/**
 * Blockchain Event Consumer Service
 *
 * Consumes wallet address creation events from blockchain-service via Kafka.
 * Updates user wallet addresses when blockchain-service derives addresses from MPC public keys.
 */

import { Injectable, Logger, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { Kafka, Consumer, logLevel, EachMessagePayload } from 'kafkajs';

// Blockchain Event Topics (events from blockchain-service)
export const BLOCKCHAIN_TOPICS = {
  WALLET_ADDRESS_CREATED: 'blockchain.wallets',
} as const;

export interface WalletAddressCreatedPayload {
  userId: string;
  publicKey: string;
  addresses: {
    chainType: string;
    address: string;
  }[];
}

export type BlockchainEventHandler<T> = (payload: T) => Promise<void>;

@Injectable()
export class BlockchainEventConsumerService implements OnModuleInit, OnModuleDestroy {
  private readonly logger = new Logger(BlockchainEventConsumerService.name);
  private kafka: Kafka;
  private consumer: Consumer;
  private isConnected = false;

  private walletAddressCreatedHandler?: BlockchainEventHandler<WalletAddressCreatedPayload>;

  constructor(private readonly configService: ConfigService) {}

  async onModuleInit() {
    const brokers = this.configService.get<string>('KAFKA_BROKERS')?.split(',') || ['localhost:9092'];
    const clientId = this.configService.get<string>('KAFKA_CLIENT_ID') || 'identity-service';
    const groupId = 'identity-service-blockchain-events';

    this.logger.log(`[INIT] Blockchain Event Consumer initializing...`);
    this.logger.log(`[INIT] ClientId: ${clientId}`);
    this.logger.log(`[INIT] GroupId: ${groupId}`);
    this.logger.log(`[INIT] Brokers: ${brokers.join(', ')}`);
    this.logger.log(`[INIT] Topics to subscribe: ${Object.values(BLOCKCHAIN_TOPICS).join(', ')}`);

    this.kafka = new Kafka({
      clientId,
      brokers,
      logLevel: logLevel.WARN,
      retry: {
        initialRetryTime: 100,
        retries: 8,
      },
    });

    this.consumer = this.kafka.consumer({
      groupId,
      sessionTimeout: 30000,
      heartbeatInterval: 3000,
    });

    try {
      this.logger.log(`[CONNECT] Connecting Blockchain Event consumer...`);
      await this.consumer.connect();
      this.isConnected = true;
      this.logger.log(`[CONNECT] Blockchain Event Kafka consumer connected successfully`);

      // Subscribe to blockchain topics
      await this.consumer.subscribe({ topics: Object.values(BLOCKCHAIN_TOPICS), fromBeginning: false });
      this.logger.log(`[SUBSCRIBE] Subscribed to blockchain topics: ${Object.values(BLOCKCHAIN_TOPICS).join(', ')}`);

      // Start consuming
      await this.startConsuming();
    } catch (error) {
      this.logger.error(`[ERROR] Failed to connect Blockchain Event Kafka consumer`, error);
    }
  }

  async onModuleDestroy() {
    if (this.isConnected) {
      await this.consumer.disconnect();
      this.logger.log('Blockchain Event Kafka consumer disconnected');
    }
  }

  /**
   * Register handler for wallet address created events
   */
  onWalletAddressCreated(handler: BlockchainEventHandler<WalletAddressCreatedPayload>): void {
    this.walletAddressCreatedHandler = handler;
    this.logger.log(`[REGISTER] WalletAddressCreated handler registered`);
  }

  private async startConsuming(): Promise<void> {
    await this.consumer.run({
      eachMessage: async ({ topic, partition, message }: EachMessagePayload) => {
        const offset = message.offset;
        this.logger.log(`[RECEIVE] Message received: topic=${topic}, partition=${partition}, offset=${offset}`);

        try {
          const value = message.value?.toString();
          if (!value) {
            this.logger.warn(`[RECEIVE] Empty message received on ${topic}`);
            return;
          }

          this.logger.log(`[RECEIVE] Raw message value: ${value.substring(0, 500)}...`);

          const parsed = JSON.parse(value);
          const payload = parsed.payload || parsed;
          const eventType = parsed.eventType || 'unknown';

          this.logger.log(`[RECEIVE] Parsed event: eventType=${eventType}`);
          this.logger.log(`[RECEIVE] Payload keys: ${Object.keys(payload).join(', ')}`);

          // Handle WalletAddressCreated events
          if (eventType === 'blockchain.wallet.address.created' || topic === BLOCKCHAIN_TOPICS.WALLET_ADDRESS_CREATED) {
            this.logger.log(`[HANDLE] Processing WalletAddressCreated event`);
            this.logger.log(`[HANDLE] userId: ${payload.userId}`);
            this.logger.log(`[HANDLE] publicKey: ${payload.publicKey?.substring(0, 30)}...`);
            this.logger.log(`[HANDLE] addresses count: ${payload.addresses?.length}`);

            if (this.walletAddressCreatedHandler) {
              await this.walletAddressCreatedHandler(payload as WalletAddressCreatedPayload);
              this.logger.log(`[HANDLE] WalletAddressCreated handler completed successfully`);
            } else {
              this.logger.warn(`[HANDLE] No handler registered for WalletAddressCreated`);
            }
          } else {
            this.logger.warn(`[RECEIVE] Unknown event type: ${eventType}`);
          }
        } catch (error) {
          this.logger.error(`[ERROR] Error processing blockchain event from ${topic}`, error);
        }
      },
    });

    this.logger.log(`[START] Started consuming blockchain events`);
  }
}