import {
  ForbiddenException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { Notification, NotificationPriority } from '../../generated/prisma';

export interface CreateNotificationInput {
  userId?: string;
  priority: NotificationPriority;
  message: string;
  relatedType?: string;
  relatedId?: string;
}

export interface NotificationFilter {
  userId?: string;
  unreadOnly?: boolean;
}

@Injectable()
export class NotificationsService {
  constructor(private readonly prisma: PrismaService) {}

  async record(input: CreateNotificationInput): Promise<Notification> {
    return this.prisma.notification.create({ data: { ...input } });
  }

  async findAll(filter: NotificationFilter = {}): Promise<Notification[]> {
    return this.prisma.notification.findMany({
      where: {
        OR: filter.userId
          ? [{ userId: filter.userId }, { userId: null }]
          : undefined,
        read: filter.unreadOnly ? false : undefined,
      },
      orderBy: { createdAt: 'desc' },
      take: 100,
    });
  }

  async markRead(id: string, actingUserId: string): Promise<Notification> {
    const notification = await this.prisma.notification.findUnique({
      where: { id },
    });
    if (!notification) {
      throw new NotFoundException('Notification not found');
    }
    if (notification.userId !== null && notification.userId !== actingUserId) {
      throw new ForbiddenException("Cannot modify another user's notification");
    }
    return this.prisma.notification.update({
      where: { id },
      data: { read: true },
    });
  }
}