# All files / microservices/server server-redis.ts

92.45% Statements 49/53
95.24% Branches 20/21
80.95% Functions 17/21
97.96% Lines 48/49

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     import { Observable } from 'rxjs';
    import {
      CONNECT_EVENT,
      ERROR_EVENT,
      MESSAGE_EVENT,
      NO_PATTERN_MESSAGE,
      REDIS_DEFAULT_URL,
    } from '../constants';
    import {
      ClientOpts,
      RedisClient,
      RetryStrategyOptions,
    } from '../external/redis.interface';
    import { CustomTransportStrategy, PacketId, ReadPacket } from '../interfaces';
    import {
      MicroserviceOptions,
      RedisOptions,
    } from '../interfaces/microservice-configuration.interface';
    import { Server } from './server';

    let redisPackage: any = {};

    export class ServerRedis extends Server implements CustomTransportStrategy {
      private readonly url: string;
      private subClient: RedisClient;
      private pubClient: RedisClient;
      private isExplicitlyTerminated = false;

      constructor(private readonly options: MicroserviceOptions['options']) {
        super();
        this.url =
          this.getOptionsProp<RedisOptions>(this.options, 'url') ||
          REDIS_DEFAULT_URL;

        redisPackage = this.loadPackage('redis', ServerRedis.name);
      }

      public listen(callback: () => void) {
        this.subClient = this.createRedisClient();
        this.pubClient = this.createRedisClient();

        this.handleError(this.pubClient);
        this.handleError(this.subClient);
        this.start(callback);
      }

      public start(callback?: () => void) {
        this.bindEvents(this.subClient, this.pubClient);
        this.subClient.on(CONNECT_EVENT, callback);
      }

      public bindEvents(subClient: RedisClient, pubClient: RedisClient) {
        subClient.on(MESSAGE_EVENT, this.getMessageHandler(pubClient).bind(this));
        const subscribePatterns = Object.keys(this.messageHandlers);
        subscribePatterns.forEach(pattern =>
          subClient.subscribe(this.getAckQueueName(pattern)),
        );
      }

      public close() {
        this.isExplicitlyTerminated = true;
        this.pubClient && this.pubClient.quit();
        this.subClient && this.subClient.quit();
      }

      public createRedisClient(): RedisClient {
        return redisPackage.createClient({
          ...this.getClientOptions(),
          url: this.url,
        });
      }

      public getMessageHandler(pub: RedisClient) {
        return async (channel, buffer) => this.handleMessage(channel, buffer, pub);
      }

      public async handleMessage(channel, buffer: string | any, pub: RedisClient) {
        const packet = this.deserialize(buffer);
        const pattern = channel.replace(/_ack$/, '');
        const publish = this.getPublisher(pub, pattern, packet.id);
        const status = 'error';

        if (!this.messageHandlers[pattern]) {
          return publish({ id: packet.id, status, err: NO_PATTERN_MESSAGE });
        }
        const handler = this.messageHandlers[pattern];
        const response$ = this.transformToObservable(
          await handler(packet.data),
        ) as Observable<any>;
        response$ && this.send(response$, publish);
      }

      public getPublisher(pub: RedisClient, pattern: any, id: string) {
        return response =>
          pub.publish(
            this.getResQueueName(pattern),
            JSON.stringify(Object.assign(response, { id })),
          );
      }

      public deserialize(content): ReadPacket & PacketId {
        try {
          return JSON.parse(content);
        } catch (e) {
          return content;
        }
      }

      public getAckQueueName(pattern: string): string {
        return `${pattern}_ack`;
      }

      public getResQueueName(pattern: string): string {
        return `${pattern}_res`;
      }

      public handleError(stream) {
        stream.on(ERROR_EVENT, err => this.logger.error(err));
      }

      public getClientOptions(): Partial<ClientOpts> {
        const retry_strategy = options => this.createRetryStrategy(options);
        return {
          retry_strategy,
        };
      }

      public createRetryStrategy(
        options: RetryStrategyOptions,
      ): undefined | number | void {
        if (options.error && (options.error as any).code === 'ECONNREFUSED') {
          return this.logger.error(`Error ECONNREFUSED: ${this.url}`);
        }
        if (
          this.isExplicitlyTerminated ||
          !this.getOptionsProp<RedisOptions>(this.options, 'retryAttempts') ||
          options.attempt >
            this.getOptionsProp<RedisOptions>(this.options, 'retryAttempts')
        ) {
          return undefined;
        }
        return this.getOptionsProp<RedisOptions>(this.options, 'retryDelay') || 0;
      }
    }