"""Точка входа FastAPI."""

from __future__ import annotations

import time
import uuid
from collections.abc import AsyncGenerator, Awaitable, Callable
from contextlib import asynccontextmanager

import structlog
from fastapi import FastAPI, Request, Response
from fastapi.middleware.cors import CORSMiddleware
from starlette.middleware.base import BaseHTTPMiddleware

from app.api.v1.router import api_router
from app.core.config import settings
from app.core.logging import configure_logging, get_logger
from app.db.session import engine
from app.services.task_queue import close_task_queue

log = get_logger(__name__)


@asynccontextmanager
async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
    configure_logging()
    log.info("app_starting", environment=settings.environment, version=app.version)
    yield
    await close_task_queue()
    await engine.dispose()
    log.info("app_stopped")


class RequestContextMiddleware(BaseHTTPMiddleware):
    """Присваивает каждому запросу идентификатор и пишет структурный access-лог.

    request_id возвращается заголовком `X-Request-ID`: по нему оператор,
    столкнувшийся с ошибкой, находится в логах за одну команду.
    """

    async def dispatch(
        self, request: Request, call_next: Callable[[Request], Awaitable[Response]]
    ) -> Response:
        request_id = request.headers.get("x-request-id") or uuid.uuid4().hex
        structlog.contextvars.clear_contextvars()
        structlog.contextvars.bind_contextvars(request_id=request_id)

        started = time.perf_counter()
        try:
            response = await call_next(request)
        except Exception:
            log.exception(
                "request_failed",
                method=request.method,
                path=request.url.path,
                duration_ms=round((time.perf_counter() - started) * 1000, 2),
            )
            raise

        duration_ms = round((time.perf_counter() - started) * 1000, 2)
        # Health-check'и опрашиваются постоянно и засоряют лог.
        if not request.url.path.startswith("/api/v1/health"):
            log.info(
                "request",
                method=request.method,
                path=request.url.path,
                status=response.status_code,
                duration_ms=duration_ms,
            )

        response.headers["X-Request-ID"] = request_id
        return response


def create_app() -> FastAPI:
    configure_logging()

    app = FastAPI(
        title=settings.project_name,
        version="0.1.0",
        description="Фіскалізація замовлень через Checkbox",
        lifespan=lifespan,
        # В проде интерактивная документация закрыта: схема API — лишняя
        # подсказка для того, кто ищет незащищённый эндпоинт.
        docs_url=None if settings.is_production else "/docs",
        redoc_url=None if settings.is_production else "/redoc",
        openapi_url=None if settings.is_production else "/openapi.json",
    )

    app.add_middleware(RequestContextMiddleware)

    if settings.cors_origins:
        app.add_middleware(
            CORSMiddleware,
            allow_origins=settings.cors_origins,
            allow_credentials=True,
            allow_methods=["*"],
            allow_headers=["*"],
            expose_headers=["X-Request-ID"],
        )

    app.include_router(api_router, prefix="/api/v1")
    return app


app = create_app()