import fs from "fs/promises";
import ExifReader from "exifreader";
import path from "path";

if (process.argv.length === 2) {
  console.error("Expected exactly one argument");
  process.exit(1);
}
const dir = process.argv[2];

let fileNames;
try {
  fileNames = await fs.readdir(dir);
} catch (error) {
  console.error("Error reading directory.", error);
  process.exit(2);
}

/**
 * @param fileName {string}
 * @return {Date|null}
 */
function getDateFromFileName(fileName) {
  const r = /(\d{4})-?(\d{2})-?(\d{2})[_\-](\d{2})-?(\d{2})-?(\d{2})/.exec(
    fileName,
  );
  if (!r) throw new Error("The file name did not match the pattern.");

  return new Date(`${r[1]}-${r[2]}-${r[3]}T${r[4]}:${r[5]}:${r[6]}`);
}

/**
 * @param filePath {string}
 * @param fileName {string}
 * @return {Promise<Date|null>}
 */
async function getDate(filePath, fileName) {
  if (/\.mp4$/.test(fileName)) {
    return getDateFromFileName(fileName);
  }

  const tags = await ExifReader.load(filePath);
  let timeString = tags.DateTime?.value[0];
  if (timeString === undefined) {
    return getDateFromFileName(fileName);
  }

  const exifDate = new Date(
    timeString.replace(
      /(\d{4}):(\d{2}):(\d{2}) (\d{2}):(\d{2}):(\d{2})/,
      "$1-$2-$3T$4:$5:$6",
    ),
  );

  if (isNaN(exifDate.getTime()) || exifDate.getFullYear() < 2000) {
    return getDateFromFileName(fileName);
  }

  return exifDate;
}

for (const fileName of fileNames) {
  const filePath = path.resolve(dir, fileName);

  let date;
  try {
    date = await getDate(filePath, fileName);
  } catch (error) {
    console.error(filePath, error.message);
    continue;
  }
  if (date === null) {
    console.error(filePath, "Could not get a date.");
    continue;
  }
  console.log(filePath, date);

  await fs.utimes(filePath, date, date);
}