import { join } from 'path';
import { unlink } from 'fs/promises'
import { tmpdir } from 'os';
import { Queue } from 'bullmq';
import { query } from '../db/client.js';
import { downloadFromS3, uploadToS3 } from '../s3/client.js';
import { transcodeVideo, transcodeImage, getMediaInfo, isHwCodec } from '../ffmpeg/executor.js';

// Read the global proxy-encoder settings from the DB. These are written by
// Settings → Proxy encoding in the GUI. Falls back to libx264 defaults if
// nothing is configured (first-run / fresh install).
async function loadProxyEncodingSettings() {
  const result = await query(
    `SELECT key, value FROM settings
     WHERE key IN ('gpu_transcode_enabled','gpu_codec','gpu_preset','gpu_bitrate_mbps',
                   'gpu_rc_mode','gpu_audio_codec','gpu_audio_bitrate_kbps')`
  );
  const map = {};
  for (const { key, value } of result.rows) map[key] = value;

  const gpuEnabled = map.gpu_transcode_enabled === 'true';
  const codec      = map.gpu_codec || (gpuEnabled ? 'h264_nvenc' : 'libx264');
  const preset     = map.gpu_preset || (gpuEnabled ? 'p4' : 'fast');
  const bitrateM   = parseInt(map.gpu_bitrate_mbps || '10', 10);
  const rcMode     = map.gpu_rc_mode || null;
  const audioCodec = map.gpu_audio_codec || 'aac';
  const audioKbps  = parseInt(map.gpu_audio_bitrate_kbps || '192', 10);

  return {
    videoCodec:   codec,
    videoPreset:  preset,
    videoBitrate: `${bitrateM}M`,
    rateControl:  rcMode,
    audioCodec,
    audioBitrate: `${audioKbps}k`,
    _gpu:         gpuEnabled && isHwCodec(codec),
  };
}

// Codec names ffprobe reports for still-image inputs. These bypass the video
// transcode entirely — see proxyWorker below.
const IMAGE_CODECS = new Set(['png', 'mjpeg', 'jpeg', 'webp', 'gif', 'tiff', 'bmp', 'jpegls']);

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

// Dispatch thumbnail job once proxy is ready — same Redis connection as the worker
const parseRedisUrl = (url) => {
  const parsed = new URL(url);
  return { host: parsed.hostname, port: parseInt(parsed.port, 10) };
};

const thumbnailQueue = new Queue('thumbnail', {
  connection: parseRedisUrl(process.env.REDIS_URL || 'redis://queue:6379'),
});

export const proxyWorker = async (job) => {
  const { assetId, inputKey, outputKey } = job.data;

  const tmpDir = tmpdir();
  const inputPath  = join(tmpDir, `proxy-input-${job.id}.mov`);
  const outputPath = join(tmpDir, `proxy-output-${job.id}.mp4`);

  try {
    // Download original from S3
    await job.updateProgress(10);
    console.log(`[proxy] Downloading ${inputKey} for asset ${assetId}`);
    await downloadFromS3(S3_BUCKET, inputKey, inputPath);

    // Extract source metadata (fps, codec, resolution, duration, size, audio)
    await job.updateProgress(20);
    let mediaInfo = {};
    let hasAudio = true;
    try {
      mediaInfo = await getMediaInfo(inputPath);
      hasAudio = !!mediaInfo.hasAudio;
      console.log(`[proxy] Metadata for ${assetId}: ${JSON.stringify(mediaInfo)}`);
    } catch (err) {
      console.warn(`[proxy] getMediaInfo failed for ${assetId}: ${err.message}`);
    }

    // Still images skip the video proxy — they have no temporal stream and
    // x264 with a one-frame PNG input fails (Could not open encoder before EOF).
    // Generate a scaled JPEG poster instead; the thumbnail job will downsize it.
    const isImage = mediaInfo.codec && IMAGE_CODECS.has(mediaInfo.codec.toLowerCase());

    if (isImage) {
      const imageOutputKey = outputKey.replace(/\.mp4$/, '.jpg');
      const imageOutputPath = outputPath.replace(/\.mp4$/, '.jpg');
      console.log(`[proxy] Image asset ${assetId} (${mediaInfo.codec}) — emitting poster instead of video proxy`);
      await job.updateProgress(40);
      await transcodeImage(inputPath, imageOutputPath);
      await job.updateProgress(70);
      await uploadToS3(S3_BUCKET, imageOutputKey, imageOutputPath);
      await job.updateProgress(90);
      await query(
        `UPDATE assets
         SET thumbnail_s3_key = $1,
             proxy_s3_key     = NULL,
             resolution       = COALESCE($2, resolution),
             file_size        = COALESCE($3, file_size),
             status           = 'ready',
             updated_at       = NOW()
         WHERE id = $4`,
        [imageOutputKey, mediaInfo.resolution ?? null, mediaInfo.fileSizeBytes ?? null, assetId]
      );
      await unlink(imageOutputPath).catch(() => {});
      await job.updateProgress(100);
      return { assetId, outputKey: imageOutputKey };
    }

    // Empty/truncated capture: probe returned a video stream but ffmpeg can't
    // read any frames. Bail with a clear message instead of dumping ~3KB of
    // ffmpeg stderr into the failed-jobs list.
    if (mediaInfo.durationMs === null && mediaInfo.codec) {
      throw new Error(
        `Empty or truncated source: codec=${mediaInfo.codec}, ` +
        `resolution=${mediaInfo.resolution || 'unknown'}, no readable frames.`
      );
    }

    // Transcode using the operator-configured encoder. The proxy worker is
    // the only consumer of these settings; recorders manage their own codecs.
    await job.updateProgress(30);
    const encSettings = await loadProxyEncodingSettings();
    console.log(
      `[proxy] Transcoding asset ${assetId} via ${encSettings._gpu ? 'GPU' : 'CPU'} ` +
      `(${encSettings.videoCodec} ${encSettings.videoPreset} ${encSettings.videoBitrate})`
    );
    try {
      await transcodeVideo(inputPath, outputPath, { ...encSettings, hasAudio });
    } catch (err) {
      if (encSettings._gpu) {
        // Hardware encoder failed — typically "no NVIDIA driver" or "VAAPI
        // device not found". Fall back to libx264 so the job doesn't fail
        // when the worker host has no GPU.
        console.warn(`[proxy] GPU encode failed (${err.message}); falling back to libx264`);
        await transcodeVideo(inputPath, outputPath, {
          videoCodec: 'libx264', videoPreset: 'fast',
          videoBitrate: encSettings.videoBitrate,
          audioCodec: encSettings.audioCodec, audioBitrate: encSettings.audioBitrate,
          hasAudio,
        });
      } else { throw err; }
    }

    // Upload proxy to S3
    await job.updateProgress(70);
    console.log(`[proxy] Uploading to ${outputKey}`);
    await uploadToS3(S3_BUCKET, outputKey, outputPath);

    // Update asset record — store extracted metadata + proxy key
    // Use COALESCE so we never overwrite fields the capture service already set
    await job.updateProgress(90);
    await query(
      `UPDATE assets
       SET proxy_s3_key = $1,
           fps          = COALESCE($2, fps),
           codec        = COALESCE($3, codec),
           resolution   = COALESCE($4, resolution),
           duration_ms  = COALESCE($5, duration_ms),
           file_size    = COALESCE($6, file_size),
           updated_at   = NOW()
       WHERE id = $7`,
      [
        outputKey,
        mediaInfo.fps          ?? null,
        mediaInfo.codec        ?? null,
        mediaInfo.resolution   ?? null,
        mediaInfo.durationMs   ?? null,
        mediaInfo.fileSizeBytes ?? null,
        assetId,
      ]
    );

    // Now proxy exists in S3 — safe to queue thumbnail generation
    const thumbnailKey = `thumbnails/${assetId}.jpg`;
    await thumbnailQueue.add('generate', {
      assetId,
      proxyKey:  outputKey,
      outputKey: thumbnailKey,
    });

    console.log(`[proxy] Asset ${assetId} proxy complete, thumbnail job queued`);
    await job.updateProgress(100);

    return { assetId, outputKey };
  } catch (error) {
    console.error(`[proxy] Error processing asset ${assetId}:`, error);
    await query(
      `UPDATE assets SET status = 'error', updated_at = NOW() WHERE id = $1`,
      [assetId]
    );
    throw error;
  } finally {
    await Promise.all([
      unlink(inputPath).catch(() => {}),
      unlink(outputPath).catch(() => {}),
    ]);
  }
};