/*
* Cliff Scroller jQuery Plugin v1.0
* @author Jaycliff Arcilla
*/

jQuery.fn.cliffScroller = function (easing_method, scroll_speed, scroll_delay, textchanger) {

    // Mimics PHP's handy isset function
    function isset(me) {
        if (me === null || me === '') return 0;
        else return 1;
    }

    /*
    Using the 'var' keyword to declare variables makes the variables local to this function.
    Otherwise the variables are declared as global.
    */

    var parentObject = jQuery(this);
    parentObject.wrapInner('<span class="cliff-scroller" />');
    var scrollingObject = parentObject.children('.cliff-scroller');
    var scroll_timeout = 0;
    var scroll_direction = 'left';
    var distance = 0;

    // Sets the default values in case the user didn't specify any specific values. Being lazy, perhaps?
    if (!isset(easing_method)) easing_method = 'swing';
    if (!isset(scroll_speed)) scroll_speed = 3000;
    if (!isset(scroll_delay)) scroll_delay = 2000;

    scrollingObject.css({
        'display': 'block',
        'position': 'absolute',
        'white-space': 'nowrap',
        'line-height': parentObject.css('height'),
        'left': '0px',
        'top': '0px'
    });

    parentObject.css({
        'position': 'relative',
        'overflow': 'hidden'
    });

    // The actual scrolling function
    function cliffScrollIt(goto_direction) {
        /*
        
        The if statement below checks whether the scrolling object's width is greater than its enclosing parent's width.
        If it is, then proceed scrolling. If otherwise, don't bother.
        
        */
        if (scroll_speed > 0 && scrollingObject.width() > parentObject.width()) {

            // Sets all animation speeds to a constant rate
            // Speed is measured in pixels per second
            /*
            
            speed = distance/duration
            distance = speed*duration
            duration = distance/speed
                
            1000ms    Math.abs(distance)
            ------ x --------------------
            1s        scroll_speed
            
            */
            var calculated_scroll_duration = 1000 * (Math.abs(distance) / scroll_speed);

            if (goto_direction == 'left') scrollingObject.animate({ left: distance }, calculated_scroll_duration, easing_method, function () { setCliffScrollTimeout('right'); });
            else scrollingObject.animate({ left: 0 }, calculated_scroll_duration, easing_method, function () { setCliffScrollTimeout('left'); });

        }
        //Trace
        jQuery('.sc-debug').html('distance: ' + Math.abs(distance) + '<br />' + 'speed: ' + scroll_speed + 'px/sec<br />' + 'calculated duration: ' + calculated_scroll_duration);
    }

    // Sets the delay before the scrolling object, uh, scrolls
    function setCliffScrollTimeout(goto_direction) {
        scroll_timeout = setTimeout(function () { cliffScrollIt(goto_direction); }, scroll_delay);
    }

    // Bind the custom event to the scrolling object
    scrollingObject.bind('cliffscroll', function () {
        distance = parentObject.width() - jQuery(this).width();
        jQuery(this).css({ left: 0 });
        //setScrollTextTimeout();
        cliffScrollIt(scroll_direction);
    });

    // Bind hover event to parent object
    parentObject.hover(
        function () {
            if (!(scrollingObject.is(':animated'))) scrollingObject.trigger('cliffscroll');
        },
        function () {
            scrollingObject.stop(true);
            clearTimeout(scroll_timeout);
            scrollingObject.css({ 'left': 0 });
        }
    );

    //Temporary feature. Subject for removal
    if (isset(textchanger)) {
        jQuery(textchanger).click(function () {
            jQuery(scrollingObject).stop(true);
            clearTimeout(scroll_timeout);
            jQuery(scrollingObject).html('- How much wood would a woodchuck chuck if a woodchuck could chuck wood? -');
        });
    }

};