choose_quiz_questions

// ==UserScript==
// @name        choose_quiz_questions
// @namespace   com.example.quiz
// @include     http://*/mod/quiz/*
// @version     1
// @grant       none
// ==/UserScript==

var defaultNumberOfQuizQuestions = 25;


var inputs=document.getElementsByTagName('input');
var checkboxes=[];
for (var i=0; i< inputs.length; i++){
	if (inputs[i].type=="checkbox" && inputs[i].title=="Select"){
		checkboxes.push(inputs[i]);
	}
}

var numberOfBankQuestions = checkboxes.length;


window.addButton = function () {
	var buttonDiv = document.createElement('div');
	buttonDiv.setAttribute('id','buttonDiv');
	
	var inputButton = document.createElement('input');
	inputButton.type = 'button';
	inputButton.value = numberOfBankQuestions + ' Bank Questions - choose:';
	if(inputButton.addEventListener) {
		inputButton.addEventListener('click', go_go_checkboxes, false);
	} else if (inputButton.attachEvent) {
		inputButton.attachEvent('on'+'click', go_go_checkboxes);
	}		

	document.getElementsByTagName("body")[0].appendChild(buttonDiv);
	document.getElementById("buttonDiv").appendChild(inputButton); 
}

window.addTextBox = function () {
	var textBoxDiv = document.createElement('div');
	textBoxDiv.setAttribute('id','textBoxDiv');
	
	var inputTextBox = document.createElement('input');
	inputTextBox.type = 'text';
	inputTextBox.value = defaultNumberOfQuizQuestions;
	inputTextBox.id = 'box'

	document.getElementsByTagName("body")[0].appendChild(textBoxDiv);
	document.getElementById("textBoxDiv").appendChild(inputTextBox); 
}
	
addButton();
addTextBox();

var myButtonDiv = document.getElementById("buttonDiv");
myButtonDiv.style.position = "fixed";
myButtonDiv.style.left = "0px";
myButtonDiv.style.bottom = "0px";
myButtonDiv.style.backgroundColor = "black";

var myTextBoxDiv = document.getElementById("textBoxDiv");
myTextBoxDiv.style.position = "fixed";
myTextBoxDiv.style.left = myButtonDiv.offsetWidth + "px";
myTextBoxDiv.style.bottom = "0px";
myTextBoxDiv.style.backgroundColor = "black";

function go_go_checkboxes() {
	randomArray =[];
	
	var box = document.getElementById("box");
	var numberOfQuizQuestions = box.value;
	
	if (numberOfQuizQuestions < 1  || isNaN(numberOfQuizQuestions)){
		alert("Number of Questions to choose must be a number > 0");
	} else if (numberOfBankQuestions < 1) {
		alert("There are no bank questions visible");
	} else if (numberOfQuizQuestions > numberOfBankQuestions){
		alert("Number of Quiz Questions must be less than or equal to number of Bank Questions")
	
	
	} else {
		while (randomArray.length < numberOfQuizQuestions) {
			var randomNumber=RandomNumber(0 , numberOfBankQuestions - 1);
			var found=false;
			for (var i=0; i<randomArray.length; i++){
				if(randomArray[i]==randomNumber){
					found=true;
					break;
				}
			} 

	
			if(!found){
				randomArray.push(randomNumber);	
			}
		}

		for (var i=0; i < checkboxes.length; i++){
				checkboxes[i].checked=false;
		}
	
		for (var i=0; i< randomArray.length; i++) {
			checkboxes[randomArray[i]].checked=true;
		}
	}

}

function RandomNumber(min,max) {
	if(max<min) {
	   var i=max;
	   max=min;
	   min=i;
	   }
	return Math.round(Math.random()*(max-min)+min);
}