📝 Task Manager - WinForms & .NET 9.0 (Version 2)

This is a desktop application developed in C# (.NET 9.0) for managing tasks within a small team. The project highlights the practical application of:

🏗️ Layered Architecture 🧩 Design Patterns 📐 SOLID Principles

👉 Version 2 introduces a modern graphical user interface and integration with a real SMTP server for notifications.

✨ New Features (v2)

🖥️ Complete Graphical User Interface (WinForms)

An interactive form for:

• Adding tasks (title, description, type, priority, deadline)
• Viewing tasks in a clean and organized DataGridView

📧 Real Email Notifications

When a task is marked as "Done", the application automatically sends an email using:

• MailKit
• SMTP (Gmail)

🔌 Dependency Injection (IoC Container)

Automatic dependency management with:

• Microsoft.Extensions.DependencyInjection

🏗️ Application Architecture

The application uses a layered architecture:

[TaskManager.UI]        → Presentation (WinForms + IoC)
        │
        ▼
[TaskManager.Core]     → Business Logic + Interfaces (no external dependencies)
        ▲
        │
[TaskManager.Data]     → Data Access (SQLite)

📌 Note: Core is the application's center – it defines the rules, while UI and Data merely implement them.

🏛️ SOLID Principles (Applied)

1. Single Responsibility Principle (SRP)

   • Validation is separated into TaskValidator.
   • TaskService only orchestrates the logic.

2. Open/Closed Principle (OCP)

   • The notification system uses ITaskNotifier.
   • ✔ Email notifications were added without modifying TaskService.

3. Liskov Substitution Principle (LSP)

   • Hierarchy: TaskItem → DeadlineTask / RecurringTask. Implementations can be swapped without affecting the application.
   • ✔ SqliteTaskRepository and InMemoryTaskRepository are interchangeable.

4. Interface Segregation Principle (ISP)

   • Interfaces are segregated: ITaskReader and ITaskWriter.
   • ✔ ReportService only uses read operations, preventing accidental modifications.

5. Dependency Inversion Principle (DIP)

   • TaskService depends on abstractions: ITaskRepository and ITaskNotifier.
   • ✔ All dependencies are injected via the constructor using the IoC Container.

💾 Database & Data Access

• 🗄️ Storage: SQLite (local tasks.db file)
• 🧱 Pattern: Repository Pattern
• 🔧 Technology: ADO.NET (Microsoft.Data.Sqlite)
• ❌ No ORM is used (as per requirements).

✔ Manual mapping from SqliteDataReader to C# objects is performed.

🧪 Automated Testing (NUnit)

The project includes unit tests that cover:

• ✔ Data validation
• ✔ Service logic
• ✔ Liskov Substitution Principle (LSP)
• ✔ Checks for ISP & DIP through reflection

⚡ The tests are:

• Fast
• Isolated
• Based on InMemoryTaskRepository

👉 Run the tests:

dotnet test

🚀 How to Run the Project

📋 Requirements

• .NET 9.0 SDK

📧 Email Configuration

In src/TaskManager.Core/Notifications/EmailNotifier.cs, you must add:

• Your Gmail address
• A Google-generated App Password

▶️ Running the Application (WinForms)

dotnet run --project src/TaskManager.UI