import fs from 'fs';
import { promises as fsp } from 'fs';
import path from 'path';
import { Router, Request, Response } from 'express';
import { config } from '../config';
import { runFFmpeg } from '../services/ffmpeg';
import { v4 as uuidv4 } from 'uuid';

const router = Router();

// GET /api/frame/:videoId?time=00:01:30.000
router.get('/:videoId', async (req: Request, res: Response) => {
  const { videoId } = req.params;
  const { time, frame } = req.query as { time?: string; frame?: string };

  const inputPath = path.resolve(config.videosDir, videoId);
  if (!inputPath.startsWith(path.resolve(config.videosDir))) {
    res.status(400).json({ error: 'Invalid video ID' });
    return;
  }
  if (!fs.existsSync(inputPath)) {
    res.status(404).json({ error: 'Video not found' });
    return;
  }

  let seekTime = '0';
  if (time) {
    seekTime = time;
  } else if (frame) {
    // frame number to time requires fps — use 30fps default
    seekTime = String(parseInt(frame, 10) / 30);
  }

  const outputFile = path.join(config.framesDir, `${uuidv4()}.jpg`);

  try {
    await runFFmpeg([
      '-accurate_seek',
      '-ss', seekTime,
      '-i', inputPath,
      '-frames:v', '1',
      '-q:v', '2',
      outputFile,
    ]);

    res.setHeader('Content-Type', 'image/jpeg');
    const stream = fs.createReadStream(outputFile);
    stream.pipe(res);
    stream.on('end', () => {
      fsp.unlink(outputFile).catch(() => {});
    });
  } catch (err) {
    res.status(500).json({ error: 'Frame extraction failed', detail: String(err) });
  }
});

export default router;