const config = require('settings/config');
const cal = require('calendar');
const redirectIfNotLogged = require('auth/views').redirectIfNotLogged;
const getUrl = require('create-url').getUrl;

function stdTimezoneOffset(date) {
    var jan = new Date(date.getFullYear(), 0, 1);
    var jul = new Date(date.getFullYear(), 6, 1);
    return Math.max(jan.getTimezoneOffset(), jul.getTimezoneOffset());
}

function isDstObserved(date) {
    return date.getTimezoneOffset() < stdTimezoneOffset(date);
}

function compareStrings(a, b) {
    if (a < b)
        return -1;
    if (a > b)
        return 1;
    return 0;
}

function computeUserTable(user, callback) {

    let result = {};

    cal.getTotal(user, (table) => {
        let courses = [];
        let total = {
            name: "Total",
            type: "",
            time: 0,
            tdEquivalent: 0,
        }

        for (let key in table) {
            courses.push({
                name: key,
                type: table[key].type,
                time: table[key].time,
                tdEquivalent: table[key].tdEquivalent,
            });

            total.time += table[key].time;
            total.tdEquivalent += table[key].tdEquivalent;
        }

        result.courses = courses;
        result.total = total;

        callback(result);

    });
}

function computeUserTableByCourse(user, callback) {

    let result = {};

    cal.getTotalByCourse(user, (table) => {
        let courses = [];
        let total = { name: "Total" };
        for (let type in cal.Type) {
            total[type] = 0;
        }
        total.totalTdEquivalent = 0;


        for (let key in table) {
            let item = {};
            item.name = key;
            for (let type in cal.Type) {
                item[type] = table[key][type];
                total[type] += table[key][type];
            }
            item.totalTdEquivalent = table[key].totalTdEquivalent;
            total.totalTdEquivalent += table[key].totalTdEquivalent;
            courses.push(item);
        }

        result.courses = courses.sort((a,b) => -(a.totalTdEquivalent - b.totalTdEquivalent));
        result.total = total;

        callback(result);

    });
}

module.exports.total = redirectIfNotLogged('total', function(req, res, render) {
    res.locals.tableUrl = getUrl('totalTable');
    render('total.pug');
});

module.exports.totalByCourse = redirectIfNotLogged('totalByCourse', function(req, res, render) {
    res.locals.tableUrl = getUrl('totalTableByCourse');
    render('total.pug');
});

module.exports.totalTable = function(req, res, render, next) {
    if (req.session.user === undefined) {
        res.status(404);

        res.setHeader('Content-Type', 'text/html');

        res.render(config.BASE_DIR + '/templates/404.pug', res.locals, function(err, result) {
            if (err)
                console.log(err);
            res.send(result);
        });
        return;
    }

    computeUserTable(req.session.user, (result) => {
        res.locals.courses = result.courses;
        res.locals.total = result.total;
        render('totalTable.pug');
    });
}

module.exports.totalTableByCourse = function(req, res, render, next) {
    if (req.session.user === undefined) {
        res.status(404);

        res.setHeader('Content-Type', 'text/html');

        res.render(config.BASE_DIR + '/templates/404.pug', res.locals, function(err, result) {
            if (err)
                console.log(err);
            res.send(result);
        });
        return;
    }

    computeUserTableByCourse(req.session.user, (result) => {
        res.locals.types = [];
        for (let type in cal.Type) {
            res.locals.types.push(type);
        }
        res.locals.courses = [];
        res.locals.noCourses = [];

        for (let course of result.courses) {
            if (course.totalTdEquivalent > 0) {
                res.locals.courses.push(course);
            } else {
                res.locals.noCourses.push(course);
            }
        }

        res.locals.total = result.total;
        render('totalTableByCourse.pug');
    });
}

module.exports.histogram = redirectIfNotLogged('histogram', function(req, res, render) {
    render('histogram.pug');
});

module.exports.histogramData = function(req, res, render, next) {
    if (req.session.user === undefined) {
        res.status(404);

        res.setHeader('Content-Type', 'text/html');

        res.render(config.BASE_DIR + '/templates/404.pug', res.locals, function(err, result) {
            if (err)
                console.log(err);
            res.send(result);
        });
        return;
    }

    cal.getCalendar(req.session.user, new Date(2000, 1, 1), new Date(3000, 1, 1), (calendar) => {

        let histogram = {};

        for (let event of calendar.events) {
            let hours = event.startTime.getHours();
            if (hours % 2 === 0) {
                hours += 2;
            } else {
                hours += 1;
            }
            hours = hours.toString().padStart(2, '0');
            let minutes = event.startTime.getMinutes().toString().padStart(2, '0');
            let key = hours + ':' + minutes;

            histogram[key] = histogram[key] || 0;
            histogram[key]++;
        }

        let histogramArray = [];
        for (let key in histogram) {
            histogramArray.push({
                time: key,
                count: histogram[key],
            });
        }

        histogramArray.sort((a, b) => compareStrings(a.time, b.time));
        res.send(JSON.stringify(histogramArray));
    });

}

module.exports.calendar = redirectIfNotLogged('calendar', function(req, res, render) {
    res.locals.calendarUrl = getUrl('calendarData');
    render('calendar.pug');
});

module.exports.calendarData = function(req, res, render) {

    if (req.session.user === undefined) {
        res.status(404);

        res.setHeader('Content-Type', 'text/html');

        res.render(config.BASE_DIR + '/templates/404.pug', res.locals, function(err, result) {
            if (err)
                console.log(err);
            res.send(result);
        });
        return;
    }

    cal.getCalendar(req.session.user, new Date(2000, 1, 1), new Date(3000, 1, 1), (calendar) => {
        let events = [];

        for (let event of calendar.events) {
            if (isDstObserved(event.startTime)) {
                event.startTime.setTime(event.startTime.getTime() + (60 * 60 * 1000));
            }

            if (isDstObserved(event.finishTime)) {
                event.finishTime.setTime(event.finishTime.getTime() + (60 * 60 * 1000));
            }

            events.push({
                title: event.name + '\n' + event.location,
                start: event.startTime,
                end: event.finishTime,
            });
        }

        res.send(JSON.stringify(events));
    });


}