feat: add ICY metadata and AzuraCast radio streaming support

Agent-Logs-Url: https://github.com/nisrael/psysonic/sessions/88faada5-28bb-446f-b53b-46a0efef387e

Co-authored-by: GitHub Copilot <198982749+copilot@users.noreply.github.com>
Signed-off-by: Nils Israel <nils@sxda.io>

src/api/azuracast.ts

@@ -0,0 +1,111 @@
+import { invoke } from '@tauri-apps/api/core';
+
+// ─── AzuraCast API types ──────────────────────────────────────────────────────
+
+export interface AzuraCastSong {
+  artist: string;
+  title: string;
+  album: string;
+  art?: string;
+  text?: string; // "Artist - Title" combined
+}
+
+export interface AzuraCastNowPlayingTrack {
+  song: AzuraCastSong;
+  duration: number;  // seconds
+  elapsed: number;   // seconds played so far
+  remaining: number; // seconds remaining
+  played_at?: number;
+}
+
+export interface AzuraCastListeners {
+  current: number;
+  unique?: number;
+  total?: number;
+}
+
+export interface AzuraCastNowPlaying {
+  now_playing: AzuraCastNowPlayingTrack;
+  playing_next?: { song: AzuraCastSong } | null;
+  song_history: Array<{ song: AzuraCastSong; played_at?: number }>;
+  listeners: AzuraCastListeners;
+  station?: { name: string; shortcode: string };
+}
+
+// ─── Detection helpers ────────────────────────────────────────────────────────
+
+/**
+ * Try to derive an AzuraCast NowPlaying API URL from a stream URL.
+ *
+ * AzuraCast stream URLs follow the pattern:
+ *   https://<host>/listen/<shortcode>/<bitrate>.<ext>
+ *
+ * Returns the candidate API URL or `null` if the pattern doesn't match.
+ */
+export function guessAzuraCastApiUrl(streamUrl: string): string | null {
+  try {
+    const u = new URL(streamUrl);
+    const parts = u.pathname.split('/').filter(Boolean);
+    // Expect: ['listen', '<shortcode>', '<file>']
+    if (parts.length >= 2 && parts[0] === 'listen') {
+      const shortcode = parts[1];
+      return `${u.origin}/api/nowplaying/${shortcode}`;
+    }
+  } catch {
+    // ignore invalid URLs
+  }
+  return null;
+}
+
+/**
+ * Check whether a homepage URL itself looks like an AzuraCast NowPlaying
+ * API endpoint and return the canonical URL to use.
+ *
+ * Accepts:
+ *   - https://<host>/api/nowplaying                  → all stations, we use as-is
+ *   - https://<host>/api/nowplaying/<shortcode>      → single station, use as-is
+ */
+export function normaliseAzuraCastHomepageUrl(homepageUrl: string): string | null {
+  try {
+    const u = new URL(homepageUrl);
+    if (/^\/api\/nowplaying(\/[^/]+)?$/.test(u.pathname)) {
+      return homepageUrl;
+    }
+  } catch {
+    // ignore
+  }
+  return null;
+}
+
+/**
+ * Fetch AzuraCast NowPlaying data from the given API URL (bypasses CORS via
+ * the Rust backend).  Returns `null` if the request fails or the response
+ * does not look like a valid AzuraCast payload.
+ *
+ * When the API URL points to the `/api/nowplaying` (array) endpoint, the
+ * first item in the array is returned.  Otherwise the single-object form is
+ * used directly.
+ */
+export async function fetchAzuraCastNowPlaying(apiUrl: string): Promise<AzuraCastNowPlaying | null> {
+  try {
+    const raw: string = await invoke('fetch_json_url', { url: apiUrl });
+    const parsed = JSON.parse(raw);
+
+    // If the response is an array (all-stations endpoint), take the first item.
+    const obj: unknown = Array.isArray(parsed) ? parsed[0] : parsed;
+    if (!obj || typeof obj !== 'object') return null;
+
+    const np = obj as Record<string, unknown>;
+    // Minimal validation: must have `now_playing` with a `song` inside.
+    if (
+      np.now_playing &&
+      typeof np.now_playing === 'object' &&
+      (np.now_playing as Record<string, unknown>).song
+    ) {
+      return np as unknown as AzuraCastNowPlaying;
+    }
+  } catch {
+    // Network error, JSON parse error, etc.
+  }
+  return null;
+}