var emptyFunction = function()  {  };
    var Slideshow = function(target, slides, settings)  {  this.init(target, slides, settings ); return this; }
	Slideshow.prototype = {
            createEvents: emptyFunction,
            target: {
                        container: null,
                        img: null,
                        title: null,
                        desc: null,
                        buttons: null
                    },
            slides: null,
            settings: null,
            pointer: 0,
            INTERVAL: null,
            ppbtn: null,

            replaceSlide: function(slide)  {
                var w = slide.cached_obj.width; var h = slide.cached_obj.height;
                this.target.img.parentNode.replaceChild(slide.cached_obj, this.target.img);
                this.target.img = slide.cached_obj;
            },

            showSlide: function(slide, onloadEvt)  {
                this.replaceSlide(slide);
                var target = this.target;
                if (slide.title)  {
                    target.title.innerHTML = slide.link ? '<a href="' + slide.link + '">' + slide.title + '</a>' : slide.title;
                }
                else
                    target.title.innerHTML = '';
                if (slide.credit && this.settings.show_credits)  {
                    target.photosource.innerHTML = 'photo: ' + slide.credit;
                } else {
                    target.photosource.innerHTML = '';
                }
                target.desc.innerHTML = slide.desc ? slide.desc : '';
                if (onloadEvt)
                    onloadEvt();
            },

            initTarget: function()  {
                var obj = this;
                var img = document.createElement('img');
                var imgContainer = document.createElement('div');
                imgContainer.appendChild(img);
                this.target.container.appendChild(imgContainer);
                var photosource = document.createElement('span');
                photosource.className = 'photosource';
                this.target.container.appendChild(photosource);
                this.target.container.className = 'slideshow ' + (this.settings.fullscreen ? 'fullscreen' : '');
               
                var btns = document.createElement('div');
                btns.className = 'buttons';
                
                var trans = document.createElement('div');
                trans.className = 'trans';

                pbtn = document.createElement('a');
                pbtn.innerHTML = '<div class="actions" id="prev"></div>';
                pbtn.onclick = function()  {  obj.pauseShow(); obj.prevSlide(); };
                pbtn.href = 'javascript: void(0)';
                btns.appendChild(pbtn);
 
                ppbtn = document.createElement('a');
                ppbtn.innerHTML = '<div class="actions" id="play"></div>';
                ppbtn.onclick = function()  {  obj.playShow();  }
                ppbtn.href = 'javascript: void(0)';
                btns.appendChild(ppbtn);               

                var nbtn = document.createElement('a');
                nbtn.innerHTML = '<div class="actions" id="next"></div>';
                nbtn.onclick = function()  {  obj.pauseShow(); obj.nextSlide();  }
                nbtn.href = 'javascript: void(0)';
                btns.appendChild(nbtn);

                var bbar = document.createElement('div');
                bbar.className = 'ssBottomBar';
                bbar.appendChild(trans);
                bbar.appendChild(btns);
                this.target.container.appendChild(bbar);

                var title = document.createElement('h3');
                this.target.container.appendChild(title);

                var desc = document.createElement('p');
                this.target.container.appendChild(desc);

                title.width = desc.width = '100%';

                title.className = this.settings.fullscreen ? 'centered' : '';
                desc.className = this.settings.fullscreen ? 'centered' : '';

                this.target.title = title;
                this.target.desc = desc;
                this.target.img = img;
                this.target.buttons = bbar;
                this.target.photosource = photosource;

                this.ppbtn = ppbtn;

                if (this.settings.width && this.settings.height)  {
                    this.target.img.style.width = this.settings.width;
                    this.target.img.style.height = this.settings.height;
                    this.width = this.settings.width;
                    this.height = this.settings.height;
                }
                else  {

                this.width = this.target.img.offsetWidth;
                this.height = this.target.img.offsetHeight;
                }

                if (this.settings.fullscreen)  {
                    var w = window.innerWidth || document.documentElement.offsetWidth;
                    var h = window.innerHeight || document.documentElement.offsetHeight;
                    w -= 100;
                    h -= 100;
                    //this.target.img.style.width = w + 'px';
                    //this.target.img.style.height = h + 'px';
                    this.width = w;
                    this.height = h;
                }

                imgContainer.style.width = this.width;
                imgContainer.style.height = this.height;

                this.target.container.style.width = this.width + 'px';
            },

            onPlay: function()  {
                var obj = this;
                this.ppbtn.innerHTML = '<div class="actions" id="pause"></div>';
                this.ppbtn.onclick = function()  {  obj.pauseShow();  };
            },
            onPause: function()  {
                var obj = this;
                this.ppbtn.innerHTML = '<div class="actions" id="play"></div>';
                this.ppbtn.onclick = function()  { obj.playShow();  };
            },

            nextSlide: function()  {
                if (this.pointer < this.slides.length -1)  {
                    this.pointer++;
                }
                else
                    this.pointer = 0;

                this.getSlide();
            },

            prevSlide: function()  {
                if (this.pointer > 0)  {
                    this.pointer--;
                }
                else
                    this.pointer = slides.length - 1;

                this.getSlide();
            },

            pauseShow: function()  {
                if (!this.INTERVAL)
                    return;
                clearInterval(this.INTERVAL);
                this.INTERVAL = null;
                this.onPause();
            },

            scaleDown: function(w, h)  {
                    var maxw = this.width;
                    var maxh = this.height;

                    var fw, fh;
                    if (h > maxh)  {  w = Math.round((maxh / h) * w); h = maxh  }
                    if (w > maxw)  {  h = Math.round((maxw / w) * h); w = maxw  };

                    return new Array(w, h)
            },

            createObj: function(slide)  {
                if (slide.width == undefined && slide.height == undefined)
                    size = new Array(this.settings.width, this.settings.height);
                else
                    size = new Array(slide.width, slide.height);

                size = this.scaleDown(size[0], size[1]);
                cached_obj = new Image(size[0], size[1]);
                cached_obj.src = slide.src;

                cached_obj.style.width = size[0];
                cached_obj.style.height = size[1];
                cached_obj.alt = 'photo: ' + slide.credit;
                //cached_obj.style.marginLeft = ((this.width / 2) - (size[0] / 2)) + 'px';

                return cached_obj;
            },

            processQueue: function()  {
                var  n = 0;
                for (var i=0; i < this.slides.length; i++)   {
                    if (n == this.settings.queue_preload)
                        break;

                    if (this.slides[i].cached_obj)
                        continue;

                    this.slides[i].cached_obj = this.createObj(this.slides[i]);
                    n += 1
                }
            },

            getSlide: function(slide, onloadEvt)  {
                if (!slide)  {
                    slide = this.slides[this.pointer];
                }
                if (!slide.cached_obj)  {
                    slide.cached_obj = this.createObj(slide);
                }
                this.showSlide(slide, onloadEvt);
                this.processQueue();
            },

            playShow: function()  {
                if (this.INTERVAL)
                    return;
                var obj = this;
                this.INTERVAL = setInterval(function()  {  obj.nextSlide() }, this.settings.delay * 1000);
                this.onPlay();
            },

            preload: function()  {
                if (document.getElementById('slideshow_preloads'))
                    return;

                var d = document.createElement('slideshow_preloads');
                d.style.display = 'none';
                for (var i=0; i < this.settings.preload_paths.length; i++)  {
                    var img = document.createElement('img');
                    img.src = this.settings.preload_paths[i];
                    d.appendChild(img);
                }
                this.target.container.appendChild(d);
            },

            init: function(target, slides, settings)  {
                var default_settings = {
                                            queue_preload: 3,
                                            preload_paths: new Array('http://cdn.wn.com/o25/st/notA_slideshow/prevO.png', 'http://cdn.wn.com/o25/st/notA_slideshow/nextO.png', 'http://cdn.wn.com/o25/st/notA_slideshow/pauseO.png'),
                                            fullscreen: false,
                                            delay: 4,
                                            show_credits: true
                                        }

                this.settings = settings || {};

                for (var k in default_settings)  {
                    if (this.settings[k] == undefined)
                        this.settings[k] = default_settings[k];
                }

                this.target.container = target;
                this.preload();
                this.slides = slides;
                this.initTarget();
                this.createEvents();
                var obj = this;
                this.getSlide(slides[0], function()  {  obj.playShow()  });
                
            }
	   }