type MessageHandler = (message: any) => void;

class MessageBus {
  private subscribers: Map<string, MessageHandler[]> = new Map();

  // Subscribe to a specific message type
  subscribe(messageType: string, handler: MessageHandler): void {
    if (!this.subscribers.has(messageType)) {
      this.subscribers.set(messageType, []);
    }
    this.subscribers.get(messageType)!.push(handler);
  }

  // Unsubscribe a specific handler from a message type
  unsubscribe(messageType: string, handler: MessageHandler): void {
    const handlers = this.subscribers.get(messageType);
    if (handlers) {
      this.subscribers.set(
        messageType,
        handlers.filter((h) => h !== handler)
      );
    }
  }

  // Publish a message of a specific type
  publish(messageType: string, message: any): void {
    const handlers = this.subscribers.get(messageType);
    if (handlers) {
      handlers.forEach((handler) => handler(message));
    }
  }
}

// Usage example

const messageBus = new MessageBus();

// Subscriber 1
messageBus.subscribe("orderPlaced", (message) => {
  console.log("Inventory Service: Order received:", message);
});

// Subscriber 2
messageBus.subscribe("orderPlaced", (message) => {
  console.log("Notification Service: Sending confirmation for:", message);
});

// Publish an event
messageBus.publish("orderPlaced", { orderId: 123, product: "Laptop", quantity: 1 });

// Another example: Unsubscribe a handler
const shippingHandler = (message: any) => {
  console.log("Shipping Service: Preparing package for:", message);
};

messageBus.subscribe("orderPlaced", shippingHandler);
messageBus.publish("orderPlaced", { orderId: 124, product: "Phone", quantity: 2 });

// Unsubscribe the shipping handler
messageBus.unsubscribe("orderPlaced", shippingHandler);

// Test after unsubscribing
messageBus.publish("orderPlaced", { orderId: 125, product: "Tablet", quantity: 3 });