import json
from typing import Any

from fastapi import APIRouter, Request, Response
from fastapi.responses import FileResponse, HTMLResponse, RedirectResponse

from resonance_engine.api import security
from resonance_engine.config import settings

router = APIRouter(include_in_schema=False)


def read_manifest() -> dict[str, Any]:
    """Return the Vite manifest, or {} if the dashboard hasn't been built yet."""
    for candidate in [
        settings.dashboard_dir / ".vite" / "manifest.json",  # Vite 5+
        settings.dashboard_dir / "manifest.json",  # Vite 4
    ]:
        if candidate.exists():
            return json.loads(candidate.read_text())
    return {}


def _not_built() -> HTMLResponse:
    return HTMLResponse(
        "<h1>503 — Dashboard not built</h1>"
        "<p>Run <code>make build-dashboard</code> and restart the server.</p>",
        status_code=503,
    )


def _serve_dashboard(full_path: str, request: Request) -> Response:
    if not settings.dashboard_dir.exists():
        return _not_built()

    if full_path:
        candidate = settings.dashboard_dir / full_path
        if candidate.is_file():
            return FileResponse(candidate)

    if not security.is_authenticated(request) and full_path != "login":
        return RedirectResponse("/dashboard/login")

    index = settings.dashboard_dir / "index.html"
    if not index.exists():
        return _not_built()

    # index.html must not be cached — it contains hashed asset URLs that change
    # on every build. Hashed assets themselves are immutably cacheable by default.
    return FileResponse(
        index,
        headers={"Cache-Control": "no-cache, no-store, must-revalidate"},
    )


# response_model=None: return type is a Starlette Response subclass, not a Pydantic model
@router.get("/dashboard", response_model=None)
async def serve_dashboard_root(request: Request) -> Response:
    return _serve_dashboard("", request)


@router.get("/dashboard/{full_path:path}", response_model=None)
async def serve_dashboard_spa(request: Request, full_path: str) -> Response:
    return _serve_dashboard(full_path, request)