index.js

const Request = require('request-promise')

/**
 * This script sends a POST request to the opentimetable endpoint to fetch classes
 * Then stores relevant info for each class in an object, and finally stores each object in one array and resolves it
 * 
 * @author Hamzah Zahoor
 * 
*/

//

const Weekdays = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'] // Used to fetch the index for a day

const ReqHeaders = {
    "Authorization": "basic T64Mdy7m[",
    "Content-Type" : "application/json; charset=utf-8",
    "credentials": "include",
    "Referer" : "https://opentimetable.dcu.ie/",
    "Origin" : "https://opentimetable.dcu.ie/"
}

//

function StartOfWeek(DateToFetch) {
    var CurrentDate = DateToFetch
    var DateDifference = CurrentDate.getDate() - CurrentDate.getDay() + (CurrentDate.getDay() === 0 ? -6 : 1);
  
    FirstDayInWeek = new Date(CurrentDate.setDate(DateDifference)).toISOString() // Convert our date to ISOString
    return FirstDayInWeek.slice(0, -14).concat("T00:00:00.000Z") // Slice the date and add a time for midnight to the end
    // Outputs: YYYY-MM-DDT00:00:00.000Z
}

function ConstructRequestBody(Day, DateToFetch, CourseIdentity) {
    let RequestBodyTemplate = require('./templates/body.json')

    FinalDayNumber = Weekdays.indexOf(Day) + 1

    RequestBodyTemplate['ViewOptions']['Weeks'][0]['FirstDayInWeek'] = StartOfWeek(DateToFetch)
    RequestBodyTemplate['ViewOptions']['Days'][0]['Name'] = Day
    RequestBodyTemplate['ViewOptions']['Days'][0]['DayOfWeek'] = Weekdays.indexOf(Day) + 1
    
    RequestBodyTemplate['CategoryIdentities'][0] = CourseIdentity

    return RequestBodyTemplate
}

async function FetchCourseCodeIdentity(Query) {

    var ReqPayload = {
        method: 'POST',
        uri: `https://opentimetable.dcu.ie/broker/api/CategoryTypes/241e4d36-60e0-49f8-b27e-99416745d98d/Categories/Filter?pageNumber=1&query=${Query}`,
        headers: ReqHeaders,
        json: true
    };

    return new Promise(function(resolve, reject) {
        Request(ReqPayload) // Send the HTTP Request
            .then(function(res_body) {
                let Results = res_body['Results']

                if (Results.length == 0) {
                    reject('Course identity not found with supplied course code.')
                } else {
                    resolve(res_body['Results'][0]['Identity'])
                }
            })
            .catch(function (err) { // Catch any errors
                reject(err)
            });
    })
}

async function FetchRawTimetableData(CourseCode, Day, DateToFetch = new Date()) {

    let CourseIdentity = await FetchCourseCodeIdentity(CourseCode);
    
    return new Promise(function(resolve, reject) {
        const ReqPayload = {
            method: 'POST',
            uri: 'https://opentimetable.dcu.ie/broker/api/categoryTypes/241e4d36-60e0-49f8-b27e-99416745d98d/categories/events/filter',
            headers: ReqHeaders,
            body: ConstructRequestBody(Day, DateToFetch, CourseIdentity),
            json: true
        };

        Request(ReqPayload) // Send the HTTP Request
            .then(function(res_body) {
                resolve(res_body)
            })
            .catch(function (err) { // Catch any errors
                reject(err)
            });
    })
}

module.exports = {
    FetchTimetable: FetchRawTimetableData
}