// Author  baixin.zhao@rokid

exports.rgb2hsv = function (rgb) {

  let R, G, B, H, S, V;

  R = (rgb >> 16) & 0xFF;
  G = (rgb >> 8) & 0xFF;
  B = rgb & 0xFF;

  const M = Math.max(R, G, B);
  const m = Math.min(R, G, B);

  V = M / 255; //range to [0, 1]
  S = M === 0 ? 0 : (1 - m / M);

  const num = R - 0.5 * G - 0.5 * B;
  const den = Math.sqrt(Math.pow(R, 2) + Math.pow(G, 2) + Math.pow(B, 2) - R * G - R * B - G * B);
  let div;
  if(den === 0) {
    div = 0;
  } else {
    div = num / den;
  }
  const count = Math.acos(div) / Math.PI * 180;
  if (G >= B) {
    H = count;
  } else {
    H = 360 - count;
  }

  return [H, S, V]
};

exports.hsv2rgb = function (hsv) {

  let R, G, B;

  let H = hsv[0];
  let S = hsv[1];
  let V = hsv[2];

  if (H === 0) {
    R = V + 2 * V * S;
    G = V - V * S;
    B = V - V * S;
  } else if (0 < H < 120) {
    R = V + V * S * Math.cos(H) / Math.cos(60 - H);
    G = V + V * S * (1 - Math.cos(H) / Math.cos(60 - H));
    B = V - V * S;
  } else if (H === 120) {
    R = V - V * S;
    G = V + 2 * V * S;
    B = V - V * S;
  } else if (120 < H < 240) {
    R = V - V * S;
    G = V + V * S * Math.cos(H - 120) / Math.cos(180 - H);
    B = V + V * S * (1 - Math.cos(H - 120) / Math.cos(180 - H));
  } else if (H === 240) {
    R = V - V * S;
    G = V - V * S;
    B = V + 2 * V * S;
  } else {
    R = V + V * S * (1 - Math.cos(H - 240) / Math.cos(300 - H));
    G = V - V * S;
    B = V + V * S * Math.cos(H - 240) / Math.cos(300 - H);
  }

  return [R, G, B]
};

exports.hsv2rgbw = function (hsv) {
  let r, g, b, w;
  let cos_h, cos_1047_h;

  let H = hsv[0];
  let S = hsv[1];
  let V = hsv[2];

  H = 3.14159 * H / 180; // Convert to radians.
  S = S > 0 ? (S < 1 ? S : 1) : 0; // clamp S and I to interval [0,1]
  V = V > 0 ? (V < 1 ? V : 1) : 0;

  if (H < 2.09439) {
    cos_h = Math.cos(H);
    cos_1047_h = Math.cos(1.047196667 - H);
    r = S * 255 * V / 3 * (1 + cos_h / cos_1047_h);
    g = S * 255 * V / 3 * (1 + (1 - cos_h / cos_1047_h));
    b = 0;
    w = 255 * (1 - S) * V;
  } else if (H < 4.188787) {
    H = H - 2.09439;
    cos_h = Math.cos(H);
    cos_1047_h = Math.cos(1.047196667 - H);
    g = S * 255 * V / 3 * (1 + cos_h / cos_1047_h);
    b = S * 255 * V / 3 * (1 + (1 - cos_h / cos_1047_h));
    r = 0;
    w = 255 * (1 - S) * V;
  } else {
    H = H - 4.188787;
    cos_h = Math.cos(H);
    cos_1047_h = Math.cos(1.047196667 - H);
    b = S * 255 * V / 3 * (1 + cos_h / cos_1047_h);
    r = S * 255 * V / 3 * (1 + (1 - cos_h / cos_1047_h));
    g = 0;
    w = 255 * (1 - S) * V;
  }

  return [w, r, g, b]
};

exports.toNum = function (arr) {
  let length = arr.length;
  let result = 0;
  arr.forEach((item, index) => {
    result += Math.round(item) * Math.pow(2, (length - 1 - index) * 8);
  });
  return result;
};