from collections.abc import AsyncIterator
from contextlib import asynccontextmanager

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from prometheus_fastapi_instrumentator import Instrumentator

from app.api.v1.router import api_router
from app.core.config import Settings, get_settings
from app.core.logging import configure_logging, get_logger
from app.db.session import get_engine

logger = get_logger(__name__)


@asynccontextmanager
async def lifespan(_: FastAPI) -> AsyncIterator[None]:
    settings = get_settings()
    logger.info(
        "Démarrage de %s %s en environnement %s", settings.name, settings.version, settings.env
    )
    yield
    await get_engine().dispose()


def create_app(settings: Settings | None = None) -> FastAPI:
    resolved = settings or get_settings()
    configure_logging(resolved)

    application = FastAPI(
        title=resolved.name,
        version=resolved.version,
        debug=resolved.debug,
        lifespan=lifespan,
        docs_url=None if resolved.is_production else "/docs",
        redoc_url=None if resolved.is_production else "/redoc",
        openapi_url=None if resolved.is_production else "/openapi.json",
    )

    if resolved.allowed_origins:
        application.add_middleware(
            CORSMiddleware,
            allow_origins=resolved.allowed_origins,
            allow_credentials=True,
            allow_methods=["*"],
            allow_headers=["*"],
        )

    Instrumentator().instrument(application).expose(
        application, endpoint="/metrics", include_in_schema=False
    )
    application.include_router(api_router, prefix=resolved.api_prefix)

    return application