/* jspsych-likert
 * a jspsych plugin for measuring items on a likert scale
 *
 * Josh de Leeuw (March 2013)
 *
 */
 
(function($) {
	jsPsych.likert = (function(){
	
		var plugin = {};
		
		plugin.create = function(params) {
			var trials = [];
			for(var i = 0; i < params.questions.length; i++)
			{
				trials.push({
					type: "likert",
					questions: params.questions[i],
					labels: params.labels[i],
					intervals: params.intervals[i],
					show_ticks: params.show_ticks || true
				});
			}			
			return trials;
		}
		
		plugin.trial = function(display_element, block, trial, part) {
		
			// add likert scale questions
			for(var i = 0; i < trial.questions.length; i++)
			{
				// create div
				display_element.append($('<div>', { "id": 'likert'+i, "class": 'likertquestion'}));
				
				// add question text
				$("#likert"+i).append('<p class="likerttext likert">'+trial.questions[i]+'</p>');
				
				// create slider
				$("#likert"+i).append($('<div>', { "id": 'slider'+i, "class": 'slider likert' }));
				$("#slider"+i).slider(
					{
						value: Math.ceil(trial.intervals[i] / 2),
						min: 1,
						max: trial.intervals[i],
						step: 1
					});
				
				// show tick marks
				if(trial.show_ticks) {
					$("#likert"+i).append($('<div>', { "id": 'sliderticks'+i, "class": 'sliderticks likert', "css":{"position":'relative'} }));
					for(var j = 1; j < trial.intervals[i]-1; j++){
						$('#slider'+i).append('<div class="slidertickmark"></div>');
					}
					
					$('#slider'+i+' .slidertickmark').each(function(index)
						{
							var left = (index+1) * (100/(trial.intervals[i]-1));
							$(this).css({
								'position':'absolute',
								'left': left+'%',
								'width': '1px',
								'height': '100%',
								'background-color':'#222222'
							});
						});
				}
				
				// create labels for slider
				$("#likert"+i).append($('<ul>', {"id": "sliderlabels"+i, "class": 'sliderlabels likert', "css":
													{
														"width":"100%",
														"margin":"10px 0px 0px 0px",
														"padding": "0px",
														"display": "block",
														"position": "relative"
													}
												}));
				
				for(var j = 0; j < trial.labels[i].length; j++)
				{
					$("#sliderlabels"+i).append('<li>'+trial.labels[i][j]+'</li>');
				}
				
				// position labels to match slider intervals
				var slider_width = $("#slider"+i).width();
				var num_items = trial.labels[i].length;
				var item_width = slider_width / num_items;
				var spacing_interval = slider_width / (num_items - 1);
				
				$("#sliderlabels"+i+" li").each(function(index){
					$(this).css({
						'display': 'inline-block',
						'width': item_width+'px',
						'margin': '0px',
						'padding': '0px',
						'text-align': 'center',
						'position': 'absolute',
						'left': (spacing_interval*index)-(item_width/2)
					});
				});
			}

			// add submit button
			display_element.append($('<button>', {'id':'next','class':'likert'}));
			$("#next").html('Submit Answers');
			$("#next").click(function(){
				// measure response time
				endTime = (new Date()).getTime();
				response_time = endTime-startTime;
				
				// create object to hold responses
				var question_data = {};
				$("div.slider").each(function(index){
					var id = "Q"+index;
					var val = $(this).slider("value");
					var obje = {};
					obje[id] = val;
					$.extend(question_data, obje);
				});
				
				// save data
				block.data[block.trial_idx] = $.extend({},{"trial_type": "likert", "trial_index": block.trial_idx, "rt": response_time}, question_data, trial.data);
				
				display_element.html('');
				
				// next trial
				block.next();
			});
			
			startTime = (new Date()).getTime();
		}		
		
		return plugin;
	})();
})(jQuery);