$(document).ready(function(){
    var total_slides = $(".slide").length;
    var current_slide = 0;
    var slides_ready = false;
    
    $('.slide').each(function(){
        $(this).css('top', (current_slide*350)+'px');
        current_slide++;
        
        if(current_slide == total_slides)
        {
            slides_ready = true;
            current_slide = 1;
        }
    });
    
    $('.next_button').click(function(){
        if(!$(this).hasClass('disabled') && slides_ready)
        {
            current_slide++;
            $('.slide').each(function(){
                $(this).animate({'top':'-=350px'}, 500);
                $('.prev_button').removeClass('disabled');
                if(current_slide == total_slides)
                {
                    $('.next_button').addClass('disabled');
                }
            });
        }
        
        return false;
    });
    
    $('.prev_button').click(function(){
        if(!$(this).hasClass('disabled') && slides_ready)
        {
            current_slide--;
            $('.slide').each(function(){
                $(this).animate({'top':'+=350px'}, 500);
                $('.next_button').removeClass('disabled');
                if(current_slide == 1)
                {
                    $('.prev_button').addClass('disabled');
                }
            });
        }
        
        return false;
    });
});