from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from sqlalchemy import text

from app.config import settings
from app.db import AsyncSessionLocal, engine
from app.routers import routers


@asynccontextmanager
async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
    async with AsyncSessionLocal() as session:
        try:
            await session.execute(text("SELECT 1"))
        except Exception:
            import logging
            logging.getLogger(__name__).warning("Database connectivity check failed on startup")
    yield
    await engine.dispose()


app = FastAPI(
    title=settings.app_name,
    debug=settings.debug,
    lifespan=lifespan,
)

allow_origins = ["*"] if settings.debug else []
app.add_middleware(
    CORSMiddleware,
    allow_origins=allow_origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

for router in routers:
    app.include_router(router, prefix=settings.api_v1_prefix)


@app.get("/health")
async def health() -> JSONResponse:
    db_status = "connected"
    try:
        async with AsyncSessionLocal() as session:
            await session.execute(text("SELECT 1"))
    except Exception:
        db_status = "unreachable"

    content = {
        "status": "ok" if db_status == "connected" else "degraded",
        "service": settings.app_name,
        "database": db_status,
    }
    status_code = 200 if db_status == "connected" else 503
    return JSONResponse(status_code=status_code, content=content)