smartipc/ts/classes.ipcclient.ts

import * as plugins from './smartipc.plugins.js';
import { IpcChannel } from './classes.ipcchannel.js';
import type { IIpcChannelOptions } from './classes.ipcchannel.js';

/**
 * Options for IPC Client
 */
export interface IConnectRetryConfig {
  /** Enable connection retry */
  enabled: boolean;
  /** Initial delay before first retry in ms */
  initialDelay?: number;
  /** Maximum delay between retries in ms */
  maxDelay?: number;
  /** Maximum number of attempts */
  maxAttempts?: number;
  /** Total timeout for all retry attempts in ms */
  totalTimeout?: number;
}

export interface IClientConnectOptions {
  /** Wait for server to be ready before attempting connection */
  waitForReady?: boolean;
  /** Timeout for waiting for server readiness in ms */
  waitTimeout?: number;
}

export interface IIpcClientOptions extends IIpcChannelOptions {
  /** Client identifier */
  clientId?: string;
  /** Client metadata */
  metadata?: Record<string, any>;
  /** Connection retry configuration */
  connectRetry?: IConnectRetryConfig;
  /** Registration timeout in ms (default: 5000) */
  registerTimeoutMs?: number;
}

/**
 * IPC Client for connecting to an IPC server
 */
export class IpcClient extends plugins.EventEmitter {
  private options: IIpcClientOptions;
  private channel: IpcChannel;
  private messageHandlers = new Map<string, (payload: any) => any | Promise<any>>();
  private isConnected = false;
  private clientId: string;
  private didRegisterOnce = false;

  constructor(options: IIpcClientOptions) {
    super();
    this.options = options;
    this.clientId = options.clientId || plugins.crypto.randomUUID();
    
    // Create the channel
    this.channel = new IpcChannel(this.options);
    this.setupChannelHandlers();
  }

  /**
   * Connect to the server
   */
  public async connect(connectOptions: IClientConnectOptions = {}): Promise<void> {
    if (this.isConnected) {
      return;
    }

    // Helper function to attempt registration
    const attemptRegistration = async (): Promise<void> => {
      await this.attemptRegistrationInternal();
    };

    // Helper function to attempt connection with retry
    const attemptConnection = async (): Promise<void> => {
      const retryConfig = this.options.connectRetry;
      const maxAttempts = retryConfig?.maxAttempts || 1;
      const initialDelay = retryConfig?.initialDelay || 100;
      const maxDelay = retryConfig?.maxDelay || 1500;
      const totalTimeout = retryConfig?.totalTimeout || 15000;
      
      const startTime = Date.now();
      let lastError: Error | undefined;
      let delay = initialDelay;

      for (let attempt = 1; attempt <= maxAttempts; attempt++) {
        // Check total timeout
        if (totalTimeout && Date.now() - startTime > totalTimeout) {
          throw new Error(`Connection timeout after ${totalTimeout}ms: ${lastError?.message || 'Unknown error'}`);
        }

        try {
          // Connect the channel
          await this.channel.connect();
          
          // Attempt registration
          await attemptRegistration();
          return; // Success!
        } catch (error) {
          lastError = error as Error;
          
          // Disconnect channel for retry
          await this.channel.disconnect().catch(() => {});
          
          // If this isn't the last attempt and retry is enabled, wait before retrying
          if (attempt < maxAttempts && retryConfig?.enabled) {
            // Check if we have time for another attempt
            if (totalTimeout && Date.now() - startTime + delay > totalTimeout) {
              break; // Will timeout, don't wait
            }
            
            await new Promise(resolve => setTimeout(resolve, delay));
            // Exponential backoff with max limit
            delay = Math.min(delay * 2, maxDelay);
          }
        }
      }

      // All attempts failed
      throw lastError || new Error('Failed to connect to server');
    };

    // If waitForReady is specified, wait for server socket to exist first
    if (connectOptions.waitForReady) {
      const waitTimeout = connectOptions.waitTimeout || 10000;
      const startTime = Date.now();
      
      while (Date.now() - startTime < waitTimeout) {
        try {
          // Try to connect
          await attemptConnection();
          return; // Success!
        } catch (error) {
          // If it's a connection refused error, server might not be ready yet
          if ((error as any).message?.includes('ECONNREFUSED') || 
              (error as any).message?.includes('ENOENT')) {
            await new Promise(resolve => setTimeout(resolve, 100));
            continue;
          }
          // Other errors should be thrown
          throw error;
        }
      }
      
      throw new Error(`Server not ready after ${waitTimeout}ms`);
    } else {
      // Normal connection attempt
      await attemptConnection();
    }
  }

  /**
   * Attempt to register this client over the current channel connection.
   * Sets connection flags and emits 'connect' on success.
   */
  private async attemptRegistrationInternal(): Promise<void> {
    const registerTimeoutMs = this.options.registerTimeoutMs || 5000;

    try {
      const response = await this.channel.request<any, any>(
        '__register__',
        {
          clientId: this.clientId,
          metadata: this.options.metadata
        },
        {
          timeout: registerTimeoutMs,
          headers: { clientId: this.clientId }
        }
      );

      if (!response.success) {
        throw new Error(response.error || 'Registration failed');
      }

      this.isConnected = true;
      this.didRegisterOnce = true;
      this.emit('connect');
    } catch (error: any) {
      throw new Error(`Failed to register with server: ${error.message}`);
    }
  }

  /**
   * Disconnect from the server
   */
  public async disconnect(): Promise<void> {
    if (!this.isConnected) {
      return;
    }

    this.isConnected = false;
    await this.channel.disconnect();
    this.emit('disconnect');
  }

  /**
   * Setup channel event handlers
   */
  private setupChannelHandlers(): void {
    // Forward channel events
    this.channel.on('connect', async () => {
      // On reconnects, re-register automatically when we had connected before
      if (this.didRegisterOnce && !this.isConnected) {
        try {
          await this.attemptRegistrationInternal();
        } catch (error) {
          this.emit('error', error);
        }
      }
      // For initial connect(), registration is handled explicitly there
    });

    this.channel.on('disconnect', (reason) => {
      this.isConnected = false;
      this.emit('disconnect', reason);
    });

    this.channel.on('error', (error: any) => {
      // If heartbeat timeout and configured not to throw, convert to heartbeatTimeout event
      if (error && error.message === 'Heartbeat timeout' && this.options.heartbeatThrowOnTimeout === false) {
        this.emit('heartbeatTimeout', error);
        return;
      }
      this.emit('error', error);
    });

    this.channel.on('heartbeatTimeout', (error) => {
      // Forward heartbeatTimeout event (when heartbeatThrowOnTimeout is false)
      this.emit('heartbeatTimeout', error);
    });

    this.channel.on('reconnecting', (info) => {
      this.emit('reconnecting', info);
    });

    // Handle messages
    this.channel.on('message', (message) => {
      // Check if we have a handler for this message type
      if (this.messageHandlers.has(message.type)) {
        const handler = this.messageHandlers.get(message.type)!;
        
        // If message expects a response
        if (message.headers?.requiresResponse && message.id) {
          Promise.resolve()
            .then(() => handler(message.payload))
            .then((result) => {
              return this.channel.sendMessage(
                `${message.type}_response`,
                result,
                { correlationId: message.id }
              );
            })
            .catch((error) => {
              return this.channel.sendMessage(
                `${message.type}_response`,
                null,
                { correlationId: message.id, error: error.message }
              );
            });
        } else {
          // Fire and forget
          handler(message.payload);
        }
      } else {
        // Emit unhandled message
        this.emit('message', message);
      }
    });
  }

  /**
   * Register a message handler
   */
  public onMessage(type: string, handler: (payload: any) => any | Promise<any>): void {
    this.messageHandlers.set(type, handler);
  }

  /**
   * Send a message to the server
   */
  public async sendMessage(type: string, payload: any, headers?: Record<string, any>): Promise<void> {
    if (!this.isConnected) {
      throw new Error('Client is not connected');
    }

    // Always include clientId in headers
    await this.channel.sendMessage(type, payload, {
      ...headers,
      clientId: this.clientId
    });
  }

  /**
   * Send a request to the server and wait for response
   */
  public async request<TReq = any, TRes = any>(
    type: string,
    payload: TReq,
    options?: { timeout?: number; headers?: Record<string, any> }
  ): Promise<TRes> {
    if (!this.isConnected) {
      throw new Error('Client is not connected');
    }

    // Always include clientId in headers
    return this.channel.request<TReq, TRes>(type, payload, {
      ...options,
      headers: {
        ...options?.headers,
        clientId: this.clientId
      }
    });
  }

  /**
   * Subscribe to a topic (pub/sub pattern)
   */
  public async subscribe(topic: string, handler: (payload: any) => void): Promise<void> {
    // Register local handler
    this.messageHandlers.set(`topic:${topic}`, handler);

    // Notify server about subscription
    await this.sendMessage('__subscribe__', { topic });
  }

  /**
   * Unsubscribe from a topic
   */
  public async unsubscribe(topic: string): Promise<void> {
    // Remove local handler
    this.messageHandlers.delete(`topic:${topic}`);

    // Notify server about unsubscription
    await this.sendMessage('__unsubscribe__', { topic });
  }

  /**
   * Publish to a topic
   */
  public async publish(topic: string, payload: any): Promise<void> {
    await this.sendMessage('__publish__', { topic, payload });
  }

  /**
   * Get client ID
   */
  public getClientId(): string {
    return this.clientId;
  }

  /**
   * Check if client is connected
   */
  public getIsConnected(): boolean {
    return this.isConnected && this.channel.isConnected();
  }

  /**
   * Get client statistics
   */
  public getStats(): any {
    return this.channel.getStats();
  }
}