# app/core/static_files.py
"""Static file serving with cache-busting-aware headers.

In production, JS/CSS/etc. URLs are versioned by `static_v(...)` in
`app/templates_config.py` (appends `?v=<commit-sha>`), so the file at a
given URL never changes within a deploy. We can therefore tell browsers
to cache it for a year and skip revalidation.

In development the version still flips per commit, but the developer often
edits files without committing, so we serve `no-cache` to force conditional
GETs (the browser still gets a 304 when nothing changed).
"""

from fastapi.staticfiles import StaticFiles
from starlette.responses import FileResponse

from app.core.environment import is_development

_IMMUTABLE = "public, max-age=31536000, immutable"
_NO_CACHE = "no-cache"


class CachedStaticFiles(StaticFiles):
    """StaticFiles that sets Cache-Control based on environment."""

    def file_response(self, *args, **kwargs) -> FileResponse:
        response = super().file_response(*args, **kwargs)
        response.headers["Cache-Control"] = (
            _NO_CACHE if is_development() else _IMMUTABLE
        )
        return response