const express = require('express');
const multer = require('multer');
const path = require('path');
const fs = require('fs');
const { v4: uuidv4 } = require('uuid');
const axios = require('axios');
const FormData = require('form-data');

const app = express();
const PORT = process.env.PORT || 7860;

// ─── Directories ───────────────────────────────────────────────────────────
const UPLOADS_DIR = path.join(__dirname, 'uploads');
const OUTPUT_DIR  = path.join(__dirname, 'output');
const FONTS_DIR   = path.join(__dirname, 'public', 'fonts');
[UPLOADS_DIR, OUTPUT_DIR, FONTS_DIR].forEach(d => fs.mkdirSync(d, { recursive: true }));

// ─── Multer ────────────────────────────────────────────────────────────────
const storage = multer.diskStorage({
  destination: (req, file, cb) => cb(null, UPLOADS_DIR),
  filename:    (req, file, cb) => cb(null, `${uuidv4()}${path.extname(file.originalname)}`),
});
const upload = multer({ storage, limits: { fileSize: 50 * 1024 * 1024 } }); // 50 MB sub limit

// ─── In-memory job store ───────────────────────────────────────────────────
const jobs = {};

app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));

// ─── SSE helper ────────────────────────────────────────────────────────────
function sendEvent(res, data) {
  res.write(`data: ${JSON.stringify(data)}\n\n`);
}

// ─── Routes ────────────────────────────────────────────────────────────────

// POST /burn  – starts the job
app.post('/burn', upload.single('subtitle'), async (req, res) => {
  const { videoUrl, pixeldrainApiKey } = req.body;

  if (!videoUrl) return res.status(400).json({ error: 'videoUrl is required' });
  if (!req.file)  return res.status(400).json({ error: 'Subtitle file is required' });

  const jobId       = uuidv4();
  const subPath     = req.file.path;
  const outputFile  = path.join(OUTPUT_DIR, `${jobId}.mp4`);

  jobs[jobId] = { status: 'queued', progress: 0, message: 'Starting…', outputFile, pixeldrainApiKey };

  res.json({ jobId });

  // Run in background
  processVideo(jobId, videoUrl, subPath, outputFile).catch(err => {
    jobs[jobId].status  = 'error';
    jobs[jobId].message = err.message;
  });
});

// GET /status/:jobId  – SSE progress stream
app.get('/status/:jobId', (req, res) => {
  const { jobId } = req.params;
  if (!jobs[jobId]) return res.status(404).json({ error: 'Job not found' });

  res.setHeader('Content-Type',  'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection',    'keep-alive');
  res.flushHeaders();

  const interval = setInterval(() => {
    const job = jobs[jobId];
    sendEvent(res, job);
    if (job.status === 'done' || job.status === 'error') {
      clearInterval(interval);
      res.end();
    }
  }, 800);

  req.on('close', () => clearInterval(interval));
});

// ─── Core processing ────────────────────────────────────────────────────────
async function processVideo(jobId, videoUrl, subPath, outputFile) {
  const job = jobs[jobId];

  // Step 1 – Download video
  job.status   = 'downloading';
  job.message  = 'Downloading video…';
  job.progress = 2;

  const videoFile = path.join(UPLOADS_DIR, `${jobId}.mp4`);
  await downloadFile(videoUrl, videoFile, (pct) => {
    job.progress = Math.round(pct * 0.3); // 0–30%
    job.message  = `Downloading… ${job.progress}%`;
  });

  // Step 2 – Burn subtitles with HandBrake
  job.status  = 'burning';
  job.message = 'Burning subtitles…';
  job.progress = 30;

  await burnSubtitles(jobId, videoFile, subPath, outputFile);

  // Step 3 – Upload to Pixeldrain
  job.status   = 'uploading';
  job.message  = 'Uploading to Pixeldrain…';
  job.progress = 95;

  const downloadUrl = await uploadToPixeldrain(outputFile, job.pixeldrainApiKey);

  // Cleanup
  [videoFile, subPath].forEach(f => { try { fs.unlinkSync(f); } catch {} });

  job.status      = 'done';
  job.progress    = 100;
  job.message     = 'Done!';
  job.downloadUrl = downloadUrl;
}

// ─── Download with progress ────────────────────────────────────────────────
async function downloadFile(url, dest, onProgress) {
  const response = await axios({ method: 'GET', url, responseType: 'stream' });
  const total    = parseInt(response.headers['content-length'] || '0', 10);
  let   received = 0;

  return new Promise((resolve, reject) => {
    const writer = fs.createWriteStream(dest);
    response.data.on('data', chunk => {
      received += chunk.length;
      if (total) onProgress(received / total);
    });
    response.data.pipe(writer);
    writer.on('finish', resolve);
    writer.on('error',  reject);
    response.data.on('error', reject);
  });
}

// ─── HandBrake subtitle burn ───────────────────────────────────────────────
function burnSubtitles(jobId, videoFile, subFile, outputFile) {
  const hbjs    = require('handbrake-js');
  const job     = jobs[jobId];
  const subExt  = path.extname(subFile).toLowerCase();
  const isSrt   = subExt === '.srt' || subExt === '.ass' || subExt === '.ssa';

  // ASS override style – NotoSans Sinhala for Sinhala chars, Roboto for Latin
  // We embed the subtitle track and burn it in
  const options = {
    input:   videoFile,
    output:  outputFile,
    encoder: 'x264',
    quality: 22,
    'subtitle-lang-list': 'und',
    'all-subtitles': true,
    'subtitle-burned': 0,
    'sub-burn': 0,
  };

  // Use SRT import for text subtitle files
  if (isSrt) {
    options['srt-file']     = subFile;
    options['srt-burn']     = 0;       // burn the imported track (index 0-based)
    options['srt-codeset']  = 'UTF-8';
  }

  return new Promise((resolve, reject) => {
    hbjs.spawn(options)
      .on('error',    reject)
      .on('progress', p => {
        if (p.percentComplete !== undefined) {
          job.progress = 30 + Math.round(p.percentComplete * 0.64); // 30–94%
          job.message  = `Burning… ${p.percentComplete.toFixed(1)}%  |  ETA: ${p.eta || '?'}`;
        }
      })
      .on('end', resolve);
  });
}

// ─── Pixeldrain upload ────────────────────────────────────────────────────
async function uploadToPixeldrain(filePath, apiKey) {
  const form     = new FormData();
  const fileName = path.basename(filePath);
  form.append('file', fs.createReadStream(filePath), fileName);

  const headers = { ...form.getHeaders() };
  if (apiKey) {
    const encoded = Buffer.from(`:${apiKey}`).toString('base64');
    headers['Authorization'] = `Basic ${encoded}`;
  }

  const resp = await axios.post('https://pixeldrain.com/api/file', form, { headers, maxContentLength: Infinity, maxBodyLength: Infinity });

  const fileId = resp.data.id;
  // Cleanup output after upload
  try { fs.unlinkSync(filePath); } catch {}
  return `https://pixeldrain.com/u/${fileId}`;
}

// ─── Start ────────────────────────────────────────────────────────────────
app.listen(PORT, () => console.log(`🎬 Subtitle Burner running on http://localhost:${PORT}`));