import { useStore } from '@nanostores/preact';
import { useEffect, useMemo, useState } from 'preact/hooks';
import {
    $isRealtimeConnected,
    $notifications,
    $unreadNotifications,
    connectNotifications,
    fetchNotifications,
    markAllNotificationsAsRead,
    markNotificationAsRead,
} from '../stores/notificationStore';
import { $accessToken, $user } from '../stores/authStore';
import NotificationDetailModal from './notifications/NotificationDetailModal';

function formatTimestamp(value) {
    if (!value) return '';
    const date = new Date(value);
    if (Number.isNaN(date.getTime())) return '';
    return new Intl.DateTimeFormat('hr-HR', {
        day: '2-digit',
        month: '2-digit',
        hour: '2-digit',
        minute: '2-digit',
    }).format(date);
}

export default function NotificationBell() {
    const [mounted, setMounted] = useState(false);
    const [open, setOpen] = useState(false);
    const [selectedNotification, setSelectedNotification] = useState(null);
    const notifications = useStore($notifications);
    const unread = useStore($unreadNotifications);
    const isConnected = useStore($isRealtimeConnected);
    const token = useStore($accessToken);
    const user = useStore($user);

    useEffect(() => {
        setMounted(true);
    }, []);

    const latestNotifications = useMemo(
        () => notifications.slice(0, 6),
        [notifications]
    );

    useEffect(() => {
        if (!token || !user?.id) return;
        fetchNotifications();
        connectNotifications();
    }, [token, user?.id]);

    // Stabilan placeholder za SSR + prvi client render.
    if (!mounted || !token) {
        return <div className="h-10 w-10" aria-hidden="true" />;
    }

    return (
        <div className="relative">
            <button
                type="button"
                onClick={() => setOpen((current) => !current)}
                className="relative inline-flex h-10 w-10 items-center justify-center rounded-lg border border-border-hairline bg-canvas-base text-text-muted hover:bg-canvas-deep"
                aria-label="Notifikacije"
            >
                <span className="text-lg">🔔</span>
                {unread > 0 && (
                    <span className="absolute -right-1 -top-1 inline-flex min-h-5 min-w-5 items-center justify-center rounded-full bg-red-600 px-1 text-xs font-bold text-white">
                        {unread > 99 ? '99+' : unread}
                    </span>
                )}
            </button>

            {open && (
                <div className="absolute right-0 z-30 mt-2 w-96 overflow-hidden rounded-xl border border-border-hairline bg-canvas-elevated shadow-lg">
                    <div className="flex items-center justify-between border-b border-border-hairline px-4 py-3">
                        <div>
                            <p className="font-semibold text-text-main">Notifikacije</p>
                            <p className="text-xs text-text-muted">
                                Realtime: {isConnected ? 'spojen' : 'nije spojen'}
                            </p>
                        </div>
                        <button
                            type="button"
                            onClick={() => markAllNotificationsAsRead()}
                            className="text-xs font-medium text-indigo-600 hover:text-indigo-800"
                        >
                            Označi sve
                        </button>
                    </div>

                    <ul className="max-h-96 overflow-y-auto">
                        {latestNotifications.length === 0 && (
                            <li className="px-4 py-6 text-sm text-text-muted">Nema notifikacija.</li>
                        )}
                        {latestNotifications.map((notification) => (
                            <li
                                key={notification.id}
                                className={`cursor-pointer border-b border-border-hairline px-4 py-3 last:border-b-0 ${
                                    notification.is_read ? 'bg-canvas-elevated' : 'bg-indigo-50/30'
                                }`}
                                onClick={async () => {
                                    if (!notification.is_read) {
                                        try {
                                            await markNotificationAsRead(notification.id);
                                        } catch {
                                            // Error handling already done in store toast.
                                        }
                                    }
                                    setSelectedNotification(notification);
                                    setOpen(false);
                                }}
                            >
                                <div className="flex items-start justify-between gap-2">
                                    <p className="text-sm font-semibold text-text-main">
                                        {notification.title}
                                    </p>
                                    <span className="shrink-0 text-[11px] text-text-muted">
                                        {formatTimestamp(notification.created_at)}
                                    </span>
                                </div>
                                <p className="mt-1 text-sm text-text-muted">{notification.message}</p>
                            </li>
                        ))}
                    </ul>
                </div>
            )}

            <NotificationDetailModal
                open={!!selectedNotification}
                notification={selectedNotification}
                onClose={() => setSelectedNotification(null)}
            />
        </div>
    );
}