// 颜色空间RGB与HSV(HSL)的转换
// http://blog.csdn.net/idfaya/article/details/6770414
// https://github.com/harthur/color-convert/blob/master/conversions.js
export const rgb2hsl = function rgb2hsl (rgb) {
  let r = rgb[0] / 255,
    g = rgb[1] / 255,
    b = rgb[2] / 255,
    min = Math.min(r, g, b),
    max = Math.max(r, g, b),
    delta = max - min,
    h, s, l;
  
  if (max == min)
    h = 0;
  else if (r == max)
    h = (g - b) / delta;
  else if (g == max)
    h = 2 + (b - r) / delta;
  else if (b == max)
    h = 4 + (r - g) / delta;
  
  h = Math.min(h * 60, 360);
  
  if (h < 0)
    h += 360;
  
  l = (min + max) / 2;
  
  if (max == min)
    s = 0;
  else if (l <= 0.5)
    s = delta / (max + min);
  else
    s = delta / (2 - max - min);
  
  return [h, s * 100, l * 100];
}

export const rgb2hsv = function rgb2hsv (rgb) {
  let r = rgb[0],
    g = rgb[1],
    b = rgb[2],
    min = Math.min(r, g, b),
    max = Math.max(r, g, b),
    delta = max - min,
    h, s, v;
  
  if (max === 0)
    s = 0;
  else
    s = (delta / max * 1000) / 10;
  
  if (max == min)
    h = 0;
  else if (r == max)
    h = (g - b) / delta;
  else if (g == max)
    h = 2 + (b - r) / delta;
  else if (b == max)
    h = 4 + (r - g) / delta;
  
  h = Math.min(h * 60, 360);
  
  if (h < 0)
    h += 360;
  
  v = ((max / 255) * 1000) / 10;
  
  return [h, s, v];
}

export const hsl2rgb = function hsl2rgb (hsl) {
  let h = hsl[0] / 360,
    s = hsl[1] / 100,
    l = hsl[2] / 100,
    t1, t2, t3, rgb, val;
  
  if (s === 0) {
    val = l * 255;
    return [val, val, val];
  }
  
  if (l < 0.5)
    t2 = l * (1 + s);
  else
    t2 = l + s - l * s;
  t1 = 2 * l - t2;
  
  rgb = [0, 0, 0];
  for (let i = 0; i < 3; i++) {
    t3 = h + 1 / 3 * -(i - 1);
    if (t3 < 0) t3++;
    if (t3 > 1) t3--;
    
    if (6 * t3 < 1)
      val = t1 + (t2 - t1) * 6 * t3;
    else if (2 * t3 < 1)
      val = t2;
    else if (3 * t3 < 2)
      val = t1 + (t2 - t1) * (2 / 3 - t3) * 6;
    else
      val = t1;
    
    rgb[i] = val * 255;
  }
  
  return rgb;
}


export const hsl2hsv = function hsl2hsv (hsl) {
  let h = hsl[0],
    s = hsl[1] / 100,
    l = hsl[2] / 100,
    sv, v;
  l *= 2;
  s *= (l <= 1) ? l : 2 - l;
  v = (l + s) / 2;
  sv = (2 * s) / (l + s);
  return [h, sv * 100, v * 100];
}

export const hsv2rgb = function hsv2rgb(hsv) {
  let h = hsv[0] / 60
  let s = hsv[1] / 100
  let v = hsv[2] / 100
  let hi = Math.floor(h) % 6
  
  let f = h - Math.floor(h)
  let p = 255 * v * (1 - s)
  let q = 255 * v * (1 - (s * f))
  let t = 255 * v * (1 - (s * (1 - f)))
  
  v = 255 * v
  
  switch (hi) {
    case 0:
      return [v, t, p]
    case 1:
      return [q, v, p]
    case 2:
      return [p, v, t]
    case 3:
      return [p, q, v]
    case 4:
      return [t, p, v]
    case 5:
      return [v, p, q]
  }
}

export const hsv2hsl = function hsv2hsl (hsv) {
  let h = hsv[0],
    s = hsv[1] / 100,
    v = hsv[2] / 100,
    sl, l;
  
  l = (2 - s) * v;
  sl = s * v;
  sl /= (l <= 1) ? l : 2 - l;
  l /= 2;
  return [h, sl * 100, l * 100];
}

// http://www.140byt.es/keywords/color
export const rgb2hex = function(
  a, // red, as a number from 0 to 255
  b, // green, as a number from 0 to 255
  c // blue, as a number from 0 to 255
): string {
  return "#" + ((256 + a << 8 | b) << 8 | c).toString(16).slice(1)
}

export const hex2rgb = function (a) {
  a = '0x' + a.slice(1).replace(a.length > 4 ? a : /./g, '$&$&') as any | 0;
  return [a >> 16, a >> 8 & 255, a & 255]
}