feat: implement asynchronous webhook service with retries and add environment configuration

.env.example

@@ -0,0 +1,23 @@
+# Server
+PORT=8080
+
+# Database
+DATABASE_URL=postgres://postgres:postgres@localhost:5432/ai_pharmacy
+
+# JWT Authentication
+JWT_SECRET=your_jwt_secret_here
+
+# OpenAI
+OPENAI_API_KEY=your_openai_api_key_here
+
+# AWS S3
+S3_KEY=your_s3_access_key_here
+S3_SECRET=your_s3_secret_key_here
+S3_BUCKET=your_bucket_name
+S3_REGION=us-east-1
+S3_BASE_PATH=
+S3_PUBLIC_BASE_PATH=
+
+# Webhooks
+WEBHOOK_SECRET=your_webhook_secret_here
+WEBHOOK_URL=http://localhost:8081/webhooks/pharmacy

src/modules/webhooks/service.ts

@@ -1,15 +1,29 @@
 import crypto from 'crypto';
 
 const WEBHOOK_SECRET = process.env.WEBHOOK_SECRET || 'test_secret_for_webhooks';
-// For demo purposes, we log it or hit a dummy URL.
-const WEBHOOK_URL = process.env.WEBHOOK_URL || 'http://localhost:8081/webhooks/pharmacy'; 
+const WEBHOOK_URL = process.env.WEBHOOK_URL || 'http://localhost:8081/webhooks/pharmacy';
+const MAX_RETRIES = 3;
 
 export class WebhookService {
-  async dispatchEvent(event: string, idempotencyKey: string, payload: any) {
+  /**
+   * Fire-and-forget: dispatches the webhook in the background.
+   * Dispensing will NEVER fail because of a webhook issue.
+   */
+  dispatchEvent(event: string, idempotencyKey: string, payload: any) {
+    // Run in background — no await, no blocking
+    this._sendWithRetry(event, idempotencyKey, payload).catch((err) => {
+      console.error(`[WEBHOOK] All retries failed for ${event}: ${err.message}`);
+    });
+  }
+
+  /**
+   * Internal: send webhook with exponential backoff retry.
+   */
+  private async _sendWithRetry(event: string, idempotencyKey: string, payload: any) {
     const timestamp = Math.floor(Date.now() / 1000);
     const bodyString = JSON.stringify(payload);
     const dataToSign = `${timestamp}.${bodyString}`;
-    
+
     const signature = crypto
       .createHmac('sha256', WEBHOOK_SECRET)
       .update(dataToSign)
@@ -17,31 +31,41 @@ export class WebhookService {
 
     const signatureHeader = `t=${timestamp},v1=${signature}`;
 
-    console.log(`[WEBHOOK] Dispatching event: ${event} (Idempotency: ${idempotencyKey})`);
-    
-    try {
-      // Assuming Node 20+, native fetch is available
-      const response = await fetch(WEBHOOK_URL, {
-        method: 'POST',
-        headers: {
-          'Content-Type': 'application/json',
-          'X-Pharmacy-Event': event,
-          'X-Pharmacy-Signature': signatureHeader,
-          'Idempotency-Key': idempotencyKey,
-        },
-        body: bodyString,
-      });
+    for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+      try {
+        console.log(`[WEBHOOK] Attempt ${attempt}/${MAX_RETRIES} — ${event} (${idempotencyKey})`);
 
-      if (!response.ok) {
-        console.error(`[WEBHOOK] Dispatch failed with status: ${response.status}`);
-      } else {
-        console.log(`[WEBHOOK] Successfully dispatched event: ${event}`);
+        const response = await fetch(WEBHOOK_URL, {
+          method: 'POST',
+          headers: {
+            'Content-Type': 'application/json',
+            'X-Pharmacy-Event': event,
+            'X-Pharmacy-Signature': signatureHeader,
+            'Idempotency-Key': idempotencyKey,
+          },
+          body: bodyString,
+        });
+
+        if (response.ok) {
+          console.log(`[WEBHOOK] ✓ Delivered: ${event}`);
+          return; // Success — stop retrying
+        }
+
+        console.warn(`[WEBHOOK] Server responded ${response.status} for ${event}`);
+      } catch (error: any) {
+        console.error(`[WEBHOOK] Attempt ${attempt} failed: ${error.message}`);
+      }
+
+      // Exponential backoff: 1s, 2s, 4s
+      if (attempt < MAX_RETRIES) {
+        const delay = Math.pow(2, attempt - 1) * 1000;
+        await new Promise((resolve) => setTimeout(resolve, delay));
       }
-    } catch (error: any) {
-      console.error(`[WEBHOOK] Failed to dispatch webhook: ${error.message}`);
-      // In a real system, this would queue for retry with exponential backoff.
     }
+
+    console.error(`[WEBHOOK] ✗ Failed after ${MAX_RETRIES} attempts: ${event}`);
   }
 }
 
 export const webhookService = new WebhookService();
+