Fix offline player play/pause button

app/src/main/java/com/github/libretube/ui/activities/OfflinePlayerActivity.kt

@@ -13,6 +13,7 @@ import androidx.activity.viewModels
 import androidx.core.view.WindowCompat
 import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.WindowInsetsControllerCompat
+import com.github.libretube.R
 import com.github.libretube.constants.IntentData
 import com.github.libretube.databinding.ActivityOfflinePlayerBinding
 import com.github.libretube.databinding.ExoStyledPlayerControlViewBinding
@@ -23,6 +24,7 @@ import com.github.libretube.util.DownloadHelper
 import com.github.libretube.util.PlayerHelper
 import com.google.android.exoplayer2.ExoPlayer
 import com.google.android.exoplayer2.MediaItem
+import com.google.android.exoplayer2.Player
 import com.google.android.exoplayer2.source.MergingMediaSource
 import com.google.android.exoplayer2.source.ProgressiveMediaSource
 import com.google.android.exoplayer2.ui.StyledPlayerView
@@ -70,6 +72,19 @@ class OfflinePlayerActivity : BaseActivity() {
         playerBinding.closeImageButton.setOnClickListener {
             finish()
         }
+        playerBinding.playPauseBTN.setOnClickListener {
+            if (!player.isPlaying) {
+                // start or go on playing
+                if (player.playbackState == Player.STATE_ENDED) {
+                    // restart video if finished
+                    player.seekTo(0)
+                }
+                player.play()
+            } else {
+                // pause the video
+                player.pause()
+            }
+        }
 
         binding.player.initialize(
             null,
@@ -77,6 +92,33 @@ class OfflinePlayerActivity : BaseActivity() {
             binding.playerGestureControlsView.binding,
             null
         )
+
+        player.addListener(object : Player.Listener {
+            override fun onEvents(player: Player, events: Player.Events) {
+                super.onEvents(player, events)
+                if (events.containsAny(
+                        Player.EVENT_PLAYBACK_STATE_CHANGED,
+                        Player.EVENT_IS_PLAYING_CHANGED,
+                        Player.EVENT_PLAY_WHEN_READY_CHANGED
+                    )
+                ) {
+                    updatePlayPauseButton()
+                }
+            }
+        })
+    }
+
+    private fun updatePlayPauseButton() {
+        if (player.isPlaying) {
+            // video is playing
+            playerBinding.playPauseBTN.setImageResource(R.drawable.ic_pause)
+        } else if (player.playbackState == Player.STATE_ENDED) {
+            // video has finished
+            playerBinding.playPauseBTN.setImageResource(R.drawable.ic_restart)
+        } else {
+            // player in any other state
+            playerBinding.playPauseBTN.setImageResource(R.drawable.ic_play)
+        }
     }
 
     private fun File.toUri(): Uri? {