"""City Knowledge Graph Admin — FastAPI entry point."""
from __future__ import annotations

from contextlib import asynccontextmanager

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
from starlette.exceptions import HTTPException as StarletteHTTPException

from app.api import api_router
from app.db import init_pool, close_pool


class SPAStaticFiles(StaticFiles):
    """Serve the admin SPA with client-side-routing fallback.

    Any unknown path under /admin (e.g. /admin/login-v2, /admin/plaza/graph)
    falls back to index.html so React Router can handle it on a hard
    navigation or page refresh — instead of returning a 404.
    """

    async def get_response(self, path: str, scope):
        try:
            return await super().get_response(path, scope)
        except StarletteHTTPException as exc:
            if exc.status_code == 404:
                return await super().get_response("index.html", scope)
            raise


@asynccontextmanager
async def lifespan(_app: FastAPI):
    await init_pool()
    yield
    await close_pool()


app = FastAPI(
    title="ZN-KG Admin",
    version="0.1.0",
    lifespan=lifespan,
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

app.include_router(api_router)

# Serve built admin-web SPA (when available)
try:
    app.mount("/admin", SPAStaticFiles(directory="app/static/admin", html=True), name="admin-web")
except Exception:
    pass