from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles
from starlette.middleware.sessions import SessionMiddleware

from app import auth
from app.config import settings
from app.routes import feed, health, me, sync, tags
from app.scheduler import shutdown_scheduler, start_scheduler


@asynccontextmanager
async def lifespan(app: FastAPI):
    start_scheduler()
    try:
        yield
    finally:
        shutdown_scheduler()


app = FastAPI(title=settings.app_name, lifespan=lifespan)

app.add_middleware(
    SessionMiddleware,
    secret_key=settings.secret_key,
    same_site="lax",
    https_only=False,
)

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

app.include_router(health.router)
app.include_router(auth.router)
app.include_router(sync.router)
app.include_router(tags.router)
app.include_router(feed.router)
app.include_router(me.router)

# The built SPA (populated by the Docker frontend build stage).
STATIC_DIR = Path(__file__).parent / "static_spa"
app.mount(
    "/assets",
    StaticFiles(directory=STATIC_DIR / "assets", check_dir=False),
    name="assets",
)


@app.get("/")
async def index() -> FileResponse:
    return FileResponse(STATIC_DIR / "index.html")


@app.get("/{full_path:path}")
async def spa_fallback(full_path: str) -> FileResponse:
    # Client-side routes fall back to index.html; real API/asset paths are matched above.
    if full_path.startswith(("api/", "auth/", "healthz", "assets/")):
        raise HTTPException(status_code=404)
    return FileResponse(STATIC_DIR / "index.html")