LocalPlaybackGate.kt

104 lines · 3.9 KB

Changed in: 0.5.0

1	package dev.stave.playback
2
3	import dev.stave.cast.raw.CastObserverApi
4	import dev.stave.ui.events.UiEvents
5	import kotlinx.coroutines.CancellationException
6	import kotlinx.coroutines.CoroutineScope
7	import kotlinx.coroutines.Dispatchers
8	import kotlinx.coroutines.SupervisorJob
9	import kotlinx.coroutines.flow.MutableStateFlow
10	import kotlinx.coroutines.flow.StateFlow
11	import kotlinx.coroutines.flow.asStateFlow
12	import kotlinx.coroutines.launch
13
14	/**
15	* "Stop following and play here?" — ported from Android on the maintainer's
16	* answer 4 (2026-09-04). Every action that would start local audio while the
17	* desktop is following the group parks here until the person answers. Yes:
18	* stop following, run the action. No: nothing happens, the follow continues.
19	* When not following, the action runs at once.
20	*
21	* Starters that go through here (audit, as on Android 2026-09-02): Party /
22	* random tracks, playlists, Now Playing's play/enqueue-and-play, and every
23	* Browse starter — play a track in context, Play all on a container, the
24	* per-genre "Play 42 random…", and Play next into an EMPTY queue (that
25	* starts audio). Deliberately not gated: Add to queue, and Play next onto a
26	* non-empty queue — they don't start audio.
27	*/
28	class LocalPlaybackGate(
29	private val rawCast: CastObserverApi,
30	private val uiEvents: UiEvents? = null,
31	) {
32	private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
33	private var pending: (suspend () -> Unit)? = null
34
35	/** Runs after the parked/immediate action has actually run (Android's
36	* hook so a screen can navigate only when something played; I.69 /
37	* Android review N.31). Dropped with the action on [dismiss]. */
38	private var pendingOnRan: (() -> Unit)? = null
39
40	private val _confirmVisible = MutableStateFlow(false)
41	val confirmVisible: StateFlow<Boolean> = _confirmVisible.asStateFlow()
42
43	// Parameter order matters (Android note): Kotlin gives a trailing lambda
44	// to the LAST parameter, so `request { … }` is the action and
45	// `request(onRan) { … }` adds the completion.
46	fun request(onRan: (() -> Unit)? = null, action: suspend () -> Unit) {
47	if (!rawCast.observing.value) {
48	run(action, onRan)
49	return
50	}
51	pending = action
52	pendingOnRan = onRan
53	_confirmVisible.value = true
54	}
55
56	fun confirm() {
57	_confirmVisible.value = false
58	rawCast.disconnect()
59	val action = pending
60	val onRan = pendingOnRan
61	pending = null
62	pendingOnRan = null
63	action?.let { run(it, onRan) }
64	}
65
66	fun dismiss() {
67	pending = null
68	pendingOnRan = null
69	_confirmVisible.value = false
70	}
71
72	private fun run(action: suspend () -> Unit, onRan: (() -> Unit)?) {
73	scope.launch {
74	try {
75	action()
76	} catch (c: CancellationException) {
77	throw c
78	} catch (t: Throwable) {
79	// Was a silent printStackTrace (Team 5 V12): say something.
80	System.err.println("[Earhorn/Gate] gated action threw (${t.javaClass.simpleName}):")
81	t.printStackTrace(System.err)
82	uiEvents?.post(MSG_FAILED)
83	return@launch
84	}
85	runOnRan(onRan)
86	}
87	}
88
89	/** Run [onRan], logging and dropping a failure — this scope outlives the
90	* UI, so the callback may touch a screen that has since gone (Android,
91	* Android parity, 2026-10-29). */
92	fun runOnRan(onRan: (() -> Unit)?) {
93	if (onRan == null) return
94	try {
95	onRan()
96	} catch (t: Throwable) {
97	System.err.println("[Earhorn/Gate] onRan failed: $t")
98	}
99	}
100
101	private companion object {
102	const val MSG_FAILED = "Something went wrong — couldn't start playback."
103	}
104	}