/**
 * @fileoverview 本地图片预览组件
 * @author 紫英（橘子）<daxingplay@gmail.com>
 * @date 2012-01-10
 * @requires KISSY 1.2+
 */

KISSY.add('gallery/form/1.3/uploader/plugins/preview/preview', function(S, D, E){
	var doc = document, 
		LOG_PRE = '[Plugin: Preview] ',
		_mode = getPreviewMode(),
		_eventList = {
			check: 'check',
			success: 'success',
			showed: 'showed',
			error: 'error'
		},
		_transparentImg = S.UA.ie < 8 ? "http://a.tbcdn.cn/p/fp/2011a/assets/space.gif" : "data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==";
	
	/**
	 * Private 检测当前浏览器适应于哪种预览方式
	 * @return {String} 检测出的预览方式
	 */
	function getPreviewMode(){
		var previewMode = '';
		// prefer to use html5 file api
		if(typeof window.FileReader === "undefined"){
			switch(S.UA.shell){
				case 'firefox':
					previewMode = 'domfile';
					break;
				case 'ie':
					switch(S.UA.ie){
						case 6:
							previewMode = 'simple';
							break;
						default:
							previewMode = 'filter';
							break;
					}
					break;
			}
		}else{
			previewMode = 'html5';
		}
		return previewMode;
	}
	
	/**
	 * Private 将图片的本地路径写入img元素，展现给用户
	 * @param {HTMLElement} imgElem img元素
	 * @param {String} data  图片的本地路径
	 * @param {Number} maxWidth 最大宽度
	 * @param {Number} maxHeight 最大高度
	 */
	function showPreviewImage(imgElem, data, width, height){
		if(!imgElem){
			return false;
		}
		if(_mode != 'filter'){
			imgElem.src = data || _transparentImg;
		}else{
			imgElem.src = _transparentImg;
			if(data){
				data = data.replace(/[)'"%]/g, function(s){
					return escape(escape(s));
				});
				imgElem.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src='" + data + "')";
				imgElem.zoom = 1;
			}
		}
		return true;
	}
	
	/**
	 * Constructor
	 * @param {Object} config 配置
	 */
	function Preview(config){
		var self = this,
			_config = {
				maxWidth: 40,
				maxHeight: 40
			};
		
		self.config = S.mix(_config, config);
		// self.mode = getPreviewMode();
		
		S.log(LOG_PRE + 'Preview initialized. The preview mode is ' + _mode);
	}
	
	S.augment(Preview, S.EventTarget, {
        /**
         * 显示预览图片，不支持IE
         * @author 明河
         * @since 1.3
         */
        show:function(file,$img){
            if(_mode != 'html5' || !$img || !$img.length) return false;
            var self = this;
            var reader = new FileReader();
            reader.onload = function(e){
                var data = self.data = e.target.result;
                self.fire(_eventList.getData, {
                    data: data,
                    mode: _mode
                });
                $img.attr('src',data);
                self.fire(_eventList.showed, {
                    img: data
                });
            };
            reader.onerror = function(e){
                S.log(LOG_PRE + 'File Reader Error. Your browser may not fully support html5 file api', 'warning');
                self.fire(_eventList.error);
            };
                reader.readAsDataURL(file);
        },
		/**
		 * 预览函数
		 * @param {HTMLElement} fileInput 文件上传的input
		 * @param {HTMLElement} imgElem 需要显示预览图片的img元素，如果不设置的话，程序则不会执行显示操作，用户可以从该函数的返回值取得预览图片的地址自行写入
		 * @return {String} 取得的图片地址
		 */
		preview: function(fileInput, imgElem){

			fileInput = D.get(fileInput);
			imgElem = D.get(imgElem);
			var self = this,
				onsuccess = function(){
					self.fire(_eventList.getData, {
						data: self.data,
						mode: _mode
					});
					if(imgElem){
						showPreviewImage(imgElem, self.data);
						self.fire(_eventList.showed, {
							img: imgElem
						});
					}
				};
			
			self.data = undefined;
			
			if(fileInput){
				S.log(LOG_PRE + 'One file selected. Getting data...');
				// get Image location path or data uri
				switch(_mode){
					case 'domfile':
						self.data = fileInput.files[0].getAsDataURL();
						break;
					case 'filter':
						// fileInput.focus();
						fileInput.select();
						try{
							self.data = doc.selection.createRange().text;
						}catch(e){
							S.log(LOG_PRE + 'Get image data error, the error is: ');
							S.log(e, 'dir');
						}finally{
							doc.selection.empty();
						}
						if(!self.data){
							self.data = fileInput.value;
						}
						break;
					case 'html5':
						// TODO Mathon3
						var reader = new FileReader();
						reader.onload = function(e){
							self.data = e.target.result;
							onsuccess();
						};
						reader.onerror = function(e){
							S.log(LOG_PRE + 'File Reader Error. Your browser may not fully support html5 file api', 'warning');
							self.fire(_eventList.error);
						};
                        if(fileInput.files){
                            reader.readAsDataURL(fileInput.files[0]);
                        }
						// alert(reader.readAsDataURL);
						// S.log(reader, 'dir');
						break;
					case 'simple':
					default:
						self.data = fileInput.value;
						break;
				}
				
				if(self.data){
					onsuccess();
				}else if(_mode != 'html5'){
					S.log(LOG_PRE + 'Retrive Data error.');
					showPreviewImage(imgElem);
					self.fire(_eventList.error);
				}
			}else{
				S.log(LOG_PRE + 'File Input Element does not exists.');
			}
			
			return self.data;
		}
	});
	
	return Preview;
	
}, {
	requires: [
		'dom',
		'event'
	]
});