"""
Zero-LLM Multi-Agent Excel/CSV Editing Engine
==============================================

Production-ready FastAPI server.  No LLM call anywhere.

Usage:
    uvicorn main:app --host 0.0.0.0 --port 8000 --reload

Endpoints:
    POST   /api/upload                Upload CSV/Excel/Parquet
    GET    /api/download/{session_id}  Download as CSV
    GET    /api/session/{session_id}   Session metadata
    DELETE /api/session/{session_id}   Delete session
    GET    /api/history/{session_id}   Command history
    WS     /ws/{session_id}            Real-time command channel
"""
from __future__ import annotations

from contextlib import asynccontextmanager
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware

from api.routes import router as rest_router
from api.websocket import websocket_handler
from services.audit_service import close as close_audit


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Startup / shutdown hooks."""
    yield
    await close_audit()


app = FastAPI(
    title="Zero-LLM Data Engine",
    description="Natural-language Excel/CSV editing — no LLM, pure Python + Polars",
    version="1.0.0",
    lifespan=lifespan,
)

# CORS — allow all origins for dev; restrict in production
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Mount REST routes under /api
app.include_router(rest_router, prefix="/api")

# WebSocket endpoint
from fastapi import WebSocket
@app.websocket("/ws/{session_id}")
async def ws_endpoint(ws: WebSocket, session_id: str):
    await websocket_handler(ws, session_id)


# ── Health check ────────────────────────────────────────────────────

@app.get("/", tags=["health"])
async def root():
    return {"status": "running", "engine": "zero-llm", "version": "1.0.0"}