import { computed, effect, inject, Injectable, signal } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { injectQuery, QueryClient } from '@tanstack/angular-query-experimental';
import { lastValueFrom } from 'rxjs';
import { HttpResponse } from '../models/response.interface';
import { injectAuthService } from './auth.service';
import { injectWebsocketService, WSEvents } from './websocket.service';

const LAST_READ_KEY = 'notifications_last_read';

export interface NotificationItem {
	unixtime: number;
	title: string;
	body: string;
}

@Injectable({
	providedIn: 'root',
})
export class NotificationsService {
	private http = inject(HttpClient);
	private queryClient = inject(QueryClient);
	private authServ = injectAuthService();
	private websocketServ = injectWebsocketService();

	public lastReadUnixtime = signal<number>(
		parseInt(localStorage.getItem(LAST_READ_KEY) || '0', 10)
	);

	private persistEffect = effect(() => {
		localStorage.setItem(LAST_READ_KEY, this.lastReadUnixtime().toString());
	});

	notifications = injectQuery(() => ({
		queryKey: ['notifications'],
		queryFn: async () => {
			const response = await lastValueFrom(
				this.http.get<HttpResponse<NotificationItem[]>>('web_push/notifications')
			);
			return response.data;
		},
		staleTime: 5 * 60 * 1000,
		refetchOnWindowFocus: true,
		enabled: !!this.authServ.loginStatus.data(),
	}));

	unreadCount = computed(() => {
		const data = this.notifications.data();
		const lastRead = this.lastReadUnixtime();
		if (!data) return 0;
		return data.filter((notification) => notification.unixtime > lastRead).length;
	});

	hasUnread = computed(() => this.unreadCount() > 0);

	constructor() {
		this.websocketServ.listen(WSEvents.NOTIFICATIONS, ['notifications']).subscribe();
	}

	markAllAsRead(): void {
		const data = this.notifications.data();
		if (data && data.length > 0) {
			const maxUnixtime = Math.max(...data.map((notification) => notification.unixtime));
			this.lastReadUnixtime.set(maxUnixtime);
		}
	}

	refreshNotifications(): void {
		this.queryClient.invalidateQueries({ queryKey: ['notifications'] });
	}
}

export const injectNotificationsService = () => inject(NotificationsService);