var _imgInterval,
	_getTitle = function(item) {
		if(item.data && item.data.title !== undefined) 
			return item.data.title;

		var src = mfp.st.image.titleSrc;

		if(src) {
			if($.isFunction(src)) {
				return src.call(mfp, item);
			} else if(item.el) {
				return item.el.attr(src) || '';
			}
		}
		return '';
	};

$.magnificPopup.registerModule('image', {

	options: {
		markup: '<div class="mfp-figure">'+
					'<div class="mfp-close"></div>'+
					'<figure>'+
						'<div class="mfp-img"></div>'+
						'<figcaption>'+
							'<div class="mfp-bottom-bar">'+
								'<div class="mfp-title"></div>'+
								'<div class="mfp-counter"></div>'+
							'</div>'+
						'</figcaption>'+
					'</figure>'+
				'</div>',
		cursor: 'mfp-zoom-out-cur',
		titleSrc: 'title', 
		verticalFit: true,
		tError: '<a href="%url%">The image</a> could not be loaded.'
	},

	proto: {
		initImage: function() {
			var imgSt = mfp.st.image,
				ns = '.image';

			mfp.types.push('image');

			_mfpOn(OPEN_EVENT+ns, function() {
				if(mfp.currItem.type === 'image' && imgSt.cursor) {
					_body.addClass(imgSt.cursor);
				}
			});

			_mfpOn(CLOSE_EVENT+ns, function() {
				if(imgSt.cursor) {
					_body.removeClass(imgSt.cursor);
				}
				_window.off('resize' + EVENT_NS);
			});

			_mfpOn('Resize'+ns, mfp.resizeImage);
			if(mfp.isLowIE) {
				_mfpOn('AfterChange', mfp.resizeImage);
			}
		},
		resizeImage: function() {
			var item = mfp.currItem;
			if(!item || !item.img) return;

			if(mfp.st.image.verticalFit) {
				var decr = 0;
				// fix box-sizing in ie7/8
				if(mfp.isLowIE) {
					decr = parseInt(item.img.css('padding-top'), 10) + parseInt(item.img.css('padding-bottom'),10);
				}
				item.img.css('max-height', mfp.wH-decr);
			}
		},
		_onImageHasSize: function(item) {
			if(item.img) {
				
				item.hasSize = true;

				if(_imgInterval) {
					clearInterval(_imgInterval);
				}
				
				item.isCheckingImgSize = false;

				_mfpTrigger('ImageHasSize', item);

				if(item.imgHidden) {
					if(mfp.content)
						mfp.content.removeClass('mfp-loading');
					
					item.imgHidden = false;
				}

			}
		},

		/**
		 * Function that loops until the image has size to display elements that rely on it asap
		 */
		findImageSize: function(item) {

			var counter = 0,
				img = item.img[0],
				mfpSetInterval = function(delay) {

					if(_imgInterval) {
						clearInterval(_imgInterval);
					}
					// decelerating interval that checks for size of an image
					_imgInterval = setInterval(function() {
						if(img.naturalWidth > 0) {
							mfp._onImageHasSize(item);
							return;
						}

						if(counter > 200) {
							clearInterval(_imgInterval);
						}

						counter++;
						if(counter === 3) {
							mfpSetInterval(10);
						} else if(counter === 40) {
							mfpSetInterval(50);
						} else if(counter === 100) {
							mfpSetInterval(500);
						}
					}, delay);
				};

			mfpSetInterval(1);
		},

		getImage: function(item, template) {

			var guard = 0,

				// image load complete handler
				onLoadComplete = function() {
					if(item) {
						if (item.img[0].complete) {
							item.img.off('.mfploader');
							
							if(item === mfp.currItem){
								mfp._onImageHasSize(item);

								mfp.updateStatus('ready');
							}

							item.hasSize = true;
							item.loaded = true;

							_mfpTrigger('ImageLoadComplete');
							
						}
						else {
							// if image complete check fails 200 times (20 sec), we assume that there was an error.
							guard++;
							if(guard < 200) {
								setTimeout(onLoadComplete,100);
							} else {
								onLoadError();
							}
						}
					}
				},

				// image error handler
				onLoadError = function() {
					if(item) {
						item.img.off('.mfploader');
						if(item === mfp.currItem){
							mfp._onImageHasSize(item);
							mfp.updateStatus('error', imgSt.tError.replace('%url%', item.src) );
						}

						item.hasSize = true;
						item.loaded = true;
						item.loadError = true;
					}
				},
				imgSt = mfp.st.image;


			var el = template.find('.mfp-img');
			if(el.length) {
				var img = document.createElement('img');
				img.className = 'mfp-img';
				if(item.el && item.el.find('img').length) {
					img.alt = item.el.find('img').attr('alt');
				}
				item.img = $(img).on('load.mfploader', onLoadComplete).on('error.mfploader', onLoadError);
				img.src = item.src;

				// without clone() "error" event is not firing when IMG is replaced by new IMG
				// TODO: find a way to avoid such cloning
				if(el.is('img')) {
					item.img = item.img.clone();
				}

				img = item.img[0];
				if(img.naturalWidth > 0) {
					item.hasSize = true;
				} else if(!img.width) {										
					item.hasSize = false;
				}
			}

			mfp._parseMarkup(template, {
				title: _getTitle(item),
				img_replaceWith: item.img
			}, item);

			mfp.resizeImage();

			if(item.hasSize) {
				if(_imgInterval) clearInterval(_imgInterval);

				if(item.loadError) {
					template.addClass('mfp-loading');
					mfp.updateStatus('error', imgSt.tError.replace('%url%', item.src) );
				} else {
					template.removeClass('mfp-loading');
					mfp.updateStatus('ready');
				}
				return template;
			}

			mfp.updateStatus('loading');
			item.loading = true;

			if(!item.hasSize) {
				item.imgHidden = true;
				template.addClass('mfp-loading');
				mfp.findImageSize(item);
			} 

			return template;
		}
	}
});