04_Problem

function problem4(input) {
    var userMap = {"students": [], "trainers": []};
    var criteria = input[0];
    for (var i = 1; i < input.length; i++) {
        var currLine = JSON.parse(input[i]);
        delete currLine.town;
        if (currLine.role == 'student') {
            delete  currLine.role;
            var grade = calcAvg(currLine.grades);
            currLine = JSON.stringify(currLine);
            currLine = currLine.replace("grades", "averageGrade");
            currLine = JSON.parse(currLine);
            currLine.averageGrade = grade.toFixed(2);
            userMap.students.push(currLine);
            //console.log(currLine);
        }
        else {
            userMap.trainers.push(currLine);
        }
    }
    if (criteria == 'level^courses') {
        userMap.students.sort(sortByLevaelID);
    }
    if (criteria == 'name^courses') {
        userMap.students.sort(sortByFirsLast);
    }
    userMap.trainers.sort(sortTrainers);
    //console.log(userMap);
    for (var i in userMap.students) {
        delete userMap.students[i].level;
    }
    for (var i in userMap.trainers) {
        delete userMap.trainers[i].role;
    }
    console.log(JSON.stringify(userMap));
    //sort trainers
    function sortTrainers(a, b) {
        if (a.courses.length - b.courses.length != 0) {
            return a.courses.length - b.courses.length;
        }
        return parseInt(a.lecturesPerDay) - parseInt(b.lecturesPerDay);
    }
//sorts by Level and ID
    function sortByLevaelID(a, b) {
        if (parseInt(a.level) - parseInt(b.level) != 0) {
            return parseInt(a.level) - parseInt(b.level);
        }
        return parseInt(a.id) - parseInt(b.id);
    }
//Sorts by First name and Last name
    function sortByFirsLast(a, b) {
        if (a.firstname.localeCompare(b.firstname) != 0) {
            return a.firstname.localeCompare(b.firstname);
        }
        //a.name.localeCompare(b.name)
        return a.lastname.localeCompare(b.lastname);
    }

    function calcAvg(arr) {
        var sum = arr.reduce(function(a, b){return parseFloat(a) + parseFloat(b)});//sum of Arr numbers
        return (sum/arr.length);
    }
}

problem4([
        //'level^courses',
        'name^courses',
    '{"id":0,"firstname":"Angel","lastname":"Yvanov","town":"Plovdiv","role":"student","grades":["5.89"],"level":2,"certificate":false}',
    '{"id":1,"firstname":"Mitko","lastname":"Nakova","town":"Dimitrovgrad","role":"trainer","courses":["PHP","Unity Basics"],"lecturesPerDay":6}',
    '{"id":2,"firstname":"Angel","lastname":"Ivanov","town":"Varna","role":"student","grades":["5.59","3.50","4.54","5.05","3.45"],"level":4,"certificate":false}',
    '{"id":3,"firstname":"Ivan","lastname":"Ivanova","town":"Vidin","role":"trainer","courses":["JS","Java","JS OOP","Database","OOP","C#"],"lecturesPerDay":7}',
    '{"id":4,"firstname":"Mitko","lastname":"Petrova","town":"Sofia","role":"trainer","courses":["Database","JS Apps","Java"],"lecturesPerDay":2}'
])