// api_v1/scanner/thumbs.js
const sharp = require('sharp');
const { exec } = require('child_process');
const path = require('path');

function deriveCastPathFromAvg(thumbAvgPath) {
  if (!thumbAvgPath) return null;

  // Caso standard: IMG_0241_avg.jpg -> IMG_0241_cast.jpg
  if (thumbAvgPath.toLowerCase().endsWith('_avg.jpg')) {
    return thumbAvgPath.replace(/_avg\.jpg$/i, '_cast.jpg');
  }

  // Fallback generico
  const ext = path.extname(thumbAvgPath);
  const base = thumbAvgPath.slice(0, -ext.length);
  return `${base}_cast.jpg`;
}

// Video: lascia solo avg + min
function createVideoThumbnail(videoPath, thumbMinPath, thumbAvgPath) {
  return new Promise((resolve) => {
    const cmd = `
      ffmpeg -y -i "${videoPath}" -ss 00:00:01.000 -vframes 1 "${thumbAvgPath}" &&
      ffmpeg -y -i "${thumbAvgPath}" -vf "scale=100:-1" "${thumbMinPath}"
    `;

    exec(cmd, () => resolve());
  });
}

// Foto: min + avg + cast
async function createThumbnails(filePath, thumbMinPath, thumbAvgPath, thumbCastPath) {
  try {
    const finalCastPath = thumbCastPath || deriveCastPathFromAvg(thumbAvgPath);

    // 1) MIN: 100px
    await sharp(filePath)
      .rotate()
      .resize({
        width: 100,
        height: 100,
        fit: 'inside',
        withoutEnlargement: true,
      })
      .jpeg({
        quality: 75,
        progressive: false,
        optimizeCoding: true,
      })
      .toFile(thumbMinPath);

    // 2) AVG: 400px
    await sharp(filePath)
      .rotate()
      .resize({
        width: 400,
        fit: 'inside',
        withoutEnlargement: true,
      })
      .jpeg({
        quality: 78,
        progressive: false,
        optimizeCoding: true,
      })
      .toFile(thumbAvgPath);

    // 3) CAST: max 4K TV, dentro 3840x2160, senza crop
    // 3) CAST: metà del 4K → 1920x1080, senza crop
    if (finalCastPath) {
      await sharp(filePath)
        .rotate()
        .resize({
          width: 1920,
          height: 1080,
          fit: 'inside',
          withoutEnlargement: true,
          fastShrinkOnLoad: true,
        })
        .jpeg({
          quality: 85,
          progressive: false,
          optimizeCoding: true,
        })
        .toFile(finalCastPath);
    }

  } catch (err) {
    console.error('Errore creazione thumbnails:', err.message, filePath);
  }
}

module.exports = {
  createVideoThumbnail,
  createThumbnails,
};