QueuePersistenceStore.kt

114 lines · 4.5 KB

Changed in: 0.5.0

1	package dev.stave.data
2
3	import android.content.Context
4	import androidx.datastore.core.handlers.ReplaceFileCorruptionHandler
5	import androidx.datastore.preferences.core.edit
6	import androidx.datastore.preferences.core.emptyPreferences
7	import androidx.datastore.preferences.core.longPreferencesKey
8	import androidx.datastore.preferences.core.stringPreferencesKey
9	import androidx.datastore.preferences.preferencesDataStore
10	import dagger.hilt.android.qualifiers.ApplicationContext
11	import kotlinx.coroutines.flow.first
12	import kotlinx.serialization.Serializable
13	import kotlinx.serialization.json.Json
14	import javax.inject.Inject
15	import javax.inject.Singleton
16
17	/** Serializable mirror of DidlItem.Track for persistence. Duration held as millis
18	* because kotlin.time.Duration isn't @Serializable without a custom serializer. */
19	@Serializable
20	data class PersistedTrack(
21	val id: String,
22	val parentId: String,
23	val title: String,
24	val artist: String? = null,
25	val albumArtist: String? = null,
26	val album: String? = null,
27	val composer: String? = null,
28	val genre: String? = null,
29	val date: String? = null,
30	val trackNumber: Int? = null,
31	val discNumber: Int? = null,
32	val durationMs: Long? = null,
33	val albumArtUri: String? = null,
34	val resourceUrl: String,
35	val mimeType: String? = null,
36	val sampleFrequency: Int? = null,
37	val bitsPerSample: Int? = null,
38	val channels: Int? = null,
39	val bitrate: Int? = null,
40	val size: Long? = null,
41	val extras: Map<String, String> = emptyMap(),
42	)
43
44	/** Full queue snapshot: the list, the currently-playing index, and where the head
45	* was in that track. Position is stored so resume starts close to where the user
46	* left off rather than restarting the track. */
47	@Serializable
48	data class PersistedQueue(
49	val tracks: List<PersistedTrack>,
50	val currentIndex: Int,
51	val positionMs: Long,
52	)
53
54	// Maintainer, 2026-10-29: a corrupt queue file crashed the app at launch;
55	// replace it with empty (no saved queue) instead.
56	private val Context.queueDataStore by preferencesDataStore(
57	name = "stave_queue",
58	corruptionHandler = ReplaceFileCorruptionHandler { emptyPreferences() },
59	)
60
61	@Singleton
62	class QueuePersistenceStore @Inject constructor(
63	@ApplicationContext private val context: Context,
64	) {
65	private val json = Json { ignoreUnknownKeys = true }
66
67	suspend fun save(snapshot: PersistedQueue) {
68	val encoded = runCatching {
69	json.encodeToString(PersistedQueue.serializer(), snapshot)
70	}.getOrNull() ?: return
71	context.queueDataStore.edit { prefs ->
72	prefs[KEY_QUEUE_JSON] = encoded
73	}
74	// Maintainer, 2026-10-29: synchronous "is there anything to resume" flag
75	// for the media-button receiver (see EarhornMediaButtonReceiver), which
76	// must decide inside onReceive and can't read DataStore.
77	setResumable(context, snapshot.tracks.any { it.resourceUrl.isNotBlank() })
78	}
79
80	/** Load the most recent snapshot, or null if nothing is saved or the blob is
81	* corrupt. Corruption returns null rather than throwing — we'd rather restore to
82	* empty queue than crash on startup because of a bad save. */
83	suspend fun load(): PersistedQueue? {
84	val prefs = context.queueDataStore.data.first()
85	val raw = prefs[KEY_QUEUE_JSON] ?: return null
86	if (raw.isBlank()) return null
87	return runCatching {
88	json.decodeFromString(PersistedQueue.serializer(), raw)
89	}.getOrNull()
90	}
91
92	suspend fun clear() {
93	context.queueDataStore.edit { it.clear() }
94	setResumable(context, false) // Maintainer, 2026-10-29: see save()
95	}
96
97	companion object {
98	private val KEY_QUEUE_JSON = stringPreferencesKey("queue_json")
99
100	private const val RESUME_PREFS = "earhorn_resume"
101	private const val KEY_RESUMABLE = "resumable"
102
103	private fun setResumable(context: Context, resumable: Boolean) {
104	context.getSharedPreferences(RESUME_PREFS, Context.MODE_PRIVATE)
105	.edit().putBoolean(KEY_RESUMABLE, resumable).apply()
106	}
107
108	/** Maintainer, 2026-10-29: true when the last saved queue has at least one
109	* playable track. Read synchronously by the media-button receiver. */
110	fun hasResumableQueue(context: Context): Boolean =
111	context.getSharedPreferences(RESUME_PREFS, Context.MODE_PRIVATE)
112	.getBoolean(KEY_RESUMABLE, false)
113	}
114	}