database.js

var database_link = "https://api.mlab.com/api/1/databases/hackroll/collections";
var lesson_collection_link = "https://api.mlab.com/api/1/databases/hackroll/collections/lesson";
var attendance_collection_link = "https://api.mlab.com/api/1/databases/hackroll/collections/lesson_attendance";
var result_collection_link = "https://api.mlab.com/api/1/databases/hackroll/collections/result";
var student_collection_link = "https://api.mlab.com/api/1/databases/hackroll/collections/student";
var apiKey = "apiKey=6158q4S1oyjh0rE3MDtYdYoqKYCQSPIL";
var domain = "";
var lesson_id ="5a6c42cec2ef1663f11a7fa7";
var lesson ="";


// create_new_lesson();

//create new lesson
function create_new_lesson()
{
	var lesson = document.getElementById("lesson").value;
	var class_time = document.getElementById("time").value;
	var class_date = getTodayDate();
	// var unique_code = generateUniqueCode();
	var classroom = document.getElementById("classroom").value;
	var new_lesson = get_lesson_json(lesson, class_date, class_time, classroom, "open");

	$.ajax({
		url: lesson_collection_link.concat("?" + apiKey),
		data: new_lesson,
		type: "POST",
		contentType: "application/json",
		success: function(return_data)
		{
			window.location.href="qrCode.html?lesson_id=" + return_data._id["$oid"];
		}
	});
}

//create new attendance
function create_new_attendance()
{
	var student_name = document.getElementById("Name").value;
	var student_id = document.getElementById("number").value;
	var new_attendance = get_attendance_json("5a6c42cec2ef1663f11a7fa7", student_id, student_name);

	$.ajax({
			url: attendance_collection_link.concat("?" + apiKey),
			data: new_attendance,
			type: "POST",
			contentType: "application/json",
			success: function(return_data)
			{
				//return single attendance obj
			}
	});

}

//get attendance by lesson id
function get_attendance_by_id(lesson_id)
{
	var get_attendance_link = attendance_collection_link.concat('?q={"lesson_id" : "' + lesson_id + '"}&' + apiKey);
	
	$.ajax({
			url: get_attendance_link.concat(apiKey),
			type: "GET",
			contentType: "application/json",
			success: function(return_data)
			{
			    compare_student_lists(return_data);
			}
	});
}

//compare student lists
// function compare_student_lists(return_data)
// {
//     $.ajax({
//         url: student_collection_link.concat(apiKey),
//         type: "GET",
//         contentType: "application/json",
//         success: function(student_list)
//         {
//             List<JSONObject> studentList = student_list;
//             List<JSONObject> attendance = return_data;
//             Collections.sort(studentList);
//             Collections.sort(attendance);
//             var j = 0;
//             for(var i = 0; i < studentList; i++) {
//                 if(studentList[j] !== attendance[i]) {
//                     var no_attendance = studentList[j];
//                     j++;
//                     $.ajax({
//                     			url: result_collection_link.concat("?" + apiKey),
//                     			data: no_attendance,
//                     			type: "POST",
//                     			contentType: "application/json",
//                     			success: function(return_data)
//                     			{
//                     			}
//                     	});
//                 }j++;
//             }
//         }
//     })
// }

//create lesson json obj 
function get_lesson_json(lesson, date, time, classroom, status)
{
	var lesson_json = JSON.stringify(
	{
		"lesson" : lesson,
		"date" : date,
		"time" : time,
		"classroom" : classroom,
		"status" : status
	});

	return lesson_json;
}

//create attendance json object
function get_attendance_json(lesson_id, student_number, student_name)
{
	var attendance_json = JSON.stringify(
	{
		"lesson_id" : lesson_id,
		"student_number" : student_number,
		"student_name" : student_name
	});

	return attendance_json;
}

// function generateUniqueCode()
// {
// 	return '_' + Math.random().toString(36).substr(2, 9);
// }

function getQueryParameterByName(name, url) {
    if (!url) url = window.location.href;
    name = name.replace(/[\[\]]/g, "\\$&");
    var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
        results = regex.exec(url);
    if (!results) return null;
    if (!results[2]) return '';
    return decodeURIComponent(results[2].replace(/\+/g, " "));
}

function getTodayDate()
{
	var today = new Date();
                var dd = today.getDate();
                var mm = today.getMonth()+1;
                var yyyy = today.getFullYear();

                if(dd<10) {
                    dd = '0'+dd
                } 

                if(mm<10) {
                    mm = '0'+mm
                } 

                today = dd + '/' + mm + '/' + yyyy;

    return today;
}