"""FastAPI-Anwendung.

Ein einzelner Prozess liefert sowohl die JSON-API unter ``/api/*`` als auch das
gebaute Frontend (``web/dist``) aus – hinter dem Nginx Proxy Manager des Nutzers.
Beim Start werden die Alembic-Migrationen angewandt und der erste Admin angelegt.
"""

from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import APIRouter, FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles

from .branding import APP_NAME, VERSION, git_sha
from .config import get_settings
from .database import SessionLocal
from .migrate import upgrade_to_head
from .routers import auth, settings as settings_router, users
from .seed import ensure_first_admin

settings = get_settings()

# Pfad zum gebauten Frontend (im Dev von Vite selbst ausgeliefert -> fehlt hier).
REPO_ROOT = Path(__file__).resolve().parent.parent.parent
DIST_DIR = REPO_ROOT / "web" / "dist"


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Schema auf den aktuellen Stand bringen (idempotent).
    upgrade_to_head()
    db = SessionLocal()
    try:
        ensure_first_admin(db)
    finally:
        db.close()
    yield


app = FastAPI(title=APP_NAME, version=VERSION, lifespan=lifespan)

# CORS nur, wenn ausdrücklich konfiguriert (Standard: gleiche Herkunft, aus).
if settings.cors_origins.strip():
    origins = (
        ["*"]
        if settings.cors_origins.strip() == "*"
        else [o.strip() for o in settings.cors_origins.split(",") if o.strip()]
    )
    app.add_middleware(
        CORSMiddleware,
        allow_origins=origins,
        allow_credentials=True,
        allow_methods=["*"],
        allow_headers=["*"],
    )

# --- API -------------------------------------------------------------------
api = APIRouter(prefix="/api")


@api.get("/health", tags=["meta"])
def health() -> dict:
    return {"status": "ok"}


@api.get("/version", tags=["meta"])
def version() -> dict:
    return {"name": APP_NAME, "version": VERSION, "git_sha": git_sha()}


api.include_router(auth.router)
api.include_router(users.router)
api.include_router(settings_router.router)

app.include_router(api)


# --- Frontend (SPA) --------------------------------------------------------
# Gebaute, gehashte Assets unter /assets aggressiv cachebar ausliefern; alle
# übrigen (nicht-/api) Pfade auf index.html abbilden, damit Client-seitige
# Routen wie /accounts direkt aufrufbar sind (verlinkbar).
if DIST_DIR.exists():
    assets_dir = DIST_DIR / "assets"
    if assets_dir.exists():
        app.mount("/assets", StaticFiles(directory=assets_dir), name="assets")

    @app.get("/{full_path:path}", include_in_schema=False)
    async def spa(full_path: str):
        # /api-Pfade, die keine echte Route trafen, sind echte 404 (kein SPA).
        if full_path.startswith("api"):
            raise HTTPException(status_code=404, detail="Not Found")
        candidate = DIST_DIR / full_path
        if full_path and candidate.is_file():
            return FileResponse(candidate)
        return FileResponse(DIST_DIR / "index.html", headers={"Cache-Control": "no-cache"})