import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { SubscribeRequestSchema, UnsubscribeRequestSchema } from '@modelcontextprotocol/sdk/types.js';
import { SubscriptionManager } from './SubscriptionManager.js';
export interface NotificationSender {
(notification: unknown, clientId?: string): Promise<void>;
}
/**
* Handles MCP subscription requests and manages notifications
*/
export class SubscriptionHandlers {
private subscriptionManager: SubscriptionManager;
private notificationSender: NotificationSender;
// For now, we'll use a default client ID since MCP doesn't provide client identification
// This could be enhanced in the future to track multiple clients
private static readonly DEFAULT_CLIENT_ID = 'default-client';
constructor(subscriptionManager: SubscriptionManager, notificationSender: NotificationSender) {
this.subscriptionManager = subscriptionManager;
this.notificationSender = notificationSender;
}
/**
* Register subscription request handlers with the MCP server
*/
registerHandlers(server: Server): void {
// Handle subscription requests
server.setRequestHandler(SubscribeRequestSchema, async (request) => {
const { uri } = request.params || {};
if (!uri) {
throw new Error('URI parameter is required');
}
// Subscribe the client to the resource
this.subscriptionManager.subscribe(SubscriptionHandlers.DEFAULT_CLIENT_ID, uri);
return {};
});
// Handle unsubscription requests
server.setRequestHandler(UnsubscribeRequestSchema, async (request) => {
const { uri } = request.params || {};
if (!uri) {
throw new Error('URI parameter is required');
}
// Unsubscribe the client from the resource
this.subscriptionManager.unsubscribe(SubscriptionHandlers.DEFAULT_CLIENT_ID, uri);
return {};
});
}
/**
* Notify all subscribed clients about a resource update
*/
async notifyResourceUpdate(resourceUri: string): Promise<void> {
const subscribedClients = this.subscriptionManager.getSubscribedClients(resourceUri);
if (subscribedClients.length === 0) {
return;
}
const notification = {
method: 'notifications/resources/updated',
params: {
uri: resourceUri
}
};
// Send notification to all subscribed clients
const notificationPromises = subscribedClients.map(clientId =>
this.notificationSender(notification, clientId)
);
await Promise.all(notificationPromises);
}
/**
* Get the subscription manager instance (for testing/debugging)
*/
getSubscriptionManager(): SubscriptionManager {
return this.subscriptionManager;
}
/**
* Cleanup subscription handlers and unsubscribe all clients
*/
cleanup(): void {
// Unsubscribe all clients from all resources
this.subscriptionManager.unsubscribeAll(SubscriptionHandlers.DEFAULT_CLIENT_ID);
}
}
