Invoice Management System

A comprehensive system for managing invoices, projects, and LPOs for the IT Department, with OCR capabilities and status tracking.

Project Overview

This project digitizes the IT department's manual invoice documentation workflow. It provides a centralized web platform to upload and track invoices, automate data entry via AI-powered OCR, and monitor invoice status in real-time. The system also includes a project number request and assignment module, enabling accurate project-specific invoice tracking while respecting existing organizational workflows.

Architecture

The system is built using a Clean Architecture approach with the following layers:

Backend (ASP.NET Core Web API)

1. Domain Layer

   • Entities: Core business models (Project, LPO, Invoice, etc.)
   • Interfaces: Contracts for repositories and services
   • Enums: Strongly-typed constants (Role, InvoiceStatus, RequestStatus, etc.)

2. Application Layer

   • Services: Business logic implementation
   • Interfaces: Service contracts
   • DTOs: Data transfer objects for API responses/requests
   • Validation: Request validation and business rules

3. Infrastructure Layer

   • Data: EF Core DbContext, Configurations
   • Repositories: CRUD operations for entities
   • Identity: Authentication/Authorization
   • External Services: OCR, Email, Notifications
   • Background Jobs: For scheduled tasks and long-running processes

4. API Layer

   • Controllers: API endpoints
   • Filters: Request/response processing
   • Middleware: Cross-cutting concerns
   • SignalR Hubs: Real-time notifications

Frontend (React)

• Components: UI components
• Services: API client services and HTTP interceptors
• State Management: Application state using Context API or Redux
• Routing: Navigation with protected routes
• PDF Viewer: For viewing and annotating invoices
• Internationalization: For multi-language support

Entity Relationship Diagram

Department 1──┐
              │
              │ *
        ┌─── Section 1──┐
        │               │
        │               │ *
        │         ┌─── Unit 1──┐
        │         │            │
        │         │            │ *
Employee *        │    ┌─────Project 1───┐
    │             │    │                 │
    │             │    │                 │ *
    │             │    │             ┌─LPO 1──┐
    │             │    │             │        │
    │             │    │             │        │ *
    │             │    │             │      Invoice 1──┐
    │             │    │             │        │        │
    │             │    │             │        │        │ *
    │             │    │             │        │   StatusHistory
    │             │    │             │        │
    │             │    │             │        │
 Notification     │    └─────────────┘        │
                  │                           │
                  └───ProjectNumberRequest    │
                                              │
                                     DocumentAttachment

Advanced Features

1. OCR and Document Processing

• Azure Form Recognizer Integration: Extract invoice data with high accuracy
• ML-Based Field Mapping: Intelligently map extraction results to database fields
• Duplicate Detection: Flag potentially duplicate invoices based on number, amount, and vendor
• PDF Handling: View, annotate, and manage PDF documents directly in the UI

2. Project Number Workflow

• Request-Approval Flow: Complete workflow for project number requests
• Automatic Notifications: Notify relevant stakeholders at each step
• History Tracking: Complete history of all project number requests
• Business Justification: Capture business justification for audit purposes

3. Invoice Lifecycle Management

• Status Tracking: Full timeline of invoice status changes
• Performance Metrics: Track time spent in each status for process improvement
• Conditional Workflows: Different paths based on invoice type/amount

4. Notifications System

• Real-time Alerts: In-app notifications for important events
• Email Notifications: Send emails for critical updates
• SignalR Integration: Push notifications to users in real-time
• Customizable Preferences: User-specific notification preferences

5. Reporting and Analytics

• Power BI Integration: Advanced reporting capabilities
• Export Options: Export data to Excel, PDF, and CSV
• Custom Dashboards: Role-specific dashboards
• Key Performance Indicators: Track processing times and efficiency metrics

Key Entities

• Employee: Users with different roles (Admin, IT Head, Regular Employee)
• Department/Section/Unit: Organizational structure
• Project: Projects with budgets, timelines, and approval workflow
• ProjectNumberRequest: Tracking project number requests and their approval workflow
• LPO: Local Purchase Orders linked to projects
• Invoice: Invoices with OCR data, file attachments, and status tracking
• StatusHistory: Complete timeline of invoice status changes
• DocumentAttachment: Files attached to invoices, projects, or LPOs
• Notification: User notifications for important events
• SystemSetting: Configurable system settings
• AuditLog: Comprehensive tracking of all system changes

Technical Stack

• Frontend: React.js with TypeScript
• Backend API: ASP.NET Core 8 (C#)
• Database: SQL Server
• AI & OCR: Azure Form Recognizer
• Authentication: JWT / OAuth 2.0
• Realtime Events: SignalR
• Reporting: Microsoft Power BI
• Background Jobs: Hangfire
• Cloud Storage: Azure Blob Storage
• Hosting: Microsoft Azure App Service

Deployment Strategy

• CI/CD Pipeline: Azure DevOps for automated builds and deployments
• Environment Separation: Development, Testing, and Production environments
• Database Migrations: Automated using Entity Framework Core
• Monitoring: Application Insights for performance monitoring
• Backup Strategy: Regular database backups and point-in-time recovery
• Scaling: Auto-scaling based on load metrics

Setup Instructions

Prerequisites

• .NET 8 SDK
• Node.js and npm
• SQL Server/LocalDB
• Azure Account (for Form Recognizer)

Backend Setup

1. Clone the repository
2. Navigate to the InvoiceManagement.Server directory
3. Update the connection string in appsettings.json if needed
4. Run migrations:

   dotnet ef migrations add InitialCreate
   dotnet ef database update
   

5. Start the API:

   dotnet run
   

Frontend Setup

1. Navigate to the invoicemanagement.client directory
2. Install dependencies:

   npm install
   

3. Start the development server:

   npm run dev
   

Features

• AI-Powered OCR: Automatically extract data from invoice PDFs using Azure Form Recognizer
• Project Number Workflow: Request, approve and assign project numbers with complete history
• Invoice Status Lifecycle: Track invoice status from receipt to payment with full timeline
• Document Management: Upload, view, and manage documents attached to invoices, projects, or LPOs
• Real-time Notifications: Receive instant notifications for important events
• Dashboard & Analytics: Power BI integration for advanced reporting capabilities
• Role-based Access Control: Granular permissions based on user roles
• Audit Logging: Comprehensive tracking of all system changes