[UI] Add teachers list feature. (#94)

* Add teachers list feature * Fix * some fixes * Auto stash before merge of "develop" and "origin/develop" * Add teachers list feature * Fix * some fixes * [UI] Fix updating badges crashing with expanded items. * Add support for fetching teachers from vulcan, fix some code * Update app/src/main/java/pl/szczodrzynski/edziennik/data/db/entity/Teacher.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update some code * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/data/db/entity/Teacher.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTeachers.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/data/db/entity/Teacher.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/data/db/migration/Migration96.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTeachers.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Optimize code * Fix loadTarget algorithm * Apply suggestions from code review Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> * Update app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl> Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl>
2024-11-24 10:54:36 -06:00 · 2021-10-18 23:46:39 +02:00 · 2021-10-18 23:46:39 +02:00 · 2807659da3
commit 2807659da3
parent 74b766f18a
18 changed files with 676 additions and 266 deletions
--- a/.idea/copyright/Antoni.xml
+++ b/.idea/copyright/Antoni.xml
@ -0,0 +1,6 @@
+<component name="CopyrightManager">
+  <copyright>
+    <option name="notice" value="Copyright (c) Antoni Czaplicki &amp;#36;{today.year}-&amp;#36;{today.month}-&amp;#36;{today.day}. " />
+    <option name="myName" value="Antoni" />
+  </copyright>
+</component>
--- a/app/src/main/java/pl/szczodrzynski/edziennik/Extensions.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/Extensions.kt
@ -44,6 +44,8 @@ import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import com.google.gson.*
 import com.google.gson.JsonArray
 import com.google.gson.JsonObject
+import com.mikepenz.iconics.typeface.IIcon
+import com.mikepenz.materialdrawer.holder.StringHolder
 import im.wangchao.mhttp.Response
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.delay
@ -59,6 +61,7 @@ import pl.szczodrzynski.edziennik.data.db.entity.Profile
 import pl.szczodrzynski.edziennik.data.db.entity.Teacher
 import pl.szczodrzynski.edziennik.data.db.entity.Team
 import pl.szczodrzynski.edziennik.utils.models.Time
+import pl.szczodrzynski.navlib.ImageHolder
 import java.io.InterruptedIOException
 import java.io.PrintWriter
 import java.io.StringWriter
@ -862,6 +865,8 @@ fun @receiver:DrawableRes Int.resolveDrawable(context: Context): Drawable {
    }
 }

+fun @receiver:StringRes Int.resolveString(context: Context) = context.getString(this)
+
 fun View.findParentById(targetId: Int): View? {
    if (id == targetId) {
        return this
@ -1371,3 +1376,7 @@ fun CharSequence.getWordBounds(position: Int, onlyInWord: Boolean = false): Pair
 }

 infix fun Int.hasSet(what: Int) = this and what == what
+
+fun Int.toStringHolder() = StringHolder(this)
+fun CharSequence.toStringHolder() = StringHolder(this)
+fun IIcon.toImageHolder() = ImageHolder(this)
--- a/app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/MainActivity.kt
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Constants.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/Constants.kt
@ -109,6 +109,7 @@ const val VULCAN_HEBE_ENDPOINT_PUSH_ALL = "api/mobile/push/all"
 const val VULCAN_HEBE_ENDPOINT_TIMETABLE = "api/mobile/schedule"
 const val VULCAN_HEBE_ENDPOINT_TIMETABLE_CHANGES = "api/mobile/schedule/changes"
 const val VULCAN_HEBE_ENDPOINT_ADDRESSBOOK = "api/mobile/addressbook"
+const val VULCAN_HEBE_ENDPOINT_TEACHERS = "api/mobile/teacher"
 const val VULCAN_HEBE_ENDPOINT_EXAMS = "api/mobile/exam"
 const val VULCAN_HEBE_ENDPOINT_GRADES = "api/mobile/grade"
 const val VULCAN_HEBE_ENDPOINT_GRADE_SUMMARY = "api/mobile/grade/summary"
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/VulcanFeatures.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/VulcanFeatures.kt
@ -21,6 +21,7 @@ const val ENDPOINT_VULCAN_HEBE_NOTICES            = 3070
 const val ENDPOINT_VULCAN_HEBE_ATTENDANCE         = 3080
 const val ENDPOINT_VULCAN_HEBE_MESSAGES_INBOX     = 3090
 const val ENDPOINT_VULCAN_HEBE_MESSAGES_SENT      = 3100
+const val ENDPOINT_VULCAN_HEBE_TEACHERS           = 3110
 const val ENDPOINT_VULCAN_HEBE_LUCKY_NUMBER       = 3200

 val VulcanFeatures = listOf(
@ -83,6 +84,7 @@ val VulcanFeatures = listOf(

        Feature(LOGIN_TYPE_VULCAN, FEATURE_ALWAYS_NEEDED, listOf(
                ENDPOINT_VULCAN_HEBE_MAIN to LOGIN_METHOD_VULCAN_HEBE,
-                ENDPOINT_VULCAN_HEBE_ADDRESSBOOK to LOGIN_METHOD_VULCAN_HEBE
+                ENDPOINT_VULCAN_HEBE_ADDRESSBOOK to LOGIN_METHOD_VULCAN_HEBE,
+                ENDPOINT_VULCAN_HEBE_TEACHERS to LOGIN_METHOD_VULCAN_HEBE
        ), listOf(LOGIN_METHOD_VULCAN_HEBE))
 )
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/VulcanData.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/VulcanData.kt
@ -27,6 +27,7 @@ class VulcanData(val data: DataVulcan, val onSuccess: () -> Unit) {
        ENDPOINT_VULCAN_HEBE_NOTICES,
        ENDPOINT_VULCAN_HEBE_MESSAGES_INBOX,
        ENDPOINT_VULCAN_HEBE_MESSAGES_SENT,
+        ENDPOINT_VULCAN_HEBE_TEACHERS,
        ENDPOINT_VULCAN_HEBE_LUCKY_NUMBER
    )

@ -103,9 +104,13 @@ class VulcanData(val data: DataVulcan, val onSuccess: () -> Unit) {
                VulcanHebePushConfig(data, lastSync, onSuccess)
            }
            ENDPOINT_VULCAN_HEBE_ADDRESSBOOK -> {
-                data.startProgress(R.string.edziennik_progress_endpoint_teachers)
+                data.startProgress(R.string.edziennik_progress_endpoint_addressbook)
                VulcanHebeAddressbook(data, lastSync, onSuccess)
            }
+            ENDPOINT_VULCAN_HEBE_TEACHERS -> {
+                data.startProgress(R.string.edziennik_progress_endpoint_teachers)
+                VulcanHebeTeachers(data, lastSync, onSuccess)
+            }
            ENDPOINT_VULCAN_HEBE_TIMETABLE -> {
                data.startProgress(R.string.edziennik_progress_endpoint_timetable)
                VulcanHebeTimetable(data, lastSync, onSuccess)
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTeachers.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/edziennik/vulcan/data/hebe/VulcanHebeTeachers.kt
@ -0,0 +1,46 @@
+/*
+ * Copyright (c) Antoni Czaplicki 2021-10-15.
+ */
+
+package pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.data.hebe
+
+import pl.szczodrzynski.edziennik.DAY
+import pl.szczodrzynski.edziennik.data.api.VULCAN_HEBE_ENDPOINT_TEACHERS
+import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.DataVulcan
+import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.ENDPOINT_VULCAN_HEBE_TEACHERS
+import pl.szczodrzynski.edziennik.data.api.edziennik.vulcan.data.VulcanHebe
+import pl.szczodrzynski.edziennik.getString
+
+class VulcanHebeTeachers(
+    override val data: DataVulcan,
+    override val lastSync: Long?,
+    val onSuccess: (endpointId: Int) -> Unit,
+) : VulcanHebe(data, lastSync) {
+    companion object {
+        const val TAG = "VulcanHebeTeachers"
+    }
+
+    init {
+        apiGetList(
+            TAG,
+            VULCAN_HEBE_ENDPOINT_TEACHERS,
+            HebeFilterType.BY_PERIOD,
+            lastSync = lastSync,
+        ) { list, _ ->
+            list.forEach { person ->
+                val name = person.getString("Name")
+                val surname = person.getString("Surname")
+                val displayName = person.getString("DisplayName")
+                val subjectName = person.getString("Description") ?: return@apiGetList
+
+                val teacher = data.getTeacherByFirstLast(
+                    name?.plus(" ")?.plus(surname) ?: displayName ?: return@forEach
+                )
+
+                teacher.addSubject(data.getSubject(null, subjectName).id)
+            }
+            data.setSyncNext(ENDPOINT_VULCAN_HEBE_TEACHERS, 2 * DAY)
+            onSuccess(ENDPOINT_VULCAN_HEBE_TEACHERS)
+        }
+    }
+}
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/db/AppDb.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/db/AppDb.kt
@ -43,7 +43,7 @@ import pl.szczodrzynski.edziennik.data.db.migration.*
    LibrusLesson::class,
    TimetableManual::class,
    Metadata::class
-], version = 95)
+], version = 96)
@TypeConverters(
        ConverterTime::class,
        ConverterDate::class,
@ -181,6 +181,7 @@ abstract class AppDb : RoomDatabase() {
                Migration93(),
                Migration94(),
                Migration95(),
+                Migration96(),
        ).allowMainThreadQueries().build()
    }
 }
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/db/entity/Teacher.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/db/entity/Teacher.kt
@ -9,14 +9,11 @@ import android.graphics.Bitmap
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.Ignore
-import pl.szczodrzynski.edziennik.R
-import pl.szczodrzynski.edziennik.fixName
-import pl.szczodrzynski.edziennik.getNameInitials
-import pl.szczodrzynski.edziennik.join
+import pl.szczodrzynski.edziennik.*
 import java.util.*

@Entity(tableName = "teachers",
-        primaryKeys = ["profileId", "teacherId"])
+    primaryKeys = ["profileId", "teacherId"])
 open class Teacher {
    companion object {
        const val TYPE_TEACHER = 0 // 1
@ -26,6 +23,7 @@ open class Teacher {
        const val TYPE_SECRETARIAT = 4 // 16
        const val TYPE_PRINCIPAL = 5 // 32
        const val TYPE_SCHOOL_ADMIN = 6 // 64
+
        // not teachers
        const val TYPE_SPECIALIST = 7 // 128
        const val TYPE_SUPER_ADMIN = 10 // 1024
@ -36,7 +34,8 @@ open class Teacher {
        const val TYPE_OTHER = 24 // 16777216
        const val IS_TEACHER_MASK = 127

-        val types: List<Int> by lazy { listOf(
+        val types: List<Int> by lazy {
+            listOf(
                TYPE_TEACHER,
                TYPE_EDUCATOR,
                TYPE_PEDAGOGUE,
@ -51,7 +50,8 @@ open class Teacher {
                TYPE_PARENTS_COUNCIL,
                TYPE_SCHOOL_PARENTS_COUNCIL,
                TYPE_OTHER
-        ) }
+            )
+        }

        fun typeName(c: Context, type: Int, typeDescription: String? = null): String {
            val suffix = typeDescription?.let { " ($typeDescription)" } ?: ""
@ -94,6 +94,9 @@ open class Teacher {
    @ColumnInfo(name = "teacherTypeDescription")
    var typeDescription: String? = null

+    @ColumnInfo(name = "teacherSubjects")
+    var subjects = mutableListOf<Long>()
+
    fun isType(checkingType: Int): Boolean {
        return type and (1 shl checkingType) >= 1
    }
@ -105,6 +108,8 @@ open class Teacher {
        type = type or (1 shl i)
    }

+    fun addSubject(subjectId: Long) = subjects.add(subjectId)
+
    fun unsetTeacherType(i: Int) {
        type = type and (1 shl i).inv()
    }
@ -128,6 +133,7 @@ open class Teacher {
     */
    @Ignore
    var recipientDisplayName: CharSequence? = null
+
    /**
     * Used in Message composing - determining the priority
     * of search result, based on the search phrase match
@ -142,8 +148,6 @@ open class Teacher {
        this.id = id
    }

-
-
    @Ignore
    constructor(profileId: Int, id: Long, name: String, surname: String) {
        this.profileId = profileId
@ -170,6 +174,7 @@ open class Teacher {
            this.surname = it.surname
            this.type = it.type
            this.typeDescription = it.typeDescription
+            this.subjects = it.subjects
            this.image = it.image
            this.recipientDisplayName = it.recipientDisplayName
        }
@ -195,6 +200,7 @@ open class Teacher {
                ", name='" + name + '\'' +
                ", surname='" + surname + '\'' +
                ", type=" + dumpType() +
+                ", subjects=" + subjects.joinToString() +
                ", typeDescription='" + typeDescription + '\'' +
                '}'
    }
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/db/migration/Migration96.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/db/migration/Migration96.kt
@ -0,0 +1,15 @@
+/*
+ * Copyright (c) Antoni Czaplicki 2021-10-17.
+ */
+
+package pl.szczodrzynski.edziennik.data.db.migration
+
+import androidx.room.migration.Migration
+import androidx.sqlite.db.SupportSQLiteDatabase
+
+class Migration96 : Migration(95, 96) {
+    override fun migrate(database: SupportSQLiteDatabase) {
+        // teachers - associated subjects list
+        database.execSQL("ALTER TABLE teachers ADD COLUMN teacherSubjects TEXT NOT NULL;")
+    }
+}
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/messages/compose/MessagesComposeSuggestionAdapter.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/messages/compose/MessagesComposeSuggestionAdapter.kt
@ -30,7 +30,7 @@ class MessagesComposeSuggestionAdapter(
    private val comparator by lazy { Comparator { o1: Teacher, o2: Teacher -> o1.recipientWeight - o2.recipientWeight } }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
-        val listItem = convertView ?: LayoutInflater.from(context).inflate(R.layout.messages_compose_suggestion_item, parent, false)
+        val listItem = convertView ?: LayoutInflater.from(context).inflate(R.layout.teacher_item, parent, false)

        val teacher = teacherList[position]
        val name = listItem.findViewById<TextView>(R.id.name)
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/teachers/TeachersAdapter.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/teachers/TeachersAdapter.kt
@ -0,0 +1,69 @@
+/*
+ * Copyright (c) Antoni Czaplicki 2021-10-15.
+ */
+
+package pl.szczodrzynski.edziennik.ui.modules.teachers
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.appcompat.app.AppCompatActivity
+import androidx.recyclerview.widget.RecyclerView
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import pl.szczodrzynski.edziennik.App
+import pl.szczodrzynski.edziennik.data.db.entity.Teacher
+import pl.szczodrzynski.edziennik.databinding.TeacherItemBinding
+import pl.szczodrzynski.edziennik.isNotNullNorEmpty
+import pl.szczodrzynski.edziennik.ui.modules.messages.MessagesUtils.getProfileImage
+import pl.szczodrzynski.edziennik.utils.BetterLink
+import kotlin.coroutines.CoroutineContext
+
+class TeachersAdapter(
+    private val activity: AppCompatActivity,
+    val onItemClick: ((item: Teacher) -> Unit)? = null,
+) : RecyclerView.Adapter<TeachersAdapter.ViewHolder>(), CoroutineScope {
+    companion object {
+        private const val TAG = "TeachersAdapter"
+    }
+
+    private val app = activity.applicationContext as App
+    // optional: place the manager here
+
+    private val job = Job()
+    override val coroutineContext: CoroutineContext
+        get() = job + Dispatchers.Main
+
+    var items = listOf<Teacher>()
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        val inflater = LayoutInflater.from(activity)
+        val view = TeacherItemBinding.inflate(inflater, parent, false)
+        return ViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        val item = items[position]
+        val b = holder.b
+
+        b.name.text = item.fullName
+        b.image.setImageBitmap(item.image?: getProfileImage(48, 24, 16, 12, 1, item.fullName))
+        var role = item.getTypeText(activity)
+        if (item.subjects.isNotNullNorEmpty()) {
+            val subjects = item.subjects.map { App.db.subjectDao().getByIdNow(App.profileId, it).longName }
+            role = role.plus(": ").plus(subjects.joinToString())
+        }
+        b.type.text = role
+
+        item.fullName.let { name ->
+            BetterLink.attach(
+                b.name,
+                teachers = mapOf(item.id to name)
+            )
+        }
+    }
+
+    override fun getItemCount() = items.size
+
+    class ViewHolder(val b: TeacherItemBinding) : RecyclerView.ViewHolder(b.root)
+}
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/teachers/TeachersListFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/modules/teachers/TeachersListFragment.kt
@ -0,0 +1,82 @@
+/*
+ * Copyright (c) Antoni Czaplicki 2021-10-15.
+ */
+
+package pl.szczodrzynski.edziennik.ui.modules.teachers
+
+import android.app.Activity
+import android.content.Intent
+import android.os.AsyncTask
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Toast
+import androidx.core.view.isVisible
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.recyclerview.widget.LinearLayoutManager
+import com.mikepenz.iconics.typeface.library.community.material.CommunityMaterial
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import pl.szczodrzynski.edziennik.*
+import pl.szczodrzynski.edziennik.databinding.TeachersListFragmentBinding
+import pl.szczodrzynski.edziennik.utils.SimpleDividerItemDecoration
+import pl.szczodrzynski.edziennik.utils.Utils
+import pl.szczodrzynski.navlib.bottomsheet.items.BottomSheetPrimaryItem
+import kotlin.coroutines.CoroutineContext
+
+class TeachersListFragment : Fragment(), CoroutineScope {
+    companion object {
+        private const val TAG = "TeachersListFragment"
+    }
+
+    private lateinit var app: App
+    private lateinit var activity: MainActivity
+    private lateinit var b: TeachersListFragmentBinding
+
+    private val job: Job = Job()
+    override val coroutineContext: CoroutineContext
+        get() = job + Dispatchers.Main
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        activity = (getActivity() as MainActivity?) ?: return null
+        context ?: return null
+        app = activity.application as App
+        b = TeachersListFragmentBinding.inflate(inflater)
+        return b.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) { startCoroutineTimer(100L) {
+        if (!isAdded) return@startCoroutineTimer
+
+        val adapter = TeachersAdapter(activity)
+
+        app.db.teacherDao().getAllTeachers(App.profileId).observe(this@TeachersListFragment, Observer { items ->
+            if (!isAdded) return@Observer
+
+            // load & configure the adapter
+            adapter.items = items
+            if (items.isNotNullNorEmpty() && b.list.adapter == null) {
+                b.list.adapter = adapter
+                b.list.apply {
+                    setHasFixedSize(true)
+                    layoutManager = LinearLayoutManager(context)
+                    addItemDecoration(SimpleDividerItemDecoration(context))
+                }
+            }
+            adapter.notifyDataSetChanged()
+
+            // show/hide relevant views
+            b.progressBar.isVisible = false
+            if (items.isNullOrEmpty()) {
+                b.list.isVisible = false
+                b.noData.isVisible = true
+            } else {
+                b.list.isVisible = true
+                b.noData.isVisible = false
+            }
+        })
+    }}
+}
--- a/app/src/main/res/layout/messages_compose_suggestion_item.xml
+++ b/app/src/main/res/layout/messages_compose_suggestion_item.xml
--- a/app/src/main/res/layout/teachers_list_fragment.xml
+++ b/app/src/main/res/layout/teachers_list_fragment.xml
@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (c) Antoni Czaplicki 2021-10-15.
+  -->
+
+<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">
+
+    <FrameLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <ProgressBar
+            android:id="@+id/progressBar"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center" />
+
+        <androidx.appcompat.widget.AppCompatTextView
+            android:id="@+id/noData"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center"
+            android:drawablePadding="16dp"
+            android:fontFamily="sans-serif-light"
+            android:gravity="center"
+            android:padding="16dp"
+            android:text="@string/teachers_no_data"
+            android:textSize="24sp"
+            android:visibility="gone"
+            app:drawableTopCompat="@drawable/ic_archive"
+            tools:visibility="visible" />
+
+        <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/list"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:visibility="gone"
+            tools:listitem="@layout/teacher_item"
+            tools:visibility="visible" />
+    </FrameLayout>
+</layout>
--- a/app/src/main/res/values-de/strings.xml
+++ b/app/src/main/res/values-de/strings.xml
@ -656,6 +656,7 @@
    <string name="menu_message">Nachricht</string>
    <string name="menu_message_compose">Schreiben Sie eine Nachricht</string>
    <string name="menu_messages">Nachrichten</string>
+    <string name="menu_more">Mehr</string>
    <string name="menu_notices">Verhalten</string>
    <string name="menu_notifications">Benachrichtigungen</string>
    <string name="menu_remove_notifications">Löschen</string>
@ -1108,6 +1109,7 @@
    <string name="teacher_super_admin">Administrator / Superadministrator</string>
    <string name="teacher_teacher">Lehrer</string>
    <string name="teachers_browse_category">Kategorie durchsuchen</string>
+    <string name="teachers_no_data">Keine Lehrer.</string>
    <string name="the_day_after">Übermorgen</string>
    <string name="the_day_before">Vorgestern</string>
    <string name="theme_amber">Bernstein</string>
@ -1236,4 +1238,6 @@
    <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>
+    <string name="menu_teachers">Lehrer</string>
+    <string name="edziennik_progress_endpoint_addressbook">Addressbuch herunterladen…</string>
 </resources>
--- a/app/src/main/res/values-en/strings.xml
+++ b/app/src/main/res/values-en/strings.xml
@ -658,6 +658,7 @@
    <string name="menu_message">Message</string>
    <string name="menu_message_compose">Compose</string>
    <string name="menu_messages">Messages</string>
+    <string name="menu_more">More</string>
    <string name="menu_notices">Behaviour</string>
    <string name="menu_notifications">Notifications</string>
    <string name="menu_remove_notifications">Clear</string>
@ -1110,6 +1111,7 @@
    <string name="teacher_super_admin">SuperAdmin</string>
    <string name="teacher_teacher">Teacher</string>
    <string name="teachers_browse_category">Browse category</string>
+    <string name="teachers_no_data">No teachers.</string>
    <string name="the_day_after">overmorrow</string>
    <string name="the_day_before">the day before yesterday</string>
    <string name="theme_amber">Amber</string>
@ -1372,4 +1374,6 @@
    <string name="permissions_generate_timetable">In order to be able to save the generated timetable, you must grant access rights to the device\'s memory.\n\nClick OK to grant permissions.</string>
    <string name="login_summary_account_child">(Child)</string>
    <string name="login_summary_account_parent">(Parent)</string>
+    <string name="menu_teachers">Teachers</string>
+    <string name="edziennik_progress_endpoint_addressbook">Syncing addressbook…</string>
 </resources>
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@ -301,6 +301,7 @@
    <string name="edziennik_notification_api_text">Dzięki niej, aplikacja Szkolny.eu może synchronizować dane z e-dziennikiem. Możesz ją zamknąć, ponieważ w tej chwili nic nie robi.</string>
    <string name="edziennik_notification_api_title">Usługa synchronizacji</string>
    <string name="edziennik_progress_endpoint_account_details">Pobieranie szczegółów konta…</string>
+    <string name="edziennik_progress_endpoint_addressbook">Pobieranie listy odbiorców…</string>
    <string name="edziennik_progress_endpoint_announcements">Pobieranie ogłoszeń szkolnych…</string>
    <string name="edziennik_progress_endpoint_attendance">Pobieranie frekwencji ucznia…</string>
    <string name="edziennik_progress_endpoint_attendance_types">Pobieranie kategorii obecności…</string>
@ -708,6 +709,7 @@
    <string name="menu_message">Wiadomość</string>
    <string name="menu_message_compose">Napisz wiadomość</string>
    <string name="menu_messages">Wiadomości</string>
+    <string name="menu_more">Więcej</string>
    <string name="menu_notices">Zachowanie</string>
    <string name="menu_notifications">Powiadomienia</string>
    <string name="menu_remove_notifications">Usuń wszystkie</string>
@ -716,6 +718,7 @@
    <string name="menu_settings">Ustawienia</string>
    <string name="menu_sync">Synchronizuj</string>
    <string name="menu_sync_all">Synchronizuj wszystkie</string>
+    <string name="menu_teachers">Nauczyciele</string>
    <string name="menu_template">Szablon</string>
    <string name="menu_timetable">Plan lekcji</string>
    <string name="menu_timetable_manual">Edytor planu lekcji</string>
@ -1180,6 +1183,7 @@
    <string name="teacher_super_admin">Administrator / SuperAdministrator</string>
    <string name="teacher_teacher">Nauczyciel</string>
    <string name="teachers_browse_category">Przeglądaj kategorię</string>
+    <string name="teachers_no_data">Brak nauczycieli.</string>
    <string name="the_day_after">pojutrze</string>
    <string name="the_day_before">przedwczoraj</string>
    <string name="theme_amber">Bursztynowy</string>