"""Admin routes: index, favicon, browse-dirs, robots."""
from __future__ import annotations

from pathlib import Path

from fastapi import APIRouter, HTTPException
from fastapi.responses import FileResponse, PlainTextResponse, Response

from core.constants import STATIC_DIR

router = APIRouter()

_BROWSE_BLOCKED: frozenset[str] = frozenset({
    "/proc", "/sys", "/dev", "/run", "/boot",
})


@router.get("/")
async def index():
    return FileResponse(
        STATIC_DIR / "index.html",
        headers={"Cache-Control": "no-store, max-age=0"},
    )


@router.get("/favicon.ico")
async def favicon():
    return Response(status_code=204)


@router.get("/api/browse-dirs")
async def browse_dirs(path: str = "/"):
    p = Path(path).resolve()
    p_str = str(p)
    if any(p_str == b or p_str.startswith(b + "/") for b in _BROWSE_BLOCKED):
        raise HTTPException(403, "Access to this path is not permitted")
    if not p.is_dir():
        raise HTTPException(404, "Not a directory")
    try:
        entries = sorted(
            [d.name for d in p.iterdir() if d.is_dir() and not d.name.startswith(".")],
            key=str.lower,
        )
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    parent = str(p.parent) if p.parent != p else None
    return {"path": str(p), "parent": parent, "dirs": entries}


@router.get("/robots.txt", response_class=PlainTextResponse)
async def robots_txt():
    return "User-agent: *\nDisallow: /"