Always save series audio & subtitle preferences regardless of preferred languages (#473)

## Description

This PR adjust the logic for audio & subtitle track selection for TV
series. Instead of only saving for future episodes if the newly selected
track is a different language than the user's preferred, always save it.

Basically this means if you change the audio or subtitle language for an
episode, the same audio or subtitle language will be used for future
episodes (if available).

Also, fixes the "default" subtitle mode to take the user's preferred
language into consideration.

## Issues
Follow up to https://github.com/damontecres/Wholphin/issues/378 &
https://github.com/damontecres/Wholphin/issues/427

Fixes #469

app/src/main/java/com/github/damontecres/wholphin/data/ItemPlaybackRepository.kt

@@ -134,9 +134,8 @@ class ItemPlaybackRepository
                 val seriesId = item.data.seriesId
                 if (seriesId != null && trackIndex != TrackIndex.UNSPECIFIED) {
                     if (type == MediaStreamType.AUDIO) {
-                        val audioLang = current.userDto.configuration?.audioLanguagePreference
                         val stream = source.mediaStreams?.first { it.index == trackIndex }
-                        if (stream?.language != null && stream.language != audioLang) {
+                        if (stream?.language != null) {
                             streamChoiceService.updateAudio(item.data, stream.language!!)
                         }
                     } else if (type == MediaStreamType.SUBTITLE) {
@@ -147,10 +146,8 @@ class ItemPlaybackRepository
                                 subtitlesDisabled = true,
                             )
                         } else {
-                            val subtitleLang =
-                                current.userDto.configuration?.subtitleLanguagePreference
                             val stream = source.mediaStreams?.first { it.index == trackIndex }
-                            if (stream?.language != null && stream.language != subtitleLang) {
+                            if (stream?.language != null) {
                                 streamChoiceService.updateSubtitles(
                                     item.data,
                                     stream.language!!,

app/src/main/java/com/github/damontecres/wholphin/services/StreamChoiceService.kt

@@ -114,16 +114,11 @@ class StreamChoiceService
             if (itemPlayback?.audioIndexEnabled == true) {
                 candidates.firstOrNull { it.index == itemPlayback.audioIndex }
             } else {
-                // TODO audio selection based on channel layout or preferences or default
+                val seriesLang =
-                val audioLanguage =
+                    playbackLanguageChoice?.audioLanguage?.takeIf { it.isNotNullOrBlank() }
-                    if (prefs.userConfig.audioLanguagePreference.isNotNullOrBlank()) {
+                // If the user has chosen a different language for the series, prefer that
-                        // If the user has chosen a preferred language, but changed tracks on the series, use that
+                val audioLanguage = seriesLang ?: prefs.userConfig.audioLanguagePreference
-                        // Otherwise, use their preferred language
+
-                        playbackLanguageChoice?.audioLanguage
-                            ?: prefs.userConfig.audioLanguagePreference
-                    } else {
-                        null
-                    }
                 if (audioLanguage.isNotNullOrBlank()) {
                     val sorted =
                         candidates.sortedWith(compareBy<MediaStream> { it.language }.thenByDescending { it.channels })
@@ -176,27 +171,21 @@ class StreamChoiceService
             } else if (itemPlayback?.subtitleIndexEnabled == true) {
                 return candidates.firstOrNull { it.index == itemPlayback.subtitleIndex }
             } else {
+                val seriesLang =
+                    playbackLanguageChoice?.subtitleLanguage?.takeIf { it.isNotNullOrBlank() }
                 val subtitleLanguage =
-                    if (prefs.userConfig.subtitleLanguagePreference.isNotNullOrBlank()) {
+                    (seriesLang ?: prefs.userConfig.subtitleLanguagePreference)
-                        // If the user has chosen a preferred language, but changed tracks on the series, use that
+                        ?.takeIf { it.isNotNullOrBlank() }
-                        // Otherwise, use their preferred language
-                        playbackLanguageChoice?.subtitleLanguage
-                            ?: prefs.userConfig.subtitleLanguagePreference
-                    } else {
-                        null
-                    }
 
                 val subtitleMode =
                     when {
-                        playbackLanguageChoice?.subtitlesDisabled == false &&
+                        playbackLanguageChoice?.subtitlesDisabled == false && seriesLang != null -> {
-                            playbackLanguageChoice.subtitleLanguage != null &&
+                            // User has chosen a series level subtitle language, so override their normal
-                            subtitleLanguage.isNotNullOrBlank() -> {
+                            // subtitle mode to display that language
-                            // User has a subtitle language preference, but has chosen a different language for the series
-                            // So override their normal playback mode to always display subtitles
                             SubtitlePlaybackMode.ALWAYS
                         }
 
-                        playbackLanguageChoice?.subtitlesDisabled == true -> {
+                        playbackLanguageChoice?.subtitlesDisabled == true && seriesLang == null -> {
                             // Series level settings disables subtitles
                             SubtitlePlaybackMode.NONE
                         }
@@ -234,8 +223,16 @@ class StreamChoiceService
                     }
 
                     SubtitlePlaybackMode.DEFAULT -> {
-                        // TODO check for language?
+                        subtitleLanguage?.let { lang ->
+                            // Find best track that is in the preferred language
                             (
+                                candidates.firstOrNull { it.isDefault && it.isForced && it.language == lang }
+                                    ?: candidates.firstOrNull { it.isDefault && it.language == lang }
+                                    ?: candidates.firstOrNull { it.isForced && it.language == lang }
+                            )
+                        }
+                            ?: (
+                                // If none in preferred language, just find the best track
                                 candidates.firstOrNull { it.isDefault && it.isForced }
                                     ?: candidates.firstOrNull { it.isDefault }
                                     ?: candidates.firstOrNull { it.isForced }