'use strict';

var colorString = require('color-string');
var convert = require('color-convert');

var _slice = [].slice;

var skippedModels = [
	// to be honest, I don't really feel like keyword belongs in color convert, but eh.
	'keyword',

	// gray conflicts with some method names, and has its own method defined.
	'gray',

	// shouldn't really be in color-convert either...
	'hex'
];

var hashedModelKeys = {};
Object.keys(convert).forEach(function (model) {
	hashedModelKeys[_slice.call(convert[model].labels).sort().join('')] = model;
});

var limiters = {};

function Color(obj, model) {
	if (!(this instanceof Color)) {
		return new Color(obj, model);
	}

	if (model && model in skippedModels) {
		model = null;
	}

	if (model && !(model in convert)) {
		throw new Error('Unknown model: ' + model);
	}

	var i;
	var channels;

	if (typeof obj === 'undefined') {
		this.model = 'rgb';
		this.color = [0, 0, 0];
		this.valpha = 1;
	} else if (obj instanceof Color) {
		this.model = obj.model;
		this.color = obj.color.slice();
		this.valpha = obj.valpha;
	} else if (typeof obj === 'string') {
		var result = colorString.get(obj);
		if (result === null) {
			throw new Error('Unable to parse color from string: ' + obj);
		}

		this.model = result.model;
		channels = convert[this.model].channels;
		this.color = result.value.slice(0, channels);
		this.valpha = typeof result.value[channels] === 'number' ? result.value[channels] : 1;
	} else if (obj.length) {
		this.model = model || 'rgb';
		channels = convert[this.model].channels;
		var newArr = _slice.call(obj, 0, channels);
		this.color = zeroArray(newArr, channels);
		this.valpha = typeof obj[channels] === 'number' ? obj[channels] : 1;
	} else if (typeof obj === 'number') {
		// this is always RGB - can be converted later on.
		obj &= 0xFFFFFF;
		this.model = 'rgb';
		this.color = [
			(obj >> 16) & 0xFF,
			(obj >> 8) & 0xFF,
			obj & 0xFF
		];
		this.valpha = 1;
	} else {
		this.valpha = 1;

		var keys = Object.keys(obj);
		if ('alpha' in obj) {
			keys.splice(keys.indexOf('alpha'), 1);
			this.valpha = typeof obj.alpha === 'number' ? obj.alpha : 0;
		}

		var hashedKeys = keys.sort().join('');
		if (!(hashedKeys in hashedModelKeys)) {
			throw new Error('Unable to parse color from object: ' + JSON.stringify(obj));
		}

		this.model = hashedModelKeys[hashedKeys];

		var labels = convert[this.model].labels;
		var color = [];
		for (i = 0; i < labels.length; i++) {
			color.push(obj[labels[i]]);
		}

		this.color = zeroArray(color);
	}

	// perform limitations (clamping, etc.)
	if (limiters[this.model]) {
		channels = convert[this.model].channels;
		for (i = 0; i < channels; i++) {
			var limit = limiters[this.model][i];
			if (limit) {
				this.color[i] = limit(this.color[i]);
			}
		}
	}

	this.valpha = Math.max(0, Math.min(1, this.valpha));

	if (Object.freeze) {
		Object.freeze(this);
	}
}

Color.prototype = {
	toString: function () {
		return this.string();
	},

	toJSON: function () {
		return this[this.model]();
	},

	string: function (places) {
		var self = this.model in colorString.to ? this : this.rgb();
		self = self.round(typeof places === 'number' ? places : 1);
		var args = self.valpha === 1 ? self.color : self.color.concat(this.valpha);
		return colorString.to[self.model](args);
	},

	percentString: function (places) {
		var self = this.rgb().round(typeof places === 'number' ? places : 1);
		var args = self.valpha === 1 ? self.color : self.color.concat(this.valpha);
		return colorString.to.rgb.percent(args);
	},

	array: function () {
		return this.valpha === 1 ? this.color.slice() : this.color.concat(this.valpha);
	},

	object: function () {
		var result = {};
		var channels = convert[this.model].channels;
		var labels = convert[this.model].labels;

		for (var i = 0; i < channels; i++) {
			result[labels[i]] = this.color[i];
		}

		if (this.valpha !== 1) {
			result.alpha = this.valpha;
		}

		return result;
	},

	unitArray: function () {
		var rgb = this.rgb().color;
		rgb[0] /= 255;
		rgb[1] /= 255;
		rgb[2] /= 255;

		if (this.valpha !== 1) {
			rgb.push(this.valpha);
		}

		return rgb;
	},

	unitObject: function () {
		var rgb = this.rgb().object();
		rgb.r /= 255;
		rgb.g /= 255;
		rgb.b /= 255;

		if (this.valpha !== 1) {
			rgb.alpha = this.valpha;
		}

		return rgb;
	},

	round: function (places) {
		places = Math.max(places || 0, 0);
		return new Color(this.color.map(roundToPlace(places)).concat(this.valpha), this.model);
	},

	alpha: function (val) {
		if (arguments.length) {
			return new Color(this.color.concat(Math.max(0, Math.min(1, val))), this.model);
		}

		return this.valpha;
	},

	// rgb
	red: getset('rgb', 0, maxfn(255)),
	green: getset('rgb', 1, maxfn(255)),
	blue: getset('rgb', 2, maxfn(255)),

	hue: getset(['hsl', 'hsv', 'hsl', 'hwb', 'hcg'], 0, function (val) { return ((val % 360) + 360) % 360; }), // eslint-disable-line brace-style

	saturationl: getset('hsl', 1, maxfn(100)),
	lightness: getset('hsl', 2, maxfn(100)),

	saturationv: getset('hsv', 1, maxfn(100)),
	value: getset('hsv', 2, maxfn(100)),

	chroma: getset('hcg', 1, maxfn(100)),
	gray: getset('hcg', 2, maxfn(100)),

	white: getset('hwb', 1, maxfn(100)),
	wblack: getset('hwb', 2, maxfn(100)),

	cyan: getset('cmyk', 0, maxfn(100)),
	magenta: getset('cmyk', 1, maxfn(100)),
	yellow: getset('cmyk', 2, maxfn(100)),
	black: getset('cmyk', 3, maxfn(100)),

	x: getset('xyz', 0, maxfn(100)),
	y: getset('xyz', 1, maxfn(100)),
	z: getset('xyz', 2, maxfn(100)),

	l: getset('lab', 0, maxfn(100)),
	a: getset('lab', 1),
	b: getset('lab', 2),

	keyword: function (val) {
		if (arguments.length) {
			return new Color(val);
		}

		return convert[this.model].keyword(this.color);
	},

	hex: function (val) {
		if (arguments.length) {
			return new Color(val);
		}

		return colorString.to.hex(this.rgb().round().color);
	},

	rgbNumber: function () {
		var rgb = this.rgb().color;
		return ((rgb[0] & 0xFF) << 16) | ((rgb[1] & 0xFF) << 8) | (rgb[2] & 0xFF);
	},

	luminosity: function () {
		// http://www.w3.org/TR/WCAG20/#relativeluminancedef
		var rgb = this.rgb().color;

		var lum = [];
		for (var i = 0; i < rgb.length; i++) {
			var chan = rgb[i] / 255;
			lum[i] = (chan <= 0.03928) ? chan / 12.92 : Math.pow(((chan + 0.055) / 1.055), 2.4);
		}

		return 0.2126 * lum[0] + 0.7152 * lum[1] + 0.0722 * lum[2];
	},

	contrast: function (color2) {
		// http://www.w3.org/TR/WCAG20/#contrast-ratiodef
		var lum1 = this.luminosity();
		var lum2 = color2.luminosity();

		if (lum1 > lum2) {
			return (lum1 + 0.05) / (lum2 + 0.05);
		}

		return (lum2 + 0.05) / (lum1 + 0.05);
	},

	level: function (color2) {
		var contrastRatio = this.contrast(color2);
		if (contrastRatio >= 7.1) {
			return 'AAA';
		}

		return (contrastRatio >= 4.5) ? 'AA' : '';
	},

	isDark: function () {
		// YIQ equation from http://24ways.org/2010/calculating-color-contrast
		var rgb = this.rgb().color;
		var yiq = (rgb[0] * 299 + rgb[1] * 587 + rgb[2] * 114) / 1000;
		return yiq < 128;
	},

	isLight: function () {
		return !this.isDark();
	},

	negate: function () {
		var rgb = this.rgb();
		for (var i = 0; i < 3; i++) {
			rgb.color[i] = 255 - rgb.color[i];
		}
		return rgb;
	},

	lighten: function (ratio) {
		var hsl = this.hsl();
		hsl.color[2] += hsl.color[2] * ratio;
		return hsl;
	},

	darken: function (ratio) {
		var hsl = this.hsl();
		hsl.color[2] -= hsl.color[2] * ratio;
		return hsl;
	},

	saturate: function (ratio) {
		var hsl = this.hsl();
		hsl.color[1] += hsl.color[1] * ratio;
		return hsl;
	},

	desaturate: function (ratio) {
		var hsl = this.hsl();
		hsl.color[1] -= hsl.color[1] * ratio;
		return hsl;
	},

	whiten: function (ratio) {
		var hwb = this.hwb();
		hwb.color[1] += hwb.color[1] * ratio;
		return hwb;
	},

	blacken: function (ratio) {
		var hwb = this.hwb();
		hwb.color[2] += hwb.color[2] * ratio;
		return hwb;
	},

	grayscale: function () {
		// http://en.wikipedia.org/wiki/Grayscale#Converting_color_to_grayscale
		var rgb = this.rgb().color;
		var val = rgb[0] * 0.3 + rgb[1] * 0.59 + rgb[2] * 0.11;
		return Color.rgb(val, val, val);
	},

	fade: function (ratio) {
		return this.alpha(this.valpha - (this.valpha * ratio));
	},

	opaquer: function (ratio) {
		return this.alpha(this.valpha + (this.valpha * ratio));
	},

	rotate: function (degrees) {
		var hsl = this.hsl();
		var hue = hsl.color[0];
		hue = (hue + degrees) % 360;
		hue = hue < 0 ? 360 + hue : hue;
		hsl.color[0] = hue;
		return hsl;
	},

	mix: function (mixinColor, weight) {
		// ported from sass implementation in C
		// https://github.com/sass/libsass/blob/0e6b4a2850092356aa3ece07c6b249f0221caced/functions.cpp#L209
		if (!mixinColor || !mixinColor.rgb) {
			throw new Error('Argument to "mix" was not a Color instance, but rather an instance of ' + typeof mixinColor);
		}
		var color1 = mixinColor.rgb();
		var color2 = this.rgb();
		var p = weight === undefined ? 0.5 : weight;

		var w = 2 * p - 1;
		var a = color1.alpha() - color2.alpha();

		var w1 = (((w * a === -1) ? w : (w + a) / (1 + w * a)) + 1) / 2.0;
		var w2 = 1 - w1;

		return Color.rgb(
				w1 * color1.red() + w2 * color2.red(),
				w1 * color1.green() + w2 * color2.green(),
				w1 * color1.blue() + w2 * color2.blue(),
				color1.alpha() * p + color2.alpha() * (1 - p));
	}
};

// model conversion methods and static constructors
Object.keys(convert).forEach(function (model) {
	if (skippedModels.indexOf(model) !== -1) {
		return;
	}

	var channels = convert[model].channels;

	// conversion methods
	Color.prototype[model] = function () {
		if (this.model === model) {
			return new Color(this);
		}

		if (arguments.length) {
			return new Color(arguments, model);
		}

		var newAlpha = typeof arguments[channels] === 'number' ? channels : this.valpha;
		return new Color(assertArray(convert[this.model][model].raw(this.color)).concat(newAlpha), model);
	};

	// 'static' construction methods
	Color[model] = function (color) {
		if (typeof color === 'number') {
			color = zeroArray(_slice.call(arguments), channels);
		}
		return new Color(color, model);
	};
});

function roundTo(num, places) {
	return Number(num.toFixed(places));
}

function roundToPlace(places) {
	return function (num) {
		return roundTo(num, places);
	};
}

function getset(model, channel, modifier) {
	model = Array.isArray(model) ? model : [model];

	model.forEach(function (m) {
		(limiters[m] || (limiters[m] = []))[channel] = modifier;
	});

	model = model[0];

	return function (val) {
		var result;

		if (arguments.length) {
			if (modifier) {
				val = modifier(val);
			}

			result = this[model]();
			result.color[channel] = val;
			return result;
		}

		result = this[model]().color[channel];
		if (modifier) {
			result = modifier(result);
		}

		return result;
	};
}

function maxfn(max) {
	return function (v) {
		return Math.max(0, Math.min(max, v));
	};
}

function assertArray(val) {
	return Array.isArray(val) ? val : [val];
}

function zeroArray(arr, length) {
	for (var i = 0; i < length; i++) {
		if (typeof arr[i] !== 'number') {
			arr[i] = 0;
		}
	}

	return arr;
}

module.exports = Color;