// YouTube importer worker — shells out to yt-dlp, lands the resulting MP4 in
// S3 at the same originals/{assetId}/<title>.mp4 path uploads use, then hands
// off to the existing proxy queue. From that point an imported asset is
// indistinguishable from an uploaded one.

import { spawn } from 'node:child_process';
import { join } from 'node:path';
import { mkdtemp, rm, stat, readdir } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { Queue } from 'bullmq';
import { query } from '../db/client.js';
import { uploadToS3 } from '../s3/client.js';
import { getMediaInfo } from '../ffmpeg/executor.js';

const S3_BUCKET = process.env.S3_BUCKET || 'wild-dragon';

const parseRedisUrl = (url) => {
  const parsed = new URL(url);
  return { host: parsed.hostname, port: parseInt(parsed.port, 10) };
};

// BUG FIX #7: Keep proxyQueue as a module-level singleton so it is only
// opened once and can be closed on SIGTERM (via the exported closer).
// Previously the worker created a new Queue on every job invocation; each
// BullMQ Queue holds an open Redis connection that prevented clean shutdown.
export const proxyQueue = new Queue('proxy', {
  connection: parseRedisUrl(process.env.REDIS_URL || 'redis://queue:6379'),
});

// Map yt-dlp stderr lines to short, operator-friendly messages. Anything that
// doesn't match here falls back to the raw stderr (truncated).
function friendlyError(stderr) {
  const s = stderr || '';
  if (/Private video/i.test(s))                                  return 'Private video — not supported.';
  if (/Sign in to confirm your age/i.test(s))                    return 'Age-restricted video — not supported.';
  if (/members[- ]only/i.test(s))                                return 'Members-only video — not supported.';
  if (/Video unavailable/i.test(s))                              return 'Video unavailable or removed.';
  if (/not available in your country|geo[- ]?restricted/i.test(s)) return 'Video is geo-blocked from this region.';
  if (/HTTP Error 429/i.test(s))                                 return 'YouTube rate-limited the importer — try again later.';
  if (/Unable to extract|Unsupported URL/i.test(s))              return 'YouTube changed its API — worker image needs a rebuild.';

  // Last-resort: the first ERROR: line from stderr, capped.
  const m = s.match(/ERROR:\s*([^\n]+)/i);
  const raw = (m ? m[1] : s).trim().slice(0, 300);
  return raw || 'yt-dlp failed with no error message';
}

// Replace anything outside [A-Za-z0-9 ._-] with '-', collapse runs of
// whitespace/dashes, trim, cap to 120 chars. The .mp4 extension is appended
// by the caller. If the result is empty we fall back to the video ID.
function sanitizeTitle(title, videoId) {
  if (!title || typeof title !== 'string') return `youtube-${videoId}`;
  let out = title
    .replace(/[^\w .\-]+/g, '-')
    .replace(/[-\s]+/g, ' ')
    .trim()
    .slice(0, 120);
  if (!out) out = `youtube-${videoId}`;
  return out;
}

// Run yt-dlp with progress streaming. Returns the parsed --print-json line.
// Throws if yt-dlp exits non-zero — the caller maps stderr to a friendly msg.
async function runYtDlp({ url, outputTemplate, onProgress }) {
  return new Promise((resolve, reject) => {
    const args = [
      '--no-playlist',
      '--no-warnings',
      '--restrict-filenames',
      '-f', "bv*[ext=mp4]+ba[ext=m4a]/b[ext=mp4]/b",
      '--merge-output-format', 'mp4',
      '--print-json',
      '--newline',
      '-o', outputTemplate,
      url,
    ];

    const proc = spawn('yt-dlp', args);
    let stdoutBuf = '';
    let stderrBuf = '';
    let lastJsonLine = null;

    proc.stdout.on('data', (chunk) => {
      stdoutBuf += chunk.toString();
      let nl;
      while ((nl = stdoutBuf.indexOf('\n')) !== -1) {
        const line = stdoutBuf.slice(0, nl);
        stdoutBuf = stdoutBuf.slice(nl + 1);

        // [download]  42.3% of 53.21MiB at 4.21MiB/s ETA 00:07
        const m = line.match(/\[download\]\s+(\d+(?:\.\d+)?)%/);
        if (m && onProgress) onProgress(parseFloat(m[1]));

        // --print-json emits one JSON line at the end of a successful download.
        if (line.startsWith('{') && line.endsWith('}')) {
          try { lastJsonLine = JSON.parse(line); } catch { /* not the json line */ }
        }
      }
    });

    proc.stderr.on('data', (chunk) => { stderrBuf += chunk.toString(); });

    proc.on('error', (err) => reject(new Error(`Failed to spawn yt-dlp: ${err.message}`)));

    proc.on('close', (code) => {
      if (code === 0) {
        resolve(lastJsonLine || {});
      } else {
        const err = new Error(friendlyError(stderrBuf));
        err.stderr = stderrBuf;
        err.code = code;
        reject(err);
      }
    });
  });
}

export const youtubeImportWorker = async (job) => {
  const { assetId, url } = job.data;

  // Each job gets its own temp directory so concurrent jobs (if we ever bump
  // concurrency above 1) can't clobber each other's intermediate files.
  const workDir = await mkdtemp(join(tmpdir(), `yt-${job.id}-`));
  const outputTemplate = join(workDir, `${assetId}.%(ext)s`);

  try {
    console.log(`[youtube] Asset ${assetId}: importing ${url}`);
    await job.updateProgress(2);

    // yt-dlp does the work; progress 5..60 covers the download.
    const meta = await runYtDlp({
      url,
      outputTemplate,
      onProgress: async (pct) => {
        const mapped = 5 + Math.floor(pct * 0.55);
        try { await job.updateProgress(mapped); } catch { /* ignore */ }
      },
    });

    await job.updateProgress(62);

    // Find the resulting MP4 — yt-dlp's --merge-output-format ensures .mp4
    // but we scan the dir defensively in case the format string changes.
    const files = await readdir(workDir);
    const mp4 = files.find((f) => f.endsWith('.mp4'));
    if (!mp4) {
      throw new Error(`yt-dlp produced no .mp4 in ${workDir} (got ${files.join(', ') || 'nothing'})`);
    }
    const localPath = join(workDir, mp4);

    const { size: fileSize } = await stat(localPath);
    if (fileSize < 4096) {
      throw new Error(`Downloaded file is suspiciously small (${fileSize} bytes) — aborting before upload.`);
    }

    // ffprobe the file ourselves — yt-dlp's metadata is sometimes missing or
    // wrong (especially fps), and we already trust ffprobe everywhere else.
    let mediaInfo = {};
    try {
      mediaInfo = await getMediaInfo(localPath);
    } catch (err) {
      console.warn(`[youtube] getMediaInfo failed for ${assetId}: ${err.message}`);
    }

    const videoId = meta.id || mp4.replace(/\..+$/, '').replace(/^.*-/, '');
    const sanitized = sanitizeTitle(meta.title || meta.fulltitle, videoId);
    const filename = `${sanitized}.mp4`;
    const originalKey = `originals/${assetId}/${filename}`;

    await job.updateProgress(70);
    console.log(`[youtube] Uploading ${localPath} → s3://${S3_BUCKET}/${originalKey} (${fileSize} bytes)`);
    await uploadToS3(S3_BUCKET, originalKey, localPath);

    await job.updateProgress(90);

    // Backfill the asset row with the real title + S3 key + ffprobe metadata,
    // then flip to 'processing' so the rest of the UI treats it like any
    // freshly-uploaded asset.
    await query(
      `UPDATE assets
       SET filename        = $1,
           display_name    = $2,
           original_s3_key = $3,
           codec           = COALESCE($4, codec),
           resolution      = COALESCE($5, resolution),
           fps             = COALESCE($6, fps),
           duration_ms     = COALESCE($7, duration_ms),
           file_size       = COALESCE($8, file_size),
           status          = 'processing',
           updated_at      = NOW()
       WHERE id = $9`,
      [
        filename,
        meta.title || meta.fulltitle || filename,
        originalKey,
        mediaInfo.codec ?? null,
        mediaInfo.resolution ?? null,
        mediaInfo.fps ?? null,
        mediaInfo.durationMs ?? null,
        mediaInfo.fileSizeBytes ?? fileSize,
        assetId,
      ]
    );

    // Hand off to the proxy queue — identical payload shape to upload.js so
    // the proxy worker doesn't need to know this came from an import.
    await proxyQueue.add('generate', {
      assetId,
      inputKey:  originalKey,
      outputKey: `proxies/${assetId}.mp4`,
    });

    console.log(`[youtube] Asset ${assetId} imported (${meta.title || 'untitled'}); proxy job queued`);
    await job.updateProgress(100);
    return { assetId, originalKey };
  } catch (error) {
    console.error(`[youtube] Import failed for asset ${assetId}:`, error.message);
    await query(
      `UPDATE assets SET status = 'error', updated_at = NOW() WHERE id = $1`,
      [assetId]
    );
    throw error;
  } finally {
    await rm(workDir, { recursive: true, force: true }).catch(() => {});
  }
};