// transform /path/to/file.ext to file.ext
export function basename(path = '') {
  return path ? path.replace(/^.*\//, '') : '';
}

// transform /path/to/file.ext to .ext
export function extname(path = '') {
  const [_, ext] = /.+(\.[^.]+)$/.exec(path) || [];
  return ext || '';
}

// join a list of path segments with slashes, ensuring no double slashes
export function joinPaths(...parts) {
  let str = '';
  for (const part of parts) {
    if (!part) continue;
    str = !str ? part : `${str.replace(/\/$/, '')}/${part.replace(/^\//, '')}`;
  }
  return str;
}

// test whether a variable is an object
export function isObject(obj) {
  return Object.prototype.toString.call(obj) === '[object Object]';
}

// returns whether a dark theme is enabled
export function isDarkTheme() {
  const style = window.getComputedStyle(document.documentElement);
  return style.getPropertyValue('--is-dark-theme').trim().toLowerCase() === 'true';
}

// removes duplicate elements in an array
export function uniq(arr) {
  return Array.from(new Set(arr));
}

// strip <tags> from a string
export function stripTags(text) {
  return text.replace(/<[^>]*>?/gm, '');
}

// searches the inclusive range [minValue, maxValue].
// credits: https://matthiasott.com/notes/write-your-media-queries-in-pixels-not-ems
export function mqBinarySearch(feature, minValue, maxValue, step, unit) {
  if (maxValue - minValue < step) {
    return minValue;
  }
  const mid = Math.ceil((minValue + maxValue) / 2 / step) * step;
  if (matchMedia(`screen and (min-${feature}:${mid}${unit})`).matches) {
    return mqBinarySearch(feature, mid, maxValue, step, unit); // feature is >= mid
  }
  return mqBinarySearch(feature, minValue, mid - step, step, unit); // feature is < mid
}

export function parseIssueHref(href) {
  const path = (href || '').replace(/[#?].*$/, '');
  const [_, owner, repo, type, index] = /([^/]+)\/([^/]+)\/(issues|pulls)\/([0-9]+)/.exec(path) || [];
  return {owner, repo, type, index};
}

// return the sub-match result as an array:  [unmatched, matched, unmatched, matched, ...]
// res[even] is unmatched, res[odd] is matched, see unit tests for examples
export function strSubMatch(full, sub) {
  const res = [''];
  let i = 0, j = 0;
  while (i < sub.length && j < full.length) {
    while (j < full.length) {
      if (sub[i] === full[j]) {
        if (res.length % 2 !== 0) res.push('');
        res[res.length - 1] += full[j];
        j++;
        i++;
      } else {
        if (res.length % 2 === 0) res.push('');
        res[res.length - 1] += full[j];
        j++;
        break;
      }
    }
  }
  if (i !== sub.length) {
    // if the sub string doesn't match the full, only return the full as unmatched.
    return [full];
  }
  if (j < full.length) {
    // append remaining chars from full to result as unmatched
    if (res.length % 2 === 0) res.push('');
    res[res.length - 1] += full.substring(j);
  }
  return res;
}

// pretty-print a number using locale-specific separators, e.g. 1200 -> 1,200
export function prettyNumber(num, locale = 'en-US') {
  if (typeof num !== 'number') return '';
  const {format} = new Intl.NumberFormat(locale);
  return format(num);
}

// parse a URL, either relative '/path' or absolute 'https://localhost/path'
export function parseUrl(str) {
  return new URL(str, str.startsWith('http') ? undefined : window.location.origin);
}