/*!
 * Shadow animation jQuery-plugin
 * http://www.bitstorm.org/jquery/shadow-animation/
 * Copyright 2010 Edwin Martin <edwin@bitstorm.org>
 * Contributor: Mark Carver
 * Released under the MIT and GPL licenses.
 */

jQuery(function($) {
	/**
	 * Check whether the browser supports RGBA color mode.
	 *
	 * @author Mehdi Kabab <http://pioupioum.fr>
	 * @type Boolean
	 * @return True if the browser support RGBA. False otherwise.
	 */
	function isRGBACapable() {
		var $script = $('script:first'),
				color = $script.css('color'),
				result = false;
		if (/^rgba/.test(color)) {
			result = true;
		} else {
			try {
				result = ( color != $script.css('color', 'rgba(0, 0, 0, 0.5)').css('color') );
				$script.css('color', color);
			} catch (e) {
			}
			;
		}

		return result;
	}

	$.extend($, {
		support: {
			'rgba': isRGBACapable()
		}
	});

	/*************************************/

	// First define which property to use
	var boxShadowProperty;
	$.each(['boxShadow', 'MozBoxShadow', 'WebkitBoxShadow'], function(i, property) {
		var val = $('html').css(property);
		if (typeof val == 'string' && val != '') {
			boxShadowProperty = property;
			return false;
		}
	});

	// Extend the animate-function
	if (boxShadowProperty) {
		$.fx.step['shadow'] = function(fx) {
			if (!fx.init) {
				fx.begin = parseShadow($(fx.elem).css(boxShadowProperty));
				fx.end = $.extend({}, fx.begin, parseShadow(fx.options.curAnim['shadow']));
				fx.init = true;
			}
			fx.elem.style[boxShadowProperty] = calculateShadow(fx.begin, fx.end, fx.pos);
		}
	}

	// Calculate an in-between shadow.
	function calculateShadow(begin, end, pos) {
		var parts = [];
		if (begin.inset) {
			parts.push('inset');
		}
		if (typeof end.left != 'undefined') {
			parts.push(parseInt(begin.left + pos * (end.left - begin.left)) + 'px '
					+ parseInt(begin.top + pos * (end.top - begin.top)) + 'px');
		}
		if (typeof end.blur != 'undefined') {
			parts.push(parseInt(begin.blur + pos * (end.blur - begin.blur)) + 'px');
		}
		if (typeof end.spread != 'undefined') {
			parts.push(parseInt(begin.spread + pos * (end.spread - begin.spread)) + 'px');
		}
		if (typeof end.color != 'undefined') {
			var color = 'rgb' + ($.support.rgba ? 'a' : '') + '('
					+ parseInt((begin.color[0] + pos * (end.color[0] - begin.color[0]))) + ','
					+ parseInt((begin.color[1] + pos * (end.color[1] - begin.color[1]))) + ','
					+ parseInt((begin.color[2] + pos * (end.color[2] - begin.color[2])));
			if ($.support.rgba) {
				color += ',' + parseFloat(begin.color[3] + pos * (end.color[3] - begin.color[3]));
			}
			color += ')';
			parts.push(color);
		}
		var value = parts.join(' ');
		return value;
	}

	// Parse the shadow value and extract the values.
	function parseShadow(shadow) {
		var match, color, parsedShadow = {};

		// Parse an CSS-syntax color. Outputs an array [r, g, b]
		// Match #aabbcc
		if (match = /#([0-9a-fA-F]{2})([0-9a-fA-F]{2})([0-9a-fA-F]{2})/.exec(shadow)) {
			color = [parseInt(match[1], 16), parseInt(match[2], 16), parseInt(match[3], 16), 1];

			// Match #abc
		} else if (match = /#([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])/.exec(shadow)) {
			color = [parseInt(match[1], 16) * 17, parseInt(match[2], 16) * 17, parseInt(match[3], 16) * 17, 1];

			// Match rgb(n, n, n)
		} else if (match = /rgb\(\s*([0-9]{1,3})\s*,\s*([0-9]{1,3})\s*,\s*([0-9]{1,3})\s*\)/.exec(shadow)) {
			color = [parseInt(match[1]), parseInt(match[2]), parseInt(match[3]), 1];

			// Match rgba(n, n, n, n)
		} else if (match = /rgba\(\s*([0-9]{1,3})\s*,\s*([0-9]{1,3})\s*,\s*([0-9]{1,3})\s*,\s*([0-1]{1}?\.?[0-9]*)\s*\)/.exec(shadow)) {
			color = [parseInt(match[1]), parseInt(match[2]), parseInt(match[3]),parseFloat(match[4])];

			// No browser returns rgb(n%, n%, n%), so little reason to support this format.
		}

		// Parse offset, blur and radius
		if (match = /([0-9]+)(?:px)?\s+([0-9]+)(?:px)?(?:\s+([0-9]+)(?:px)?)?(?:\s+([0-9]+)(?:px)?)?/.exec(shadow)) {
			parsedShadow = {left: parseInt(match[1]), top: parseInt(match[2]), blur: match[3] ? parseInt(match[3]) : undefined, spread: match[4] ? parseInt(match[4]) : undefined};
		}

		// Inset or not
		parsedShadow.inset = /inset/.test(shadow);

		parsedShadow.color = color;
		return parsedShadow;
	}
});