import i18n, { t } from 'i18next';

const dateTimeFullFormatter1 = new Intl.DateTimeFormat(i18n.language, {
    weekday: 'short',
    month: 'short',
    day: 'numeric',
});

const dateTimeFullFormatter2 = new Intl.DateTimeFormat(i18n.language, {
    year: 'numeric',
});
const dateTimeShortFormatter = new Intl.DateTimeFormat(i18n.language, {
    month: 'short',
    day: 'numeric',
    year: 'numeric',
    hour: '2-digit',
    minute: '2-digit',
});

const timeFormatter = new Intl.DateTimeFormat(i18n.language, {
    timeStyle: 'short',
});

export function formatDateFull(date: number | Date) {
    return [dateTimeFullFormatter1, dateTimeFullFormatter2]
        .map((f) => f.format(date))
        .join(' ');
}

export function formatDate(date: number | Date) {
    const withinYear =
        new Date().getFullYear() === new Date(date).getFullYear();
    const dateTimeFormat2 = !withinYear ? dateTimeFullFormatter2 : null;
    return [dateTimeFullFormatter1, dateTimeFormat2]
        .filter((f) => !!f)
        .map((f) => f.format(date))
        .join(' ');
}

export function formatDateTimeShort(date: number | Date) {
    return dateTimeShortFormatter.format(date);
}

export function formatTime(date: number | Date) {
    return timeFormatter.format(date).toUpperCase();
}

export function formatDateTimeFull(dateTime: number | Date): string {
    return [formatDateFull(dateTime), t('at'), formatTime(dateTime)].join(' ');
}

export function formatDateTime(dateTime: number | Date): string {
    return [formatDate(dateTime), t('at'), formatTime(dateTime)].join(' ');
}

export function formatDateRelative(date: number) {
    const units = {
        year: 24 * 60 * 60 * 1000 * 365,
        month: (24 * 60 * 60 * 1000 * 365) / 12,
        day: 24 * 60 * 60 * 1000,
        hour: 60 * 60 * 1000,
        minute: 60 * 1000,
        second: 1000,
    };
    const relativeDateFormat = new Intl.RelativeTimeFormat(i18n.language, {
        localeMatcher: 'best fit',
        numeric: 'always',
        style: 'long',
    });
    const elapsed = date - Date.now(); // "Math.abs" accounts for both "past" & "future" scenarios

    for (const u in units)
        if (Math.abs(elapsed) > units[u] || u === 'second')
            return relativeDateFormat.format(
                Math.round(elapsed / units[u]),
                u as Intl.RelativeTimeFormatUnit
            );
}