const execa = require('execa');

function parseFps(fps) {
  const match = typeof fps === 'string' && fps.match(/^([0-9]+)\/([0-9]+)$/);
  if (match) {
    const num = parseInt(match[1], 10);
    const den = parseInt(match[2], 10);
    if (den > 0) return num / den;
  }
  return undefined;
}

async function readFileInfo(p) {
  const { stdout } = await execa('ffprobe', [
    '-select_streams', 'v:0', '-show_entries', 'stream', '-of', 'json', p,
  ]);
  const json = JSON.parse(stdout);
  const stream = json.streams[0];
  return {
    // numFrames: parseInt(stream.nb_frames, 10),
    duration: parseFloat(stream.duration, 10),
    width: stream.width, // TODO coded_width?
    height: stream.height,
    framerateStr: stream.r_frame_rate,
  };
}

const multipleOf2 = (x) => (x + (x % 2));

module.exports = {
  parseFps,
  readFileInfo,
  multipleOf2,
};