save audio message id and position when activity is destroyed,

also restores view position to that message and then resumes audio playback if was playing.
it allows to continue playing audio on screen rotation.

Signed-off-by: Giacomo Pacini <giacomopacini98@gmail.com>

app/src/main/java/com/nextcloud/talk/chat/ChatActivity.kt

@@ -11,6 +11,7 @@
  * Copyright (C) 2021-2022 Marcel Hibbe <dev@mhibbe.de>
  * Copyright (C) 2017-2019 Mario Danic <mario@lovelyhq.com>
  * Copyright (C) 2023 Ezhil Shanmugham <ezhil56x.contact@gmail.com>
+ * Copyright (C) 2024 Giacomo Pacini <giacomo@paciosoft.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -420,6 +421,14 @@ class ChatActivity :
 
     var callStarted = false
 
+    private val CURRENT_AUDIO_MESSAGE_KEY = "CURRENT_AUDIO_MESSAGE"
+    private val CURRENT_AUDIO_POSITION_KEY = "CURRENT_AUDIO_POSITION"
+    private val CURRENT_AUDIO_WAS_PLAYING_KEY = "CURRENT_AUDIO_PLAYING"
+    private var RESUME_AUDIO_TAG = "RESUME_AUDIO_TAG"
+    private var voiceMessageToRestoreId = ""
+    private var voiceMessageToRestoreAudioPosition = 0
+    private var voiceMessageToRestoreWasPlaying = false
+
     private val localParticipantMessageListener = object : SignalingMessageReceiver.LocalParticipantMessageListener {
         override fun onSwitchTo(token: String?) {
             if (token != null) {
@@ -490,6 +499,31 @@ class ChatActivity :
         onBackPressedDispatcher.addCallback(this, onBackPressedCallback)
 
         initObservers()
+
+        if (savedInstanceState != null) {
+            // Restore value of members from saved state
+            var voiceMessageId = savedInstanceState.getString(CURRENT_AUDIO_MESSAGE_KEY, "")
+            var voiceMessagePosition = savedInstanceState.getInt(CURRENT_AUDIO_POSITION_KEY, 0)
+            var wasAudioPLaying = savedInstanceState.getBoolean(CURRENT_AUDIO_WAS_PLAYING_KEY, false)
+            if( ! voiceMessageId.equals("")) {
+                Log.d(RESUME_AUDIO_TAG, "restored voice messageID: " + voiceMessageId)
+                Log.d(RESUME_AUDIO_TAG, "audio position: " + voiceMessagePosition)
+                Log.d(RESUME_AUDIO_TAG, "audio was playing: " + wasAudioPLaying.toString())
+                voiceMessageToRestoreId = voiceMessageId
+                voiceMessageToRestoreAudioPosition = voiceMessagePosition
+                voiceMessageToRestoreWasPlaying = wasAudioPLaying
+            }else{
+                Log.d(RESUME_AUDIO_TAG, "stored voice message id is empty, not resuming audio playing")
+                voiceMessageToRestoreId = ""
+                voiceMessageToRestoreAudioPosition = 0
+                voiceMessageToRestoreWasPlaying = false
+            }
+
+        }else{
+            voiceMessageToRestoreId = ""
+            voiceMessageToRestoreAudioPosition = 0
+            voiceMessageToRestoreWasPlaying = false
+        }
     }
 
     override fun onNewIntent(intent: Intent) {
@@ -551,6 +585,21 @@ class ChatActivity :
         this.lifecycle.addObserver(ChatViewModel.LifeCycleObserver)
     }
 
+    override fun onSaveInstanceState(outState: Bundle) {
+        if(currentlyPlayedVoiceMessage != null) {
+            // stores audio message ID and audio position
+            // so that can be restored in resumeAudioPlaybackIfNeeded method
+            outState.putString( CURRENT_AUDIO_MESSAGE_KEY, currentlyPlayedVoiceMessage!!.getId())
+            outState.putInt(CURRENT_AUDIO_POSITION_KEY, currentlyPlayedVoiceMessage!!.voiceMessagePlayedSeconds)
+            outState.putBoolean(CURRENT_AUDIO_WAS_PLAYING_KEY, currentlyPlayedVoiceMessage!!.isPlayingVoiceMessage)
+            Log.d(RESUME_AUDIO_TAG, "Stored current audio message ID: " + currentlyPlayedVoiceMessage!!.getId())
+            Log.d(RESUME_AUDIO_TAG, "Audio Position: " + currentlyPlayedVoiceMessage!!.voiceMessagePlayedSeconds
+                .toString() + " | isPLaying: " + currentlyPlayedVoiceMessage!!.isPlayingVoiceMessage)
+            // stores also audio currently playing status
+        }
+        super.onSaveInstanceState(outState)
+    }
+
     override fun onStop() {
         super.onStop()
         active = false
@@ -1350,7 +1399,7 @@ class ChatActivity :
         }
     }
 
-    private fun setUpWaveform(message: ChatMessage) {
+    private fun setUpWaveform(message: ChatMessage, thenPlay : Boolean = true) {
         val filename = message.selectedIndividualHashMap!!["name"]
         val file = File(context.cacheDir, filename!!)
         if (file.exists() && message.voiceMessageFloatArray == null) {
@@ -1361,11 +1410,11 @@ class ChatActivity :
                 appPreferences.saveWaveFormForFile(filename, r.toTypedArray())
                 message.voiceMessageFloatArray = r
                 withContext(Dispatchers.Main) {
-                    startPlayback(message)
+                    startPlayback(message, thenPlay)
                 }
             }
         } else {
-            startPlayback(message)
+            startPlayback(message, thenPlay)
         }
     }
 
@@ -2319,7 +2368,7 @@ class ChatActivity :
         }
     }
 
-    private fun startPlayback(message: ChatMessage) {
+    private fun startPlayback(message: ChatMessage, doPlay : Boolean = true) {
         if (!active) {
             // don't begin to play voice message if screen is not visible anymore.
             // this situation might happen if file is downloading but user already left the chatview.
@@ -2331,7 +2380,7 @@ class ChatActivity :
         initMediaPlayer(message)
 
         mediaPlayer?.let {
-            if (!it.isPlaying) {
+            if (!it.isPlaying && doPlay) {
                 audioFocusRequest(true) {
                     it.start()
                     handleBecomingNoisyBroadcast(register = true)
@@ -2363,7 +2412,11 @@ class ChatActivity :
             })
 
             message.isDownloadingVoiceMessage = false
-            message.isPlayingVoiceMessage = true
+            message.isPlayingVoiceMessage = doPlay
+            //message.voiceMessagePlayedSeconds = lastRecordMediaPosition / VOICE_MESSAGE_SEEKBAR_BASE
+            //message.voiceMessageSeekbarProgress = lastRecordMediaPosition
+            // the commented instructions objective was to update audio seekbarprogress
+            // in the case in which audio status is paused when the position is resumed
             adapter?.update(message)
         }
     }
@@ -2406,6 +2459,8 @@ class ChatActivity :
                                 lastRecordedSeeked = true
                             }
                         }
+                        // this ensures that audio can be resumed at a given position
+                        this.seekTo(lastRecordMediaPosition)
                     }
                     setOnCompletionListener {
                         stopMediaPlayer(message)
@@ -2424,6 +2479,7 @@ class ChatActivity :
         adapter?.update(message)
 
         currentlyPlayedVoiceMessage = null
+        lastRecordMediaPosition = 0 //this ensures that if audio track is changed, then it is played from the beginning
 
         mediaPlayerHandler.removeCallbacksAndMessages(null)
 
@@ -3753,6 +3809,9 @@ class ChatActivity :
             adapter?.addToEnd(chatMessageList, false)
         }
         scrollToRequestedMessageIfNeeded()
+        //FENOM: add here audio resume policy
+        resumeAudioPlaybackIfNeeded()
+
     }
 
     private fun scrollToFirstUnreadMessage() {
@@ -3857,6 +3916,52 @@ class ChatActivity :
         }
     }
 
+    /**
+     * this method must be called after that the adatper has finished loading ChatMessages items
+     * it searches by ID the message that was playing,
+     * then, if it finds it, it restores audio position
+     * and eventually resumes audio playback
+     * @author Giacomo Pacini
+     */
+    private fun resumeAudioPlaybackIfNeeded(){
+        if( ! voiceMessageToRestoreId.equals("")) {
+            Log.d(RESUME_AUDIO_TAG, "begin method to resume audio playback")
+
+            if (adapter != null) {
+                Log.d(RESUME_AUDIO_TAG, "adapter is not null, proceeding")
+                val voiceMessagePosition = adapter!!.items!!.indexOfFirst {
+                    it.item is ChatMessage && (it.item as ChatMessage).id == voiceMessageToRestoreId
+                }
+                if(voiceMessagePosition >= 0) {
+                    val currentItem = adapter?.items?.get(voiceMessagePosition)?.item
+                    if (currentItem is ChatMessage && currentItem.id == voiceMessageToRestoreId) {
+                        currentlyPlayedVoiceMessage = currentItem
+                        lastRecordMediaPosition = voiceMessageToRestoreAudioPosition * 1000
+                        Log.d(RESUME_AUDIO_TAG, "trying to resume audio")
+                        binding.messagesListView.scrollToPosition(voiceMessagePosition)
+                        // WORKAROUND TO FETCH FILE INFO:
+                        currentlyPlayedVoiceMessage!!.getImageUrl()
+                        // see getImageUrl() source code
+                        setUpWaveform(currentlyPlayedVoiceMessage!!, voiceMessageToRestoreWasPlaying)
+                        Log.d(RESUME_AUDIO_TAG, "resume audio procedure completed")
+                    } else {
+                        Log.d(RESUME_AUDIO_TAG, "currentItem retrieved was not chatmessage or its id was not correct")
+                    }
+                }else{
+                    Log.d(RESUME_AUDIO_TAG, "voiceMessagePosition is -1, adapter # of items: " + adapter!!.getItemCount())
+                }
+            } else {
+                Log.d(RESUME_AUDIO_TAG, "TalkMessagesListAdapater is null")
+            }
+        }else{
+            Log.d(RESUME_AUDIO_TAG, "No voice message to restore")
+        }
+        voiceMessageToRestoreId = ""
+        voiceMessageToRestoreAudioPosition = 0
+        voiceMessageToRestoreWasPlaying = false
+
+    }
+
     private fun scrollToRequestedMessageIfNeeded() {
         intent.getStringExtra(BundleKeys.KEY_MESSAGE_ID)?.let {
             scrollToMessageWithId(it)