞ contributions" />
+        </LinearLayout>
+    </LinearLayout>
+</layout>
diff --git a/app/src/main/res/layout/grades_item_stats.xml b/app/src/main/res/layout/grades_item_stats.xml
index 8ffeab4f..8bddb7de 100644
--- a/app/src/main/res/layout/grades_item_stats.xml
+++ b/app/src/main/res/layout/grades_item_stats.xml
@@ -32,6 +32,7 @@
             android:layout_gravity="center_horizontal"
             android:layout_margin="8dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/grades_stats_no_data"
             android:textSize="16sp"
             android:visibility="gone"
diff --git a/app/src/main/res/layout/grades_list_fragment.xml b/app/src/main/res/layout/grades_list_fragment.xml
index faf8264d..ec2d7a59 100644
--- a/app/src/main/res/layout/grades_list_fragment.xml
+++ b/app/src/main/res/layout/grades_list_fragment.xml
@@ -29,6 +29,7 @@
                 android:layout_gravity="center"
                 android:drawablePadding="16dp"
                 android:fontFamily="sans-serif-light"
+                android:gravity="center"
                 android:text="@string/grades_no_data"
                 android:textSize="24sp"
                 android:visibility="gone"
diff --git a/app/src/main/res/layout/homework_list_fragment.xml b/app/src/main/res/layout/homework_list_fragment.xml
index d53b9d17..53949d24 100644
--- a/app/src/main/res/layout/homework_list_fragment.xml
+++ b/app/src/main/res/layout/homework_list_fragment.xml
@@ -24,6 +24,7 @@
             android:layout_gravity="center"
             android:drawablePadding="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/homework_no_data"
             android:textSize="24sp"
             android:visibility="gone"
diff --git a/app/src/main/res/layout/lab_fragment.xml b/app/src/main/res/layout/lab_fragment.xml
index 8152f917..6c4bca77 100644
--- a/app/src/main/res/layout/lab_fragment.xml
+++ b/app/src/main/res/layout/lab_fragment.xml
@@ -3,7 +3,8 @@
   ~ Copyright (c) Kuba Szczodrzyński 2020-4-3.
   -->
 
-<layout xmlns:tools="http://schemas.android.com/tools"
+<layout xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
     xmlns:android="http://schemas.android.com/apk/res/android"
     tools:ignore="HardcodedText">
 
@@ -38,6 +39,12 @@
                 android:layout_height="match_parent"
                 app:layout_behavior="@string/appbar_scrolling_view_behavior" />-->
 
+            <Switch
+                android:id="@+id/chucker"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="Chucker" />
+
             <Button
                 android:id="@+id/last10unseen"
                 android:layout_width="match_parent"
@@ -101,6 +108,14 @@
                 android:layout_height="wrap_content"
                 android:checked="@={app.config.archiverEnabled}"
                 android:text="Archiver enabled" />
+
+            <Button
+                android:id="@+id/disableDebug"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="Disable Dev Mode"
+                android:textAllCaps="false"
+                app:backgroundTint="@color/windowBackgroundRed" />
         </LinearLayout>
     </ScrollView>
 </layout>
diff --git a/app/src/main/res/layout/message_fragment.xml b/app/src/main/res/layout/message_fragment.xml
index 1bae5bb5..2ca32c3d 100644
--- a/app/src/main/res/layout/message_fragment.xml
+++ b/app/src/main/res/layout/message_fragment.xml
@@ -57,7 +57,7 @@
             android:visibility="visible"
             tools:visibility="gone"/>
 
-        <ScrollView
+        <androidx.core.widget.NestedScrollView
             android:id="@+id/content"
             android:layout_width="match_parent"
             android:layout_height="0dp"
@@ -306,6 +306,6 @@
                     </LinearLayout>
                 </LinearLayout>
             </LinearLayout>
-        </ScrollView>
+        </androidx.core.widget.NestedScrollView>
     </LinearLayout>
 </layout>
diff --git a/app/src/main/res/layout/messages_list_fragment.xml b/app/src/main/res/layout/messages_list_fragment.xml
index 0399af9b..78de5194 100644
--- a/app/src/main/res/layout/messages_list_fragment.xml
+++ b/app/src/main/res/layout/messages_list_fragment.xml
@@ -24,6 +24,7 @@
             android:layout_gravity="center"
             android:drawablePadding="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/messages_no_data"
             android:textSize="24sp"
             android:visibility="gone"
diff --git a/app/src/main/res/layout/notifications_list_fragment.xml b/app/src/main/res/layout/notifications_list_fragment.xml
index a5c9aa90..e73d45d5 100644
--- a/app/src/main/res/layout/notifications_list_fragment.xml
+++ b/app/src/main/res/layout/notifications_list_fragment.xml
@@ -24,6 +24,7 @@
             android:layout_gravity="center"
             android:drawablePadding="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/notifications_no_data"
             android:textSize="24sp"
             android:visibility="gone"
diff --git a/app/src/main/res/layout/template_list_fragment.xml b/app/src/main/res/layout/template_list_fragment.xml
index 79646608..19c7221c 100644
--- a/app/src/main/res/layout/template_list_fragment.xml
+++ b/app/src/main/res/layout/template_list_fragment.xml
@@ -29,6 +29,7 @@
                 android:layout_gravity="center"
                 android:drawablePadding="16dp"
                 android:fontFamily="sans-serif-light"
+                android:gravity="center"
                 android:text="@string/grades_no_data"
                 android:textSize="24sp"
                 android:visibility="gone"
diff --git a/app/src/main/res/layout/template_list_page_fragment.xml b/app/src/main/res/layout/template_list_page_fragment.xml
index 09f8bfda..062b4c89 100644
--- a/app/src/main/res/layout/template_list_page_fragment.xml
+++ b/app/src/main/res/layout/template_list_page_fragment.xml
@@ -24,6 +24,7 @@
             android:layout_gravity="center"
             android:drawablePadding="16dp"
             android:fontFamily="sans-serif-light"
+            android:gravity="center"
             android:text="@string/grades_no_data"
             android:textSize="24sp"
             android:visibility="gone"
diff --git a/app/src/main/res/layout/timetable_day_fragment.xml b/app/src/main/res/layout/timetable_day_fragment.xml
index 5464482d..041f6e1f 100644
--- a/app/src/main/res/layout/timetable_day_fragment.xml
+++ b/app/src/main/res/layout/timetable_day_fragment.xml
@@ -36,12 +36,6 @@
                 android:layout_marginHorizontal="8dp"
                 android:background="@color/md_red_500"
                 tools:layout_marginTop="100dp" />
-
-            <com.linkedin.android.tachyon.DayView
-                android:id="@+id/dayView"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                tools:layout_height="match_parent" />
         </FrameLayout>
     </pl.szczodrzynski.edziennik.utils.ListenerScrollView>
 
diff --git a/app/src/main/res/values-de/strings.xml b/app/src/main/res/values-de/strings.xml
index 431fd960..b86e42af 100644
--- a/app/src/main/res/values-de/strings.xml
+++ b/app/src/main/res/values-de/strings.xml
@@ -856,7 +856,7 @@
     <string name="settings_about_licenses_text">Open-Source-Lizenzen</string>
     <string name="settings_about_privacy_policy_text">Datenschutzrichtlinie</string>
     <string name="settings_card_register_title">E-Klassenbuch</string>
-    <string name="settings_about_title_subtext">© Kuba Szczodrzyński &amp;&amp; Kacper Ziubryniewicz\nSeptember 2018 - Mai 2021</string>
+    <string name="settings_about_title_subtext">© Kuba Szczodrzyński &amp;&amp; Kacper Ziubryniewicz\nSeptember 2018 - Juni 2021</string>
     <string name="settings_about_update_subtext">Klicken Sie hier, um nach Aktualisierungen zu suchen</string>
     <string name="settings_about_update_text">Aktualisierung</string>
     <string name="settings_about_version_text">Version</string>
@@ -1234,4 +1234,6 @@
     <string name="you_are_offline_title">Netzwerkverbindung</string>
     <string name="login_summary_account_child">(Kind)</string>
     <string name="login_summary_account_parent">(Elternteil)</string>
+    <string name="settings_about_contributors_text">Anwendungsentwickler</string>
+    <string name="settings_about_contributors_subtext">Liste der Szkolny-Entwickler</string>
 </resources>
diff --git a/app/src/main/res/values-en/plurals.xml b/app/src/main/res/values-en/plurals.xml
index 1bada092..a600f325 100644
--- a/app/src/main/res/values-en/plurals.xml
+++ b/app/src/main/res/values-en/plurals.xml
@@ -55,4 +55,13 @@
         <item quantity="one">%1$s - %2$d unread</item>
         <item quantity="other">%1$s - %2$d unread</item>
     </plurals>
-</resources>
\ No newline at end of file
+
+    <plurals name="contributions_quantity">
+        <item quantity="one">%d contribution</item>
+        <item quantity="other">%d contributions</item>
+    </plurals>
+    <plurals name="translations_quantity">
+        <item quantity="one">%d translation</item>
+        <item quantity="other">%d translations</item>
+    </plurals>
+</resources>
diff --git a/app/src/main/res/values-en/strings.xml b/app/src/main/res/values-en/strings.xml
index e519d272..a557681a 100644
--- a/app/src/main/res/values-en/strings.xml
+++ b/app/src/main/res/values-en/strings.xml
@@ -858,7 +858,7 @@
     <string name="settings_about_licenses_text">Open-source licenses</string>
     <string name="settings_about_privacy_policy_text">Privacy policy</string>
     <string name="settings_card_register_title">E-register</string>
-    <string name="settings_about_title_subtext">© Kuba Szczodrzyński &amp;&amp; Kacper Ziubryniewicz\nSeptember 2018 - May 2021</string>
+    <string name="settings_about_title_subtext">© Kuba Szczodrzyński &amp;&amp; Kacper Ziubryniewicz\nSeptember 2018 - June 2021</string>
     <string name="settings_about_update_subtext">Click to check for updates</string>
     <string name="settings_about_update_text">Update</string>
     <string name="settings_about_version_text">Version</string>
@@ -1237,6 +1237,10 @@
     <string name="permissions_attachment">In order to download the file, you have to grant file storage permission for the application.\n\nClick OK to grant the permission.</string>
     <string name="permissions_denied">You denied the required permissions for the application.\n\nIn order to grant the permission, open the Permissions screen for Szkolny.eu in phone settings.\n\nClick OK to open app settings now.</string>
     <string name="permissions_required">Required permissions</string>
+    <string name="settings_about_contributors_text">App contributors</string>
+    <string name="settings_about_contributors_subtext">List of Szkolny.eu contributors</string>
+    <string name="contributors">Contributors</string>
+    <string name="translators">Translators</string>
     <string name="settings_register_hide_sticks_from_old">Hide sticks from old</string>
     <string name="build_official">Official build</string>
     <string name="build_platform_play">Google Play</string>
diff --git a/app/src/main/res/values/errors.xml b/app/src/main/res/values/errors.xml
index d90af9ed..827227c5 100644
--- a/app/src/main/res/values/errors.xml
+++ b/app/src/main/res/values/errors.xml
@@ -165,6 +165,7 @@
     <string name="error_363" translatable="false">ERROR_VULCAN_HEBE_CERTIFICATE_GONE</string>
     <string name="error_364" translatable="false">ERROR_VULCAN_HEBE_SERVER_ERROR</string>
     <string name="error_365" translatable="false">ERROR_VULCAN_HEBE_ENTITY_NOT_FOUND</string>
+    <string name="error_366" translatable="false">ERROR_VULCAN_HEBE_MISSING_SENDER_ENTRY</string>
     <string name="error_390" translatable="false">ERROR_VULCAN_API_DEPRECATED</string>
 
     <string name="error_501" translatable="false">ERROR_LOGIN_EDUDZIENNIK_WEB_INVALID_LOGIN</string>
@@ -363,6 +364,7 @@
     <string name="error_363_reason">VULCAN®: urządzenie usunięte. Zaloguj się ponownie do dziennika.</string>
     <string name="error_364_reason">VULCAN®: błąd serwera. Dziennik może być przeciążony.</string>
     <string name="error_365_reason">VULCAN®: nie znaleziono bytu</string>
+    <string name="error_366_reason">Błąd wysyłania wiadomości - brak informacji o nadawcy.</string>
     <string name="error_390_reason">W związku z wygaszeniem aplikacji Dzienniczek+ przez firmę Vulcan, należy zalogować się ponownie.\n\nAby móc dalej korzystać z aplikacji Szkolny.eu, otwórz Ustawienia i wybierz opcję Dodaj nowego ucznia.\nNastępnie zaloguj się do dziennika Vulcan zgodnie z instrukcją.\n\nPrzepraszamy za niedogodności.</string>
 
     <string name="error_501_reason">Błędny email lub hasło</string>
diff --git a/app/src/main/res/values/plurals.xml b/app/src/main/res/values/plurals.xml
index bb74ba85..bcd87eca 100644
--- a/app/src/main/res/values/plurals.xml
+++ b/app/src/main/res/values/plurals.xml
@@ -159,4 +159,15 @@
         <item quantity="few">%d oceny</item> <!-- 2, 3, 4, 32, 33, 34 -->
         <item quantity="other">%d ocen</item> <!-- 5, 10, 12, 13, 21, 25 -->
     </plurals>
+
+    <plurals name="contributions_quantity">
+        <item quantity="one">%d commit</item>
+        <item quantity="few">%d commity</item>
+        <item quantity="other">%d commit\'ów</item>
+    </plurals>
+    <plurals name="translations_quantity">
+        <item quantity="one">%d tłumaczenie</item>
+        <item quantity="few">%d tłumaczenia</item>
+        <item quantity="other">%d tłumaczeń</item>
+    </plurals>
 </resources>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 5aa206af..b11631b5 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -921,7 +921,7 @@
     <string name="settings_about_licenses_text">Licencje open-source</string>
     <string name="settings_about_privacy_policy_text">Polityka prywatności</string>
     <string name="settings_card_register_title">E-dziennik</string>
-    <string name="settings_about_title_subtext">© Kuba Szczodrzyński &amp;&amp; Kacper Ziubryniewicz\nwrzesień 2018 - maj 2021</string>
+    <string name="settings_about_title_subtext">© Kuba Szczodrzyński &amp;&amp; Kacper Ziubryniewicz\nwrzesień 2018 - czerwiec 2021</string>
     <string name="settings_about_update_subtext">Kliknij, aby sprawdzić aktualizacje</string>
     <string name="settings_about_update_text">Aktualizacja</string>
     <string name="settings_about_version_text">Wersja</string>
@@ -1391,6 +1391,10 @@
     <string name="see_also">Zobacz także</string>
     <string name="settings_about_homepage_text">Wejdź na stronę aplikacji</string>
     <string name="settings_about_homepage_subtext">Uzyskaj pomoc lub wesprzyj autorów</string>
+    <string name="settings_about_contributors_text">Twórcy aplikacji</string>
+    <string name="settings_about_contributors_subtext">Lista twórców Szkolnego</string>
+    <string name="contributors">Współtwórcy</string>
+    <string name="translators">Tłumacze</string>
     <string name="settings_about_github_text">Kod źródłowy</string>
     <string name="settings_about_github_subtext">Pomóż w rozwoju aplikacji na GitHubie</string>
     <string name="profile_config_name_hint">Nazwa profilu</string>
@@ -1457,4 +1461,6 @@
     <string name="notification_grade_long_format">Ocena: %s (waga %s)\nPrzedmiot: %s\nKategoria: %s\nOpis: %s\nNauczyciel: %s</string>
     <string name="notification_notice_long_format">Rodzaj: %s\nNauczyciel: %s\nTreść: %s</string>
     <string name="notification_attendance_long_format">Rodzaj: %s\nTermin: %s, %s\nNr lekcji: %s\nPrzedmiot: %s\nNauczyciel: %s\nTemat lekcji: %s</string>
+    <string name="contributors_subtext_format" translatable="false">\@%s - %s</string>
+    <string name="contributors_headline">Najłatwiejszy sposób na korzystanie z e-dziennika.</string>
 </resources>
diff --git a/build.gradle b/build.gradle
index a2eb932b..7e6fb9f9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,11 +2,11 @@
 
 buildscript {
     ext {
-        kotlin_version = '1.4.31'
+        kotlin_version = '1.5.20'
 
         release = [
-                versionName: "4.8",
-                versionCode: 4080099
+                versionName: "4.9",
+                versionCode: 4090099
         ]
 
         setup = [
@@ -21,10 +21,10 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath "com.android.tools.build:gradle:4.2.0-beta06"
+        classpath 'com.android.tools.build:gradle:7.0.2'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        classpath 'com.google.gms:google-services:4.3.5'
-        classpath 'com.google.firebase:firebase-crashlytics-gradle:2.5.1'
+        classpath 'com.google.gms:google-services:4.3.10'
+        classpath 'com.google.firebase:firebase-crashlytics-gradle:2.7.1'
     }
 }
 
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 9bd0ad16..80cea62c 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 #Wed Feb 17 14:04:38 CET 2021
 distributionBase=GRADLE_USER_HOME
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.0.2-all.zip
 distributionPath=wrapper/dists
 zipStorePath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME