# Task Manager API

A RESTful API for managing tasks, built with FastAPI and SQLite.

## Features

- Task CRUD operations
- Task status and priority management
- Task completion tracking
- API documentation with Swagger UI and ReDoc
- Health endpoint for monitoring

## Tech Stack

- FastAPI: Modern, high-performance web framework for building APIs
- SQLAlchemy: SQL toolkit and Object-Relational Mapping (ORM)
- Alembic: Database migration tool
- SQLite: Lightweight relational database
- Pydantic: Data validation and settings management
- Uvicorn: ASGI server for FastAPI applications

## API Endpoints

### API Information

- `GET /`: Get API information and available endpoints

### Task Management

- `GET /tasks`: Get all tasks
- `POST /tasks`: Create a new task
- `GET /tasks/{task_id}`: Get a specific task
- `PUT /tasks/{task_id}`: Update a task
- `DELETE /tasks/{task_id}`: Delete a task
- `POST /tasks/{task_id}/complete`: Mark a task as completed

### Health and Diagnostic Endpoints

- `GET /health`: Application health check
- `GET /db-test`: Database connection diagnostic endpoint

## Example Curl Commands

### Create a new task

```bash
curl -X 'POST' \
  'https://taskmanagerapi-ttkjqk.backend.im/tasks/' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "title": "Complete project documentation",
  "description": "Write comprehensive documentation for the project",
  "priority": "high",
  "status": "todo",
  "due_date": "2023-06-30T18:00:00.000Z",
  "completed": false
}'
```

### Get all tasks

```bash
curl -X 'GET' \
  'https://taskmanagerapi-ttkjqk.backend.im/tasks/' \
  -H 'accept: application/json'
```

### Get a specific task

```bash
curl -X 'GET' \
  'https://taskmanagerapi-ttkjqk.backend.im/tasks/1' \
  -H 'accept: application/json'
```

### Update a task

```bash
curl -X 'PUT' \
  'https://taskmanagerapi-ttkjqk.backend.im/tasks/1' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "title": "Updated title",
  "description": "Updated description",
  "status": "in_progress"
}'
```

### Delete a task

```bash
curl -X 'DELETE' \
  'https://taskmanagerapi-ttkjqk.backend.im/tasks/1' \
  -H 'accept: application/json'
```

### Mark a task as completed

```bash
curl -X 'POST' \
  'https://taskmanagerapi-ttkjqk.backend.im/tasks/1/complete' \
  -H 'accept: application/json'
```

## Project Structure

```
taskmanagerapi/
├── alembic/               # Database migrations
│   └── versions/          # Migration scripts
├── app/
│   ├── api/               # API endpoints
│   │   └── routers/       # API route definitions
│   ├── core/              # Core application code
│   ├── crud/              # CRUD operations
│   ├── db/                # Database setup and models
│   ├── models/            # SQLAlchemy models
│   └── schemas/           # Pydantic schemas/models
├── main.py                # Application entry point
└── requirements.txt       # Project dependencies
```

## Database Configuration

The application is configured to use SQLite with the following database locations (in order of priority):

1. Path defined in the `DB_PATH` environment variable (if set)
2. `/app/db/db.sqlite` (production environment)
3. `./db/db.sqlite` (local development)
4. `/tmp/taskmanager/db.sqlite` (fallback)

The application automatically selects the first available and writable location from this list.

### Enhanced Database Reliability

The application includes several features to ensure robust and reliable database operations:

1. **Multi-path discovery**: Automatically finds and uses the first writable database location
2. **Directory creation**: Creates database directories if they don't exist
3. **Database initialization**: Initializes the database with required tables using both SQLAlchemy and direct SQLite
4. **Connection retry logic**: Automatically retries database connections with exponential backoff
5. **SQLite optimizations**: Uses WAL journal mode and other SQLite performance optimizations
6. **Error diagnostic logging**: Comprehensive error logging for easier troubleshooting
7. **Fallback mechanisms**: Falls back to direct SQLite operations if SQLAlchemy fails

### Alembic Migration Enhancements

Alembic migrations include robust error handling and initialization:

1. **Pre-migration checks**: Verifies database directories exist and are writable
2. **Auto-creation**: Creates necessary directories and initializes the database file
3. **Retry logic**: Implements retry logic for migration operations
4. **Detailed diagnostics**: Provides detailed error information for failed migrations

## Getting Started

### Installation

1. Clone the repository
2. Install dependencies:
   ```
   pip install -r requirements.txt
   ```

### Running Migrations

```
alembic upgrade head
```

The migration process will automatically:
1. Create the database directory if it doesn't exist
2. Initialize the database file if needed
3. Apply all migrations with retry logic for reliability

### Starting the Application

```
uvicorn main:app --reload
```

The API will be available at http://localhost:8000

### API Documentation

- Swagger UI: http://localhost:8000/docs
- ReDoc: http://localhost:8000/redoc