import dayjs from 'dayjs';
import duration from 'dayjs/plugin/duration';
import relativeTime from 'dayjs/plugin/relativeTime';
import isToday from 'dayjs/plugin/isToday';
import isYesterday from 'dayjs/plugin/isYesterday';
import utc from 'dayjs/plugin/utc';
import timezone from 'dayjs/plugin/timezone';
import weekOfYear from 'dayjs/plugin/weekOfYear';
import { getUserTimezone, getWeekStart } from '@/utils/useUser';
import updateLocale from 'dayjs/plugin/updateLocale';
import { computed } from 'vue';

dayjs.extend(relativeTime);
dayjs.extend(isToday);
dayjs.extend(isYesterday);
dayjs.extend(duration);
dayjs.extend(utc);
dayjs.extend(timezone);
dayjs.extend(updateLocale);
dayjs.extend(weekOfYear);

export function getDayJsInstance() {
    dayjs.updateLocale('en', {
        weekStart: firstDayIndex.value,
    });
    return dayjs;
}

export const firstDayIndex = computed(() => {
    const apiDayOrder = [
        'sunday',
        'monday',
        'tuesday',
        'wednesday',
        'thursday',
        'friday',
        'saturday',
    ];
    return apiDayOrder.indexOf(getWeekStart());
});

export function formatHumanReadableDuration(duration: number): string {
    const dayJsDuration = dayjs.duration(duration, 's');
    const hours = dayJsDuration.hours() + dayJsDuration.days() * 24;
    const minutes = dayJsDuration.minutes();
    return `${hours}h ${minutes.toString().padStart(2, '0')}min`;
}

export function calculateDifference(start: string, end: string | null) {
    if (end === null) {
        end = dayjs().utc().format();
    }
    return dayjs(end).diff(dayjs(start), 'second');
}

/**
 * Returns a formatted time.
 * @param date - A UTC date time string.
 */
export function formatTime(date: string) {
    return dayjs.utc(date).tz(getUserTimezone()).format('HH:mm');
}

export function getLocalizedDayJs(timestamp: string | null) {
    return dayjs.utc(timestamp).tz(getUserTimezone());
}

export function getLocalizedDateFromTimestamp(timestamp: string) {
    return getLocalizedDayJs(timestamp).format('YYYY-MM-DD');
}

/*
 * Returns a formatted date.
 * @param date - date in the format of 'YYYY-MM-DD'
 */
export function formatDate(date: string): string {
    return dayjs(date).format('DD.MM.YYYY');
}

export function formatWeek(date: string | null): string {
    return 'Week ' + dayjs(date).week();
}

/*
 * Returns a human readable date format.
 * @param date - date in the format of 'YYYY-MM-DD'
 */
export function formatHumanReadableDate(date: string) {
    if (dayjs(date).isToday()) {
        return 'Today';
    } else if (dayjs(date).isYesterday()) {
        return 'Yesterday';
    }
    return dayjs(date).fromNow();
}

export function formatStartEnd(start: string, end: string | null) {
    if (end) {
        return `${formatTime(start)} - ${formatTime(end)}`;
    } else {
        return `${formatTime(start)} - ...`;
    }
}