# Stock Adjustment Module Implementation

## Overview

A complete Stock Adjustment module has been implemented for the Admin panel, allowing users to upload Excel files to adjust stock levels for specific branches. The implementation follows the existing inventory system patterns and ensures data integrity.

## Features Implemented

### Backend (Laravel)

1. **StockAdjustmentController** (`app/Http/Controllers/Admin/StockAdjustmentController.php`)

    - `downloadTemplate()` - Downloads Excel template with sample data
    - `preview()` - Processes uploaded Excel file and validates data
    - `commit()` - Commits validated adjustments to inventory system

2. **API Routes** (`routes/api.php`)

    - `GET /api/admin/stock-adjustments/template` - Download template
    - `POST /api/admin/stock-adjustments/preview` - Preview upload
    - `POST /api/admin/stock-adjustments/commit` - Commit adjustments

3. **Transaction Integration**
    - Uses `trans_type_id = 9` ("Stock Repair" from seeds.sql)
    - Follows existing transaction numbering logic
    - Creates `inventory_header` and `inventory_detail` records
    - Updates `warehouses` table with new quantities

### Frontend (React + TypeScript)

1. **StockAdjustmentPage** (`resources/js/components/Pages/Admin/StockAdjustmentPage.tsx`)

    - Branch selection dropdown
    - File upload with validation
    - Template download functionality
    - Preview table with before/after quantities
    - Validation error display
    - Confirmation modal for commit
    - Success feedback with transaction number

2. **Navigation Integration**
    - Added to Admin → Transactions submenu
    - Route: `/admin/transactions/stock-adjustment`

## Excel Template Format

The template includes three columns:

-   `barcode` - Product barcode (required)
-   `qty` - Adjustment quantity (positive to add, negative to subtract)
-   `comment` - Optional comment for the adjustment

## Validation Rules

### Frontend Validation

-   Branch selection required
-   File upload required
-   File type validation (.xlsx, .xls)
-   File size limit (10MB)

### Backend Validation

-   Required columns: barcode, qty
-   All barcodes must exist in items table
-   Duplicate barcodes are merged (quantities summed)
-   Prevents negative stock (after_qty < 0)
-   Preview token expiration (15 minutes)

## Data Flow

1. **Template Download**: User downloads Excel template
2. **File Upload**: User fills template and uploads with branch selection
3. **Preview**: System validates data and shows preview with current/after quantities
4. **Validation**: System checks for negative stock and unknown barcodes
5. **Commit**: If valid, creates inventory transaction and updates warehouse stock
6. **Confirmation**: User receives transaction number and item count

## Transaction Details

-   **Transaction Type**: 9 (Stock Adjustment / Stock Repair)
-   **Transaction Number**: Generated using existing sequence logic
-   **Document Number**: Generated using existing sequence logic
-   **Status**: Posted (status = 1)
-   **Inventory Records**: Creates header and detail records for audit trail
-   **Stock Updates**: Atomic updates to warehouses table

## Error Handling

-   Excel parsing errors
-   Missing required columns
-   Unknown barcodes
-   Duplicate barcode merging
-   Negative stock prevention
-   Preview token expiration
-   Database transaction rollback on errors

## Security

-   Authentication required for all endpoints
-   File type validation
-   File size limits
-   SQL injection prevention through Eloquent ORM
-   CSRF protection through Laravel middleware

## Testing

The implementation includes comprehensive error handling and validation at both frontend and backend levels. All database operations are wrapped in transactions to ensure data consistency.

## Files Modified/Created

### New Files

-   `app/Http/Controllers/Admin/StockAdjustmentController.php`
-   `resources/js/components/Pages/Admin/StockAdjustmentPage.tsx`
-   `docs/STOCK_ADJUSTMENT_IMPLEMENTATION.md`

### Modified Files

-   `routes/api.php` - Added stock adjustment routes
-   `resources/js/App.tsx` - Added route and import
-   `resources/js/components/Layout/AdminSidebar.tsx` - Added navigation item

## Usage

1. Navigate to Admin → Transactions → Stock Adjustment
2. Select a branch from the dropdown
3. Download the Excel template
4. Fill in the template with barcode, quantity, and optional comments
5. Upload the completed file
6. Review the preview table
7. Add optional comments
8. Click "Submit Adjustment" to commit changes
9. Receive confirmation with transaction number

The implementation ensures full integration with the existing inventory system while maintaining data integrity and providing a user-friendly interface for stock adjustments.