Show playing tab when current chapter is tapped

[ashiagr]

Fixes #41

Description

Clicking a current chapter would start the chapter from the beginning. This PR addresses the issue by navigating to the "Now Playing" tab if the chapter clicked is the current one.

show-player-tab-on-current-chapter-click.mp4

P.S. I updated ListData UI state with the showPlayer value based on this principle:

UI actions that originate from the ViewModel—ViewModel events—should always result in a UI state update.

I couldn't find a good example in the existing code for handling ViewModel events. So feel free to point me in the right direction. 😅

Checklist

• Should this change be included in the release notes? If yes, please add a line in RELEASE-NOTES.md
• Have you tested in landscape?
• Have you tested accessibility with TalkBack?
• Have you tested in different themes?
• Does the change work with a large display font?
• Are all the strings localized?
• Could you have written any new tests?
• Did you include Compose previews with any components?

[geekygecko]

I haven't used it before but is this where you could use one of the new SharedFlow classes?

[ashiagr]

Yeah, SharedFlow can be a good candidate here. Thanks for suggesting it. Used it in e058f41.

[geekygecko]

I wonder if it's possible to get the current chapter with the data already in the PlayerViewModel.

    fun onChapterClick(chapter: Chapter) {
        launch {
            val listData = listDataLive.value
            if (listData?.isSameChapter(chapter) == true) {
                showPlayerObservable.accept(true)
            } else {
                playbackManager.skipToChapter(chapter)
            }
        }
    }

    data class ListData(
        var podcastHeader: PlayerHeader,
        var chaptersExpanded: Boolean,
        var chapters: List<Chapter>,
        var currentChapter: Chapter?,
        var upNextExpanded: Boolean,
        var upNextEpisodes: List<Playable>,
        var upNextSummary: UpNextSummary,
        var showPlayer: Boolean,
    ) {
        fun isSameChapter(chapter: Chapter) = currentChapter?
           .let { it.index == chapter.index } ?: false
    }

        val currentChapter = playbackState.chapters.getChapter(playbackState.positionMs)

[ashiagr]

This looks better, see in fb81785.