app/main.py

"""
Sema Translation API - Main Application
Enterprise-grade translation API with proper FastAPI structure
"""

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.trustedhost import TrustedHostMiddleware
from slowapi import _rate_limit_exceeded_handler
from slowapi.errors import RateLimitExceeded

from .core.config import settings
from .core.logging import configure_logging, get_logger
from .middleware.request_middleware import request_middleware
from .services.translation import load_models
from .api.v1.endpoints import router as v1_router, limiter

# Configure logging
configure_logging()
logger = get_logger()


def create_application() -> FastAPI:
    """Create and configure the FastAPI application"""

    app = FastAPI(
        title=settings.app_name,
        description="""
## 🌍 Enterprise Translation API

A powerful, production-ready translation API supporting 200+ languages with automatic language detection.

### 🚀 Key Features
- **Automatic Language Detection**: Detects source language if not provided
- **200+ Language Support**: Full FLORES-200 language code support
- **Rate Limiting**: 60 requests/minute per IP address
- **Usage Tracking**: Character count and request metrics
- **High Performance**: CTranslate2 optimized inference
- **Enterprise Monitoring**: Prometheus metrics and structured logging

### 🔒 Rate Limits
- **Per IP**: 60 requests per minute
- **Character Limit**: 5000 characters per request
- **Concurrent Requests**: Async processing for optimal performance

### 📊 Monitoring
- **Health Checks**: `/health` endpoint for system monitoring
- **Metrics**: `/metrics` endpoint for Prometheus integration
- **Request Tracking**: Unique request IDs for debugging

### 🌐 Language Support
Supports all FLORES-200 language codes including:
- **African Languages**: Swahili (swh_Latn), Kikuyu (kik_Latn), Luo (luo_Latn)
- **European Languages**: English (eng_Latn), French (fra_Latn), Spanish (spa_Latn)
- **And 190+ more languages**

### 📝 Usage Examples
```bash
# Basic translation with auto-detection
curl -X POST "/translate" \\
  -H "Content-Type: application/json" \\
  -d '{"text": "Habari ya asubuhi", "target_language": "eng_Latn"}'

# Translation with specified source language
curl -X POST "/translate" \\
  -H "Content-Type: application/json" \\
  -d '{"text": "Hello world", "source_language": "eng_Latn", "target_language": "swh_Latn"}'
```
        """,
        version=settings.app_version,
        docs_url="/docs",
        redoc_url="/redoc",
        openapi_url="/openapi.json",
        contact={
            "name": "Sema AI Team",
            "url": "https://github.com/lewiskimaru/sema",
            "email": "support@sema.ai"
        },
        license_info={
            "name": "MIT License",
            "url": "https://opensource.org/licenses/MIT"
        },
        servers=[
            {
                "url": "https://sematech-sema-api.hf.space",
                "description": "Production server"
            },
            {
                "url": "http://localhost:8000",
                "description": "Development server"
            }
        ]
    )

    # Add rate limiting
    app.state.limiter = limiter
    app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

    # Security middleware
    if settings.allowed_hosts != ["*"]:
        app.add_middleware(TrustedHostMiddleware, allowed_hosts=settings.allowed_hosts)

    # CORS middleware
    app.add_middleware(
        CORSMiddleware,
        allow_origins=settings.cors_origins,
        allow_credentials=True,
        allow_methods=["GET", "POST", "OPTIONS"],
        allow_headers=["*"],
    )

    # Request middleware
    app.middleware("http")(request_middleware)

    # Include API routes
    app.include_router(v1_router, prefix="/api/v1")
    app.include_router(v1_router)  # Also include at root for backward compatibility

    return app


# Create the application instance
app = create_application()


@app.on_event("startup")
async def startup_event():
    """Initialize the application on startup"""
    logger.info("application_startup", version=settings.app_version, environment=settings.environment)

    print(f"\n🎵 Starting {settings.app_name} v{settings.app_version}")
    print("🎼 Loading the Orchestra... 🦋")

    try:
        load_models()
        logger.info("models_loaded_successfully")
        print("🎉 API started successfully!")
        print(f"📊 Metrics enabled: {settings.enable_metrics}")
        print(f"🔒 Environment: {settings.environment}")
        print(f"📝 Documentation: /docs")
        print(f"📈 Metrics: /metrics")
        print(f"❤️  Health: /health")
        print(f"🔗 API v1: /api/v1/")
        print()

    except Exception as e:
        logger.error("startup_failed", error=str(e))
        print(f"❌ Startup failed: {e}")
        raise


@app.on_event("shutdown")
async def shutdown_event():
    """Cleanup on application shutdown"""
    logger.info("application_shutdown")
    print("\n👋 Shutting down Sema Translation API...")
    print("🧹 Cleaning up resources...")
    print("✅ Shutdown complete\n")


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(
        "app.main:app",
        host="0.0.0.0",
        port=8000,
        reload=settings.debug
    )