"""FastAPI application entrypoint — ``create_app()`` factory + lifespan."""

from __future__ import annotations

from collections.abc import AsyncIterator
from contextlib import asynccontextmanager

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import RedirectResponse

from app.core.errors import register_exception_handlers
from app.core.logging import configure_logging
from app.core.settings import get_settings
from app.routers import health


@asynccontextmanager
async def _lifespan(_: FastAPI) -> AsyncIterator[None]:
    configure_logging()
    # M2: warm the fast engine here, then flip /health readiness once weights load.
    yield


def create_app() -> FastAPI:
    settings = get_settings()
    app = FastAPI(
        title=f"{settings.app_name} API",
        version=settings.version,
        description=(
            "Uzbek speech-to-text service. Errors follow RFC 9457 "
            "(application/problem+json). No authentication by design — see the README."
        ),
        lifespan=_lifespan,
    )

    app.add_middleware(
        CORSMiddleware,
        allow_origins=settings.cors_origins,
        allow_methods=["GET", "POST", "OPTIONS"],
        allow_headers=["*"],
    )

    register_exception_handlers(app)
    app.include_router(health.router)

    @app.get("/", include_in_schema=False)
    async def _root() -> RedirectResponse:
        # M3 mounts the Gradio UI here; until then, send visitors to the API docs.
        return RedirectResponse(url="/docs")

    return app


app = create_app()