/*!
 * jQuery.SerialScroll
 * Copyright (c) 2007-2008 Ariel Flesler - aflesler(at)gmail(dot)com | http://flesler.blogspot.com
 * Dual licensed under MIT and GPL.
 * Date: 06/14/2009
 *
 * @projectDescription Animated scrolling of series.
 * @author Ariel Flesler
 * @version 1.2.2
 *
 * @id jQuery.serialScroll
 * @id jQuery.fn.serialScroll
 * @param {Object} settings Hash of settings, it is passed in to jQuery.ScrollTo, none is required.
 * @return {jQuery} Returns the same jQuery object, for chaining.
 *
 * @link {http://flesler.blogspot.com/2008/02/jqueryserialscroll.html Homepage}
 *
 * Notes:
 *  - The plugin requires jQuery.ScrollTo.
 *  - The hash of settings, is passed to jQuery.ScrollTo, so its settings can be used as well.
 */
;(function( $ ){

    var $serialScroll = $.serialScroll = function( settings ){
        return $(window).serialScroll( settings );
    };

    // Many of these defaults, belong to jQuery.ScrollTo, check it's demo for an example of each option.
    // @link {http://demos.flesler.com/jquery/scrollTo/ ScrollTo's Demo}
    $serialScroll.defaults = {// the defaults are public and can be overriden.
        duration:1000, // how long to animate.
        axis:'x', // which of top and left should be scrolled
        event:'click', // on which event to react.
        start:0, // first element (zero-based index)
        step:1, // how many elements to scroll on each action
        lock:true,// ignore events if already animating
        cycle:true, // cycle endlessly ( constant velocity )
        constant:true // use contant speed ?
        /*
        navigation:null,// if specified, it's a selector a collection of items to navigate the container
        target:window, // if specified, it's a selector to the element to be scrolled.
        interval:0, // it's the number of milliseconds to automatically go to the next
        lazy:false,// go find the elements each time (allows AJAX or JS content, or reordering)
        stop:false, // stop any previous animations to avoid queueing
        force:false,// force the scroll to the first element on start ?
        jump: false,// if true, when the event is triggered on an element, the pane scrolls to it
        items:null, // selector to the items (relative to the matched elements)
        prev:null, // selector to the 'prev' button
        next:null, // selector to the 'next' button
        onBefore: function(){}, // function called before scrolling, if it returns false, the event is ignored
        exclude:0 // exclude the last x elements, so we cannot scroll past the end
        */
    };

    $.fn.serialScroll = function( options ){

        return this.each(function(){
            var 
                settings = $.extend( {}, $serialScroll.defaults, options ),
                event = settings.event, // this one is just to get shorter code when compressed
                step = settings.step, // ditto
                lazy = settings.lazy, // ditto
                context = settings.target ? this : document, // if a target is specified, then everything's relative to 'this'.
                $pane = $(settings.target || this, context),// the element to be scrolled (will carry all the events)
                pane = $pane[0], // will be reused, save it into a variable
                items = settings.items, // will hold a lazy list of elements
                active = settings.start, // active index
                auto = settings.interval, // boolean, do auto or not
                nav = settings.navigation, // save it now to make the code shorter
                timer, // holds the interval id
        helptimer,
        firstrun = 0;

            if( !lazy )// if not lazy, save the items now
                items = getItems();

            if( settings.force )
                jump( {}, active );// generate an initial call

            // Button binding, optional
            $(settings.prev||[], context).bind( event, -step, move );
            $(settings.next||[], context).bind( event, step, move );

            // Custom events bound to the container
            if( !pane.ssbound )// don't bind more than once
                $pane
                    .bind('prev.serialScroll', -step, move ) // you can trigger with just 'prev'
                    .bind('next.serialScroll', step, move ) // f.e: $(container).trigger('next');
                    .bind('goto.serialScroll', jump ); // f.e: $(container).trigger('goto', 4 );

            if( auto )
                $pane
                    .bind('start.serialScroll', function(e){
                        if( !auto ){
                            clear(timer);
                            auto = true;
                            next();
                        }
                     })
                    .bind('stop.serialScroll', function(){// stop a current animation
                        clear(timer);
                        auto = false;
                    });

            $pane.bind('notify.serialScroll', function(e, elem){// let serialScroll know that the index changed externally
                var i = index(elem);
                if( i > -1 )
                    active = i;
            });

            pane.ssbound = true;// avoid many bindings

            if( settings.jump )// can't use jump if using lazy items and a non-bubbling event
                (lazy ? $pane : getItems()).bind( event, function( e ){
                    jump( e, index(e.target) );
                });

            if( nav )
                nav = $(nav, context).bind(event, function( e ){
                    e.data = Math.round(getItems().length / nav.length) * nav.index(this);
                    jump( e, this );
                });

            function move( e ){
                e.data += active;
                jump( e, this );
            };
            function jump( e, button ){
                if( !isNaN(button) ){// initial or special call from the outside $(container).trigger('goto',[index]);
                    e.data = button;
                    button = pane;
                }

                var
                    pos = e.data, n,
                    real = e.type, // is a real event triggering ?
                    $items = settings.exclude ? getItems().slice(0,-settings.exclude) : getItems(),// handle a possible exclude
                    limit = $items.length,
                    elem = $items[pos],
                    duration = settings.duration;

                if( real )// real event object
                    e.preventDefault();

                if( auto ){
                    clear(timer);// clear any possible automatic scrolling.
                    timer = setTimeout( next, settings.interval ); 
                }

                if( !elem ){ // exceeded the limits
                    n = pos < 0 ? 0 : limit - 1;
                    if( active != n )// we exceeded for the first time
                        pos = n;
                    else if( !settings.cycle )// this is a bad case
                        return;
                    else
                        pos = limit - n - 1;// invert, go to the other side
                    elem = $items[pos];
                    clear(timer);
                    firstrun = 1;
          helptimer = setTimeout( starttimer, duration * (pos + 5) );
                }

                if( !elem || settings.lock && $pane.is(':animated') || // no animations while busy
                    real && settings.onBefore &&
                    settings.onBefore(e, elem, $pane, getItems(), pos) === false ) return;

                if( settings.stop )
                    $pane.queue('fx',[]).stop();// remove all its animations

                if( settings.constant )
                    duration = Math.abs(duration/step * (active - pos ));// keep constant velocity

                $pane
                    .scrollTo( elem, duration, settings )// do scroll
                    .trigger('notify.serialScroll',[pos]);// in case serialScroll was called on this elem more than once.
            };

            function next(){// I'll use the namespace to avoid conflicts
                $pane.trigger('next.serialScroll');
            };

            function starttimer(){
        //alert(firstrun);
        //if(firstrun > 0)
        //{
          firstrun = 0;
          clear(helptimer);
          timer = setTimeout( next, settings.interval );
        //}
        firstrun = 1;
            };

            function clear(t){
                clearTimeout(t);
            };

            function getItems(){
                return $( items, pane );
            };

            function index( elem ){
                if( !isNaN(elem) ) return elem;// number
                var $items = getItems(), i;
                while(( i = $items.index(elem)) == -1 && elem != pane )// see if it matches or one of its ancestors
                    elem = elem.parentNode;
                return i;
            };
        });
    };

})( jQuery );