import { AmcpClient } from './amcp.js';

// Playout manager — owns one CasparCG channel's lifecycle inside this sidecar.
//
// One sidecar container == one CasparCG Server == one logical channel (channel
// index 1 in CasparCG terms). We add the output consumer (DeckLink / NDI / SRT
// / RTMP) at start, then walk a playlist by cueing the next clip on a background
// layer (LOADBG ... AUTO) so CasparCG performs a gapless transition at end of
// the current clip.
//
// Media is referenced by a path relative to CasparCG's configured media folder
// (/media inside the container). The mam-api stages assets from S3 to that
// shared volume and passes the resolved relative path on each item.

const CHANNEL = 1;       // single CasparCG channel per sidecar
const FG_LAYER = 10;     // foreground (on-air) layer
const MEDIA_ROOT = process.env.CASPAR_MEDIA_ROOT || '/media';

// Channel-id-derived HLS preview path. The mam-api proxies /live/<channel_id>/
// to this directory (shared media volume) so the UI's existing HLS player
// (capture's /live/<id> plumbing) works for playout monitors with zero new
// transport.
const CHANNEL_ID = process.env.CHANNEL_ID || '';
const HLS_DIR    = CHANNEL_ID ? `${MEDIA_ROOT}/live/${CHANNEL_ID}` : '';

// CasparCG SEEK / LENGTH are in frames, not seconds. Capture standard is 59.94;
// SD/film modes need their own values. Default 60000/1001 matches both
// '1080p5994' and '1080i5994'.
function fpsFor(videoFormat) {
  const f = String(videoFormat || '').toLowerCase();
  if (f.endsWith('5994')) return 60000 / 1001;
  if (f.endsWith('p60') || f.endsWith('i60'))  return 60;
  if (f.endsWith('p50') || f.endsWith('i50'))  return 50;
  if (f.endsWith('2997')) return 30000 / 1001;
  if (f.endsWith('p30'))  return 30;
  if (f.endsWith('p25'))  return 25;
  if (f.endsWith('p24') || f.endsWith('2398')) return 24000 / 1001;
  return 60000 / 1001;   // safe default for the house standard
}

// CasparCG transition syntax fragments keyed by our item.transition value.
function transitionArgs(transition, ms, fps) {
  if (!transition || transition === 'cut' || !ms) return '';
  const frames = Math.max(1, Math.round((ms / 1000) * fps));
  if (transition === 'mix') return ` MIX ${frames}`;
  if (transition === 'wipe') return ` WIPE ${frames}`;
  return '';
}

// Turn an absolute /media path (or a relative one) into the token CasparCG
// expects: a path relative to MEDIA_ROOT, without extension, forward-slashed.
// CasparCG resolves "subdir/clip" against its media folder + probes extensions.
function toCasparToken(mediaPath) {
  let p = String(mediaPath || '');
  if (p.startsWith(MEDIA_ROOT)) p = p.slice(MEDIA_ROOT.length);
  p = p.replace(/^\/+/, '');
  p = p.replace(/\.[^/.]+$/, ''); // strip extension
  return p;
}

export class PlayoutManager {
  constructor() {
    this.amcp = new AmcpClient({
      host: process.env.CASPAR_HOST || '127.0.0.1',
      port: parseInt(process.env.CASPAR_PORT || '5250', 10),
    });
    this.state = {
      running: false,
      outputType: null,
      outputConfig: null,
      videoFormat: null,
      playlist: [],        // resolved items in play order
      currentIndex: -1,
      loop: false,
      currentClip: null,
      startedAt: null,
      lastError: null,
    };
    this._advanceTimer = null;
  }

  async _consumerCommand(outputType, cfg) {
    // Returns the AMCP ADD argument string for the requested output target.
    if (outputType === 'decklink') {
      const dev = cfg.device_index || 1;
      return `DECKLINK DEVICE ${dev} EMBEDDED_AUDIO`;
    }
    if (outputType === 'ndi') {
      const name = cfg.ndi_name || 'DRAGONFLIGHT';
      return `NDI NAME "${name}"`;
    }
    if (outputType === 'srt' || outputType === 'rtmp') {
      // CasparCG 2.3+ FFMPEG consumer streams the channel out via libavformat.
      // SRT/RTMP both go through the ffmpeg mpegts/flv muxers.
      const url = cfg.url || '';
      if (outputType === 'srt') {
        const latency = cfg.latency || 200;
        const full = url.includes('latency=') ? url : `${url}${url.includes('?') ? '&' : '?'}latency=${latency}`;
        return `FFMPEG "${full}" -format mpegts -vcodec libx264 -preset veryfast -tune zerolatency -b:v 6M -acodec aac -b:a 192k`;
      }
      const target = cfg.key ? `${url}/${cfg.key}` : url;
      return `FFMPEG "${target}" -format flv -vcodec libx264 -preset veryfast -tune zerolatency -b:v 6M -acodec aac -b:a 192k`;
    }
    throw new Error(`Unknown output_type: ${outputType}`);
  }

  // Start the channel: bring up CasparCG's primary output consumer for the
  // target, plus a second FFMPEG consumer writing HLS for the UI preview
  // monitor (~4-6s lag, reuses capture's /live/<id> plumbing).
  async startChannel({ outputType, outputConfig = {}, videoFormat = '1080p5994' }) {
    await this.amcp.waitReady(30000);

    // Set the channel video mode, then attach the output consumer.
    try { await this.amcp.send(`SET ${CHANNEL} MODE ${videoFormat}`); }
    catch (err) { console.warn(`[playout] SET MODE failed (continuing): ${err.message}`); }

    const consumer = await this._consumerCommand(outputType, outputConfig);
    await this.amcp.send(`ADD ${CHANNEL} ${consumer}`);

    if (HLS_DIR) {
      try {
        await this._addHlsConsumer();
        console.log(`[playout] HLS preview at ${HLS_DIR}/index.m3u8`);
      } catch (err) {
        // HLS preview is non-fatal — operators still get the on-air output.
        console.warn(`[playout] HLS preview consumer failed: ${err.message}`);
      }
    }

    this.state.running = true;
    this.state.outputType = outputType;
    this.state.outputConfig = outputConfig;
    this.state.videoFormat = videoFormat;
    this.state.fps = fpsFor(videoFormat);
    this.state.startedAt = new Date().toISOString();
    this.state.lastError = null;
    console.log(`[playout] channel started output=${outputType} mode=${videoFormat} fps=${this.state.fps.toFixed(3)}`);
    return this.getStatus();
  }

  // Low-bitrate HLS for the web UI preview. Segments land in the shared media
  // volume; the mam-api serves /live/<channel_id>/* from there.
  async _addHlsConsumer() {
    // mkdir is done by the entrypoint; CasparCG's ffmpeg consumer creates the
    // playlist on first segment. 2s segments / 6-window list keeps lag low
    // without thrashing disk.
    const out = `${HLS_DIR}/index.m3u8`;
    const args = [
      `FFMPEG "${out}"`,
      '-format hls',
      '-hls_time 2',
      '-hls_list_size 6',
      '-hls_flags delete_segments+append_list',
      '-vcodec libx264 -preset veryfast -tune zerolatency -b:v 800k -maxrate 1M -bufsize 2M',
      '-g 60 -keyint_min 60 -sc_threshold 0',
      '-acodec aac -b:a 96k',
    ].join(' ');
    await this.amcp.send(`ADD ${CHANNEL} ${args}`);
  }

  async stopChannel() {
    this._clearAdvance();
    try { await this.amcp.send(`STOP ${CHANNEL}-${FG_LAYER}`); } catch (_) {}
    try { await this.amcp.send(`CLEAR ${CHANNEL}`); } catch (_) {}
    this.state.running = false;
    this.state.playlist = [];
    this.state.currentIndex = -1;
    this.state.currentClip = null;
    console.log('[playout] channel stopped');
    return { stopped: true };
  }

  // Load a playlist (array of { id, asset_id, media_path, in_point, out_point,
  // transition, transition_ms, clip_name }) and start playing from index 0.
  async loadPlaylist({ items = [], loop = false }) {
    this.state.playlist = items;
    this.state.loop = !!loop;
    this.state.currentIndex = -1;
    if (items.length === 0) return this.getStatus();
    await this._playIndex(0);
    return this.getStatus();
  }

  async _playIndex(index) {
    const item = this.state.playlist[index];
    if (!item) return;
    const fps = this.state.fps || fpsFor(this.state.videoFormat);
    const token = toCasparToken(item.media_path);
    const seek = item.in_point ? ` SEEK ${Math.round(item.in_point * fps)}` : '';
    const length = (item.out_point && item.out_point > (item.in_point || 0))
      ? ` LENGTH ${Math.round((item.out_point - (item.in_point || 0)) * fps)}`
      : '';
    const trans = transitionArgs(item.transition, item.transition_ms, fps);

    // PLAY puts the clip on the foreground layer immediately (first clip), with
    // the configured transition. Subsequent clips are cued via LOADBG ... AUTO
    // for a gapless hand-off; see _scheduleAdvance.
    await this.amcp.send(`PLAY ${CHANNEL}-${FG_LAYER} "${token}"${seek}${length}${trans}`);
    this.state.currentIndex = index;
    this.state.currentClip = item.clip_name || token;
    console.log(`[playout] PLAY [${index}] ${token}`);
    this._reportAsRunStart(item);
    this._scheduleAdvance(item);
  }

  // CasparCG's LOADBG ... AUTO automatically swaps the background layer to
  // foreground when the current clip ends. To keep our bookkeeping (currentIndex
  // / as-run) in sync we additionally poll INFO and advance our pointer when the
  // foreground clip changes. For Phase A we use a simpler model: cue the next
  // clip with AUTO and use a duration-based timer to move our pointer.
  _scheduleAdvance(item) {
    this._clearAdvance();
    const next = this._nextIndex();
    if (next === null) return;
    const nextItem = this.state.playlist[next];
    const nextToken = toCasparToken(nextItem.media_path);
    const fps = this.state.fps || fpsFor(this.state.videoFormat);
    const trans = transitionArgs(nextItem.transition, nextItem.transition_ms, fps);
    // Cue next on background with AUTO so CasparCG performs the gapless take.
    this.amcp.send(`LOADBG ${CHANNEL}-${FG_LAYER} "${nextToken}" AUTO${trans}`)
      .catch((err) => console.warn(`[playout] LOADBG failed: ${err.message}`));
  }

  _nextIndex() {
    const n = this.state.currentIndex + 1;
    if (n < this.state.playlist.length) return n;
    if (this.state.loop && this.state.playlist.length > 0) return 0;
    return null;
  }

  _clearAdvance() {
    if (this._advanceTimer) { clearTimeout(this._advanceTimer); this._advanceTimer = null; }
  }

  async skip() {
    const next = this._nextIndex();
    if (next === null) { await this.stopChannel(); return this.getStatus(); }
    await this._playIndex(next);
    return this.getStatus();
  }

  async pause() {
    try { await this.amcp.send(`PAUSE ${CHANNEL}-${FG_LAYER}`); } catch (_) {}
    return this.getStatus();
  }

  async resume() {
    try { await this.amcp.send(`RESUME ${CHANNEL}-${FG_LAYER}`); } catch (_) {}
    return this.getStatus();
  }

  _reportAsRunStart(item) {
    // The mam-api owns the as-run table; the sidecar just logs locally. The API
    // polls /status and writes as-run rows on clip change. Keeping the DB write
    // in the API avoids giving the sidecar a DB connection.
    this.state.currentItemId = item.id || null;
    this.state.currentItemStartedAt = new Date().toISOString();
  }

  getStatus() {
    return {
      running: this.state.running,
      outputType: this.state.outputType,
      videoFormat: this.state.videoFormat,
      currentIndex: this.state.currentIndex,
      currentClip: this.state.currentClip,
      currentItemId: this.state.currentItemId || null,
      currentItemStartedAt: this.state.currentItemStartedAt || null,
      playlistLength: this.state.playlist.length,
      loop: this.state.loop,
      startedAt: this.state.startedAt,
      lastError: this.state.lastError,
    };
  }
}

export default new PlayoutManager();