feat: add webchat pwa push subscription support

src/gateway/server.ts

@@ -131,6 +131,23 @@ export interface GatewayServerConfig {
   feishuHandler?: Pick<FeishuAdapter, 'handleRequest'>;
   /** Optional Zalo adapter for inbound webhook events. */
   zaloHandler?: Pick<ZaloAdapter, 'handleRequest'>;
+  /** Optional WebChat PWA push-subscription settings. */
+  webchatPush?: {
+    enabled?: boolean;
+    vapidPublicKey?: string;
+    maxSubscriptions?: number;
+  };
+}
+
+interface WebchatPushSubscriptionRecord {
+  endpoint: string;
+  keys: {
+    p256dh: string;
+    auth: string;
+  };
+  userAgent?: string;
+  createdAt: number;
+  updatedAt: number;
 }
 
 export class GatewayServer {
@@ -158,6 +175,7 @@ export class GatewayServer {
     windowStartMs: number;
   }> = new Map();
   private connectionStateMap: Map<string, NodeConnectionState> = new Map();
+  private webchatPushSubscriptions: Map<string, WebchatPushSubscriptionRecord> = new Map();
   private config: GatewayServerConfig;
   private startTime: number = Date.now();
 
@@ -670,6 +688,160 @@ export class GatewayServer {
     };
   }
 
+  private getWebchatPushConfig(): { enabled: boolean; vapidPublicKey?: string; maxSubscriptions: number } {
+    const runtimeConfig = this.config.config?.server.webchat_push;
+    const override = this.config.webchatPush;
+    const enabled = override?.enabled ?? runtimeConfig?.enabled ?? false;
+    const vapidPublicKey = override?.vapidPublicKey ?? runtimeConfig?.vapid_public_key;
+    const maxSubscriptions = override?.maxSubscriptions ?? runtimeConfig?.max_subscriptions ?? 5000;
+    return { enabled, vapidPublicKey, maxSubscriptions };
+  }
+
+  private async handleWebchatPushRequest(req: IncomingMessage, res: ServerResponse): Promise<boolean> {
+    if (!req.url?.startsWith('/webchat/push')) {
+      return false;
+    }
+
+    const parsed = new URL(req.url, `http://${req.headers.host ?? 'localhost'}`);
+    const pathname = parsed.pathname;
+    const cfg = this.getWebchatPushConfig();
+
+    if (pathname === '/webchat/push/public-key' && req.method === 'GET') {
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({
+        enabled: cfg.enabled,
+        vapidPublicKey: cfg.vapidPublicKey ?? null,
+      }));
+      return true;
+    }
+
+    if (pathname === '/webchat/push/subscriptions' && req.method === 'GET') {
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({
+        enabled: cfg.enabled,
+        count: this.webchatPushSubscriptions.size,
+        maxSubscriptions: cfg.maxSubscriptions,
+      }));
+      return true;
+    }
+
+    if (pathname === '/webchat/push/subscriptions' && req.method === 'POST') {
+      if (!cfg.enabled) {
+        res.writeHead(409, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'WebChat push is disabled' }));
+        return true;
+      }
+
+      let rawBody: string;
+      try {
+        rawBody = await this.readRequestBody(req);
+      } catch (err) {
+        if (err instanceof RequestBodyTooLargeError) {
+          res.writeHead(413, { 'Content-Type': 'application/json' });
+          res.end(JSON.stringify({ error: 'Payload too large' }));
+          return true;
+        }
+        res.writeHead(400, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Invalid request body' }));
+        return true;
+      }
+
+      let parsedBody: unknown;
+      try {
+        parsedBody = JSON.parse(rawBody);
+      } catch {
+        res.writeHead(400, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Invalid JSON' }));
+        return true;
+      }
+
+      const body = parsedBody as {
+        endpoint?: unknown;
+        keys?: { p256dh?: unknown; auth?: unknown };
+        userAgent?: unknown;
+      };
+      const endpoint = typeof body.endpoint === 'string' ? body.endpoint.trim() : '';
+      const p256dh = typeof body.keys?.p256dh === 'string' ? body.keys.p256dh.trim() : '';
+      const auth = typeof body.keys?.auth === 'string' ? body.keys.auth.trim() : '';
+      const userAgent = typeof body.userAgent === 'string' ? body.userAgent.trim() : undefined;
+
+      if (!endpoint || !p256dh || !auth) {
+        res.writeHead(400, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Missing subscription endpoint or keys' }));
+        return true;
+      }
+
+      if (!this.webchatPushSubscriptions.has(endpoint) && this.webchatPushSubscriptions.size >= cfg.maxSubscriptions) {
+        res.writeHead(429, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: `Subscription cap reached (${cfg.maxSubscriptions})` }));
+        return true;
+      }
+
+      const now = Date.now();
+      const previous = this.webchatPushSubscriptions.get(endpoint);
+      this.webchatPushSubscriptions.set(endpoint, {
+        endpoint,
+        keys: { p256dh, auth },
+        userAgent,
+        createdAt: previous?.createdAt ?? now,
+        updatedAt: now,
+      });
+
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({
+        stored: true,
+        count: this.webchatPushSubscriptions.size,
+      }));
+      return true;
+    }
+
+    if (pathname === '/webchat/push/subscriptions' && req.method === 'DELETE') {
+      let rawBody = '';
+      try {
+        rawBody = await this.readRequestBody(req);
+      } catch (err) {
+        if (err instanceof RequestBodyTooLargeError) {
+          res.writeHead(413, { 'Content-Type': 'application/json' });
+          res.end(JSON.stringify({ error: 'Payload too large' }));
+          return true;
+        }
+        res.writeHead(400, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Invalid request body' }));
+        return true;
+      }
+
+      let endpoint = '';
+      if (rawBody.trim().length > 0) {
+        try {
+          const body = JSON.parse(rawBody) as { endpoint?: unknown };
+          endpoint = typeof body.endpoint === 'string' ? body.endpoint.trim() : '';
+        } catch {
+          res.writeHead(400, { 'Content-Type': 'application/json' });
+          res.end(JSON.stringify({ error: 'Invalid JSON' }));
+          return true;
+        }
+      } else {
+        endpoint = parsed.searchParams.get('endpoint')?.trim() ?? '';
+      }
+
+      if (!endpoint) {
+        res.writeHead(400, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Missing subscription endpoint' }));
+        return true;
+      }
+
+      const removed = this.webchatPushSubscriptions.delete(endpoint);
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({
+        removed,
+        count: this.webchatPushSubscriptions.size,
+      }));
+      return true;
+    }
+
+    return false;
+  }
+
   /**
    * Handle incoming HTTP requests.
    * Optionally applies auth (when authHttp is enabled and a token is configured).
@@ -777,6 +949,11 @@ export class GatewayServer {
       }
     }
 
+    // WebChat PWA push-subscription endpoints (auth-protected)
+    if (await this.handleWebchatPushRequest(req, res)) {
+      return;
+    }
+
     const uiDir = this.config.uiDir;
 
     if (uiDir) {