Refactor rgbTo256Color

  "█▓▒░@#B8&WM%*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\\|()1{}[]?-_+~<>i!lI;:,\"^`'. ";

// cSpell: enable

const CUBE_VALUES = [0, 95, 135, 175, 215, 255];

const findClosestIndex = (value: number): number => {

  let minDiff = Infinity;

  let closestIndex = 0;

  for (let idx = 0; idx < CUBE_VALUES.length; idx++) {

    const diff = Math.abs(value - CUBE_VALUES[idx]);

    if (diff < minDiff) {

      minDiff = diff;

      closestIndex = idx;

    }

  }

  return closestIndex;

};

export function rgbTo256Color(r: number, g: number, b: number): number {

  // Check if it's a grayscale color first (when all RGB values are very close)

  const gray = Math.round((r + g + b) / 3);

  // Handle grayscale colors (colors 232-255) - but exclude exact cube values

  if (isGrayscale) {

    const cubeValues = [0, 95, 135, 175, 215, 255];

    const isExactCubeValue = cubeValues.includes(r) && r === g && g === b;

    const isExactCubeValue = CUBE_VALUES.includes(r) && r === g && g === b;

    if (!isExactCubeValue) {

      if (gray < 8) return 232; // Darkest grayscale

  // Handle RGB colors (colors 16-231)

  // XTerm 256 color cube values: [0, 95, 135, 175, 215, 255]

  const cubeValues = [0, 95, 135, 175, 215, 255];

  const findClosestIndex = (value: number): number => {

    let minDiff = Infinity;

    let closestIndex = 0;

    for (let i = 0; i < cubeValues.length; i++) {

      const diff = Math.abs(value - cubeValues[i]);

      if (diff < minDiff) {

        minDiff = diff;

        closestIndex = i;

      }

    }

    return closestIndex;

  };

  const r6 = findClosestIndex(r);

  const g6 = findClosestIndex(g);