import asyncio
import time
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi import Request
from contextlib import asynccontextmanager
from .core.config import settings
from .api.v1 import api_router
from .core.database import SessionLocal, get_db
from .core.init_db import init_default_data
from .services.attendance_service import close_stale_attendance_sessions
from sqlalchemy.orm import Session


async def close_stale_attendance_loop():
    """Periodically close forgotten RFID check-ins after midnight."""
    while True:
        await asyncio.sleep(3600)
        db = SessionLocal()
        try:
            close_stale_attendance_sessions(db)
        except Exception as exc:
            print(f"Failed to close stale attendance sessions: {exc}")
        finally:
            db.close()


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Handle startup and shutdown events"""
    # Startup
    db: Session = next(get_db())
    try:
        init_default_data(db)
        close_stale_attendance_sessions(db)
    finally:
        db.close()

    attendance_task = asyncio.create_task(close_stale_attendance_loop())
    
    yield
    
    # Shutdown (if needed)
    attendance_task.cancel()
    try:
        await attendance_task
    except asyncio.CancelledError:
        pass


app = FastAPI(
    title=settings.APP_NAME,
    version=settings.APP_VERSION,
    openapi_url=f"{settings.API_V1_PREFIX}/openapi.json",
    lifespan=lifespan
)

# Set up CORS
app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.BACKEND_CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.middleware("http")
async def add_request_timing_headers(request: Request, call_next):
    started_at = time.perf_counter()
    response = await call_next(request)
    elapsed_ms = (time.perf_counter() - started_at) * 1000
    response.headers["X-Process-Time-Ms"] = f"{elapsed_ms:.1f}"
    response.headers["Server-Timing"] = f"app;dur={elapsed_ms:.1f}"
    return response

# Include API router
app.include_router(api_router, prefix=settings.API_V1_PREFIX)


@app.get("/")
async def root():
    return {
        "message": f"Welcome to {settings.APP_NAME}",
        "version": settings.APP_VERSION,
        "docs": "/docs"
    }


@app.get("/health")
async def health_check():
    return {"status": "healthy"}