# ================================================================
# services/training/app/main.py - FIXED VERSION
# ================================================================
"""
Training Service Main Application
Enhanced with proper error handling, monitoring, and lifecycle management
"""

import structlog
import asyncio
from contextlib import asynccontextmanager
from fastapi import FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.trustedhost import TrustedHostMiddleware
from fastapi.responses import JSONResponse
import uvicorn

from app.core.config import settings
from app.core.database import initialize_training_database, cleanup_training_database
from app.api import training, models
from app.services.messaging import setup_messaging, cleanup_messaging
from shared.monitoring.logging import setup_logging
from shared.monitoring.metrics import MetricsCollector
# REMOVED: from shared.auth.decorators import require_auth

# Setup structured logging
setup_logging("training-service", settings.LOG_LEVEL)
logger = structlog.get_logger()

# Initialize metrics collector
metrics_collector = MetricsCollector("training-service")

@asynccontextmanager
async def lifespan(app: FastAPI):
    """
    Application lifespan manager for startup and shutdown events
    """
    # Startup
    logger.info("Starting Training Service", version="1.0.0")
    
    try:
        # Initialize database
        logger.info("Initializing database connection")
        await initialize_training_database()
        logger.info("Database initialized successfully")
        
        # Initialize messaging
        logger.info("Setting up messaging")
        await setup_messaging()
        logger.info("Messaging setup completed")
        
        # Start metrics server
        logger.info("Starting metrics server")
        metrics_collector.start_metrics_server(8080)
        logger.info("Metrics server started on port 8080")
        
        # Store metrics collector in app state
        app.state.metrics_collector = metrics_collector
        
        # Mark service as ready
        app.state.ready = True
        logger.info("Training Service startup completed successfully")
        
        yield
        
    except Exception as e:
        logger.error("Failed to start Training Service", error=str(e))
        app.state.ready = False
        raise
    
    # Shutdown
    logger.info("Shutting down Training Service")
    
    try:
        # Stop metrics server
        if hasattr(app.state, 'metrics_collector'):
            await app.state.metrics_collector.shutdown()
        
        # Cleanup messaging
        await cleanup_messaging()
        logger.info("Messaging cleanup completed")
        
        # Close database connections
        await cleanup_training_database()
        logger.info("Database connections closed")
        
    except Exception as e:
        logger.error("Error during shutdown", error=str(e))
    
    logger.info("Training Service shutdown completed")

# Create FastAPI application with lifespan
app = FastAPI(
    title="Bakery Training Service",
    description="ML training service for bakery demand forecasting",
    version="1.0.0",
    docs_url="/docs",
    redoc_url="/redoc",
    lifespan=lifespan
)

# Add middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.CORS_ORIGINS_LIST,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


# Request middleware for logging and metrics
@app.middleware("http")
async def process_request(request: Request, call_next):
    """Process requests with logging and metrics"""
    start_time = asyncio.get_event_loop().time()
    
    try:
        response = await call_next(request)
        duration = asyncio.get_event_loop().time() - start_time
        
        logger.info(
            "Request completed",
            method=request.method,
            path=request.url.path,
            status_code=response.status_code,
            duration_ms=round(duration * 1000, 2)
        )
        
        # Update metrics
        metrics_collector.record_request(
            method=request.method,
            endpoint=request.url.path,
            status_code=response.status_code,
            duration=duration
        )
        
        return response
        
    except Exception as e:
        duration = asyncio.get_event_loop().time() - start_time
        
        logger.error(
            "Request failed",
            method=request.method,
            path=request.url.path,
            error=str(e),
            duration_ms=round(duration * 1000, 2)
        )
        
        metrics_collector.increment_counter("http_requests_failed_total")
        raise

# Exception handlers
@app.exception_handler(Exception)
async def global_exception_handler(request: Request, exc: Exception):
    """Global exception handler for unhandled errors"""
    logger.error(
        "Unhandled exception",
        path=request.url.path,
        method=request.method,
        error=str(exc),
        exc_info=True
    )
    
    metrics_collector.increment_counter("unhandled_exceptions_total")
    
    return JSONResponse(
        status_code=500,
        content={
            "detail": "Internal server error",
            "error_id": structlog.get_logger().new().info("Error logged", error=str(exc))
        }
    )

# Include API routers
app.include_router(training.router, prefix="/api/v1", tags=["training"])
app.include_router(models.router, prefix="/api/v1", tags=["models"])


# Health check endpoints
@app.get("/health")
async def health_check():
    """Basic health check endpoint"""
    return {
        "status": "healthy" if app.state.ready else "starting",
        "service": "training-service",
        "version": "1.0.0",
        "timestamp": structlog.get_logger().new().info("Health check")
    }

@app.get("/health/ready")
async def readiness_check():
    """Kubernetes readiness probe endpoint"""
    checks = {
        "database": await get_db_health(),
        "application": getattr(app.state, 'ready', False)
    }
    
    if all(checks.values()):
        return {"status": "ready", "checks": checks}
    else:
        return JSONResponse(
            status_code=503,
            content={"status": "not ready", "checks": checks}
        )

@app.get("/metrics")
async def get_metrics():
    """Prometheus metrics endpoint"""
    if hasattr(app.state, 'metrics_collector'):
        return app.state.metrics_collector.get_metrics()
    return {"status": "metrics not available"}

@app.get("/health/live")
async def liveness_check():
    return {"status": "alive"}

@app.get("/health/ready") 
async def readiness_check():
    ready = getattr(app.state, 'ready', True)
    return {"status": "ready" if ready else "not ready"}

@app.get("/")
async def root():
    return {"service": "training-service", "version": "1.0.0"}

if __name__ == "__main__":
    uvicorn.run(
        "app.main:app",
        host="0.0.0.0",
        port=settings.PORT,
        reload=settings.DEBUG,
        log_level=settings.LOG_LEVEL.lower()
    )