A professional B2B system for managing invoices, cash flow, and contractors. Designed to comply with Polish accounting standards.

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📺 Demo (Preview)

🚀 About the Project

Invoice Manager is more than just a document generator. It solves real Cash Flow management problems for small service businesses (B2B).

The application addresses real-world business challenges:

• Data Integrity: What happens to an old invoice if the client changes their address? (Solution: Snapshotting).
• Financial Liquidity: Who is late with payments? How much was paid in advance? (Solution: KPI Dashboard and Split Payments).
• Legal Compliance: Does the invoice meet official requirements? (Solution: Validations and Humanizer).

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🛠️ Key Features

1. 🛡️ Data Integrity & Snapshotting

I implemented the Snapshot pattern to "freeze" client data when an invoice is created.

• Updates to the Clients table do not affect historical invoices.
• This guarantees data immutability for accounting purposes.

2. 💰 Payment Handling (Partial Payments)

The system supports partial payments and down payments.

• Automatically calculates the Remaining Amount.
• Real-time status updates: Draft → Pending → Paid.
• Business logic prevents editing of invoices that have been paid or sent.

3. 📄 PDF Generator & Compliance

Generates legally binding PDF documents using the Rotativa library.

• Automatic "number to words" conversion (Humanizer).
• Dynamic mapping of VAT rates.
• Supports various units (hours, km, pcs, set).

4. 📊 Analytical Dashboard

A command center for the business owner:

• KPIs: Real-time revenue from the last 30 days.
• Alerts: Overdue invoices highlighted in red.
• Quick Actions: One-click payment registration.

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💻 Tech Stack

Backend:

• C# / .NET Framework
• ASP.NET MVC 5
• Entity Framework 6 (Code First)
• LINQ

Database:

• MS SQL Server
• Repository Pattern (Separation of logic from data access)

Frontend:

• Razor Views (.cshtml)
• Bootstrap 5 (Dark Mode Support)
• jQuery / AJAX (Modal handling)
• FontAwesome

Tools:

• Rotativa: Generating PDFs from HTML views.
• Humanizer: Logic for converting numbers to text.
• Git: Version control.

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⚙️ Installation & Setup

1. Clone the repository:

   git clone [https://github.com/TwojNick/InvoiceManager.git](https://github.com/TwojNick/InvoiceManager.git)

2. Open the .sln file in Visual Studio 2022.
3. Update the connectionString in Web.config to match your local SQL Server.
4. Run Update-Database in the Package Manager Console:

   Update-Database

5. Run the project (F5).

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🔮 Roadmap

• Add unit tests (NUnit/xUnit).
• Migrate to .NET 8 / ASP.NET Core.
• Integrate with GUS API (fetch company data by Tax ID).
• Email sending (SMTP).

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📬 Contact

Kacper Kotecki 📧 kacperkotecki@protonmail.com 🔗 LinkedIn Profile