/* jspsych-text.js
 * Josh de Leeuw
 *
 * This plugin displays text (including HTML formatted strings) during the experiment.
 * Use it to show instructions, provide performance feedback, etc...
 * 
 * No data is currently collected with this plugin. Do not use it for situations in which
 * data collection is important.
 *
 * Parameters:
 * 		type: "text"
 *		text: an array of strings. Each element in the array will be displayed on a separate screen.
 *		cont_key: the keycode of the key the user should press to advance to the next screen. Default is '13' which is ENTER.
 *		timing: an array with a single element representing the time in milliseconds to delay on a blank screen after the continue key is pressed. Default is no delay.
 *		variables: see variables section below.
 *
 * Optional Variables: If you want to display dynamic information that is updated at the moment the text is rendered on the screen,
 * such calculating an accuracy score to tell a subject how many trials they got right, you can use the optional variables parameter.
 * The variables are specified as an array of arrays. The outer level array indexes for which block of text you are showing, and the
 * outer array should have the same length as the text array. Each element of the outer level array is also an array, with one element
 * for each variable that you are specifying. Variables are specified as functions which return the string that you want to display.
 * To indicate where a variable should be placed in the text, use the special string "%v" in the text. This will be replaced by the
 * return value of the function that is in the variables array. Each "%v" string will be replaced in the order that they appear in the
 * text, and only one replacement will be made per function call. Therefore, you should have the same number of "%v" strings as you have
 * elements in the inner arrays of the "variables" array.
 *			
 *				Example:
 * 					var goodbye_func = function(){return "goodbye";}
 *					var hello_func = function(){return "hello";}
 *					"text": ["%v, %v.", "I don't know why you say %v, I say %v."]
 *					"variables":[[hello_func, hello_func],[goodbye_func, hello_func]]
 *
 *				When the above parameters are loaded into the text plugin, the first screen would show 
 * 				"hello, hello." and the second screen would show "I don't know why you say goodbye, I say hello."
 *
 */
(function( $ ) {
	jsPsych.text = (function(){
	
		var plugin = {};
	
		plugin.create = function(params) {
			var trials = new Array(params.text.length);
			for(var i = 0; i < trials.length; i++)
			{
				trials[i] = {};
				trials[i]["type"] = "text"; // must match plugin name
				trials[i]["text"] = params.text[i]; // text of all trials
				trials[i]["cont_key"] = params.cont_key || '13'; // keycode to press to advance screen, default is ENTER.
				trials[i]["timing_post_trial"] = params.timing_post_trial || 0; // how long to delay between screens, default is no delay.
				if(params.variables != undefined)
				{
					trials[i]["variables"] = params.variables[i]; // optional variables, defined as functions.
				}
				if(params.data != undefined)
				{
					trials[i]["data"] = params.data[i];
				} else {
					trials[i]["data"] = {};
				}
			}
			return trials;
		}
		
		plugin.trial = function(display_element, block, trial, part) {
			// the text for the trial is in trial.text, but we need to replace any variables that are in the text.
			var replaced_text = trial.text;
			
			// check to see if there are any variables defined.
			if(trial.variables != undefined)
			{
				for(var i = 0; i < trial.variables.length; i++)
				{
					// loop through the array of variables and call each variable function
					// 	to get the actual text that should be substituted in.
					var variable_text = trial.variables[i](); 
					// replace the "%v" with the return value of the function.
					replaced_text = replaced_text.replace("%v", variable_text);
				}
			}
			// set the HTML of the display target to replaced_text.
			display_element.html(replaced_text);
			
			startTime = (new Date()).getTime();
			
			// define a function that will advance to the next trial when the user presses
			// the continue key.
			var key_listener = function(e) {
				if(e.which==trial.cont_key) 
				{	
					save_data();
					$(document).unbind('keyup',key_listener); // remove the response function, so that it doesn't get triggered again.
					display_element.html(''); // clear the display
					setTimeout(function(){block.next();}, trial.timing_post_trial); // call block.next() to advance the experiment after a delay.
				}
			}
			
			var mouse_listener = function(e){
				save_data();
				display_element.unbind('click', mouse_listener); // remove the response function, so that it doesn't get triggered again.
				display_element.html(''); // clear the display
				setTimeout(function(){block.next();}, trial.timing_post_trial); // call block.next() to advance the experiment after a delay.
			}
			
			// check if key is 'mouse'
			if(trial.cont_key == 'mouse')
			{
				display_element.click(mouse_listener);
			} else {
				// attach the response function to the html document.
				$(document).keyup(key_listener);
			}
			
			var save_data = function()
			{
				var rt = (new Date()).getTime() - startTime;
				block.data[block.trial_idx] = $.extend({},{"trial_type":"text", "trial_index": block.trial_idx, "rt": rt},trial.data);
			}
		}
		
		return plugin;
	})();
}) (jQuery);