export function basename()

in desktop/flipper-plugin/src/utils/path.tsx [220:285]
50 lines of code
19 McCabe index (conditional complexity)

export function basename(path: string, ext?: string) {
  let start = 0;
  let end = -1;
  let matchedSlash = true;

  if (ext !== undefined && ext.length > 0 && ext.length <= path.length) {
    if (ext === path) return '';
    let extIdx = ext.length - 1;
    let firstNonSlashEnd = -1;
    for (let i = path.length - 1; i >= 0; --i) {
      const code = path.charCodeAt(i);
      if (code === CHAR_FORWARD_SLASH) {
        // If we reached a path separator that was not part of a set of path
        // separators at the end of the string, stop now
        if (!matchedSlash) {
          start = i + 1;
          break;
        }
      } else {
        if (firstNonSlashEnd === -1) {
          // We saw the first non-path separator, remember this index in case
          // we need it if the extension ends up not matching
          matchedSlash = false;
          firstNonSlashEnd = i + 1;
        }
        if (extIdx >= 0) {
          // Try to match the explicit extension
          if (code === ext.charCodeAt(extIdx)) {
            if (--extIdx === -1) {
              // We matched the extension, so mark this as the end of our path
              // component
              end = i;
            }
          } else {
            // Extension does not match, so our result is the entire path
            // component
            extIdx = -1;
            end = firstNonSlashEnd;
          }
        }
      }
    }

    if (start === end) end = firstNonSlashEnd;
    else if (end === -1) end = path.length;
    return path.slice(start, end);
  }
  for (let i = path.length - 1; i >= 0; --i) {
    if (path.charCodeAt(i) === CHAR_FORWARD_SLASH) {
      // If we reached a path separator that was not part of a set of path
      // separators at the end of the string, stop now
      if (!matchedSlash) {
        start = i + 1;
        break;
      }
    } else if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // path component
      matchedSlash = false;
      end = i + 1;
    }
  }

  if (end === -1) return '';
  return path.slice(start, end);
}