# Invoice Controller Migration to V2

## Summary

Successfully converted the legacy `InvoiceController` to `ApiInvoiceControllerV2` following the established V2 controller pattern used throughout the application.

## Changes Made

### 1. Created ApiInvoiceControllerV2
- **File**: `/src/lib/api/controllers/ApiInvoiceControllerV2.ts`
- **Pattern**: Extends `ApiBaseControllerV2` for consistent API key authentication
- **Features**: 
  - Proper tenant isolation with `runWithTenant`
  - Simplified error handling (no manual try/catch blocks)
  - Built-in authentication and permission checking
  - Support for all invoice operations

### 2. Converted Controller Methods
All methods from the original InvoiceController were converted to the V2 pattern:

#### Core CRUD Operations
- `list()` - List invoices with advanced filtering
- `getById()` - Get invoice details with includes
- `create()` - Create new invoice
- `update()` - Update existing invoice
- `delete()` - Delete invoice

#### Invoice Generation
- `generateFromBillingCycle()` - Generate from billing cycle
- `createManualInvoice()` - Create manual invoice
- `previewInvoice()` - Preview invoice before generation

#### Status Transitions
- `finalize()` - Finalize invoice (draft → pending)
- `send()` - Send invoice to customer
- `approve()` - Approve invoice
- `reject()` - Reject invoice

#### Payment Processing
- `recordPayment()` - Record payment against invoice
- `applyCredit()` - Apply credit to invoice

#### Document Management
- `generatePDF()` - Generate PDF for invoice
- `downloadPDF()` - Download invoice PDF

#### Tax Operations
- `calculateTax()` - Calculate tax for invoice items

#### Bulk Operations
- `bulkUpdateStatus()` - Bulk update invoice status
- `bulkSend()` - Bulk send invoices
- `bulkDelete()` - Bulk delete invoices
- `bulkApplyCredit()` - Bulk apply credit

#### Search and Analytics
- `search()` - Advanced invoice search
- `getAnalytics()` - Get invoice analytics
- `export()` - Export invoices

#### Recurring Invoices
- `listRecurringTemplates()` - List recurring templates
- `createRecurringTemplate()` - Create recurring template
- `updateRecurringTemplate()` - Update recurring template
- `deleteRecurringTemplate()` - Delete recurring template

#### Invoice Items & Transactions
- `listItems()` - List invoice items
- `listTransactions()` - List invoice transactions
- `duplicate()` - Duplicate invoice

### 3. Updated All Invoice Routes
Updated 24 invoice route files to use the new V2 controller:

#### Main Routes
- `/src/app/api/v1/invoices/route.ts`
- `/src/app/api/v1/invoices/[id]/route.ts`

#### Specialized Routes
- `/src/app/api/v1/invoices/generate/route.ts`
- `/src/app/api/v1/invoices/manual/route.ts`
- `/src/app/api/v1/invoices/preview/route.ts`
- `/src/app/api/v1/invoices/search/route.ts`
- `/src/app/api/v1/invoices/analytics/route.ts`
- `/src/app/api/v1/invoices/export/route.ts`

#### Invoice-Specific Operations
- `/src/app/api/v1/invoices/[id]/finalize/route.ts`
- `/src/app/api/v1/invoices/[id]/send/route.ts`
- `/src/app/api/v1/invoices/[id]/approve/route.ts`
- `/src/app/api/v1/invoices/[id]/reject/route.ts`
- `/src/app/api/v1/invoices/[id]/payment/route.ts`
- `/src/app/api/v1/invoices/[id]/credit/route.ts`
- `/src/app/api/v1/invoices/[id]/pdf/route.ts`
- `/src/app/api/v1/invoices/[id]/tax/route.ts`
- `/src/app/api/v1/invoices/[id]/items/route.ts`
- `/src/app/api/v1/invoices/[id]/transactions/route.ts`
- `/src/app/api/v1/invoices/[id]/duplicate/route.ts`

#### Bulk Operations
- `/src/app/api/v1/invoices/bulk/route.ts`
- `/src/app/api/v1/invoices/bulk/send/route.ts`
- `/src/app/api/v1/invoices/bulk/delete/route.ts`
- `/src/app/api/v1/invoices/bulk/credit/route.ts`

#### Recurring Invoices
- `/src/app/api/v1/invoices/recurring/route.ts`
- `/src/app/api/v1/invoices/recurring/[id]/route.ts`

### 4. Route Pattern Changes
**Before (V1 Pattern):**
```typescript
import { InvoiceController } from 'server/src/lib/api/controllers/InvoiceController';
import { handleApiError } from 'server/src/lib/api/middleware/apiMiddleware';

const controller = new InvoiceController();

export async function GET(request: Request) {
  try {
    return await controller.list()(request as any);
  } catch (error) {
    return handleApiError(error);
  }
}
```

**After (V2 Pattern):**
```typescript
import { ApiInvoiceControllerV2 } from 'server/src/lib/api/controllers/ApiInvoiceControllerV2';

const controller = new ApiInvoiceControllerV2();

export async function GET(request: Request) {
  return controller.list()(request as any);
}
```

### 5. Removed Legacy Files
- Deleted `/src/lib/api/controllers/InvoiceController.ts`
- Cleaned up temporary migration scripts

## Benefits of V2 Migration

1. **Consistent Authentication**: All routes now use the same API key authentication pattern
2. **Better Error Handling**: Centralized error handling in the base controller
3. **Tenant Isolation**: Proper tenant context management with `runWithTenant`
4. **Cleaner Code**: Reduced boilerplate in route handlers
5. **Type Safety**: Better TypeScript integration with Zod schemas
6. **Permission Management**: Unified permission checking across all endpoints

## Verification

- ✅ All 24 invoice route files updated
- ✅ No remaining references to old `InvoiceController`
- ✅ All invoice schemas properly imported and used
- ✅ Controller follows established V2 pattern
- ✅ TypeScript compilation successful (no invoice-related errors)

## Next Steps

The invoice API is now fully migrated to the V2 pattern and ready for use with proper API key authentication and tenant isolation.