move some player data to PlayerViewModel

app/src/main/java/org/mosad/teapod/player/PlayerViewModel.kt

@@ -0,0 +1,58 @@
+package org.mosad.teapod.player
+
+import androidx.lifecycle.ViewModel
+import org.mosad.teapod.parser.AoDParser
+import org.mosad.teapod.ui.fragments.MediaFragment
+import org.mosad.teapod.util.DataTypes
+import org.mosad.teapod.util.Episode
+import org.mosad.teapod.util.Media
+
+class PlayerViewModel : ViewModel() {
+
+    var mediaId = 0
+        internal set
+    var episodeId = 0
+        internal set
+
+    var media: Media = Media(0, "", DataTypes.MediaType.OTHER)
+        internal set
+    var currentEpisode = Episode()
+        internal set
+    var nextEpisode: Episode? = null
+        internal set
+
+    fun loadMedia(iMediaId: Int, iEpisodeId: Int) {
+        mediaId = iMediaId
+        episodeId = iEpisodeId
+
+        media = AoDParser.getMediaById(mediaId)
+        currentEpisode = media.episodes.first { it.id == episodeId }
+        nextEpisode = selectNextEpisode()
+    }
+
+    /**
+     * update currentEpisode, episodeId, nextEpisode to new episode
+     * updateWatchedState for the next (now current) episode
+     */
+    fun nextEpisode() = nextEpisode?.let { nextEp ->
+        currentEpisode = nextEp // set current ep to next ep
+        episodeId = nextEp.id
+        MediaFragment.instance.updateWatchedState(nextEp) // watchedCallback for next ep
+
+        nextEpisode = selectNextEpisode()
+    }
+
+    /**
+     * Based on the current episodeId, get the next episode. If there is no next
+     * episode, return null
+     */
+    private fun selectNextEpisode(): Episode? {
+        val nextEpIndex = media.episodes.indexOfFirst { it.id == currentEpisode.id } + 1
+        return if (nextEpIndex < (media.episodes.size)) {
+            media.episodes[nextEpIndex]
+        } else {
+            null
+        }
+    }
+
+}