import { DateTime, IANAZone } from 'luxon';

const CONTINENT_ICONS: Record<string, string> = {
    Africa: 'globe-africa',
    America: 'globe-americas',
    Antarctica: 'globe',
    Arctic: 'globe',
    Asia: 'globe-asia',
    Atlantic: 'globe-americas',
    Australia: 'globe-asia',
    Europe: 'globe-europe',
    Indian: 'globe-asia',
    Pacific: 'globe-asia',
};

const timezoneOverrides: Record<string, string> = {
    'Europe/Kiev': 'Europe/Kyiv',
};

export interface TimezoneInfo {
    timezone: string;
    area: string;
    location: string;
    displayLocation: string;
    icon: string;
    offset: number;
    offsetFormatted: string;
    short: string;
    long: string;
}

export default () => {
    const detectBrowserTimezone = (): string => {
        return DateTime.local().zone.name;
    };
    const getTimezoneInfo = (timezone: string | null): TimezoneInfo | null => {
        if (!timezone) {
            return null;
        }
        const parts = timezone.split('/');
        const displayParts = timezoneDisplayName(timezone).split('/');
        const area = parts[0];
        const location = parts[parts.length - 1].replace(/_/g, ' ');
        const displayLocation = displayParts[parts.length - 1].replace(/_/g, ' ');
        const tz = new IANAZone(timezone);
        if (!tz.isValid) {
            return null;
        }
        const dt = DateTime.local().setZone(tz);

        return {
            timezone,
            area,
            location,
            displayLocation,
            icon: CONTINENT_ICONS[area],
            offset: dt.offset,
            // @ts-expect-error: DateTime.ts: number not in typings but in code (probably version mismatch)
            offsetFormatted: tz.formatOffset(dt.ts, 'short'),
            short: dt.offsetNameShort,
            long: dt.offsetNameLong,
        };
    };
    const timezoneDisplayName = (timezone: string): string => {
        return (timezoneOverrides[timezone] || timezone).replaceAll('_', ' ');
    };
    return {
        detectBrowserTimezone,
        getTimezoneInfo,
        timezoneDisplayName,
    };
};