Add ability to scroll up and view history

app/src/main/kotlin/im/pattle/app/data/chat/event/ChatEventRemoteSource.kt

@@ -19,6 +19,7 @@
  */
 package im.pattle.app.data.chat.event
 
+import android.util.Log
 import im.pattle.app.data.chat.event.model.*
 import im.pattle.app.data.sync.SyncManager
 import im.pattle.app.sdk.Matrix
@@ -27,6 +28,7 @@ import io.reactivex.Flowable
 import org.matrix.androidsdk.data.RoomState
 import org.matrix.androidsdk.data.timeline.EventTimeline
 import org.matrix.androidsdk.listeners.MXEventListener
+import org.matrix.androidsdk.rest.callback.ApiCallback
 import org.matrix.androidsdk.rest.callback.SimpleApiCallback
 import org.matrix.androidsdk.rest.model.Event
 import org.matrix.androidsdk.rest.model.TokensChunkEvents
@@ -37,7 +39,17 @@ class ChatEventRemoteSource(private val matrix: Matrix,
                             private val syncManager: SyncManager)
     : ChatEventSource {
 
+    /**
+     * Unsorted collection of alle events that are in memory right now.
+     */
     private val roomEvents = mutableMapOf<String, MutableList<ChatEvent>>()
+    private fun eventsForRoom(chatId: String): MutableList<ChatEvent> {
+        if (roomEvents[chatId] == null) {
+            roomEvents[chatId] = mutableListOf()
+        }
+        return roomEvents[chatId]!!
+    }
+
 
     fun send(chatId: String, message: Message) {
 
@@ -54,11 +66,7 @@ class ChatEventRemoteSource(private val matrix: Matrix,
     @Suppress("UNCHECKED_CAST")
     override fun getChatEvents(chatId: String): Flowable<List<ChatEvent>> {
         val dataHandler = matrix.dataHandler
-
-        if (roomEvents[chatId] == null) {
-            roomEvents[chatId] = mutableListOf()
-        }
-        val events = roomEvents[chatId]!!
+        val events = eventsForRoom(chatId)
 
         return matrix.waitForInitialSync().andThen(
             Flowable.create({
@@ -123,4 +131,45 @@ class ChatEventRemoteSource(private val matrix: Matrix,
             }, BackpressureStrategy.BUFFER)
         )
     }
+
+    override fun getHistoricChatEvents(chatId: String,
+                                       from: ChatEvent): Flowable<List<ChatEvent>> {
+        return Flowable.create({
+
+            val room = matrix.dataHandler.getRoom(chatId)
+            val token = from.original.mToken
+
+            if (token != null) {
+                val events = eventsForRoom(chatId)
+
+                room.requestServerRoomHistory(token, 20,
+                        object : SimpleApiCallback<TokensChunkEvents>() {
+                            override fun onSuccess(response: TokensChunkEvents?) {
+                                if (response != null) {
+                                    for (event in response.chunk) {
+                                        // TODO: Reuse code
+                                        val chatEvent = event.toChatEvent(room)
+
+                                        if (chatEvent != null) {
+                                            val old = events.find { it.id == chatEvent.id }
+                                            if (old != null) {
+                                                events.remove(old)
+                                            }
+
+                                            events.add(chatEvent)
+                                        }
+                                    }
+
+                                    it.onNext(events)
+                                }
+                            }
+
+                        })
+            } else {
+                Log.e("ChatEventRemoteSource", "token is null")
+            }
+
+
+        }, BackpressureStrategy.BUFFER)
+    }
 }

app/src/main/kotlin/im/pattle/app/data/chat/event/ChatEventRepository.kt

@@ -28,4 +28,7 @@ class ChatEventRepository(
 
     fun send(chatId: String, message: Message)
             = remoteSource.send(chatId, message)
+
+    fun getHistoricChatEvents(chatId: String, from: ChatEvent)
+            = remoteSource.getHistoricChatEvents(chatId, from)
 }
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/data/chat/event/ChatEventSource.kt

@@ -25,4 +25,6 @@ import io.reactivex.Flowable
 
 interface ChatEventSource {
     fun getChatEvents(chatId: String): Flowable<List<ChatEvent>>
+
+    fun getHistoricChatEvents(chatId: String, from: ChatEvent): Flowable<List<ChatEvent>>
 }
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/data/chat/event/model/ChatEvent.kt

@@ -29,6 +29,10 @@ abstract class ChatEvent {
     abstract val id: String
     abstract val sentAt: Date
     abstract val sender: User?
+    /**
+     * Underlying Matrix SDK event.
+     */
+    abstract val original: Event
 
     override fun equals(other: Any?): Boolean {
         return when (other) {
@@ -66,6 +70,7 @@ fun Event.toChatEvent(room: Room): ChatEvent? {
                             id = id,
                             sentAt = sentAt,
                             sender = sender,
+                            original = this,
                             text = text
                     )
                 }
@@ -74,6 +79,7 @@ fun Event.toChatEvent(room: Room): ChatEvent? {
                             id = id,
                             sentAt = sentAt,
                             sender = sender,
+                            original = this,
                             text = text
                     )
                 }
@@ -83,6 +89,7 @@ fun Event.toChatEvent(room: Room): ChatEvent? {
                             id = id,
                             sentAt = sentAt,
                             sender = sender,
+                            original = this,
                             text = text
                     )
                 }
@@ -108,6 +115,7 @@ fun Event.toChatEvent(room: Room): ChatEvent? {
                     sentAt = sentAt,
                     sender = sender,
                     subject = subject,
+                    original = this,
                     type = type
             )
         }
@@ -136,7 +144,8 @@ fun Event.toChatEvent(room: Room): ChatEvent? {
             EncryptedChatMessage(
                     id = eventId,
                     sentAt = sentAt,
-                    sender = sender
+                    sender = sender,
+                    original = this
             )
         }
         else -> {
@@ -144,6 +153,7 @@ fun Event.toChatEvent(room: Room): ChatEvent? {
                 override val id = eventId
                 override val sentAt = sentAt
                 override val sender = sender
+                override val original = this@toChatEvent
             }
         }
     }

app/src/main/kotlin/im/pattle/app/data/chat/event/model/ChatMessage.kt

@@ -19,6 +19,7 @@
 package im.pattle.app.data.chat.event.model
 
 import im.pattle.app.data.user.User
+import org.matrix.androidsdk.rest.model.Event
 import java.util.*
 
 enum class MessageType {
@@ -34,6 +35,7 @@ interface Message {
 open class ChatMessage(override val id: String,
                        override val sentAt: Date,
                        override val sender: User,
+                       override val original: Event,
                        override val text: String) : ChatEvent(), Message {
     override val type = MessageType.MESSAGE
 }
@@ -41,4 +43,6 @@ open class ChatMessage(override val id: String,
 data class EncryptedChatMessage(override val id: String,
                                 override val sentAt: Date,
                                 override val sender: User,
-                                override val text: String = "") : ChatMessage(id, sentAt, sender, text)
\ No newline at end of file
+                                override val original: Event,
+                                override val text: String = "")
+    : ChatMessage(id, sentAt, sender, original, text)
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/data/chat/event/model/ChatNotice.kt

@@ -19,12 +19,14 @@
 package im.pattle.app.data.chat.event.model
 
 import im.pattle.app.data.user.User
+import org.matrix.androidsdk.rest.model.Event
 import java.util.*
 
 data class ChatNotice(override val id: String,
                       override val sentAt: Date,
                       override val sender: User,
+                      override val original: Event,
                       override val text: String)
-    : ChatMessage(id, sentAt, sender, text) {
+    : ChatMessage(id, sentAt, sender, original, text) {
     override val type = MessageType.NOTICE
 }
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/data/chat/event/model/MemberChangeEvent.kt

@@ -19,6 +19,7 @@
 package im.pattle.app.data.chat.event.model
 
 import im.pattle.app.data.user.User
+import org.matrix.androidsdk.rest.model.Event
 import java.util.*
 
 enum class MemberChangeType {
@@ -32,6 +33,7 @@ enum class MemberChangeType {
 data class MemberChangeEvent(override val id: String,
                              override val sentAt: Date,
                              override val sender: User,
+                             override val original: Event,
                              val subject: User,
                              val type: MemberChangeType)
     : ChatEvent()
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/data/chat/event/model/TypingEvent.kt

 package im.pattle.app.data.chat.event.model
 
 import im.pattle.app.data.user.User
+import org.matrix.androidsdk.rest.model.Event
 import java.util.*
 
 /**
@@ -20,4 +21,9 @@ data class TypingEvent(val users: List<User>) : ChatEvent() {
     override lateinit var sentAt: Date
 
     override val sender: User? = null
+
+    /**
+     * Should be ignored.
+     */
+    override lateinit var original: Event
 }
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/ui/main/chat/ChatFragment.kt

@@ -23,6 +23,8 @@ import android.os.Bundle
 import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
+import android.view.View.GONE
+import android.view.View.VISIBLE
 import android.view.ViewGroup
 import android.view.WindowManager
 import androidx.appcompat.app.ActionBar
@@ -30,11 +32,13 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.LinearLayoutManager
 import im.pattle.app.R
+import im.pattle.app.data.chat.event.model.ChatEvent
 import im.pattle.app.data.chat.event.model.ChatMessage
 import im.pattle.app.data.chat.event.model.Message
 import im.pattle.app.data.chat.event.model.MessageType
 import im.pattle.app.ui.base.BaseFragment
 import im.pattle.app.ui.util.ImageLoader
+import im.pattle.app.ui.util.PaginatingScrollListener
 import im.pattle.app.ui.util.toPx
 import io.reactivex.rxkotlin.addTo
 import io.reactivex.rxkotlin.subscribeBy
@@ -67,6 +71,22 @@ class ChatFragment : BaseFragment<ChatViewModel>() {
         Unit
     }
 
+    private val onShouldPaginate = {
+        val from = adapter.items.filterIsInstance<ChatEvent>().first()
+
+        progressBar.visibility = VISIBLE
+        model.getHistoricChatEvents(from)
+                .subscribe {
+                    runOnUiThread {
+                        adapter.submitList(it)
+                        progressBar.visibility = GONE
+                    }
+                }
+                .addTo(compDisposable)
+
+        Unit
+    }
+
     override fun onAttach(context: Context?) {
         super.onAttach(context)
 
@@ -95,6 +115,7 @@ class ChatFragment : BaseFragment<ChatViewModel>() {
 
         view.chatEventsView.layoutManager = layoutManager
         view.chatEventsView.adapter = adapter
+        view.chatEventsView.addOnScrollListener(PaginatingScrollListener(onShouldPaginate))
 
         view.toolbar.title = model.chatName
 
@@ -113,7 +134,7 @@ class ChatFragment : BaseFragment<ChatViewModel>() {
                         onNext = {
                             runOnUiThread {
                                 adapter.submitList(it)
-                                view.chatEventsView.smoothScrollToPosition(adapter.itemCount - 1)
+                                //view.chatEventsView.smoothScrollToPosition(adapter.itemCount - 1)
                             }
                         }
                 )

app/src/main/kotlin/im/pattle/app/ui/main/chat/ChatViewModel.kt

@@ -35,5 +35,8 @@ class ChatViewModel(private val eventRepo: ChatEventRepository,
 
     fun getChatEvents() = eventRepo.getChatEvents(chatId)
 
+    fun getHistoricChatEvents(from: ChatEvent)
+            = eventRepo.getHistoricChatEvents(chatId, from)
+
     fun send(message: Message) = eventRepo.send(chatId, message)
 }
\ No newline at end of file

app/src/main/kotlin/im/pattle/app/ui/util/PaginatingScrollListener.kt

+package im.pattle.app.ui.util
+
+import android.util.Log
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.RecyclerView.SCROLL_STATE_DRAGGING
+import androidx.recyclerview.widget.RecyclerView.SCROLL_STATE_SETTLING
+
+class PaginatingScrollListener(val onShouldPaginate: () -> Unit) : RecyclerView.OnScrollListener() {
+
+    private var scrollingUp = false
+
+    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
+        super.onScrolled(recyclerView, dx, dy)
+
+        scrollingUp = dy < 0
+    }
+
+    override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
+        super.onScrollStateChanged(recyclerView, newState)
+
+        val layoutManager = recyclerView.layoutManager as LinearLayoutManager
+
+        if (layoutManager.findFirstCompletelyVisibleItemPosition() == 0
+        && (newState == SCROLL_STATE_DRAGGING
+         || newState == SCROLL_STATE_SETTLING)
+        && scrollingUp) {
+            onShouldPaginate()
+            Log.d("PAGINATE!", "please")
+        }
+    }
+}
\ No newline at end of file

app/src/main/res/layout/fragment_chat.xml

@@ -79,4 +79,20 @@ along with Pattle.  If not, see <https://www.gnu.org/licenses/>.
             android:inputType="textAutoComplete" />
     </com.google.android.material.textfield.TextInputLayout>
 
+    <ProgressBar
+        android:id="@+id/progressBar"
+        style="?android:attr/progressBarStyle"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
+        android:layout_marginLeft="8dp"
+        android:layout_marginTop="16dp"
+        android:layout_marginEnd="8dp"
+        android:layout_marginRight="8dp"
+        android:indeterminate="true"
+        android:visibility="gone"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="@+id/chatEventsView" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file