export function rgba(rgb: string): { r: number, g: number, b: number, a: number } {
  const result = /^rgba?\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*(?:,\s*(\d+(?:\.\d+)?))?\s*\)$/.exec(
    rgb.toLowerCase()
  );
  if (result) {
    const r = parseInt(result[1], 10);
    const g = parseInt(result[2], 10);
    const b = parseInt(result[3], 10);
    const a = result[4] !== undefined ? parseFloat(result[4]) : 1;

    return { r, g, b, a };
  } else {
    throw new Error('rgba color parsed failed');
  }
}

export function rgb2hex(r: number, g: number, b: number): string {
  return ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
}