fix: prevent scheduling of campaign if billing limit reached

apps/api/src/services/CampaignService.ts

@@ -1,17 +1,18 @@
 import type {Campaign, Contact, Prisma} from '@plunk/db';
-import {CampaignAudienceType, CampaignStatus} from '@plunk/db';
+import {CampaignAudienceType, CampaignStatus, EmailSourceType} from '@plunk/db';
 import type {FilterCondition} from '@plunk/types';
 
 import {prisma} from '../database/prisma.js';
 import {HttpException} from '../exceptions/index.js';
 import {buildEmailFieldsUpdate} from '../utils/modelUpdate.js';
 
+import {BillingLimitService} from './BillingLimitService.js';
 import {DomainService} from './DomainService.js';
 import {EmailService} from './EmailService.js';
 import {NtfyService} from './NtfyService.js';
 import {QueueService} from './QueueService.js';
 import {SegmentService} from './SegmentService.js';
-import {DASHBOARD_URI} from '../app/constants.js';
+import {DASHBOARD_URI, STRIPE_ENABLED} from '../app/constants.js';
 import {sendRawEmail} from './SESService.js';
 
 const BATCH_SIZE = 500; // Number of emails to process per batch (increased for better performance)
@@ -324,6 +325,24 @@ export class CampaignService {
       throw new HttpException(400, 'Campaign has no recipients');
     }
 
+    // Check billing limits before scheduling/sending the campaign
+    // This ensures users cannot schedule campaigns that would exceed their quota
+    if (STRIPE_ENABLED) {
+      const limitCheck = await BillingLimitService.checkLimit(projectId, EmailSourceType.CAMPAIGN);
+
+      // If there's a limit set, verify the campaign won't exceed it
+      if (limitCheck.limit !== null) {
+        const projectedUsage = limitCheck.usage + recipientCount;
+
+        if (projectedUsage > limitCheck.limit) {
+          throw new HttpException(
+            403,
+            `Cannot ${scheduledFor ? 'schedule' : 'send'} campaign: would exceed billing limit. Current usage: ${limitCheck.usage}/${limitCheck.limit} emails, campaign recipients: ${recipientCount}. Upgrade your plan or reduce campaign recipients.`,
+          );
+        }
+      }
+    }
+
     if (scheduledFor) {
       // Schedule for later
       if (scheduledFor.getTime() <= Date.now()) {