/*! Copyright (c) 2008 Brandon Aaron (http://brandonaaron.net)
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php) 
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 *
 * Color functions from Steve's Cross Browser Gradient Backgrounds v1.0 (steve@slayeroffice.com && http://slayeroffice.com/code/gradient/)
 *
 * Version 1.0.1-pre
 */
(function($) {
 
/**
 * Adds a gradient to the background of an element.
 *
 * @example $('div').gradient({ from: '000000', to: 'CCCCCC' });
 *
 * @param Map options Settings/options to configure the gradient.
 * @option String from The hex color code to start the gradient with.
 *     By default the value is "000000".
 * @option String to The hex color code to end the gradient with.
 *     By default the value is "FFFFFF".
 * @option String direction This tells the gradient to be horizontal
 *      or vertical. By default the value is "horizontal".
 * @option Number length This is used to constrain the gradient to a
 *      particular width or height (depending on the direction). By default
 *      the length is set to null, which will use the width or height
 *      (depending on the direction) of the element.
 * @option String position This tells the gradient to be positioned
 *      at the top, bottom, left and/or right within the element. The
 *      value is just a string that specifices top or bottom and left or right.
 *      By default the value is 'top left'.
 *
 * @name gradient
 * @type jQuery
 * @cat Plugins/gradient
 * @author Brandon Aaron (brandon.aaron@gmail.com || http://brandonaaron.net)
 */
$.fn.gradient = function(options) {
  options = $.extend({ from: '000000', to: 'ffffff', direction: 'horizontal', position: 'top', length: null }, options || {});
  var createColorPath = function(startColor, endColor, distance) {
    var colorPath = [],
        colorPercent = 1.0,
      distance = (distance < 100) ? distance : 100;
    do {
      colorPath[colorPath.length] = setColorHue(longHexToDec(startColor), colorPercent, longHexToDec(endColor));  
      colorPercent -= ((100/distance)*0.01);
    } while (colorPercent>0);
    return colorPath;
  },
  setColorHue = function(originColor, opacityPercent, maskRGB) {
    var returnColor = [];
    for (var i=0; i<originColor.length; i++)
      returnColor[i] = Math.round(originColor[i]*opacityPercent) + Math.round(maskRGB[i]*(1.0-opacityPercent));
    return returnColor;
  },
  longHexToDec = function(longHex) {
    return new Array(toDec(longHex.substring(0,2)),toDec(longHex.substring(2,4)),toDec(longHex.substring(4,6)));
  },
  toDec = function(hex) {
    return parseInt(hex,16);
  };
  return this.each(function() {
    var $this = $(this), width = $this.innerWidth(), height = $this.innerHeight(), x = 0, y = 0, w = 1, h = 1, html = [],
        length = options.length || (options.direction == 'vertical' ? width : height),
        position = (options.position == 'bottom' ? 'bottom:0;' : 'top:0;') + (options.position == 'right' ? 'right:0;' : 'left:0;'), 
        colorArray = createColorPath(options.from, options.to, length);
    
    if (options.direction == 'horizontal') {
      h = Math.round(length/colorArray.length) || 1;
      w = width;
    } else {
      w = Math.round(length/colorArray.length) || 1;
      h = height;
    }
    
    html.push('<div class="gradient" style="position: absolute; ' + position + ' width: ' + (options.direction == 'vertical' ? length+"px" : "100%") +'; height: ' + (options.direction == 'vertical' ? "100%" : length+"px") + '; overflow: hidden; z-index: 0; background-color: #' + (options.position.indexOf('bottom') != -1 ? options.from : options.to) + '">');
    for(var i=0; i<colorArray.length; i++) {
      html.push('<div style="position:absolute;z-index:1;top:' + y + 'px;left:' + x + 'px;height:' + (options.direction == 'vertical' ? "100%" : h+"px") + ';width:' + (options.direction == 'vertical' ? w+"px" : "100%") + ';background-color:rgb(' + colorArray[i][0] + ',' + colorArray[i][1] + ',' + colorArray[i][2] + ');"></div>');
      options.direction == 'vertical' ? x+=w : y+=h;
      
      if ( y >= height || x >= width) break;
    }
    html.push('</div>');
    
    if ( $this.css('position') == 'static' )
      $this.css('position', 'relative');
    
    $this
      .html('<div style="display:' + $this.css("display") + '; position: relative; z-index: 2;">' + this.innerHTML + '</div>')
      .prepend(html.join(''));
  });
};
 
})(jQuery);