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 app.core.config import settings
from app.core.database import Base, SessionLocal, engine
from app.routers import admin, auth, exams, export, settings as settings_router, students, subjects, wrong_questions
from app.services import ocr as ocr_service
from app.services.migrate import run_migrations
from app.services.seed import seed_admin_and_settings, seed_subjects


def resolve_frontend_dist() -> Path | None:
    backend_dir = Path(__file__).resolve().parent.parent
    dist = Path(settings.FRONTEND_DIST)
    if not dist.is_absolute():
        dist = (backend_dir / dist).resolve()
    if dist.is_dir() and (dist / "index.html").is_file():
        return dist
    return None


@asynccontextmanager
async def lifespan(app: FastAPI):
    Path(settings.UPLOAD_DIR).mkdir(parents=True, exist_ok=True)
    Base.metadata.create_all(bind=engine)
    run_migrations()
    db = SessionLocal()
    try:
        seed_subjects(db)
        seed_admin_and_settings(db)
    finally:
        db.close()
    ocr_service.warmup_ocr_engine()
    yield


app = FastAPI(title="中学成绩档案", version="1.0.0", lifespan=lifespan)

origins = [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=["*"],
)

app.include_router(auth.router, prefix="/api")
app.include_router(settings_router.router, prefix="/api")
app.include_router(admin.router, prefix="/api")
app.include_router(students.router, prefix="/api")
app.include_router(subjects.router, prefix="/api")
app.include_router(exams.router, prefix="/api")
app.include_router(wrong_questions.router, prefix="/api")
app.include_router(export.router, prefix="/api")


@app.get("/api/health")
def health():
    return {"status": "ok"}


dist_dir = resolve_frontend_dist()
if dist_dir is not None:
    assets_dir = dist_dir / "assets"
    if assets_dir.is_dir():
        app.mount("/assets", StaticFiles(directory=assets_dir), name="assets")

    @app.get("/{full_path:path}", include_in_schema=False)
    async def serve_spa(full_path: str):
        if full_path.startswith("api") or full_path.startswith("api/"):
            raise HTTPException(status_code=404, detail="Not Found")
        if full_path in ("", "index.html"):
            return FileResponse(dist_dir / "index.html")
        candidate = dist_dir / full_path
        if candidate.is_file():
            return FileResponse(candidate)
        return FileResponse(dist_dir / "index.html")