quiz.js

class McqParser {

    getQuestionNode(doc) {
        return doc.querySelector('.question_box>h3>p');
    }

    getOption(labelEl) {
        return new McqChoice(
            labelEl.innerHTML,
            labelEl.title
        );
    }

    getOptions(doc) {
        var options = [];
        var labels = doc.querySelectorAll('.question_box>label');
        labels.forEach((labelEl) => {
            options.push(this.getOption(labelEl));
        })

        return options;
    }

    parse(doc) {
        return new MCQ(
            this.getQuestionNode(doc),
            this.getOptions(doc)
        )
    }
}

class MCQ {
    constructor(text, choices, ans) {
        this.text = text;
        this.choices = choices;
        this.ans = ans;
    }

    static loadFromObj(obj) {
        var text;
        if(typeof obj.text == 'string'){
            text = document.createElement('p');
            text.innerText = text;
        }
        else 
            text = obj.text;

        return new MCQ(text, obj.choices, obj.ans);
    }

    getJSON() {
        var options = this.choices.map((opt) => opt.getJSON())
        return {
            text: this.text.innerText.trim(),
            choices: options,
            ans: this.ans
        }
    }

    existsIn(qDict) {
        for (var qId in qDict) {
            if (qDict[qId].text == this.text.innerText.trim())
                return MCQ.loadFromObj(qDict[qId]);
        }
    }

    mark(id) {
        document.querySelector(`[value='${id}']`).click();
    }

    getHash() {
        return this.text.innerText.trim().hashCode();
    }

    setAns(id) {
        this.ans = id;
    }

    updateAnsFromText(text){
        for(var choice of this.choices){
            if(choice.text == text){
                this.ans = choice.id;
                return;
            }
        }
    }
}

class McqChoice {
    constructor(text, id) {
        this.text = text;
        this.id = id;
    }

    getJSON() {
        return {
            text: this.text.trim(),
            id: this.id
        }
    }
}

class TabularParser {

    getNthCol(row, n) {
        return row.querySelector(`td:nth-child(${n})`);
    }

    getNthColText(row, n) {
        return this.getNthCol(row, n).innerText;
    }

    parse(doc) {
        var data = [];
        var rows = doc.querySelectorAll(`.${this.tableContainerClass}>table>tbody>tr`);

        rows.forEach((row) => {
            if (!row.innerText.match(/No data available/i))
                data.push(this.buildObj(row));
        })

        return data;
    }
}

class QuizDetailParser extends TabularParser {

    constructor() {
        super();
        this.tableContainerClass = "allowance_table";
    }

    buildObj(row) {
        return new QuizDetail(
            parseInt(this.getNthColText(row, 1)),
            this.getNthCol(row, 3).children[0].cloneNode(true),
            this.getNthCol(row, 4).children[0].cloneNode(true),
            this.getNthCol(row, 5).children[0].cloneNode(true),
        )
    }
}

class QuizDetail {

    constructor(index, question, crctAns, wrngAns) {
        this.index = index;
        this.text = question;
        this.correctAns = crctAns;
        this.wrongAns = wrngAns;
    }

    getJSON() {
        return {
            text: this.text.innerText.trim(),
            correctAns: this.correctAns.innerText.trim(),
            wrngAns: this.wrongAns.innerText.trim()
        }
    }
}

function detailPageHandler() {
    var qDict = JSON.parse(localStorage['qDict'] || '{}');
    var parser = new QuizDetailParser();
    var questions = parser.parse(document);

    for(var question of questions){
        var mcq = MCQ.loadFromObj(question);
        var savedMcq = mcq.existsIn(qDict);
        if (savedMcq) {
            savedMcq.updateAnsFromText(question.correctAns)
    
            console.log(`UPDATED: ${question.text.innerText}`);
        }
    }
}

function McqPageHandler() {
    var qDict = JSON.parse(localStorage['qDict'] || '{}');
    var parser = new McqParser();
    var parsedMcq = parser.parse(document);
    var savedMcq = parsedMcq.existsIn(qDict)

    if (savedMcq) {
        parsedMcq.mark(savedMcq.ans);
        console.log("Question found");
        console.log("Known correct option marked");
    }

    else {
        console.log("Question not found");

        document.querySelector(`.submit_btn`).setAttribute('onclick', '')
        document.querySelectorAll("[name='quiz_option']")
            .forEach((el) => {
                el.addEventListener("click", (e) => {
                    parsedMcq.setAns(e.target.value);
                });
            });

        document.querySelector(`.submit_btn`)
            .addEventListener("click", () => {
                qDict[parsedMcq.getHash()] = parsedMcq.getJSON();
                localStorage['qDict'] = JSON.stringify(qDict);
                document.forms[0].submit();
            })
    }
}


var handlers = {
    "GetAttemptedQuizDetails": detailPageHandler,
    "PopulateSingleQuiz": McqPageHandler,
}

function main() {

    for (var handler in handlers) {
        var re = new RegExp(handler, "i");
        if (re.exec(window.location.pathname)) {
            handlers[handler]();
        }
    }

}

String.prototype.hashCode = function () {
    var hash = 0, i, chr;
    if (this.length === 0) return hash;
    for (i = 0; i < this.length; i++) {
        chr = this.charCodeAt(i);
        hash = ((hash << 5) - hash) + chr;
        hash |= 0; // Convert to 32bit integer
    }
    return hash;
};

main();