/*
 * Pixastic Lib - HSL Adjust  - v0.1.1
 * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
 * License: [http://www.pixastic.com/lib/license.txt]
 */

Pixastic.Actions.hsl = {
	process : function(params) {

		var hue = parseInt(params.options.hue,10)||0;
		var saturation = (parseInt(params.options.saturation,10)||0) / 100;
		var lightness = (parseInt(params.options.lightness,10)||0) / 100;


		// this seems to give the same result as Photoshop
		if (saturation < 0) {
			var satMul = 1+saturation;
		} else {
			var satMul = 1+saturation*2;
		}

		hue = (hue%360) / 360;
		var hue6 = hue * 6;

		var rgbDiv = 1 / 255;

		var light255 = lightness * 255;
		var lightp1 = 1 + lightness;
		var lightm1 = 1 - lightness;
		if (Pixastic.Client.hasCanvasImageData()) {
			var data = Pixastic.prepareData(params);

			var rect = params.options.rect;

			var p = rect.width * rect.height;

			var pix = p*4, pix1 = pix + 1, pix2 = pix + 2, pix3 = pix + 3;

			while (p--) {

				var r = data[pix-=4];
				var g = data[pix1=pix+1];
				var b = data[pix2=pix+2];

				if (hue != 0 || saturation != 0) {
					// ok, here comes rgb to hsl + adjust + hsl to rgb, all in one jumbled mess. 
					// It's not so pretty, but it's been optimized to get somewhat decent performance.
					// The transforms were originally adapted from the ones found in Graphics Gems, but have been heavily modified.
					var vs = r;
					if (g > vs) vs = g;
					if (b > vs) vs = b;
					var ms = r;
					if (g < ms) ms = g;
					if (b < ms) ms = b;
					var vm = (vs-ms);
					var l = (ms+vs)/510;
					if (l > 0) {
						if (vm > 0) {
							if (l <= 0.5) {
								var s = vm / (vs+ms) * satMul;
								if (s > 1) s = 1;
								var v = (l * (1+s));
							} else {
								var s = vm / (510-vs-ms) * satMul;
								if (s > 1) s = 1;
								var v = (l+s - l*s);
							}
							if (r == vs) {
								if (g == ms)
									var h = 5 + ((vs-b)/vm) + hue6;
								else
									var h = 1 - ((vs-g)/vm) + hue6;
							} else if (g == vs) {
								if (b == ms)
									var h = 1 + ((vs-r)/vm) + hue6;
								else
									var h = 3 - ((vs-b)/vm) + hue6;
							} else {
								if (r == ms)
									var h = 3 + ((vs-g)/vm) + hue6;
								else
									var h = 5 - ((vs-r)/vm) + hue6;
							}
							if (h < 0) h+=6;
							if (h >= 6) h-=6;
							var m = (l+l-v);
							var sextant = h>>0;
							if (sextant == 0) {
								r = v*255; g = (m+((v-m)*(h-sextant)))*255; b = m*255;
							} else if (sextant == 1) {
								r = (v-((v-m)*(h-sextant)))*255; g = v*255; b = m*255;
							} else if (sextant == 2) {
								r = m*255; g = v*255; b = (m+((v-m)*(h-sextant)))*255;
							} else if (sextant == 3) {
								r = m*255; g = (v-((v-m)*(h-sextant)))*255; b = v*255;
							} else if (sextant == 4) {
								r = (m+((v-m)*(h-sextant)))*255; g = m*255; b = v*255;
							} else if (sextant == 5) {
								r = v*255; g = m*255; b = (v-((v-m)*(h-sextant)))*255;
							}
						}
					}
				}

				if (lightness < 0) {
					r *= lightp1;
					g *= lightp1;
					b *= lightp1;
				} else if (lightness > 0) {
					r = r * lightm1 + light255;
					g = g * lightm1 + light255;
					b = b * lightm1 + light255;
				}

				if (r < 0) 
					data[pix] = 0
				else if (r > 255)
					data[pix] = 255
				else
					data[pix] = r;

				if (g < 0) 
					data[pix1] = 0
				else if (g > 255)
					data[pix1] = 255
				else
					data[pix1] = g;

				if (b < 0) 
					data[pix2] = 0
				else if (b > 255)
					data[pix2] = 255
				else
					data[pix2] = b;

			}

			return true;
		}
	},
	checkSupport : function() {
		return Pixastic.Client.hasCanvasImageData();
	}

}