import { Router } from 'express';
import { spotifyAsHost } from './hostAuth.js';

const router = Router();

// Simple in-memory TTL cache — playlists/tracks don't need to be fresher
// than this, and it keeps a session-start from hammering Spotify's API.
const CACHE_TTL_MS = 5 * 60 * 1000;
const cache = new Map();
function cached(key, fn) {
  const hit = cache.get(key);
  if (hit && Date.now() - hit.ts < CACHE_TTL_MS) return Promise.resolve(hit.data);
  return fn().then(data => { cache.set(key, { data, ts: Date.now() }); return data; });
}

function summarizePlaylist(p) {
  return {
    id: p.id,
    name: p.name,
    trackCount: p.items?.total ?? p.tracks?.total ?? 0, // Spotify's field name for this varies by endpoint/version; checked the real response directly
    image: p.images?.[0]?.url ?? null,
  };
}

// Both facets of the card, plus cover art — track title, primary artist,
// and album art, everything a square could render as.
function summarizeTrack(entry) {
  const t = entry.item;
  if (!t) return null;
  return {
    id: t.id,
    title: t.name,
    artist: t.artists?.[0]?.name ?? 'Unknown artist',
    album: t.album?.name ?? '',
    image: t.album?.images?.[0]?.url ?? null,
    uri: t.uri,
  };
}

// GET /api/host/playlists — the host's own playlists as candidate song pools.
router.get('/playlists', async (req, res) => {
  try {
    const data = await cached('host-playlists', async () => {
      const out = [];
      let url = '/me/playlists?limit=50';
      while (url) {
        const page = await spotifyAsHost(url);
        out.push(...(page.items ?? []));
        url = page.next ? page.next.replace('https://api.spotify.com/v1', '') : null;
      }
      return out.map(summarizePlaylist);
    });
    res.json(data);
  } catch (e) {
    res.status(502).json({ error: e.message });
  }
});

// GET /api/host/playlist/:id/tracks — full track pool for one playlist.
router.get('/playlist/:id/tracks', async (req, res) => {
  try {
    const data = await cached(`host-tracks:${req.params.id}`, async () => {
      const out = [];
      let url = `/playlists/${req.params.id}/items?limit=100&fields=next,items(item(id,name,uri,artists(name),album(name,images)))`;
      while (url) {
        const page = await spotifyAsHost(url);
        out.push(...(page.items ?? []));
        url = page.next ? page.next.replace('https://api.spotify.com/v1', '') : null;
      }
      return out.map(summarizeTrack).filter(Boolean);
    });
    res.json(data);
  } catch (e) {
    res.status(502).json({ error: e.message });
  }
});

// GET /api/host/now-playing — thin wrapper for the auto-call poller.
router.get('/now-playing', async (req, res) => {
  try {
    const data = await spotifyAsHost('/me/player/currently-playing');
    res.json(data ?? { playing: false });
  } catch (e) {
    res.status(502).json({ error: e.message });
  }
});

export default router;