Hex Color Code

export interface RgbColor {
  r: number;
  g: number;
  b: number;
  a?: number;
}

export function rgbToHex(r: number, g: number, b: number, a?: number): string {
  const clamp = (val: number) => Math.max(0, Math.min(255, Math.round(val)));
  const toHexByte = (n: number) => clamp(n).toString(16).padStart(2, '0').toUpperCase();

  let hex = `#${toHexByte(r)}${toHexByte(g)}${toHexByte(b)}`;
  if (typeof a === 'number') {
    const alphaByte = Math.round(Math.max(0, Math.min(1, a)) * 255);
    hex += toHexByte(alphaByte);
  }
  return hex;
}

export function hexToRgb(hex: string): RgbColor | null {
  let clean = hex.replace(/^#/, '').trim();
  if (clean.length === 3 || clean.length === 4) {
    clean = clean.split('').map(c => c + c).join('');
  }
  if (clean.length !== 6 && clean.length !== 8) return null;

  const num = parseInt(clean, 16);
  if (isNaN(num)) return null;

  if (clean.length === 6) {
    return {
      r: (num >> 16) & 255,
      g: (num >> 8) & 255,
      b: num & 255
    };
  }

  return {
    r: (num >> 24) & 255,
    g: (num >> 16) & 255,
    b: (num >> 8) & 255,
    a: Math.round(((num & 255) / 255) * 100) / 100
  };
}