const app = () => ({
    futureTimes: [],

    locationId: Alpine.$persist('11104'),
    lastUpdated: Alpine.$persist(null),
    userMinutes: 0,
    now: new Date(),
    debug: location.hash === '#debug',
    geolocation: null,

    async init() {
        await this.refreshIfStale();
        setInterval(() => {
            this.now = new Date();
        }, 500);

        getUserLocation()
            .then(loc => {
                this.geolocation = {latitude: loc.latitude, longitude: loc.longitude};
                this.refreshIfStale();
            })
            .catch(() => this.geolocation = null)
    },

    onHash() {
        this.debug = location.hash === '#debug'
    },

    get userNow() {
        if (!this.debug) {
            return this.now;
        }

        const d = new Date();
        d.setHours(0, this.userMinutes, 0, 0);
        return d;
    },

    get userTime() {
        return formatTime(this.userNow);
    },

    async refreshIfStale() {
        const updatedAt = new Date(this.lastUpdated);
        const now = new Date();

        const elapsedSeconds = (now - updatedAt) / 1000;

        if (this.geolocation !== null) {
            this.futureTimes = await fetchJSON(`/api/v1/diyanet/prayertimes?latitude=${this.geolocation.latitude}&longitude=${this.geolocation.longitude}`);
        } else {
            this.futureTimes = await fetchJSON(`/api/v1/diyanet/prayertimes?location_id=${this.locationId}`);
        }
        this.lastUpdated = now.toISOString();
    },

    get todayTimes() {
        if (this.futureTimes.length === 0) {
            return null;
        }
        return new PrayerTimes(this.futureTimes[0], () => this.userNow);
    },

    translate(key, lang) {
        return translations[key][lang] ?? key
    }
});

class PrayerTimes {
    static salaths = ['fajr', 'sunrise', 'dhuhr', 'asr', 'maghrib', 'isha'];
    static translations = {
        fajr: {tr: 'İmsak', de: 'Frühgebet', ar: 'صلاة الفجر'},
        sunrise: {tr: 'Güneş', de: 'Sonnenaufgang', ar: 'الشروق'},
        dhuhr: {tr: 'Öğle', de: 'Mittagsgebet', ar: 'صلاة الظهر'},
        asr: {tr: 'İkindi', de: 'Nachmittagsgebet', ar: 'صلاة العصر'},
        maghrib: {tr: 'Akşam', de: 'Abendgebet', ar: 'صلاة المغرب'},
        isha: {tr: 'Yatsı', de: 'Nachtgebet', ar: 'صلاة العشاء'},
    }

    constructor({date, ...rest}, clock = () => new Date()) {
        this.date = date;
        this.clock = clock
        this.salathTimes = rest
    }

    get times() {
        const now = this.clock()
        return PrayerTimes.salaths.map(k => {
            // "2023-03-05T00:00:00Z"
            const startsAt = new Date(this.date.replace('T00:00', `T${this.salathTimes[k]}`).replace(/Z$/, ''));

            return {
                salath: k,
                name: lang => PrayerTimes.translations[k][lang] ?? '??',
                startsAt,
                timeLocal: this.salathTimes[k],
                get untilSeconds() {
                    let untilSeconds = (startsAt - now) / 1000;
                    return now > startsAt ? 0 : untilSeconds;
                },
                get untilHuman() {
                    return formatDuration(this.untilSeconds)
                },
            }
        })
    }

    get currentSalath() {
        let current = this.times.filter(it => it.untilSeconds === 0).at(-1);
        if (current === undefined) {
            // we're in isha -> today's fajr is almost the same as tomorrows
            const prevDay = new Date(this.date);
            prevDay.setDate(prevDay.getDate() - 1);

            current = new PrayerTimes({date: prevDay.toISOString(), ...this.salathTimes}, this.clock).times.at(-1);
        }
        return current
    }

    get nextSalath() {
        let next = this.times
            .filter(it => it.untilSeconds > 0)[0]
        if (next === undefined) {
            // we're in isha -> today's fajr is almost the same as tomorrows
            const nextDay = new Date(this.date);
            nextDay.setDate(nextDay.getDate() + 1);

            next = new PrayerTimes({date: nextDay.toISOString(), ...this.salathTimes}, this.clock).times[0];
        }

        return {
            ...next,
        }
    }
}

/**
 * @param {number} seconds
 * @return {string}
 * */
function formatDuration(seconds) {
    const d = new Date(0, 0, 0, 0, 0, seconds);
    return formatTime(d);
}

/**
 * @param {Date} then
 * @return {string}
 * */
function formatTime(then) {
    return new Intl.DateTimeFormat(navigator.language, {
        hour: "numeric",
        minute: "numeric",
        second: "numeric"
    }).format(then);
}

/**
 * @param {Date} then
 * @return {string}
 * */
function formatDate(then) {
    return new Intl.DateTimeFormat(navigator.language, {
        year: "numeric",
        month: "2-digit",
        day: "2-digit"
    }).format(then);
}

/**
 * @param {Date} then
 * @return {string}
 * */
function formatDateHijri(then) {
    return new Intl.DateTimeFormat("en-u-ca-islamic-umalqura-nu-latn", {
        year: "numeric",
        month: "long",
        day: "numeric",
    }).format(then);
}

/**
 * @param {string} url
 * @param {RequestInit} req
 * */
async function fetchJSON(url, req = {}) {
    const res = await fetch(url, {
        ...req,
    })
    return res.json()
}

/**
 * @return {Promise<GeolocationCoordinates>}
 * */
function getUserLocation() {
    return new Promise((resolve, reject) => {
        if (!navigator.geolocation) {
            reject("Geolocation is not supported by this browser.");
            return;
        }

        navigator.geolocation.getCurrentPosition(
            (position) => resolve(position.coords),
            (error) => reject(error.message)
        );
    });
}