/**
 * jquery.scrollFollow.js
 * Copyright (c) 2008 Net Perspective (http://kitchen.net-perspective.com/)
 * Licensed under the MIT License (http://www.opensource.org/licenses/mit-license.php)
 * 
 * @author R.A. Ray
 *
 * @projectDescription	jQuery plugin for allowing an element to animate down as the user scrolls the page.
 * 
 * @version 0.4.0
 * 
 * @requires jquery.js (tested with 1.2.6)
 * @requires ui.core.js (tested with 1.5.2)
 * 
 * @optional jquery.cookie.js (http://www.stilbuero.de/2006/09/17/cookie-plugin-for-jquery/)
 * @optional jquery.easing.js (http://gsgd.co.uk/sandbox/jquery/easing/ - tested with 1.3)
 * 
 * @param speed		int - Duration of animation (in milliseconds)
 * 								default: 500
 * @param offset			int - Number of pixels box should remain from top of viewport
 * 								default: 0
 * @param easing		string - Any one of the easing options from the easing plugin - Requires jQuery Easing Plugin < http://gsgd.co.uk/sandbox/jquery/easing/ >
 * 								default: 'linear'
 * @param container	string - ID of the containing div
 * 								default: box's immediate parent
 * @param killSwitch	string - ID of the On/Off toggle element
 * 								default: 'killSwitch'
 * @param onText		string - killSwitch text to be displayed if sliding is enabled
 * 								default: 'Turn Slide Off'
 * @param offText		string - killSwitch text to be displayed if sliding is disabled
 * 								default: 'Turn Slide On'
 * @param relativeTo	string - Scroll animation can be relative to either the 'top' or 'bottom' of the viewport
 * 								default: 'top'
 * @param delay			int - Time between the end of the scroll and the beginning of the animation in milliseconds
 * 								default: 0
 */

( function( $ ) {
	
  $.scrollFollow = function ( box, options )
  {
    // Convert box into a jQuery object
    box = $( box );
		
    // 'box' is the object to be animated
    var position = box.css( 'position' );
		
    function ani()
    {
      // The script runs on every scroll which really means many times during a scroll.
      // We don't want multiple slides to queue up.
      box.queue( [ ] );
      
      var pageScroll;
		
      if(options.direction == 'v')
      {
        // A bunch of values we need to determine where to animate to
        var viewportHeight = parseInt( $( window ).height() );
        pageScroll =  parseInt( $( document ).scrollTop() );
        var parentTop =  parseInt( box.cont.offset().top );
        var parentHeight = parseInt( box.cont.attr( 'offsetHeight' ) );
        var boxHeight = parseInt( box.attr( 'offsetHeight' ) + ( parseInt( box.css( 'marginTop' ) ) || 0 ) + ( parseInt( box.css( 'marginBottom' ) ) || 0 ) );
        var aniTop;
      }
      else if(options.direction == 'h')
      {
        // A bunch of values we need to determine where to animate to
        var viewportWidth = parseInt( $( window ).width() );
        pageScroll =  parseInt( $( document ).scrollLeft() );
        var parentLeft =  parseInt( box.cont.offset().left );
        //var parentWidth = parseInt( box.cont.attr( 'offsetWidth' ) );
        var parentWidth = parseInt($('#'+options.container).attr( 'offsetWidth' ));
        var boxWidth = parseInt( box.attr( 'offsetWidth' ) + ( parseInt( box.css( 'marginLeft' ) ) || 0 ) + ( parseInt( box.css( 'marginRight' ) ) || 0 ) );
        var aniLeft;
      }
			
      // Make sure the user wants the animation to happen
      if ( isActive )
      {
        if(options.direction == 'v')
        {
          // If the box should animate relative to the top of the window
          if ( options.relativeTo == 'top' )
          {
            // Don't animate until the top of the window is close enough to the top of the box
            if ( box.initialOffsetTop >= ( pageScroll + options.offset ) )
            {
              aniTop = box.initialTop;
            }
            else
            {
              aniTop = Math.min( ( Math.max( ( -parentTop ), ( pageScroll - box.initialOffsetTop + box.initialTop ) ) + options.offset ), ( parentHeight - boxHeight - box.paddingAdjustment ) );
            }
          }
          // If the box should animate relative to the bottom of the window
          else if ( options.relativeTo == 'bottom' )
          {
            // Don't animate until the bottom of the window is close enough to the bottom of the box
            if ( ( box.initialOffsetTop + boxHeight ) >= ( pageScroll + options.offset + viewportHeight ) )
            {
              aniTop = box.initialTop;
            }
            else
            {
              aniTop = Math.min( ( pageScroll + viewportHeight - boxHeight - options.offset ), ( parentHeight - boxHeight ) );
            }
          }
        }
        else if(options.direction == 'h')
        {
          // If the box should animate relative to the top of the window
          if ( options.relativeTo == 'left' )
          {

            recalInitialLeft();
            // Don't animate until the top of the window is close enough to the top of the box
            if ( box.initialOffsetLeft >= ( pageScroll + options.offset ) )
            {
              aniLeft = box.initialLeft;
            }
            else
            {
              aniLeft = Math.min( ( Math.max( ( -parentLeft ), ( pageScroll - box.initialOffsetLeft + box.initialLeft ) ) + options.offset ), ( parentWidth - boxWidth - box.paddingAdjustment ) );
            }
          }
          // If the box should animate relative to the bottom of the window
          else if ( options.relativeTo == 'right' )
          {
            // Don't animate until the bottom of the window is close enough to the bottom of the box
            if ( ( box.initialOffsetLeft + boxWidth ) >= ( pageScroll + options.offset + viewportWidth ) )
            {
              aniLeft = box.initialLeft;
            }
            else
            {
              aniLeft = Math.min( ( pageScroll + viewportWidth - boxWidth - options.offset ), ( parentWidth - boxWidth ) );
            }
          }
        }
				
        // Checks to see if the relevant scroll was the last one
        // "-20" is to account for inaccuracy in the timeout
        if ( ( new Date().getTime() - box.lastScroll ) >= ( options.delay - 20 ) &&  options.direction == 'v')
        {
          box.animate(
          {
            top: aniTop
          }, options.speed, options.easing
          );
        }
				
        // Checks to see if the relevant scroll was the last one
        // "-20" is to account for inaccuracy in the timeout
        if ( ( new Date().getTime() - box.lastScroll ) >= ( options.delay - 20 ) &&  options.direction == 'h')
        {
          box.animate(
          {
            left: aniLeft
          }, options.speed, options.easing
          );
        }
      }
    };

    function recalInitialLeft()
    {
      if(options.initialPos == 'center')
        box.initialLeft = parseInt( ( parseInt( $( window ).width() ) / 2 ) - ( parseInt( box.css( 'width' ) ) / 2 ) ) || 0;
      else
        box.initialLeft = parseInt( box.css( 'left' ) ) || 0;
    }
		
    // For user-initiated stopping of the slide
    var isActive = true;
		
    if ( $.cookie != undefined )
    {
      if( $.cookie( 'scrollFollowSetting' + box.attr( 'id' ) ) == 'false' )
      {
        isActive = false;
				
        $( '#' + options.killSwitch ).text( options.offText )
        .toggle(
          function ()
          {
            isActive = true;
							
            $( this ).text( options.onText );
							
            $.cookie( 'scrollFollowSetting' + box.attr( 'id' ), true, {
              expires: 365,
              path: '/'
            } );
							
            ani();
          },
          function ()
          {
            isActive = false;
							
            $( this ).text( options.offText );
							
            box.animate(
            {
              top: box.initialTop
            }, options.speed, options.easing
            );
							
            $.cookie( 'scrollFollowSetting' + box.attr( 'id' ), false, {
              expires: 365,
              path: '/'
            } );
          }
          );
      }
      else
      {
        $( '#' + options.killSwitch ).text( options.onText )
        .toggle(
          function ()
          {
            isActive = false;
							
            $( this ).text( options.offText );
							
            box.animate(
            {
              top: box.initialTop
            }, 0
            );
							
            $.cookie( 'scrollFollowSetting' + box.attr( 'id' ), false, {
              expires: 365,
              path: '/'
            } );
          },
          function ()
          {
            isActive = true;
							
            $( this ).text( options.onText );
							
            $.cookie( 'scrollFollowSetting' + box.attr( 'id' ), true, {
              expires: 365,
              path: '/'
            } );
							
            ani();
          }
          );
      }
    }
		
    // If no parent ID was specified, and the immediate parent does not have an ID
    // options.container will be undefined. So we need to figure out the parent element.
    if ( options.container == '')
    {
      box.cont = box.parent();
    }
    else
    {
      box.cont = $( '#' + options.container );
    }
		
    // Finds the default positioning of the box.
    box.initialOffsetTop =  parseInt( box.offset().top );
    box.initialOffsetLeft =  parseInt( box.offset().left );
    box.initialTop = parseInt( box.css( 'top' ) ) || 0;
    if(options.initialPos == 'center')
      box.initialLeft = parseInt( ( parseInt( $( window ).width() ) / 2 ) - ( parseInt( box.css( 'width' ) ) / 2 ) ) || 0;
    else
      box.initialLeft = parseInt( box.css( 'left' ) ) || 0;
		  
    // Hack to fix different treatment of boxes positioned 'absolute' and 'relative'
    if ( box.css( 'position' ) == 'relative' )
    {
      if(options.direction == 'v')
        box.paddingAdjustment = parseInt( box.cont.css( 'paddingTop' ) ) + parseInt( box.cont.css( 'paddingBottom' ) );
      if(options.direction == 'h')
        box.paddingAdjustment = parseInt( box.cont.css( 'paddingLeft' ) ) + parseInt( box.cont.css( 'paddingRight' ) );
    }
    else
    {
      box.paddingAdjustment = 0;
    }
		
    // Animate the box when the page is scrolled
    $( window ).scroll( function ()
    {
      // Sets up the delay of the animation
      $.fn.scrollFollow.interval = setTimeout( function(){
        ani();
      } , options.delay );
				
      // To check against right before setting the animation
      box.lastScroll = new Date().getTime();
    }
    );
		
    // Animate the box when the page is resized
    $( window ).resize( function ()
    {
      // Sets up the delay of the animation
      $.fn.scrollFollow.interval = setTimeout( function(){
        ani();
      } , options.delay );
				
      // To check against right before setting the animation
      box.lastScroll = new Date().getTime();
    }
    );

    // Run an initial animation on page load
    box.lastScroll = 0;
		
    ani();
  };
	
  $.fn.scrollFollow = function ( options )
  {
    options = options || {};
    options.relativeTo = options.relativeTo || 'top';
    options.speed = options.speed || 500;
    options.offset = options.offset || 0;
    options.easing = options.easing || 'swing';
    options.container = options.container || this.parent().attr( 'id' );
    options.killSwitch = options.killSwitch || 'killSwitch';
    options.onText = options.onText || 'Turn Slide Off';
    options.offText = options.offText || 'Turn Slide On';
    options.delay = options.delay || 0;
    options.direction = options.direction || 'v';
    options.initialPos = options.initialPos || 'center';
		
    this.each( function()
    {
      new $.scrollFollow( this, options );
    }
    );
		
    return this;
  };
})( jQuery );