"""FastAPI application factory."""
from __future__ import annotations

from collections.abc import AsyncIterator
from contextlib import asynccontextmanager

from fastapi import FastAPI

from app.api.routes import api_router
from app.core.cache import init_cache, shutdown_cache
from app.core.config import settings
from app.core.middleware.cache_monitor import CacheAvailabilityMiddleware


def create_app() -> FastAPI:
    """Build FastAPI application instance."""
    @asynccontextmanager
    async def lifespan(_: FastAPI) -> AsyncIterator[None]:
        await init_cache()
        try:
            yield
        finally:
            await shutdown_cache()

    application = FastAPI(title=settings.project_name, version=settings.version, lifespan=lifespan)
    application.include_router(api_router)
    application.add_middleware(CacheAvailabilityMiddleware)
    return application


app = create_app()