import { Injectable, Logger } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { ConfigService } from '@nestjs/config';
import * as admin from 'firebase-admin';
import {
  Notification,
  NotificationType,
} from './entities/notification.entity';
import { UsersService } from '../users/users.service';

@Injectable()
export class NotificationsService {
  private readonly logger = new Logger(NotificationsService.name);
  private firebaseApp: admin.app.App | null = null;

  constructor(
    @InjectRepository(Notification)
    private readonly notificationsRepository: Repository<Notification>,
    private readonly usersService: UsersService,
    private readonly configService: ConfigService,
  ) {
    this.initializeFirebase();
  }

  private initializeFirebase() {
    const projectId = this.configService.get('FIREBASE_PROJECT_ID');
    const clientEmail = this.configService.get('FIREBASE_CLIENT_EMAIL');
    const privateKey = this.configService.get('FIREBASE_PRIVATE_KEY');

    if (projectId && clientEmail && privateKey && !privateKey.includes('YOUR_KEY')) {
      try {
        this.firebaseApp = admin.initializeApp({
          credential: admin.credential.cert({
            projectId,
            clientEmail,
            privateKey: privateKey.replace(/\\n/g, '\n'),
          }),
        });
        this.logger.log('Firebase initialized successfully');
      } catch (error) {
        this.logger.error('Failed to initialize Firebase:', error.message);
      }
    } else {
      this.logger.warn('Firebase not configured - push notifications disabled');
    }
  }

  async sendPush(
    userId: string,
    type: NotificationType,
    title: string,
    body: string,
    data?: Record<string, unknown>,
  ): Promise<Notification> {
    // Create notification record
    const notification = this.notificationsRepository.create({
      userId,
      type,
      title,
      body,
      data,
    });

    await this.notificationsRepository.save(notification);

    // Try to send push notification
    const user = await this.usersService.findById(userId);
    if (user?.fcmToken && this.firebaseApp) {
      try {
        await admin.messaging().send({
          token: user.fcmToken,
          notification: { title, body },
          data: data ? this.stringifyData(data) : undefined,
          android: {
            priority: 'high',
            notification: {
              channelId: 'miinventario_default',
            },
          },
          apns: {
            payload: {
              aps: {
                sound: 'default',
                badge: 1,
              },
            },
          },
        });

        notification.isPushSent = true;
        await this.notificationsRepository.save(notification);
        this.logger.log(`Push sent to user ${userId}: ${title}`);
      } catch (error) {
        this.logger.error(`Failed to send push to ${userId}:`, error.message);

        // If token is invalid, clear it
        if (error.code === 'messaging/invalid-registration-token' ||
            error.code === 'messaging/registration-token-not-registered') {
          await this.usersService.updateFcmToken(userId, null);
        }
      }
    } else if (!this.firebaseApp) {
      this.logger.warn(`Push simulation for ${userId}: ${title}`);
    }

    return notification;
  }

  async notifyVideoProcessingComplete(
    userId: string,
    videoId: string,
    itemsDetected: number,
  ) {
    return this.sendPush(
      userId,
      NotificationType.VIDEO_PROCESSING_COMPLETE,
      'Video procesado',
      `Se detectaron ${itemsDetected} productos en tu anaquel`,
      { videoId, itemsDetected },
    );
  }

  async notifyVideoProcessingFailed(
    userId: string,
    videoId: string,
    errorMessage: string,
  ) {
    return this.sendPush(
      userId,
      NotificationType.VIDEO_PROCESSING_FAILED,
      'Error al procesar video',
      'Hubo un problema al procesar tu video. Intenta de nuevo.',
      { videoId, error: errorMessage },
    );
  }

  async notifyLowCredits(userId: string, currentBalance: number) {
    return this.sendPush(
      userId,
      NotificationType.LOW_CREDITS,
      'Creditos bajos',
      `Te quedan ${currentBalance} creditos. Recarga para seguir escaneando.`,
      { balance: currentBalance },
    );
  }

  async notifyPaymentComplete(
    userId: string,
    paymentId: string,
    creditsGranted: number,
  ) {
    return this.sendPush(
      userId,
      NotificationType.PAYMENT_COMPLETE,
      'Pago completado',
      `Se agregaron ${creditsGranted} creditos a tu cuenta`,
      { paymentId, creditsGranted },
    );
  }

  async notifyPaymentFailed(userId: string, paymentId: string) {
    return this.sendPush(
      userId,
      NotificationType.PAYMENT_FAILED,
      'Pago fallido',
      'Tu pago no pudo ser procesado. Intenta con otro metodo.',
      { paymentId },
    );
  }

  async notifyReferralBonus(
    userId: string,
    bonusCredits: number,
    referredName: string,
  ) {
    return this.sendPush(
      userId,
      NotificationType.REFERRAL_BONUS,
      'Bonus de referido',
      `${referredName} uso tu codigo. Ganaste ${bonusCredits} creditos.`,
      { bonusCredits, referredName },
    );
  }

  async getUserNotifications(
    userId: string,
    page = 1,
    limit = 20,
  ): Promise<{ notifications: Notification[]; total: number }> {
    const [notifications, total] = await this.notificationsRepository.findAndCount({
      where: { userId },
      order: { createdAt: 'DESC' },
      skip: (page - 1) * limit,
      take: limit,
    });

    return { notifications, total };
  }

  async markAsRead(userId: string, notificationId: string): Promise<void> {
    await this.notificationsRepository.update(
      { id: notificationId, userId },
      { isRead: true },
    );
  }

  async markAllAsRead(userId: string): Promise<void> {
    await this.notificationsRepository.update(
      { userId, isRead: false },
      { isRead: true },
    );
  }

  async getUnreadCount(userId: string): Promise<number> {
    return this.notificationsRepository.count({
      where: { userId, isRead: false },
    });
  }

  private stringifyData(data: Record<string, unknown>): Record<string, string> {
    const result: Record<string, string> = {};
    for (const [key, value] of Object.entries(data)) {
      result[key] = typeof value === 'string' ? value : JSON.stringify(value);
    }
    return result;
  }
}