const path = require('path');
const crypto = require('crypto');

function toPosix(p) {
  return p.split(path.sep).join('/');
}

function sha256(s) {
  return crypto.createHash('sha256').update(s).digest('hex');
}

function inferMimeFromExt(ext) {
  switch (ext.toLowerCase()) {
    case '.jpg':
    case '.jpeg': return 'image/jpeg';
    case '.png':  return 'image/png';
    case '.webp': return 'image/webp';
    case '.heic':
    case '.heif': return 'image/heic';
    case '.mp4': return 'video/mp4';
    case '.mov': return 'video/quicktime';
    case '.m4v': return 'video/x-m4v';
    default:      return 'application/octet-stream';
  }
}

function parseExifDateUtc(s) {
  if (!s) return null;
  const re = /^(\d{4}):(\d{2}):(\d{2}) (\d{2}):(\d{2}):(\d{2})$/;
  const m = re.exec(s);
  if (!m) return null;
  const dt = new Date(Date.UTC(+m[1], +m[2]-1, +m[3], +m[4], +m[5], +m[6]));
  return dt.toISOString();
}

module.exports = {
  toPosix,
  sha256,
  inferMimeFromExt,
  parseExifDateUtc
};