const https = require("https");
const config = require("worker_threads").workerData;
const models = require("../models");

const reg_event = /(?:(?:BEGIN:VEVENT\nDTSTAMP:(?:[A-Z0-9]*?)\nDTSTART:([A-Z0-9]*?)\nDTEND:([A-Z0-9]*?)\nSUMMARY: {0,}([a-zéèàA-Z0-9-. \, \\/ô]*?)\nLOCATION:([a-zA-Zéèà0-9-. \,\\]*?)\nDESCRIPTION:(?:\\n){0,}((?:(?:LP(?:[ a-zA-Z0-9\\]*?))\\n){1,})((?:(?:[A-Z]*) (?:[A-Z]*)(?: (?:[A-Z]*)){0,}\\n){0,})(?:.*?)\nEND:VEVENT)|(?:BEGIN:VEVENT\nDTSTAMP:(?:[A-Z0-9]*?)\nDTSTART:([A-Z0-9]*?)\nDTEND:([A-Z0-9]*?)\nSUMMARY: {0,}((?:S(?:[A-Z0-9-]*)|M(?:[A-Z0-9-]*)(?:\/M(?:[A-Z0-9-]*)){0,}|Conférence|)[a-zéèàA-Z0-9-. \, \\/]*?)\nLOCATION:([a-zA-Zéèà0-9-. \,\\]*?)\nDESCRIPTION:(?:\\n){0,}((?:(?:G[0-9]S[0-9]|S[0-9]|ASPE)\\n){0,})((?:(?:[A-Z]*) (?:[A-Z]*)(?: (?:[A-Z]*)){0,}\\n){0,})(?:.*?)\nEND:VEVENT))/gs;
const reg_location = /((?:[SH0-9][0-9]{2})|(?:(?:Préfa |Amphi)[0-9]))/g;
const reg_teachers = /^(?:((?:[a-zA-Z]*[ -]{0,}){0,}) ([a-zA-Z]*))$/m;
const reg_date = /([0-9]{4})([0-9]{2})([0-9]{2})T([0-9]{2})([0-9]{2})([0-9]{2})Z/;
const reg_group = /(?:(LP)[ -]{0,}(.*)|(?:(G[0-9])(S[0-9])))/;
const base_url = config["edt"];
const capitalizeFirstLetter = (string) => string.charAt(0).toUpperCase() + string.slice(1).toLowerCase();


function fetchEvents(days = 1, TS_Start = new Date()) {
    return new Promise((resolve, reject) => {
        let start = new Date(TS_Start);
        if (start == "Invalid Date")
            start = new Date();
        let end = new Date(start);
        end.setDate(end.getDate() + days);

        let url = base_url + start.getFullYear() + "-" + start.getMonth() + "-" + start.getDate() + "&lastDate=" + end.getFullYear() + "-" + end.getMonth() + "-" + end.getDate();
        https.get(url, (resp) => {
            let data = "";
            resp.on("data", (chunk) => {
                data += chunk;
            });
            resp.on("end", () => {
                let output = [];
                data = data.replace(/\r/g, "");
                let m;
                while ((m = reg_event.exec(data)) !== null) {
                    if (m.index === reg_event.lastIndex) {
                        reg_event.lastIndex++;
                    }
                    let event = [];
                    let semester = [];
                    let group = [];
                    /*
                            m = [
                                    FullMatch,
                                    StartTime,
                                    EndTime,
                                    EventDescription ( SubjectID,Name,Class?) ,
                                    Location,
                                    ClassGroup,
                                    Teacher(s)
                                ]
                         */
                    if (m[1] !== undefined) {
                        // LPXXXX
                    } else {
                        m.splice(1, 6);
                        // GXSX | SX | ASPE
                    }
                    let csplit = m[5].split("\\n");
                    csplit.pop();
                    csplit.forEach(e => {
                        if (e === "ASPE") {
                            semester.push(e);
                        }else if(/^S[0-9]$/.test(e)) {
                            semester.push(e);
                        }else{
                            let groupSplit = reg_group.exec(e);
                            if (groupSplit[1] === 'LP') {
                                group.push([groupSplit[2], groupSplit[1]]);
                            } else {
                                group.push([groupSplit[3], groupSplit[4]]);
                            }
                        }
                    });

                    event["title"] = m[3];
                    event["semesters"] = semester;
                    event["groups"] = group;
                    /*
                    Date
                     */
                    let d1 = reg_date.exec(m[1]);
                    let d2 = reg_date.exec(m[2]);
                    event["startDate"] = new Date(d1[1] + "-" + d1[2] + "-" + d1[3] + "T" + d1[4] + ":" + d1[5] + ":" + d1[6] + ".00Z");
                    event["endDate"] = new Date(d2[1] + "-" + d2[2] + "-" + d2[3] + "T" + d2[4] + ":" + d2[5] + ":" + d2[6] + ".00Z");
                    /*
                    Location
                     */
                    event["locations"] = [];
                    let loc;
                    while ((loc = reg_location.exec(m[4])) !== null) {
                        if (loc.index === reg_location.lastIndex) {
                            reg_location.lastIndex++;
                        }
                        event["locations"].push(loc[1]);
                    }
                    /*
                    Teachers
                     */
                    event['teachers'] = [];
                    let fullTeachers = m[6].split('\\n');
                    fullTeachers.forEach(e => {
                        if(e !== ""){
                            let splittedTeachers = reg_teachers.exec(e);
                            event['teachers'].push([splittedTeachers[1],splittedTeachers[2]]);
                        }
                    });
                    output.push(event);
                }
                resolve(output);
            });
        }).on("error", (err) => {
            reject(err);
        });
    });
}

function compare(a, b) {
    if (a.length !== b.length) {
        return false;
    }
    let set = {};
    a.forEach((i) => {
        if (set[i] !== undefined) {
            set[i]++;
        } else {
            set[i] = 1;
        }
    });
    let difference = b.every((i) => {
        if (set[i] === undefined) {
            return false;
        } else {
            set[i]--;
            if (set[i] === 0) {
                delete set[i];
            }
            return true;
        }
    });
    return Object.keys(set) == 0 && difference;
}

function compareGroups(list1, list2) {
    return compare(list1.map(g => g[0] + " " + g[1]), list2.map(g => g.number + " " + g.Semester.name));
}

function compareTeachers(list1, list2) {
    return compare(list1.map(t => t[0].toUpperCase() + " " + t[1].toUpperCase()), list2.map(t => t.lastName.toUpperCase() + " " + t.firstName.toUpperCase()));
}

function compareSemesters(list1, list2) {
    return compare(list1, list2.map(s => s.name));
}

async function updateDatabase() {
    let events = await fetchEvents(365, new Date(2020, 8, 1));
    for (let event of await models.Event.findAll({
        include: [{
            model: models.Group,
            include: {model: models.Semester, required: true}
        }, models.User, models.Semester]
    })) {
        let ev = events.find(e => (e.title === event.name && e.startDate.getTime() === event.startDate.getTime() &&
            e.endDate.getTime() === event.endDate.getTime() && e.locations.join(", ") === event.locations &&
            compareGroups(e.groups, event.Groups) && compareTeachers(e.teachers, event.Users) &&
            compareSemesters(e.semesters, event.Semesters)));
        if (!ev)
            await event.destroy();
        else
            events = events.filter(e => e !== ev);
    }

    for (let event of events) {
        let e = await models.Event.create({
            name: event.title,
            startDate: event.startDate,
            endDate: event.endDate,
            locations: event.locations.join(", ")
        });

        let teachers = [];
        for (let teacher of event.teachers) {
            let t = await models.User.findOne({where: {permissions: 2, lastName: teacher[0].toUpperCase(), firstName: capitalizeFirstLetter(teacher[1])}});
            if (!t)
                t = await models.User.create({
                    email: teacher[1].toLowerCase().replaceAll(" ", "-") + "." + teacher[0].toLowerCase().replaceAll(" ", "-") + "@univ-lyon1.fr",
                    firstName: capitalizeFirstLetter(teacher[1]),
                    lastName: teacher[0].toUpperCase(),
                    permissions: 2,
                    passwordHash: Math.round((Math.pow(36, 12 + 1) - Math.random() * Math.pow(36, 12))).toString(36).slice(1)
                });
            teachers.push(t);
        }
        await e.addUsers(teachers);

        let semesters = [];
        for (let semester of event.semesters) {
            let s = await models.Semester.findOne({where: {name: semester, year: event.startDate.getFullYear()}});
            if (!s)
                s = await models.Semester.create({
                    name: semester,
                    year: event.startDate.getFullYear()
                });
            semesters.push(s);
        }
        await e.addSemesters(semesters);

        let groups = [];
        for (let group of event.groups) {
            let s = await models.Semester.findOne({where: {name: group[1], year: event.startDate.getFullYear()}});
            if (!s)
                s = await models.Semester.create({
                    name: group[1],
                    year: event.startDate.getFullYear()
                });

            let g = await models.Group.findOne({where: {number: group[0], SemesterId: s.id}});
            if (!g)
                g = await models.Group.create({
                    number: group[0],
                    SemesterId: s.id
                });
            groups.push(g);
        }
        await e.addGroups(groups);
    }
}

updateDatabase().then(() => setInterval(updateDatabase, 30000));