function makeTZData()

in src/components/TimezoneProvider/index.tsx [15:66]
43 lines of code
8 McCabe index (conditional complexity)

function makeTZData() {
  const timezoneData = Object.entries(spacetime().timezones).filter(
    (key) => !key[0].includes('etc') && !key[0].includes('utc'),
  );

  // [string, string] = [value, label]
  const tzs: [string, string][] = [];
  timezoneData.forEach(([key, value], index) => {
    const parseHour = (value: number) => {
      if (value < -9.5 || value > 9.5) {
        return value > 9 ? `+${Math.floor(value)}` : value;
      } else {
        return value < 0 ? `-0${Math.floor(value * -1)}` : `+0${Math.floor(value)}`;
      }
    };

    // offsets end section can be 00, 15, 30, or 45
    const offset = `${parseHour(spacetime().goto(key).timezone().current.offset)}:${
      Number.isInteger(value.offset) ? '00' : `${60 * (value.offset - Math.floor(value.offset))}`
    }`;

    let region = key.split('/')[0];
    region = `${region[0].toUpperCase()}${region.slice(1)}`
      .replace('Us', 'US')
      .replace('Uk', 'UK')
      .replace('Gb', 'GB')
      .replace('Uct', 'UCT')
      .replace('Nz', 'NZ')
      .replace('Gmt', 'GMT')
      .replace('Prc', 'PRC')
      .replace('Roc', 'ROC')
      .replace('Rok', 'ROK')
      .replace('eire', 'Eire');
    let city = '';
    if (key.includes('/')) {
      city = key.split('/')[1].replace(/_/g, ' ');
      city = `${city[0].toUpperCase()}${city.slice(1)}`.replace(/([\s-])(\w)/g, (_, p1, p2) => p1 + p2.toUpperCase());
      // we need to add index to differentiate the offsets from one another
      tzs.push([`${offset}|${index}`, `(GMT${offset}) ${region}/${city}`]);
    } else {
      // we need to add index to differentiate the offsets from one another
      tzs.push([`${offset}|${index}`, `(GMT${offset}) ${region}`]);
    }
  });

  const getOffset = (a: string) => parseFloat(a.split('|')[0]);
  tzs.sort((a, b) =>
    getOffset(a[0]) === getOffset(b[0]) ? a[1].localeCompare(b[1]) : getOffset(a[0]) - getOffset(b[0]),
  );

  return tzs;
}