feat(billing): cap active users on an owner subscription

Super admin can set a seat limit of 3, 10, 20, or a negotiated number so an owner cannot add users past that cap.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/src/billing/billing.service.ts

@@ -11,6 +11,7 @@ import type {
   BillingAccountStatus,
   BillingPlanCode,
   OrgModuleKey,
+  OwnerSeatUsageDto,
   SubscriptionSummaryDto,
 } from '@mento/shared';
 import {
@@ -64,6 +65,7 @@ export class BillingService {
     startsAt: Date;
     expiresAt: Date;
     maxOrganizations: number;
+    maxUsers?: number | null;
     externalPaymentRef: string | null;
     notes: string | null;
   }): BillingAccountDto {
@@ -72,11 +74,71 @@ export class BillingService {
       id: row.id,
       ownerUserId: row.ownerUserId,
       ...summary,
+      maxUsers: row.maxUsers ?? null,
       externalPaymentRef: row.externalPaymentRef,
       notes: row.notes,
     };
   }
 
+  async seatUsage(ownerUserId: string): Promise<OwnerSeatUsageDto> {
+    const account = await this.getByOwnerUserId(ownerUserId);
+    const orgIds = await this.ownedOrganizationIds(ownerUserId);
+    const usedUsers = await this.countActiveUsers(orgIds);
+    return { usedUsers, maxUsers: account?.maxUsers ?? null };
+  }
+
+  async setMaxUsers(ownerUserId: string, maxUsers: number): Promise<OwnerSeatUsageDto> {
+    await this.prisma.billingAccount.update({
+      where: { ownerUserId },
+      data: { maxUsers },
+    });
+    return this.seatUsage(ownerUserId);
+  }
+
+  /** کاربر جدید فقط وقتی سقف اشتراک جا دارد. کسی که از قبل در محیط‌های همین مالک فعال است صندلی تازه نمی‌گیرد. */
+  async assertSeatAvailable(organizationId: string, userId: string | null): Promise<void> {
+    const owner = await this.prisma.membership.findFirst({
+      where: { organizationId, role: 'owner', isActive: true },
+      orderBy: { createdAt: 'asc' },
+      select: { userId: true },
+    });
+    if (!owner) return;
+    const account = await this.getByOwnerUserId(owner.userId);
+    if (!account || account.maxUsers == null) return;
+    const orgIds = await this.ownedOrganizationIds(owner.userId);
+    if (userId) {
+      const already = await this.prisma.membership.findFirst({
+        where: { userId, organizationId: { in: orgIds }, isActive: true },
+        select: { id: true },
+      });
+      if (already) return;
+    }
+    const used = await this.countActiveUsers(orgIds);
+    if (used >= account.maxUsers) {
+      throw new ForbiddenException(
+        `سقف کاربر این اشتراک ${account.maxUsers} نفر است. برای افزودن کاربر باید سقف اشتراک بیشتر شود.`,
+      );
+    }
+  }
+
+  private async ownedOrganizationIds(ownerUserId: string): Promise<string[]> {
+    const rows = await this.prisma.membership.findMany({
+      where: { userId: ownerUserId, role: 'owner', isActive: true },
+      select: { organizationId: true },
+    });
+    return rows.map((row) => row.organizationId);
+  }
+
+  private async countActiveUsers(organizationIds: string[]): Promise<number> {
+    if (!organizationIds.length) return 0;
+    const rows = await this.prisma.membership.findMany({
+      where: { organizationId: { in: organizationIds }, isActive: true },
+      select: { userId: true },
+      distinct: ['userId'],
+    });
+    return rows.length;
+  }
+
   async getByOwnerUserId(ownerUserId: string) {
     return this.prisma.billingAccount.findUnique({ where: { ownerUserId } });
   }