AlbumInfoLoader.kt

93 lines · 3.9 KB

Changed in: 0.5.0

1	package dev.stave.upnp
2
3	import kotlinx.coroutines.Dispatchers
4	import kotlinx.coroutines.withContext
5	import okhttp3.OkHttpClient
6	import okhttp3.Request
7	import java.util.concurrent.TimeUnit
8	import javax.inject.Inject
9	import javax.inject.Singleton
10
11	/**
12	* Locate prose notes for an album.
13	*
14	* Source priority:
15	* 1. ID3 COMMENT / Vorbis DESCRIPTION embedded in the first track's
16	* audio file. [AudioMetadataReader] surfaces these under the display
17	* key "Comment". Most ripped-from-CD libraries store album reviews
18	* and liner notes here.
19	* 2. Sibling `.txt` file alongside the audio. A few UPnP servers
20	* (notably MinimServer) expose adjacent filesystem entries; many do
21	* not, in which case the fetch quietly 404s and we return null.
22	*
23	* The fetch is best-effort — both paths are wrapped in [runCatching] and
24	* any failure (network, parse, missing tag) collapses to null. The UI
25	* surfaces a generic "no information available" state when null comes back.
26	*
27	* No file caching beyond OkHttp's defaults: album views are short-lived,
28	* the comment payload is at worst a few KB, and a stale-cache invalidation
29	* story is more code than the savings justify.
30	*/
31	@Singleton
32	class AlbumInfoLoader @Inject constructor(
33	private val reader: AudioMetadataReader,
34	) {
35	private val http: OkHttpClient = OkHttpClient.Builder()
36	.connectTimeout(5, TimeUnit.SECONDS)
37	.readTimeout(15, TimeUnit.SECONDS)
38	.writeTimeout(5, TimeUnit.SECONDS)
39	.build()
40
41	/**
42	* Returns the album-info text, or null when nothing is available.
43	*
44	* @param resourceUrl the streaming URL of any track in the album. ID3
45	* tags are read from this URL directly; the sibling `.txt` lookup
46	* replaces the trailing `.<ext>` with `.txt` and tries that.
47	*/
48	suspend fun load(resourceUrl: String): String? = withContext(Dispatchers.IO) {
49	// 1. ID3 COMMENT / Vorbis DESCRIPTION via the existing reader.
50	val tags = runCatching { reader.readTags(resourceUrl) }.getOrNull().orEmpty()
51	val comment = tags["Comment"]?.takeIf { it.isNotBlank() }
52	if (comment != null) return@withContext comment
53
54	// 2. Sibling .txt file. Try a couple of common review filename
55	// patterns: same basename with .txt, plus generic "review.txt"
56	// and "info.txt" in the same directory.
57	val siblings = siblingTxtUrls(resourceUrl)
58	for (url in siblings) {
59	val body = fetchText(url)?.trim()
60	if (!body.isNullOrEmpty()) return@withContext body
61	}
62	null
63	}
64
65	/** Build candidate URLs for sibling `.txt` files. The UPnP resource URL
66	* is typically `http://server:port/path/to/track.flac`; we replace the
67	* filename with several common review-text conventions. Return order
68	* matters — most-specific first so we don't pick up a generic
69	* `review.txt` at a higher directory level when the album-specific
70	* text is right next to the file. */
71	private fun siblingTxtUrls(resourceUrl: String): List<String> {
72	val slash = resourceUrl.lastIndexOf('/')
73	if (slash <= 0) return emptyList()
74	val dir = resourceUrl.substring(0, slash + 1)
75	val filename = resourceUrl.substring(slash + 1)
76	val basename = filename.substringBeforeLast('.', filename)
77	return listOf(
78	"$dir$basename.txt", // track-name.txt
79	"${dir}review.txt", // album-folder/review.txt
80	"${dir}info.txt", // album-folder/info.txt
81	"${dir}notes.txt", // album-folder/notes.txt
82	)
83	}
84
85	private fun fetchText(url: String): String? {
86	val req = Request.Builder().url(url).build()
87	return runCatching {
88	http.newCall(req).execute().use { r ->
89	if (!r.isSuccessful) null else r.body?.string()
90	}
91	}.getOrNull()
92	}
93	}