RadioStatusClient.kt
91 lines · 4.5 KB
Changed in: 0.5.0
| 1 | package dev.stave.cast.radio |
| 2 | |
| 3 | import kotlinx.coroutines.Dispatchers |
| 4 | import kotlinx.coroutines.withContext |
| 5 | import org.json.JSONObject |
| 6 | import java.net.HttpURLConnection |
| 7 | import java.net.URL |
| 8 | import java.net.URLEncoder |
| 9 | |
| 10 | /** |
| 11 | * One read of musicnow's `/status` for a speaker group (ported from Android, |
| 12 | * design decision, 2026-09-04): when the group plays a radio station, |
| 13 | * musicnow knows the song, artist and art the station is broadcasting and |
| 14 | * serves them here. The desktop shows them over the station's name. The |
| 15 | * address is a setting (`SettingsStore.musicnowStatusUrl`); blank = off. |
| 16 | * |
| 17 | * The result distinguishes the three cases Android learned to keep apart |
| 18 | * (fleet-wide flash-then-default incident, 2026-08-29): |
| 19 | * - [Poll.Station] — radio with real metadata. |
| 20 | * - [Poll.NoStation] — HTTP 200 with `station: null`: a library session (or |
| 21 | * a station that publishes nothing). Counts toward the |
| 22 | * caller's latch. |
| 23 | * - [Poll.Failed] — timeout, non-200, malformed body. Says NOTHING about |
| 24 | * the session: the caller must keep the last good |
| 25 | * overlay on screen and back off, never blank it. |
| 26 | * - [Poll.Disabled] — no address configured. |
| 27 | * |
| 28 | * Polling cadence/latching lives in the caller (RawCastObserver), which owns |
| 29 | * the session lifetime. musicnow's HTTP server handles one request at a time |
| 30 | * and other clients already poll it — callers must not shorten the |
| 31 | * interval below [POLL_INTERVAL_MS]. |
| 32 | */ |
| 33 | class RadioStatusClient(private val settings: dev.stave.data.SettingsStore) { |
| 34 | data class RadioNow(val station: String, val title: String?, val artist: String?, val albumArtUrl: String?) |
| 35 | |
| 36 | sealed interface Poll { |
| 37 | data class Station(val now: RadioNow) : Poll |
| 38 | data object NoStation : Poll |
| 39 | data object Failed : Poll |
| 40 | data object Disabled : Poll |
| 41 | } |
| 42 | |
| 43 | suspend fun poll(group: String): Poll = withContext(Dispatchers.IO) { |
| 44 | val base = settings.musicnowStatusUrl.value.trim() |
| 45 | if (base.isBlank()) return@withContext Poll.Disabled |
| 46 | try { |
| 47 | val conn = (URL("$base?group=${URLEncoder.encode(group, "UTF-8")}").openConnection() as HttpURLConnection) |
| 48 | .apply { connectTimeout = 4_000; readTimeout = 4_000; requestMethod = "GET" } |
| 49 | try { |
| 50 | if (conn.responseCode != 200) { |
| 51 | System.err.println("[EarhornRadio] GET /status for '$group' -> HTTP ${conn.responseCode}") |
| 52 | return@withContext Poll.Failed |
| 53 | } |
| 54 | val json = JSONObject(conn.inputStream.bufferedReader().use { it.readText() }) |
| 55 | // Never optString: it returns the literal "null" for a JSON |
| 56 | // null, which turned every library session into "radio". |
| 57 | fun str(k: String): String? = if (json.isNull(k)) null else json.optString(k).trim().ifBlank { null } |
| 58 | val station = str("station") ?: return@withContext Poll.NoStation |
| 59 | Poll.Station(RadioNow(station, str("title"), str("artist"), str("album_art"))) |
| 60 | } finally { |
| 61 | conn.disconnect() |
| 62 | } |
| 63 | } catch (e: java.io.IOException) { |
| 64 | System.err.println("[EarhornRadio] /status for '$group' failed: ${e.javaClass.simpleName}: ${e.message}") |
| 65 | Poll.Failed |
| 66 | } catch (e: org.json.JSONException) { |
| 67 | System.err.println("[EarhornRadio] /status for '$group' returned malformed JSON: ${e.message}") |
| 68 | Poll.Failed |
| 69 | } catch (e: IllegalArgumentException) { |
| 70 | // Malformed URL in settings. |
| 71 | System.err.println("[EarhornRadio] musicnow address is not a valid URL: ${e.message}") |
| 72 | Poll.Failed |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | /** Back-compat single read: the overlay or null. Prefer [poll]. */ |
| 77 | suspend fun fetch(group: String): RadioNow? = (poll(group) as? Poll.Station)?.now |
| 78 | |
| 79 | companion object { |
| 80 | /** Within the memo's 10–15 s. Do not shorten (see class KDoc). */ |
| 81 | const val POLL_INTERVAL_MS = 12_000L |
| 82 | |
| 83 | /** Consecutive station:null reads tolerated before latching off — |
| 84 | * covers musicnow's ~20 s pre-fetch window at the start of a radio |
| 85 | * session (3 × 12 s) without polling forever on library sessions. */ |
| 86 | const val NULL_READS_BEFORE_LATCH = 3 |
| 87 | |
| 88 | /** Failure backoff ceiling. */ |
| 89 | const val MAX_BACKOFF_MS = 60_000L |
| 90 | } |
| 91 | } |