export function getColorVariation(hex: string, lum: number) {
  hex = checkIfIsHexColor(hex) ? hex : getRandomColor();

  // validate hex string
  hex = String(hex).replace(/[^0-9a-f]/gi, '');
  if (hex.length < 6) {
    hex = (hex[0] as string) + hex[0] + hex[1] + hex[1] + hex[2] + hex[2];
  }
  lum = lum || 0;

  // convert to decimal and change luminosity
  let rgb = '#',
    c,
    i;
  for (i = 0; i < 3; i++) {
    c = parseInt(hex.substr(i * 2, 2), 16);
    c = Math.round(Math.min(Math.max(0, c + c * lum), 255)).toString(16);
    rgb += ('00' + c).substr(c.length);
  }

  return rgb;
}

export const checkIfIsHexColor = (color: string) => {
  const Reg_Exp = /(^#[0-9A-F]{6}$)|(^#[0-9A-F]{3}$)/i;
  return Reg_Exp.test(color);
};

export function getRandomColor() {
  const letters = '0123456789ABCDEF';
  let color = '#';
  for (let i = 0; i < 6; i++) {
    color += letters[Math.floor(Math.random() * 16)];
  }
  return color;
}