📦 Inventory Management RESTful API

The system manages supplier purchases, stock storage across multiple warehouses, inter-warehouse transfers, and simulates inventory audits by allowing manual stock adjustments due to surplus, damage, or missing items.

📦 Key Features

🔑 Authentication & Authorization

• Secured using JWT with refresh & revoke tokens
• Role information is embedded in tokens for protected route handling
• JWT-based access with roles (admin, Inventory Manager, Supplier, Sales Viewer)

🧑‍💼 User Management

• Admin can register and manage all users and their roles
• Suppliers can register themselves
• Support for viewing user details and updating profile information

🔐 Role-Based Access Control

• Roles: Admin, InventoryManager, Supplier, SalesViewer
• Admin has full access; in future updates, Inventory Managers will be restricted to their own warehouse

📦 Product Management

• Products are created by suppliers with base data (name, price, etc.), and extended by the inventory system (barcode, availability)
• Supports full product CRUD operations, bulk creation, and category-based queries

🧑‍💼 Supplier Onboarding & Verification

• Only verified suppliers can receive purchase orders or upload products
• A supplier cannot perform any action in the system until verified by an Admin.

📥 Purchase Orders

• Inventory managers and Admin can create purchase orders with multiple products and send them to suppliers
• Purchase orders support multiple statuses: Draft, Sent, PartiallyReceived, Received, and Cancelled

🏢 Warehouse Management

• Multiple warehouses supported, each with individual inventory levels
• Products can be stored in multiple warehouses with separate stock quantities

🔄 Stock Transfers

• Enables transferring products between warehouses
• Automatically updates inventory records and logs the transfer as a stock movement

🛠️ Inventory Adjustments (Stock Audit Simulation)

• Allows manual adjustments to stock quantities (e.g., for lost, damaged, or extra items)
• All adjustments are logged in the stock movement history

📊 Stock Movement Tracking

• Logs every inventory action (purchase, sale, transfer, manual adjustment) with quantity, date, product, and warehouse details
• Query stock movements by product or warehouse

🚀 Technical Features

• ✅ Built using clean RESTful principles and SOLID architecture
• ✅ EF Core with Code First approach, using Fluent API for full control over relationships and configurations
• ✅ Soft Delete supported in selected entities like Category and ApplicationUser, with automatic filtering
• ✅ All key List endpoints support:
  • 🔍 Search
  • 🧩 Dynamic Filtering
  • ↕️ Sorting
  • 📄 Pagination
• ✅ Middleware pipeline includes:
  • 🎯 Global Exception Handling
  • 🖼️ Image Validation
  • 🛡️ Request Lock Middleware (prevents duplicate Purchase Order submission within 1 minute)
• ✅ FluentValidation integrated for all DTOs that require complex validation logic
• ✅ Fully implemented JWT Authentication with:
  • Access & Refresh Tokens
  • Token rotation and secure reissue endpoints
• ✅ Role-based access control (RBAC) with [Authorize(Roles = "...")], supporting roles like Admin, InventoryManager, Supplier, and SalesViewer
• ✅ All stock-related actions (Purchase, Transfer, Manual Adjustments) are logged via the StockMovement table
• ✅ Advanced entity mappings using Fluent API

🏗️ Project Structure

InventoryManagement/
├── API/
│   └── InventoryManagement/
│       ├── wwwroot/
│       ├── Controllers/
│       ├── Filters/
│       ├── Middleware/
│       ├── Settings/
│       ├── appsettings.json
│       ├── InventoryManagement.http
│       ├── Program.cs
│       └── ServiceCollectionExtensions.cs
│
├── Application/
│   └── Application/
│       ├── Constants/
│       ├── DTO's/
│       ├── Exceptions/
│       ├── Interfaces/
│       ├── Mappings/
│       ├── ResponseDTO's/
│       ├── Services/
│       ├── Settings/
│       ├── validations/
│       └── ServiceCollectionExtensions.cs
│
├── Domain/
│   └── Domain/
│       ├── Entity/
│       ├── Enum/
│       └── Interface/
│
└── Infrastructure/
    └── Infrastructure/
        ├── Configurations/
        ├── Context/
        ├── Enum/
        ├── Identity Models/
        ├── Internal Interfaces/
        ├── Mappings/
        ├── Migrations/
        ├── Repository/
        ├── Seeds/
        ├── Services/
        ├── Settings/
        ├── UnitOfWork/
        ├── Views/
        └── ServiceCollectionExtensions.cs

⚠️ Note:
To follow clean architecture principles and separation of concerns, the Identity-related models like ApplicationUser are not placed inside the Domain layer.
Instead, they are defined in the Infrastructure layer only, and the relationship (e.g., between Supplier and ApplicationUser) is configured using Fluent API inside DbContext.

🚀 Technical Features

✅ Authentication & Authorization

• JWT-based authentication with Refresh Token support
• Role-based authorization using Claims (Admin, Supplier, InventoryManager, SalesViewer)
• Centralized user context extraction using custom middleware: UserContextMiddleware
• Relies on UserContextService to access UserId, Roles, IsSupplier, Route from any layer of the application
• Custom RequireVerifiedSupplierAttribute is an IAsyncAuthorizationFilter that provides additional verification to ensure only verified suppliers can perform specific operations

🧱 Architecture & Patterns

• Clean Architecture applied with separation into: Domain, Application, Infrastructure, and API layers
• Uses Repository Pattern with Unit of Work for better data handling abstraction
• Dependency Injection is used across the project to manage services and repositories
• Middleware:
  • Global Exception Handling
  • UserContextMiddleware to extract and reuse authenticated user info
  • Request locking middleware to prevent duplicate purchase requests in the same minute (admin/inventory manager)

🗄️ Database Features

• Entity Framework Core as ORM
• Support for both Soft Delete (e.g., on Suppliers) and Hard Delete where needed
• All entity configurations done through Fluent API (example: CategoryConfigurations)
• Includes SQL Views, such as SupplierProfileView, for optimized read access
• Proper indexing and Check constraints applied to ensure data integrity (e.g., builder.HasCheckConstraint("CK_PurchaseOrder_TotalCost_Positive", "[TotalCost] > 0"))

🧰 Other Features

• Global Exception Handling with centralized logic
• Custom Action Filters:
  • ValidateImageAttribute – Validates image file format and size
  • ValidateModelAttribute – Automatically validates incoming DTOs using FluentValidation
• DTO Validation with FluentValidation
• Full API documentation via Swagger UI
• Dynamic configuration for image uploads using IOptions<ImageSettings> pattern:
• Example:

  "ImageSettings": {
    "MaxFileSize": 5242880,
    "AllowedExtensions": [ ".jpg", ".jpeg", ".png" ]
  }

• These settings are strongly typed using a custom ImageSettings class and injected using the IOptions<T> interface, allowing seamless configuration changes per environment (e.g., development vs production)

🗄️ Database Documentation

⚙️ Database Configuration

• ORM: Entity Framework Core
• Type: Relational Database
• Approach: Code-First
• Features:
  • Migrations
  • Relationships (One-to-One, One-to-Many)
  • Views
  • Indexing
  • Soft Delete

👁️ Database Views

Purpose & Clean Architecture Compliance

This project implements Clean Architecture principles where:

• Domain Layer: Contains core business entities like Supplier and cannot see any other layers
• Infrastructure Layer: Contains ApplicationUser (Identity tables) and can see the Domain Layer

The Problem:

• Cannot add ApplicationUser as a Navigation Property in Supplier because the Domain Layer cannot see the Infrastructure Layer
• However, we need access to user information related to the supplier

The Solution:

Database Views were created to retrieve complete supplier and related user information without violating Clean Architecture principles.

Benefits:

• ✅ Maintains Clean Architecture principles
• ✅ Does not violate dependency rules
• ✅ Retrieves complete data in a single query
• ✅ Improves performance

🔗 Entity Relationships Table

Parent Entity	Child Entity	Relationship Type	Foreign Key	Description
Category	Product	One-to-Many	CategoryId	One category can have multiple products
Supplier	Product	One-to-Many	SupplierId	One supplier can provide multiple products
ApplicationUser	Supplier	One-to-One	userid	One user is linked to one supplier
Supplier	PurchaseOrder	One-to-Many	SupplierId	One supplier can create multiple purchase orders
Warehouse	PurchaseOrder	One-to-Many	WarehouseId	One warehouse can receive multiple purchase orders
PurchaseOrder	PurchaseOrderItem	One-to-Many	PurchaseOrderId	One purchase order contains multiple items
Product	PurchaseOrderItem	One-to-Many	ProductId	One product can be in multiple purchase order items
Warehouse	Inventory	One-to-Many	WarehouseId	One warehouse contains inventory of multiple products
Product	Inventory	One-to-Many	ProductId	One product can have inventory in multiple warehouses
Product	StockMovement	One-to-Many	ProductId	One product can have multiple stock movements
Warehouse	StockMovement (Source)	One-to-Many	SourceWarehouseId	One warehouse can be source of multiple stock movements
Warehouse	StockMovement (Destination)	One-to-Many	DestinationWarehouseId	One warehouse can be destination of multiple stock movements

🚀 How to Use the System

POST /api/auth/login
{
  "email": "admin@Inventory.com",
  "password": "P@ssword123"
}