/**
 * @author David Furber
 */

 $.fn.slideshow = function(options) {
    var settings = {
        timeout: '5000',
        type: 'sequence',
        tagname: 'li'
    }
    if(options)
        $.extend(settings, options);

    this.css('position', 'relative');
    var slides = this.find(settings.tagname).get();
    for ( var i = 0; i < slides.length; i++ ) {
        $(slides[i]).css('zIndex', slides.length - i);
    }
    if ( settings.type == 'sequence' ) {
        setTimeout(function(){
            $.slideshow.next(slides, settings, 1, 0);
        }, settings.timeout);
    }
    else if ( settings.type == 'random' ) {
        setTimeout(function(){
            do { current = Math.floor ( Math.random ( ) * ( slides.length ) ); } while ( current == 0 )
            $.slideshow.next(slides, settings, current, 0);
        }, settings.timeout);
    }
    else {
        alert('type must either be \'sequence\' or \'random\'');
    }
};
$.slideshow = function() {}
$.slideshow.next = function (slides, settings, current, last) {
    for (var i = 0; i < slides.length; i++) {
        $(slides[i]).css('display', 'none');
    }
    $(slides[last]).css('display', 'block').css('zIndex', '0');
    $(slides[current]).css('zIndex', '1').fadeIn(2000);

    if ( settings.type == 'sequence' ) {
        if ( ( current + 1 ) < slides.length ) {
            current = current + 1;
            last = current - 1;
        }
        else {
            current = 0;
            last = slides.length - 1;
        }
    }
    else if ( settings.type == 'random' ) {
        last = current;
        while ( current == last ) {
            current = Math.floor ( Math.random ( ) * ( slides.length ) );
        }
    }
    else {
        alert('type must either be \'sequence\' or \'random\'');
    }
    setTimeout((function(){$.slideshow.next(slides, settings, current, last);}), settings.timeout);
}