from pathlib import Path

from fastapi import FastAPI
from fastapi import Response
from fastapi import status
from fastapi.responses import RedirectResponse
from fastapi.staticfiles import StaticFiles


def mount_docs_static(app: FastAPI, *, docs_route: str, site_dir: Path) -> None:
    """Mount the pre-built static docs site, or expose a clear missing-build response."""
    normalized_route = docs_route.rstrip("/") or "/docs"
    docs_root = f"{normalized_route}/"

    async def redirect_to_docs_root() -> RedirectResponse:
        return RedirectResponse(
            url=docs_root, status_code=status.HTTP_307_TEMPORARY_REDIRECT
        )

    app.add_api_route(
        normalized_route,
        redirect_to_docs_root,
        methods=["GET", "HEAD"],
        include_in_schema=False,
    )

    if site_dir.is_dir():
        app.mount(
            normalized_route,
            StaticFiles(directory=site_dir, html=True),
            name="docs",
        )
        return

    async def docs_not_built() -> Response:
        return Response(
            content=(
                "Static docs have not been built yet. "
                "Run `uv run zensical build` before using this route."
            ),
            media_type="text/plain",
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
        )

    app.add_api_route(
        normalized_route,
        docs_not_built,
        methods=["GET"],
        include_in_schema=False,
    )
    app.add_api_route(
        f"{normalized_route}/{{path:path}}",
        docs_not_built,
        methods=["GET"],
        include_in_schema=False,
    )