[Android auto] first instruction fix

[korshaknn]

Description

This PR fixes an issue when the first instruction is not played.
It's related to libnavui-androidauto module only and can be tested with 1Tap.
Also it might be useful to have some activity (or a separate test app?) in examples to test libnavui-androidauto module.

issue details:

• when routes observer triggered we cancel previous voice instructions flow, create a new flow with a new instructions observer
• new instructions observer ^^ created too late and we lost the first instruction

changes:

• start/stop listening for routes, instructions, tripSessionState on attach/detach
• pass values ^^ to flows stored in MapboxAudioGuidanceServicesImpl

[korshaknn]

not sure about the changelog, do we need it?

[LukasPaczos]

not sure about the changelog, do we need it?

We have a separate file in libnavui-androidauto/CHANGELOG.md, could you move the note there?

[codecov]

Codecov Report

Merging #5825 (3a78af2) into main (4a2600b) will not change coverage.
The diff coverage is n/a.

❗ Current head 3a78af2 differs from pull request most recent head 22417e2. Consider uploading reports for the commit 22417e2 to get more accurate results

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[kmadsen]

Is this the fix to convert the underlying flowables into hot flowable? Meaning, they stay subscribed even after the top level is unsubscribed.

This also means that the MapboxAudioGuidance observer cannot be unsubscribed entirely. The developer would have no way to unregister this class besides the MapboxNavigationApp lifecycle ending

[kmadsen]

MapboxNavigationApp.unregisterObserver(mapboxAudioGuidance) should also unregister all of the observers it is responsible for.

[kmadsen]

I've considered this issue before but haven't added support for it. I'd like to make it difficult to create leaking subscriptions with MapboxNavigationApp #5829

With 5829, we could turn MapboxVoiceInstructions into an object and make it so it is the only subscriber. In case there are too many issues trying to unregister MapboxNavigation when MapboxNavigationApp.unregisterObserver(mapboxAudioGuidance) is called.

[kmadsen]

Also it might be useful to have some activity (or a separate test app?) in examples to test libnavui-androidauto module.

Side note, yeah this is happening. We're consolidating 1tap, drop-in-ui, and android-auto implementations for audio guidance. Essentially, all examples will use the same implementation. Right now it is in transition, sorry the qa-test-app support at the moment is lacking.

[kmadsen]

https://github.com/mapbox/mapbox-navigation-android/pull/5825/files#r876477888

Sorry it is a confusing because MapboxCarApp controls a single subscription by subscribing and never unsubscribing from MapboxAudioGuidance (at the moment).

MapboxAudioGuidance is not actually a singleton. Doing something like this should not leak subscriptions.

audioGuidance: MapboxAudioGuidance = MapboxAudioGuidanceImpl(...)
MapboxNavigationApp.registerObserver(audioGuidance)
MapboxNavigationApp.unregisterObserver(audioGuidance)
audioGuidance: MapboxAudioGuidance = MapboxAudioGuidanceImpl(...)
MapboxNavigationApp.registerObserver(audioGuidance)
MapboxNavigationApp.unregisterObserver(audioGuidance)

[korshaknn]

@kmadsen thanks for the feedback!

Is this the fix to convert the underlying flowables into hot flowable? Meaning, they stay subscribed even after the top level is unsubscribed.

yes, we need it because with cold flows we miss the first instruction.

MapboxNavigationApp.unregisterObserver(mapboxAudioGuidance) should also unregister all of the observers it is responsible for.

fixed with

override fun onAttached(mapboxNavigation: MapboxNavigation) {
        mapboxVoiceInstructions.registerObservers(mapboxNavigation)
        job = scope.launch { audioGuidanceFlow(mapboxNavigation).collect() }
}

override fun onDetached(mapboxNavigation: MapboxNavigation) {
        mapboxVoiceInstructions.unregisterObservers(mapboxNavigation)
        job?.cancel()
        job = null
}

also MapboxVoiceInstructions is not a MapboxNavigationObserver anymore, so we need to manually register/unregister observers like we do it in MapboxAudioGuidanceImpl.
I think we should be good with it at least for now, MapboxVoiceInstructions is only used in MapboxAudioGuidanceImpl.

[kmadsen]

LGTM