export const userId = (params: { username: string; database: string }) => {
  const { username, database } = params;
  const dbUrl = new URL(database);
  return `@${username}>${dbUrl.hostname}`;
};

export const parseUserId = (id: string) => {
  const matches = id.match(/^@([^>]+)>(.+)$/);
  if (!matches) {
    return null;
  }
  return { username: matches[1], database: matches[2] };
};

function hex2a(hex: string) {
  var str = '';
  for (var i = 0; i < hex.length; i += 2) {
    var v = parseInt(hex.substr(i, 2), 16);
    if (v) str += String.fromCharCode(v);
  }
  return str;
}

export const parseDbUrl = (urlString: string) => {
  origin;
  const url = new URL(urlString);
  const match = url.pathname.match(/\/userdb-(.*)\//);
  if (!match || match.length < 2) {
    return { username: '', database: url.hostname };
  }
  const [_, encodedUser] = match;
  return { username: hex2a(encodedUser), database: urlString };
};

export const dbUrlToUserId = (urlString: string) => {
  if (!urlString) {
    return null;
  }
  return userId(parseDbUrl(urlString));
};