# Phase 9: Procurement & GRN - Implementation Complete

## ✅ Completed Tasks

### 1. Vendor Service Implementation
- ✅ Created `vendors.js` service with:
  - `createVendor` - Create vendors (OPEN_MARKET or REGISTERED)
  - `getVendor` - Get vendor by ID
  - `updateVendor` - Update vendor
  - `deleteVendor` - Delete vendor
  - `listVendors` - List vendors with filters and pagination

### 2. Purchase Order Service Implementation
- ✅ Created `purchaseOrders.js` service with:
  - `createPurchaseOrder` - Create purchase orders
  - `getPurchaseOrder` - Get purchase order by ID
  - `updatePurchaseOrder` - Update purchase order
  - `deletePurchaseOrder` - Delete purchase order (if no GRNs linked)
  - `listPurchaseOrders` - List purchase orders with filters
  - `updatePurchaseOrderStatus` - Update PO status (DRAFT, CONFIRMED, CLOSED)

### 3. GRN Service Implementation
- ✅ Created `grns.js` service with:
  - `createGRN` - Create GRN (with or without PO - open-market friendly)
  - `getGRN` - Get GRN by ID with items
  - `listGRNs` - List GRNs with filters and pagination
  - `processGRN` - Process GRN by adding stock to inventory and generating UIDs

### 4. Controllers
- ✅ Created procurement controllers for all operations:
  - Vendor controllers (CRUD)
  - Purchase order controllers (CRUD + status update)
  - GRN controllers (CRUD + process)

### 5. Validations
- ✅ Created comprehensive validation rules for:
  - Vendor operations
  - Purchase order operations
  - GRN operations

### 6. Routes
- ✅ Created RESTful routes with Swagger documentation:
  - `POST /api/procurement/vendors` - Create vendor
  - `GET /api/procurement/vendors` - List vendors
  - `GET /api/procurement/vendors/:id` - Get vendor
  - `PUT /api/procurement/vendors/:id` - Update vendor
  - `DELETE /api/procurement/vendors/:id` - Delete vendor
  - `POST /api/procurement/purchase-orders` - Create purchase order
  - `GET /api/procurement/purchase-orders` - List purchase orders
  - `GET /api/procurement/purchase-orders/:id` - Get purchase order
  - `PUT /api/procurement/purchase-orders/:id` - Update purchase order
  - `DELETE /api/procurement/purchase-orders/:id` - Delete purchase order
  - `PUT /api/procurement/purchase-orders/:id/status` - Update PO status
  - `POST /api/procurement/grns` - Create GRN
  - `GET /api/procurement/grns` - List GRNs
  - `GET /api/procurement/grns/:id` - Get GRN
  - `POST /api/procurement/grns/:id/process` - Process GRN

### 7. Integration
- ✅ GRN routes mounted in main routes file
- ✅ All services exported through index.js

## 📋 Features Implemented

### Vendor Management
- ✅ Support for OPEN_MARKET and REGISTERED vendor types
- ✅ CRUD operations with validation
- ✅ Search and filter capabilities

### Purchase Order Management
- ✅ Optional PO workflow (GRN can exist without PO)
- ✅ Status management (DRAFT, CONFIRMED, CLOSED)
- ✅ PO deletion protection (cannot delete if GRNs linked)
- ✅ Vendor association

### GRN (Goods Receipt Note) Management
- ✅ **Open-market friendly:** GRN can be created without PO
- ✅ **Cost tracking:** Unit cost tracked in GRN items
- ✅ **Inventory integration:**
  - Adds stock to quantity-based inventory
  - Generates UIDs for inventory items (if enabled)
  - Creates inventory movements for audit trail
  - Syncs UID-based and quantity-based inventory
- ✅ **Support for both workflows:**
  - With PO: Links to purchase order
  - Without PO: Standalone GRN for open-market purchases
- ✅ **Processing:**
  - Adds stock to inventory
  - Generates UIDs and barcodes for tracked items
  - Records all inventory movements
  - Maintains dual inventory system (quantity + UID)

## 🔄 Inventory Integration Details

### When Processing GRN with UID Generation:
1. For each GRN item:
   - Generates UID and barcode for each unit
   - Creates InventoryItem records with UIDs
   - Increments quantity-based inventory (syncs both layers)
   - Creates InventoryMovement records for audit trail

### When Processing GRN without UID Generation:
1. For each GRN item:
   - Adds quantity to quantity-based inventory
   - Creates InventoryMovement records
   - No UID items created

### Cost Tracking
- ✅ Unit cost stored in GRNItem model
- ✅ Cost information available for reporting and analysis
- ✅ Cost tracked per product/variant received

## 🎯 Acceptance Criteria Status

- ✅ Can create vendors (OPEN_MARKET and REGISTERED types)
- ✅ Can create POs (optional - not required for GRN)
- ✅ Can create GRN with/without PO (open-market friendly)
- ✅ Stock added correctly on GRN processing
  - Quantity-based inventory incremented
  - UID items created if enabled
  - Both inventory layers kept in sync
- ✅ Inventory items created with UIDs (when enabled)
- ✅ Costs tracked in GRN items (unit_cost field)

## 📁 Files Created

```
server/modules/procurement/
├── services/
│   ├── vendors.js
│   ├── purchaseOrders.js
│   ├── grns.js
│   └── index.js
├── controllers/
│   └── index.js
├── validations/
│   └── index.js
└── routes/
    └── index.js
```

## 🔗 Dependencies

- Phase 2: Products (for product references in GRN items)
- Phase 6: Inventory (for UID generation and inventory management)
- Models: Vendor, PurchaseOrder, GRN, GRNItem (already existed)

## 🚀 Usage Examples

### Create Vendor (Open Market)
```javascript
POST /api/procurement/vendors
{
  "name": "Street Vendor ABC",
  "type": "OPEN_MARKET"
}
```

### Create GRN without PO (Open Market)
```javascript
POST /api/procurement/grns
{
  "vendor_id": 1,
  "items": [
    {
      "product_id": 1,
      "quantity": 100,
      "unit_cost": 50.00
    }
  ]
}
```

### Process GRN (Add Stock + Generate UIDs)
```javascript
POST /api/procurement/grns/1/process
{
  "generateUIDs": true
}
```

### Create Purchase Order
```javascript
POST /api/procurement/purchase-orders
{
  "vendor_id": 1,
  "status": "DRAFT"
}
```

### Create GRN with PO
```javascript
POST /api/procurement/grns
{
  "purchase_order_id": 1,
  "items": [
    {
      "product_id": 1,
      "quantity": 50,
      "unit_cost": 45.00
    }
  ]
}
```

## 📝 Notes

- GRN processing is atomic (transaction-based) - all or nothing
- UID generation happens automatically when processing GRN (if enabled)
- Cost tracking is per GRN item, allowing cost analysis
- Open-market workflow fully supported (no PO required)
- Purchase orders are optional but can be used for formal procurement
- Inventory movements are created for full audit trail
- Both quantity-based and UID-based inventory are kept in sync

---

**Phase 9 Implementation: ✅ COMPLETE**

**All procurement features functional:**
1. ✅ Vendor management
2. ✅ Purchase order management (optional)
3. ✅ GRN creation and processing
4. ✅ Stock addition via GRN
5. ✅ UID generation on GRN
6. ✅ Cost tracking in GRN items
7. ✅ Open-market support (GRN without PO)

