import * as Sentry from '@sentry/node';
import { Router } from 'express';
import type { Response } from 'express';
import { getH3Event } from 'h3-express';
import { createEvents } from 'ics';
import SQL from 'sql-template-strings';

import type { LocaleDescription } from '../../locale/locales.ts';

import { normalise } from './user.ts';

import { Calendar, Day } from '#shared/calendar/helpers.ts';
import type { Event } from '#shared/calendar/helpers.ts';
import { handleErrorAsync, clearLinkedText } from '#shared/helpers.ts';
import type { Translator } from '#shared/translator.ts';
import type { Config } from '~~/locale/config.ts';
import { getLocale, loadCalendar, loadConfig, loadTranslator } from '~~/server/data.ts';

// TODO caching? // import { caches } from "../../src/cache";

const renderEvents = (
    yearEvents: Record<number, Event[]>,
    translator: Translator,
    res: Response,
    onlyFirstDays: boolean = false,
    calNameExtra: string = '',
) => {
    const events = [];
    let i = 1;
    for (const year in yearEvents) {
        if (!Object.hasOwn(yearEvents, year)) {
            continue;
        }
        for (const event of yearEvents[year]) {
            if (!event) {
                continue;
            }
            const ics = event.toIcs(parseInt(year), translator, clearLinkedText, i, onlyFirstDays, calNameExtra);
            if (ics !== null) {
                events.push(ics);
            }
        }
        i++;
    }

    if (events.length === 0) {
        return res.status(404).json({ error: 'Not found' });
    }

    createEvents(
        events,
        (error, value) => {
            if (error) {
                Sentry.captureException(error);
                return res.status(500).json({ error: 'Unexpected server error' });
            }

            res.header('Content-type', 'text/calendar');
            res.send(value);
        },
    );
};

const getEventName = (name: string, translator: Translator): string => {
    name = translator.get<string | undefined>(`calendar.events.${name}`) ?? name;
    name = name.replace(/{.*?=(.*?)}/g, '$1');
    return name;
};

const buildMessage = (
    events: string[],
    locale: LocaleDescription,
    translator: Translator,
    day: Day,
    link: string,
): string | null => {
    if (events.length === 0) {
        return null;
    }

    let message = `[${locale.name}] ${day.toString()}\n\n${translator.translate('calendar.banner')}:\n`;
    for (const event of events) {
        message += ` - ${event}\n`;
    }
    message += `\n${link}`;

    return message;
};

const eventsSummary = async (config: Config, day: Day, locale: LocaleDescription) => {
    const [translator, calendar] = await Promise.all([loadTranslator(config.locale), loadCalendar(config.locale)]);
    const eventsRaw = calendar.getCurrentYear()!.eventsByDate[day.toString()];

    const link = `${locale.url}/${encodeURIComponent(config.calendar!.route!)}/${day}`;
    const image = `${locale.url}/calendar/${locale.code}/${day}.png`;

    let message = null;
    const events = [];
    if (eventsRaw !== undefined && eventsRaw.length > 0) {
        for (const event of eventsRaw) {
            events.push(getEventName(event.name, translator));
            delete event.daysMemoise;
        }
    }
    let eventsForMessage = [...events];
    while (true) {
        message = buildMessage(eventsForMessage, locale, translator, day, link);

        if (message === null || message.length <= 280) {
            break;
        } else {
            eventsForMessage = eventsForMessage.slice(0, eventsForMessage.length - 1);
        }
    }

    return {
        day: day.toString(),
        link,
        image,
        message,
        events,
        eventsRaw: eventsRaw || [],
    };
};

const generateURIEncodedPathAlternative = (path: string): string[] => {
    return [path, path.replace('@', encodeURIComponent('@'))];
};

interface ProfileRaw {
    events: string;
    customEvents: string;
}

const router = Router();

router.get('/calendar/today', handleErrorAsync(async (req, res) => {
    const locale = getLocale(getH3Event(req));
    const config = await loadConfig(locale);
    return res.json(await eventsSummary(
        config,
        Day.today(),
        req.locales[locale],
    ));
}));

router.get('/calendar/:year-:month-:day', handleErrorAsync(async (req, res) => {
    const locale = getLocale(getH3Event(req));
    const config = await loadConfig(locale);
    return res.json(await eventsSummary(
        config,
        new Day(parseInt(req.params.year), parseInt(req.params.month), parseInt(req.params.day)),
        req.locales[locale],
    ));
}));

router.get(
    generateURIEncodedPathAlternative(`/queer-calendar-:locale-@:username.ics`),
    handleErrorAsync(async (req, res) => {
        const [translator, calendar] =
            await Promise.all([loadTranslator(req.params.locale), loadCalendar(req.params.locale)]);
        const profiles = await req.db.all<Pick<ProfileRaw, 'events' | 'customEvents'>>(SQL`
            SELECT events, customEvents FROM profiles p
            LEFT JOIN users u ON p.userId = u.id
            WHERE u.usernameNorm = ${normalise(req.params.username)}
            AND p.locale = ${req.params.locale}
        `);

        if (!profiles.length) {
            return res.status(404).json({ error: 'Not found' });
        }

        const events = Calendar.generatePersonalCalendarEvents([
            ...JSON.parse(profiles[0].events),
            ...JSON.parse(profiles[0].customEvents),
        ], calendar.getCurrentYear()!);

        const groupedEvents: Record<number, Event[]> = {};
        for (const year of calendar.getAllYears()) {
            groupedEvents[year.year] = events;
        }

        renderEvents(
            groupedEvents,
            translator,
            res,
            req.query.only_first_days !== undefined,
            ` (@${req.params.username})`,
        );
    }),
);

router.get(`/queer-calendar-:locale.ics`, handleErrorAsync(async (req, res) => {
    const [translator, calendar] =
        await Promise.all([loadTranslator(req.params.locale), loadCalendar(req.params.locale)]);
    const events: Record<number, Event[]> = {};
    for (const year of calendar.getAllYears()) {
        events[year.year] = year.events;
    }

    renderEvents(events, translator, res, req.query.only_first_days !== undefined);
}));

router.get(`/queer-calendar-:locale-:year-:uuid.ics`, handleErrorAsync(async (req, res) => {
    const [translator, calendar] =
        await Promise.all([loadTranslator(req.params.locale), loadCalendar(req.params.locale)]);
    const year = calendar.getYear(parseInt(req.params.year));
    if (!year) {
        return res.status(404).json({ error: 'Not found' });
    }

    renderEvents({ [year.year]: [year.eventsByUuid[req.params.uuid]] }, translator, res);
}));

router.get(`/queer-calendar-:locale-:year.ics`, handleErrorAsync(async (req, res) => {
    const [translator, calendar] =
        await Promise.all([loadTranslator(req.params.locale), loadCalendar(req.params.locale)]);
    const year = calendar.getYear(parseInt(req.params.year));
    if (!year) {
        return res.status(404).json({ error: 'Not found' });
    }

    renderEvents({ [year.year]: year.events }, translator, res);
}));

export default router;