// Synced lyrics from LRCLIB, same lookup as the iOS app: exact match first, then a search.

const cache = new Map();

function parse(lrc) {
  const out = [];
  for (const line of (lrc || "").split("\n")) {
    const stamps = [...line.matchAll(/\[(\d+):(\d+(?:\.\d+)?)\]/g)];
    if (!stamps.length) continue;
    const text = line.replace(/\[[^\]]*\]/g, "").trim();
    for (const m of stamps) out.push({ t: +m[1] * 60 + +m[2], text });
  }
  return out.sort((a, b) => a.t - b.t);
}

// -> {lines: [{t, text}] | null, plain: string | null, instrumental: bool} or null if not found.
export async function lyricsFor(t) {
  const id = t.id;
  if (cache.has(id)) return cache.get(id);
  const p = (async () => {
    const q = { track_name: t.title, artist_name: t.artist, album_name: t.album };
    if (t.duration) q.duration = Math.round(t.duration / 1000);
    const get = async (path, params) => {
      const r = await fetch(`https://lrclib.net${path}?${new URLSearchParams(params)}`, { signal: AbortSignal.timeout(8000) });
      return r.ok ? r.json() : null;
    };
    let hit = await get("/api/get", q).catch(() => null);
    if (!hit) {
      const list = await get("/api/search", { track_name: t.title, artist_name: t.artist }).catch(() => null) || [];
      hit = list.find(x => x.syncedLyrics) || list[0] || null;
    }
    if (!hit) return null;
    return { lines: hit.syncedLyrics ? parse(hit.syncedLyrics) : null, plain: hit.plainLyrics || null, instrumental: !!hit.instrumental };
  })();
  cache.set(id, p);
  const res = await p;
  if (!res) cache.delete(id);
  return res;
}

// Index of the line playing at `sec`, or -1 before the first.
export function lineAt(lines, sec) {
  let lo = 0, hi = lines.length - 1, ans = -1;
  while (lo <= hi) { const mid = (lo + hi) >> 1; if (lines[mid].t <= sec + 0.15) { ans = mid; lo = mid + 1; } else hi = mid - 1; }
  return ans;
}