/* MIT license */
/* eslint-disable no-mixed-operators */
const cssKeywords = require('color-name');

// NOTE: conversions should only return primitive values (i.e. arrays, or
//       values that give correct `typeof` results).
//       do not use box values types (i.e. Number(), String(), etc.)

const reverseKeywords = {};
for (const key of Object.keys(cssKeywords)) {
  reverseKeywords[cssKeywords[key]] = key;
}

const convert = {
  rgb: { channels: 3, labels: 'rgb' },
  hsl: { channels: 3, labels: 'hsl' },
  hsv: { channels: 3, labels: 'hsv' },
  hwb: { channels: 3, labels: 'hwb' },
  cmyk: { channels: 4, labels: 'cmyk' },
  xyz: { channels: 3, labels: 'xyz' },
  lab: { channels: 3, labels: 'lab' },
  lch: { channels: 3, labels: 'lch' },
  hex: { channels: 1, labels: ['hex'] },
  keyword: { channels: 1, labels: ['keyword'] },
  ansi16: { channels: 1, labels: ['ansi16'] },
  ansi256: { channels: 1, labels: ['ansi256'] },
  hcg: { channels: 3, labels: ['h', 'c', 'g'] },
  apple: { channels: 3, labels: ['r16', 'g16', 'b16'] },
  gray: { channels: 1, labels: ['gray'] },
};

module.exports = convert;

// Hide .channels and .labels properties
for (const model of Object.keys(convert)) {
  if (!('channels' in convert[model])) {
    throw new Error('missing channels property: ' + model);
  }

  if (!('labels' in convert[model])) {
    throw new Error('missing channel labels property: ' + model);
  }

  if (convert[model].labels.length !== convert[model].channels) {
    throw new Error('channel and label counts mismatch: ' + model);
  }

  const { channels, labels } = convert[model];
  delete convert[model].channels;
  delete convert[model].labels;
  Object.defineProperty(convert[model], 'channels', { value: channels });
  Object.defineProperty(convert[model], 'labels', { value: labels });
}

convert.rgb.hsl = function (rgb) {
  const r = rgb[0] / 255;
  const g = rgb[1] / 255;
  const b = rgb[2] / 255;
  const min = Math.min(r, g, b);
  const max = Math.max(r, g, b);
  const delta = max - min;
  let h;
  let s;

  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;
  }

  const 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];
};

convert.rgb.hsv = function (rgb) {
  let rdif;
  let gdif;
  let bdif;
  let h;
  let s;

  const r = rgb[0] / 255;
  const g = rgb[1] / 255;
  const b = rgb[2] / 255;
  const v = Math.max(r, g, b);
  const diff = v - Math.min(r, g, b);
  const diffc = function (c) {
    return (v - c) / 6 / diff + 1 / 2;
  };

  if (diff === 0) {
    h = 0;
    s = 0;
  } else {
    s = diff / v;
    rdif = diffc(r);
    gdif = diffc(g);
    bdif = diffc(b);

    if (r === v) {
      h = bdif - gdif;
    } else if (g === v) {
      h = 1 / 3 + rdif - bdif;
    } else if (b === v) {
      h = 2 / 3 + gdif - rdif;
    }

    if (h < 0) {
      h += 1;
    } else if (h > 1) {
      h -= 1;
    }
  }

  return [h * 360, s * 100, v * 100];
};

convert.rgb.hwb = function (rgb) {
  const r = rgb[0];
  const g = rgb[1];
  let b = rgb[2];
  const h = convert.rgb.hsl(rgb)[0];
  const w = (1 / 255) * Math.min(r, Math.min(g, b));

  b = 1 - (1 / 255) * Math.max(r, Math.max(g, b));

  return [h, w * 100, b * 100];
};

convert.rgb.cmyk = function (rgb) {
  const r = rgb[0] / 255;
  const g = rgb[1] / 255;
  const b = rgb[2] / 255;

  const k = Math.min(1 - r, 1 - g, 1 - b);
  const c = (1 - r - k) / (1 - k) || 0;
  const m = (1 - g - k) / (1 - k) || 0;
  const y = (1 - b - k) / (1 - k) || 0;

  return [c * 100, m * 100, y * 100, k * 100];
};

function comparativeDistance(x, y) {
  /*
		See https://en.m.wikipedia.org/wiki/Euclidean_distance#Squared_Euclidean_distance
	*/
  return (x[0] - y[0]) ** 2 + (x[1] - y[1]) ** 2 + (x[2] - y[2]) ** 2;
}

convert.rgb.keyword = function (rgb) {
  const reversed = reverseKeywords[rgb];
  if (reversed) {
    return reversed;
  }

  let currentClosestDistance = Infinity;
  let currentClosestKeyword;

  for (const keyword of Object.keys(cssKeywords)) {
    const value = cssKeywords[keyword];

    // Compute comparative distance
    const distance = comparativeDistance(rgb, value);

    // Check if its less, if so set as closest
    if (distance < currentClosestDistance) {
      currentClosestDistance = distance;
      currentClosestKeyword = keyword;
    }
  }

  return currentClosestKeyword;
};

convert.keyword.rgb = function (keyword) {
  return cssKeywords[keyword];
};

convert.rgb.xyz = function (rgb) {
  let r = rgb[0] / 255;
  let g = rgb[1] / 255;
  let b = rgb[2] / 255;

  // Assume sRGB
  r = r > 0.04045 ? ((r + 0.055) / 1.055) ** 2.4 : r / 12.92;
  g = g > 0.04045 ? ((g + 0.055) / 1.055) ** 2.4 : g / 12.92;
  b = b > 0.04045 ? ((b + 0.055) / 1.055) ** 2.4 : b / 12.92;

  const x = r * 0.4124 + g * 0.3576 + b * 0.1805;
  const y = r * 0.2126 + g * 0.7152 + b * 0.0722;
  const z = r * 0.0193 + g * 0.1192 + b * 0.9505;

  return [x * 100, y * 100, z * 100];
};

convert.rgb.lab = function (rgb) {
  const xyz = convert.rgb.xyz(rgb);
  let x = xyz[0];
  let y = xyz[1];
  let z = xyz[2];

  x /= 95.047;
  y /= 100;
  z /= 108.883;

  x = x > 0.008856 ? x ** (1 / 3) : 7.787 * x + 16 / 116;
  y = y > 0.008856 ? y ** (1 / 3) : 7.787 * y + 16 / 116;
  z = z > 0.008856 ? z ** (1 / 3) : 7.787 * z + 16 / 116;

  const l = 116 * y - 16;
  const a = 500 * (x - y);
  const b = 200 * (y - z);

  return [l, a, b];
};

convert.hsl.rgb = function (hsl) {
  const h = hsl[0] / 360;
  const s = hsl[1] / 100;
  const l = hsl[2] / 100;
  let t2;
  let t3;
  let 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;
  }

  const t1 = 2 * l - t2;

  const 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;
};

convert.hsl.hsv = function (hsl) {
  const h = hsl[0];
  let s = hsl[1] / 100;
  let l = hsl[2] / 100;
  let smin = s;
  const lmin = Math.max(l, 0.01);

  l *= 2;
  s *= l <= 1 ? l : 2 - l;
  smin *= lmin <= 1 ? lmin : 2 - lmin;
  const v = (l + s) / 2;
  const sv = l === 0 ? (2 * smin) / (lmin + smin) : (2 * s) / (l + s);

  return [h, sv * 100, v * 100];
};

convert.hsv.rgb = function (hsv) {
  const h = hsv[0] / 60;
  const s = hsv[1] / 100;
  let v = hsv[2] / 100;
  const hi = Math.floor(h) % 6;

  const f = h - Math.floor(h);
  const p = 255 * v * (1 - s);
  const q = 255 * v * (1 - s * f);
  const t = 255 * v * (1 - s * (1 - f));
  v *= 255;

  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];
  }
};

convert.hsv.hsl = function (hsv) {
  const h = hsv[0];
  const s = hsv[1] / 100;
  const v = hsv[2] / 100;
  const vmin = Math.max(v, 0.01);
  let sl;
  let l;

  l = (2 - s) * v;
  const lmin = (2 - s) * vmin;
  sl = s * vmin;
  sl /= lmin <= 1 ? lmin : 2 - lmin;
  sl = sl || 0;
  l /= 2;

  return [h, sl * 100, l * 100];
};

// http://dev.w3.org/csswg/css-color/#hwb-to-rgb
convert.hwb.rgb = function (hwb) {
  const h = hwb[0] / 360;
  let wh = hwb[1] / 100;
  let bl = hwb[2] / 100;
  const ratio = wh + bl;
  let f;

  // Wh + bl cant be > 1
  if (ratio > 1) {
    wh /= ratio;
    bl /= ratio;
  }

  const i = Math.floor(6 * h);
  const v = 1 - bl;
  f = 6 * h - i;

  if ((i & 0x01) !== 0) {
    f = 1 - f;
  }

  const n = wh + f * (v - wh); // Linear interpolation

  let r;
  let g;
  let b;
  /* eslint-disable max-statements-per-line,no-multi-spaces */
  switch (i) {
    default:
    case 6:
    case 0:
      r = v;
      g = n;
      b = wh;
      break;
    case 1:
      r = n;
      g = v;
      b = wh;
      break;
    case 2:
      r = wh;
      g = v;
      b = n;
      break;
    case 3:
      r = wh;
      g = n;
      b = v;
      break;
    case 4:
      r = n;
      g = wh;
      b = v;
      break;
    case 5:
      r = v;
      g = wh;
      b = n;
      break;
  }
  /* eslint-enable max-statements-per-line,no-multi-spaces */

  return [r * 255, g * 255, b * 255];
};

convert.cmyk.rgb = function (cmyk) {
  const c = cmyk[0] / 100;
  const m = cmyk[1] / 100;
  const y = cmyk[2] / 100;
  const k = cmyk[3] / 100;

  const r = 1 - Math.min(1, c * (1 - k) + k);
  const g = 1 - Math.min(1, m * (1 - k) + k);
  const b = 1 - Math.min(1, y * (1 - k) + k);

  return [r * 255, g * 255, b * 255];
};

convert.xyz.rgb = function (xyz) {
  const x = xyz[0] / 100;
  const y = xyz[1] / 100;
  const z = xyz[2] / 100;
  let r;
  let g;
  let b;

  r = x * 3.2406 + y * -1.5372 + z * -0.4986;
  g = x * -0.9689 + y * 1.8758 + z * 0.0415;
  b = x * 0.0557 + y * -0.204 + z * 1.057;

  // Assume sRGB
  r = r > 0.0031308 ? 1.055 * r ** (1.0 / 2.4) - 0.055 : r * 12.92;

  g = g > 0.0031308 ? 1.055 * g ** (1.0 / 2.4) - 0.055 : g * 12.92;

  b = b > 0.0031308 ? 1.055 * b ** (1.0 / 2.4) - 0.055 : b * 12.92;

  r = Math.min(Math.max(0, r), 1);
  g = Math.min(Math.max(0, g), 1);
  b = Math.min(Math.max(0, b), 1);

  return [r * 255, g * 255, b * 255];
};

convert.xyz.lab = function (xyz) {
  let x = xyz[0];
  let y = xyz[1];
  let z = xyz[2];

  x /= 95.047;
  y /= 100;
  z /= 108.883;

  x = x > 0.008856 ? x ** (1 / 3) : 7.787 * x + 16 / 116;
  y = y > 0.008856 ? y ** (1 / 3) : 7.787 * y + 16 / 116;
  z = z > 0.008856 ? z ** (1 / 3) : 7.787 * z + 16 / 116;

  const l = 116 * y - 16;
  const a = 500 * (x - y);
  const b = 200 * (y - z);

  return [l, a, b];
};

convert.lab.xyz = function (lab) {
  const l = lab[0];
  const a = lab[1];
  const b = lab[2];
  let x;
  let y;
  let z;

  y = (l + 16) / 116;
  x = a / 500 + y;
  z = y - b / 200;

  const y2 = y ** 3;
  const x2 = x ** 3;
  const z2 = z ** 3;
  y = y2 > 0.008856 ? y2 : (y - 16 / 116) / 7.787;
  x = x2 > 0.008856 ? x2 : (x - 16 / 116) / 7.787;
  z = z2 > 0.008856 ? z2 : (z - 16 / 116) / 7.787;

  x *= 95.047;
  y *= 100;
  z *= 108.883;

  return [x, y, z];
};

convert.lab.lch = function (lab) {
  const l = lab[0];
  const a = lab[1];
  const b = lab[2];
  let h;

  const hr = Math.atan2(b, a);
  h = (hr * 360) / 2 / Math.PI;

  if (h < 0) {
    h += 360;
  }

  const c = Math.sqrt(a * a + b * b);

  return [l, c, h];
};

convert.lch.lab = function (lch) {
  const l = lch[0];
  const c = lch[1];
  const h = lch[2];

  const hr = (h / 360) * 2 * Math.PI;
  const a = c * Math.cos(hr);
  const b = c * Math.sin(hr);

  return [l, a, b];
};

convert.rgb.ansi16 = function (args, saturation = null) {
  const [r, g, b] = args;
  let value = saturation === null ? convert.rgb.hsv(args)[2] : saturation; // Hsv -> ansi16 optimization

  value = Math.round(value / 50);

  if (value === 0) {
    return 30;
  }

  let ansi =
    30 +
    ((Math.round(b / 255) << 2) |
      (Math.round(g / 255) << 1) |
      Math.round(r / 255));

  if (value === 2) {
    ansi += 60;
  }

  return ansi;
};

convert.hsv.ansi16 = function (args) {
  // Optimization here; we already know the value and don't need to get
  // it converted for us.
  return convert.rgb.ansi16(convert.hsv.rgb(args), args[2]);
};

convert.rgb.ansi256 = function (args) {
  const r = args[0];
  const g = args[1];
  const b = args[2];

  // We use the extended greyscale palette here, with the exception of
  // black and white. normal palette only has 4 greyscale shades.
  if (r === g && g === b) {
    if (r < 8) {
      return 16;
    }

    if (r > 248) {
      return 231;
    }

    return Math.round(((r - 8) / 247) * 24) + 232;
  }

  const ansi =
    16 +
    36 * Math.round((r / 255) * 5) +
    6 * Math.round((g / 255) * 5) +
    Math.round((b / 255) * 5);

  return ansi;
};

convert.ansi16.rgb = function (args) {
  let color = args % 10;

  // Handle greyscale
  if (color === 0 || color === 7) {
    if (args > 50) {
      color += 3.5;
    }

    color = (color / 10.5) * 255;

    return [color, color, color];
  }

  const mult = (~~(args > 50) + 1) * 0.5;
  const r = (color & 1) * mult * 255;
  const g = ((color >> 1) & 1) * mult * 255;
  const b = ((color >> 2) & 1) * mult * 255;

  return [r, g, b];
};

convert.ansi256.rgb = function (args) {
  // Handle greyscale
  if (args >= 232) {
    const c = (args - 232) * 10 + 8;
    return [c, c, c];
  }

  args -= 16;

  let rem;
  const r = (Math.floor(args / 36) / 5) * 255;
  const g = (Math.floor((rem = args % 36) / 6) / 5) * 255;
  const b = ((rem % 6) / 5) * 255;

  return [r, g, b];
};

convert.rgb.hex = function (args) {
  const integer =
    ((Math.round(args[0]) & 0xff) << 16) +
    ((Math.round(args[1]) & 0xff) << 8) +
    (Math.round(args[2]) & 0xff);

  const string = integer.toString(16).toUpperCase();
  return '000000'.substring(string.length) + string;
};

convert.hex.rgb = function (args) {
  const match = args.toString(16).match(/[a-f0-9]{6}|[a-f0-9]{3}/i);
  if (!match) {
    return [0, 0, 0];
  }

  let colorString = match[0];

  if (match[0].length === 3) {
    colorString = colorString
      .split('')
      .map((char) => {
        return char + char;
      })
      .join('');
  }

  const integer = parseInt(colorString, 16);
  const r = (integer >> 16) & 0xff;
  const g = (integer >> 8) & 0xff;
  const b = integer & 0xff;

  return [r, g, b];
};

convert.rgb.hcg = function (rgb) {
  const r = rgb[0] / 255;
  const g = rgb[1] / 255;
  const b = rgb[2] / 255;
  const max = Math.max(Math.max(r, g), b);
  const min = Math.min(Math.min(r, g), b);
  const chroma = max - min;
  let grayscale;
  let hue;

  if (chroma < 1) {
    grayscale = min / (1 - chroma);
  } else {
    grayscale = 0;
  }

  if (chroma <= 0) {
    hue = 0;
  } else if (max === r) {
    hue = ((g - b) / chroma) % 6;
  } else if (max === g) {
    hue = 2 + (b - r) / chroma;
  } else {
    hue = 4 + (r - g) / chroma;
  }

  hue /= 6;
  hue %= 1;

  return [hue * 360, chroma * 100, grayscale * 100];
};

convert.hsl.hcg = function (hsl) {
  const s = hsl[1] / 100;
  const l = hsl[2] / 100;

  const c = l < 0.5 ? 2.0 * s * l : 2.0 * s * (1.0 - l);

  let f = 0;
  if (c < 1.0) {
    f = (l - 0.5 * c) / (1.0 - c);
  }

  return [hsl[0], c * 100, f * 100];
};

convert.hsv.hcg = function (hsv) {
  const s = hsv[1] / 100;
  const v = hsv[2] / 100;

  const c = s * v;
  let f = 0;

  if (c < 1.0) {
    f = (v - c) / (1 - c);
  }

  return [hsv[0], c * 100, f * 100];
};

convert.hcg.rgb = function (hcg) {
  const h = hcg[0] / 360;
  const c = hcg[1] / 100;
  const g = hcg[2] / 100;

  if (c === 0.0) {
    return [g * 255, g * 255, g * 255];
  }

  const pure = [0, 0, 0];
  const hi = (h % 1) * 6;
  const v = hi % 1;
  const w = 1 - v;
  let mg = 0;

  /* eslint-disable max-statements-per-line */
  switch (Math.floor(hi)) {
    case 0:
      pure[0] = 1;
      pure[1] = v;
      pure[2] = 0;
      break;
    case 1:
      pure[0] = w;
      pure[1] = 1;
      pure[2] = 0;
      break;
    case 2:
      pure[0] = 0;
      pure[1] = 1;
      pure[2] = v;
      break;
    case 3:
      pure[0] = 0;
      pure[1] = w;
      pure[2] = 1;
      break;
    case 4:
      pure[0] = v;
      pure[1] = 0;
      pure[2] = 1;
      break;
    default:
      pure[0] = 1;
      pure[1] = 0;
      pure[2] = w;
  }
  /* eslint-enable max-statements-per-line */

  mg = (1.0 - c) * g;

  return [
    (c * pure[0] + mg) * 255,
    (c * pure[1] + mg) * 255,
    (c * pure[2] + mg) * 255,
  ];
};

convert.hcg.hsv = function (hcg) {
  const c = hcg[1] / 100;
  const g = hcg[2] / 100;

  const v = c + g * (1.0 - c);
  let f = 0;

  if (v > 0.0) {
    f = c / v;
  }

  return [hcg[0], f * 100, v * 100];
};

convert.hcg.hsl = function (hcg) {
  const c = hcg[1] / 100;
  const g = hcg[2] / 100;

  const l = g * (1.0 - c) + 0.5 * c;
  let s = 0;

  if (l > 0.0 && l < 0.5) {
    s = c / (2 * l);
  } else if (l >= 0.5 && l < 1.0) {
    s = c / (2 * (1 - l));
  }

  return [hcg[0], s * 100, l * 100];
};

convert.hcg.hwb = function (hcg) {
  const c = hcg[1] / 100;
  const g = hcg[2] / 100;
  const v = c + g * (1.0 - c);
  return [hcg[0], (v - c) * 100, (1 - v) * 100];
};

convert.hwb.hcg = function (hwb) {
  const w = hwb[1] / 100;
  const b = hwb[2] / 100;
  const v = 1 - b;
  const c = v - w;
  let g = 0;

  if (c < 1) {
    g = (v - c) / (1 - c);
  }

  return [hwb[0], c * 100, g * 100];
};

convert.apple.rgb = function (apple) {
  return [
    (apple[0] / 65535) * 255,
    (apple[1] / 65535) * 255,
    (apple[2] / 65535) * 255,
  ];
};

convert.rgb.apple = function (rgb) {
  return [
    (rgb[0] / 255) * 65535,
    (rgb[1] / 255) * 65535,
    (rgb[2] / 255) * 65535,
  ];
};

convert.gray.rgb = function (args) {
  return [(args[0] / 100) * 255, (args[0] / 100) * 255, (args[0] / 100) * 255];
};

convert.gray.hsl = function (args) {
  return [0, 0, args[0]];
};

convert.gray.hsv = convert.gray.hsl;

convert.gray.hwb = function (gray) {
  return [0, 100, gray[0]];
};

convert.gray.cmyk = function (gray) {
  return [0, 0, 0, gray[0]];
};

convert.gray.lab = function (gray) {
  return [gray[0], 0, 0];
};

convert.gray.hex = function (gray) {
  const val = Math.round((gray[0] / 100) * 255) & 0xff;
  const integer = (val << 16) + (val << 8) + val;

  const string = integer.toString(16).toUpperCase();
  return '000000'.substring(string.length) + string;
};

convert.rgb.gray = function (rgb) {
  const val = (rgb[0] + rgb[1] + rgb[2]) / 3;
  return [(val / 255) * 100];
};