# DICOM Migration REST API

This REST API provides an endpoint to trigger DICOM study migration for a specific Accession Number.

## Features

- Migrate DICOM studies by Accession Number
- Token-based authentication
- Detailed JSON responses with operation status
- Proper logging and error handling
- Automatic cleanup of DICOM files after each request

## Requirements

- Python 3.9 or higher
- FastAPI
- Uvicorn
- Dependencies from the main DICOM migration project

## Installation

1. Install the required dependencies:

```bash
cd api-app
pip install -r requirements.txt
```

## Configuration

The API uses the same configuration settings as the main DICOM migration project.

### Authentication

The API uses token-based authentication. Set your token using the environment variable:

```bash
export API_TOKEN=your-secure-token
```

If no token is provided, a default token will be used (not recommended for production).

## Usage

### Starting the API Server

```bash
# Start the server on default port 8000
python run.py

# Specify a custom port
python run.py --port 9000

# Specify a custom token
python run.py --token your-secure-token

# Enable auto-reload for development
python run.py --reload
```

### API Endpoints

#### 1. Migrate Study by Accession Number

```
POST /migrate/{accession_number}
```

**Authentication:**
- Bearer token in Authorization header

**Response:**

Successful migration:
```json
{
  "success": true,
  "message": "Successfully migrated study for accession number: ABC12345",
  "details": {
    "study_uid": "1.2.826.0.1.3680043.9.7307.1.123456",
    "his_integration_success": true
  }
}
```

Failed migration:
```json
{
  "success": false,
  "message": "Failed to process study: Study not found",
  "details": null
}
```

## Example API Calls

### Using curl

```bash
# Migrate a study by accession number
curl -X POST "http://localhost:8000/migrate/ABC12345" \
  -H "Authorization: Bearer your-token" \
  -H "Content-Type: application/json"
```

### Using Python requests

```python
import requests

url = "http://localhost:8000/migrate/ABC12345"
headers = {
    "Authorization": "Bearer your-token",
    "Content-Type": "application/json"
}

response = requests.post(url, headers=headers)
print(response.json())
```

## Logs

The API logs are stored in the `logs/api.log` file. The log includes information about:

- API startup and shutdown
- Migration requests
- Errors during migration process
- Integration with HIS results

## Troubleshooting

1. **Authentication Error**:
   - Make sure you're providing the correct token in the Authorization header
   - Check that the token format is `Bearer your-token`

2. **Study Not Found**:
   - Verify that the accession number is correct
   - Check if the PACS server is reachable
   - Verify that the study exists in the source PACS

3. **Connection Error**:
   - Check PACS connectivity
   - Verify network settings in `config/settings.py`

## Integrating with External Systems

You can call this API from other systems to trigger DICOM migrations for specific studies:

1. Obtain the API token
2. Make a POST request to `/migrate/{accession_number}`
3. Handle the JSON response based on the `success` field

## Technical Details

### DICOM File Cleanup

The API implements a robust cleanup mechanism to ensure that DICOM files are always removed after processing:

1. **Exit Handlers**: The application registers cleanup handlers via Python's `atexit` module and signal handlers for graceful cleanup during server shutdown.

2. **Per-Request Cleanup**: After each migration request completes (whether successful or not), the API explicitly calls the cleanup function to remove all DICOM files associated with the study.

3. **Directory Registration**: All temporary directories created during the migration process are registered for cleanup, ensuring no files are left behind.

This dual approach (exit handlers + explicit cleanup) ensures that:
- DICOM files are immediately removed after each API request completes
- No files are left behind even if the server crashes or is terminated abnormally
- Disk space is efficiently managed during high-volume operations

### Authentication

The API uses Bearer token authentication. The token is specified through: