/**
 * NovaSonic Scrobble Service
 * ---------------------------
 * A tiny, isolated service that records a timestamped, per-user play-log — the
 * foundation for day/month/year listening stats and a yearly "Wrapped".
 *
 * Deliberately SEPARATE from the download backend: the download server is heavy
 * (yt-dlp/ffmpeg subprocesses), may crash, and restarts regularly (to re-pull
 * yt-dlp). This archive needs high uptime + data integrity, so it runs on its own.
 *
 * Storage: node:sqlite (built into Node 22; run with --experimental-sqlite).
 *   DB file: {DATA_PATH}/novasonic-plays.db  (own persistent volume)
 *
 * Auth / multi-user: every request carries the same Subsonic token creds the PWA
 * already uses (u, t=md5(pass+salt), s=salt). We verify them against Navidrome's
 * ping.view once (cached briefly) → the `user` we store is real, not spoofable.
 * No new login, no new password.
 *
 * Phase 1 routes:
 *   POST   /scrobble/plays              ingest a batch, idempotent by uuid
 *   GET    /scrobble/history            raw chronological log (= the archive)
 *   DELETE /scrobble/plays?user=NAME    purge one user's rows (test cleanup)
 *   GET    /scrobble/health             liveness + total row count
 */

const { DatabaseSync } = require('node:sqlite');
const express = require('express');
const path    = require('path');
const fs      = require('fs');
const crypto  = require('crypto');

const PORT          = process.env.PORT || 3710;
const DATA_PATH     = process.env.DATA_PATH || '/data';
const NAVIDROME_URL = (process.env.NAVIDROME_URL || '').replace(/\/$/, '');

if (!NAVIDROME_URL) console.warn('⚠ NAVIDROME_URL not set — auth verification will reject everything.');

// ─── DB ─────────────────────────────────────────────────────────────────────
fs.mkdirSync(DATA_PATH, { recursive: true });
const db = new DatabaseSync(path.join(DATA_PATH, 'novasonic-plays.db'));
db.exec('PRAGMA journal_mode = WAL;');   // survive restarts / concurrent reads
db.exec(`
  CREATE TABLE IF NOT EXISTS plays (
    id         INTEGER PRIMARY KEY,
    user       TEXT    NOT NULL,
    song_id    TEXT    NOT NULL,
    title      TEXT,
    artist     TEXT,
    artist_id  TEXT,
    album      TEXT,
    album_id   TEXT,
    duration   INTEGER,
    played_at  INTEGER NOT NULL,   -- Unix epoch, UTC
    source     TEXT,               -- 'web' | 'android'
    uuid       TEXT UNIQUE         -- idempotency for offline-retry
  );
`);
db.exec('CREATE INDEX IF NOT EXISTS ix_plays_user_time   ON plays(user, played_at);');
db.exec('CREATE INDEX IF NOT EXISTS ix_plays_user_artist ON plays(user, artist_id);');
db.exec('CREATE INDEX IF NOT EXISTS ix_plays_user_song   ON plays(user, song_id);');

const _insert = db.prepare(`
  INSERT OR IGNORE INTO plays
    (user, song_id, title, artist, artist_id, album, album_id, duration, played_at, source, uuid)
  VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
`);
const _history = db.prepare(`
  SELECT id, song_id, title, artist, artist_id, album, album_id, duration, played_at, source
  FROM plays WHERE user = ? AND played_at < ? ORDER BY played_at DESC LIMIT ?
`);
const _purge   = db.prepare('DELETE FROM plays WHERE user = ?');
const _count   = db.prepare('SELECT COUNT(*) AS n FROM plays');

// ─── Auth (Navidrome ping.view, cached) ─────────────────────────────────────
const _authCache = new Map(); // "u|t|s" -> { ok, exp }
const _AUTH_TTL = 5 * 60 * 1000;

async function verifyUser(req) {
  const u = req.query.u || req.body?.u;
  const t = req.query.t || req.body?.t;
  const s = req.query.s || req.body?.s;
  if (!u || !t || !s || !NAVIDROME_URL) return null;

  const key = `${u}|${t}|${s}`;
  const now = Date.now();
  const cached = _authCache.get(key);
  if (cached && cached.exp > now) return cached.ok ? u : null;

  try {
    const url = `${NAVIDROME_URL}/rest/ping.view?u=${encodeURIComponent(u)}&t=${encodeURIComponent(t)}&s=${encodeURIComponent(s)}&v=1.16.1&c=NovaSonic&f=json`;
    const r = await fetch(url, { signal: AbortSignal.timeout(8000) });
    const j = await r.json();
    const ok = j?.['subsonic-response']?.status === 'ok';
    _authCache.set(key, { ok, exp: now + _AUTH_TTL });
    return ok ? u : null;
  } catch {
    return null;
  }
}

// ─── App ────────────────────────────────────────────────────────────────────
const app = express();
app.use((req, res, next) => {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET,POST,DELETE,OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');
  res.setHeader('Access-Control-Allow-Private-Network', 'true');
  if (req.method === 'OPTIONS') { res.sendStatus(204); return; }
  next();
});
app.use(express.json({ limit: '2mb' }));

// Normalize a client timestamp to Unix seconds (accepts s or ms; defaults to now)
function _toEpochSec(v) {
  const n = Number(v);
  if (!Number.isFinite(n) || n <= 0) return Math.floor(Date.now() / 1000);
  return n > 1e12 ? Math.floor(n / 1000) : Math.floor(n);
}

// POST /scrobble/plays — ingest a batch { plays: [ {...} ] }, idempotent by uuid
app.post('/scrobble/plays', async (req, res) => {
  const user = await verifyUser(req);
  if (!user) return res.status(401).json({ error: 'unauthorized' });

  const plays = Array.isArray(req.body?.plays) ? req.body.plays : [];
  if (!plays.length) return res.json({ accepted: 0, duplicates: 0 });

  let accepted = 0, duplicates = 0, invalid = 0;
  for (const p of plays) {
    if (!p || !p.songId) { invalid++; continue; }
    const uuid = String(p.uuid || crypto.randomUUID());
    try {
      const r = _insert.run(
        user,
        String(p.songId),
        p.title ?? null,
        p.artist ?? null,
        p.artistId ?? null,
        p.album ?? null,
        p.albumId ?? null,
        Number.isFinite(Number(p.duration)) ? Math.floor(Number(p.duration)) : null,
        _toEpochSec(p.playedAt),
        p.source === 'android' ? 'android' : 'web',
        uuid
      );
      if (r.changes > 0) accepted++; else duplicates++;
    } catch { invalid++; }
  }
  res.json({ accepted, duplicates, invalid });
});

// GET /scrobble/history?limit=&before=  — raw chronological log (the archive)
app.get('/scrobble/history', async (req, res) => {
  const user = await verifyUser(req);
  if (!user) return res.status(401).json({ error: 'unauthorized' });

  const limit  = Math.min(Math.max(parseInt(req.query.limit, 10) || 100, 1), 500);
  const before = _toEpochSec(req.query.before || Date.now());
  const rows = _history.all(user, before, limit);
  res.json({ user, count: rows.length, plays: rows });
});

// GET /scrobble/stats — aggregated listening stats for the authed user.
//   ?from=&to=   Unix seconds window (default: all time)
//   ?tz=         seconds east of UTC for local-day bucketing (default 0)
//   ?bucket=     day | month | year  — granularity of the time series (default day)
//   ?limit=      top-list size (default 20, max 100)
// Buckets are computed on the fly (GROUP BY strftime) — no rollup tables.
const _STATS_FMT = { day: '%Y-%m-%d', month: '%Y-%m', year: '%Y' };

app.get('/scrobble/stats', async (req, res) => {
  const user = await verifyUser(req);
  if (!user) return res.status(401).json({ error: 'unauthorized' });

  const tz     = Math.trunc(Number(req.query.tz) || 0);
  // Default window = all time. Parse `from` directly — do NOT route through _toEpochSec, which maps
  // 0 → now (so the client's explicit from=0 for "all time" would wrongly become an empty window).
  const fromN  = Number(req.query.from);
  const from   = Number.isFinite(fromN) && fromN > 0 ? (fromN > 1e12 ? Math.floor(fromN / 1000) : Math.floor(fromN)) : 0;
  const to     = req.query.to ? _toEpochSec(req.query.to) : Math.floor(Date.now() / 1000) + 1;
  const bucket = _STATS_FMT[req.query.bucket] ? req.query.bucket : 'day';
  const fmt    = _STATS_FMT[bucket];
  const limit  = Math.min(Math.max(parseInt(req.query.limit, 10) || 20, 1), 100);

  const win  = { user, from, to };            // node:sqlite throws on extra named params —
  const winL = { user, from, to, limit };     // so each query gets exactly the params it uses.
  const winT = { user, from, to, tz };
  const WHERE = 'user = :user AND played_at >= :from AND played_at < :to';

  const totals = db.prepare(
    `SELECT COUNT(*) AS plays, COALESCE(SUM(duration), 0) AS seconds FROM plays WHERE ${WHERE}`
  ).get(win);

  const topArtists = db.prepare(`
    SELECT MAX(artist) AS name, MAX(artist_id) AS artistId, COUNT(*) AS plays, COALESCE(SUM(duration),0) AS seconds
    FROM plays WHERE ${WHERE} AND artist IS NOT NULL AND artist <> ''
    GROUP BY lower(artist) ORDER BY plays DESC, seconds DESC LIMIT :limit
  `).all(winL);

  const topAlbums = db.prepare(`
    SELECT MAX(album) AS name, MAX(album_id) AS albumId, MAX(artist) AS artist, COUNT(*) AS plays
    FROM plays WHERE ${WHERE} AND album IS NOT NULL AND album <> ''
    GROUP BY lower(album), lower(COALESCE(artist,'')) ORDER BY plays DESC LIMIT :limit
  `).all(winL);

  const topTracks = db.prepare(`
    SELECT MAX(title) AS title, MAX(artist) AS artist, MAX(album) AS album,
           MAX(album_id) AS albumId, MAX(artist_id) AS artistId, song_id AS songId, COUNT(*) AS plays
    FROM plays WHERE ${WHERE}
    GROUP BY song_id ORDER BY plays DESC LIMIT :limit
  `).all(winL);

  const series = db.prepare(`
    SELECT strftime('${fmt}', played_at + :tz, 'unixepoch') AS bucket, COUNT(*) AS plays, COALESCE(SUM(duration),0) AS seconds
    FROM plays WHERE ${WHERE} GROUP BY bucket ORDER BY bucket
  `).all(winT);

  const hourRows = db.prepare(`
    SELECT CAST(strftime('%H', played_at + :tz, 'unixepoch') AS INTEGER) AS hr, COUNT(*) AS plays
    FROM plays WHERE ${WHERE} GROUP BY hr
  `).all(winT);
  const byHour = Array.from({ length: 24 }, (_, h) => ({ hour: h, plays: 0 }));
  for (const r of hourRows) if (r.hr >= 0 && r.hr < 24) byHour[r.hr].plays = r.plays;

  res.json({
    user,
    range: { from, to, tz, bucket },
    totalPlays: totals.plays,
    totalSeconds: totals.seconds,
    topArtists, topAlbums, topTracks, series, byHour,
  });
});

// DELETE /scrobble/plays?user=NAME — purge one user's rows (for test cleanup).
// Requires ANY valid Navidrome login (a deleted user can't authenticate as itself,
// so cleanup after deletion must be authorized by a currently-valid account).
app.delete('/scrobble/plays', async (req, res) => {
  const caller = await verifyUser(req);
  if (!caller) return res.status(401).json({ error: 'unauthorized' });
  const target = req.query.user || caller;
  const r = _purge.run(String(target));
  res.json({ purged: r.changes, user: target });
});

// GET /scrobble/health — liveness + total rows (no auth)
app.get('/scrobble/health', (_req, res) => {
  res.json({ ok: true, plays: _count.get().n, navidrome: !!NAVIDROME_URL });
});

app.listen(PORT, () => console.log(`✅ NovaSonic scrobble service on :${PORT} (data: ${DATA_PATH})`));