from fastapi import FastAPI, WebSocket, WebSocketDisconnect, Depends
from fastapi.middleware.cors import CORSMiddleware
from sqlalchemy import create_engine, Column, Integer, String, DateTime
from sqlalchemy.orm import declarative_base, sessionmaker, Session
import datetime

# --- DATABASE SETUP (SQLAlchemy + SQLite) ---
SQLALCHEMY_DATABASE_URL = "sqlite:///./volatile.db"

# check_same_thread=False is needed for SQLite in FastAPI
engine = create_engine(SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

# Define the Message Model
class Message(Base):
    __tablename__ = "messages"
    id = Column(Integer, primary_key=True, index=True)
    sender = Column(String, index=True)
    content = Column(String)
    timestamp = Column(DateTime, default=datetime.datetime.utcnow)

# Create the database tables
Base.metadata.create_all(bind=engine)

# Dependency to get DB session
def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

# --- FASTAPI APP SETUP ---
app = FastAPI(title="Volatile API")

# Allow your Next.js Vercel frontend to connect
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"], # Update this to your Vercel domain later!
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# --- ROUTES ---
@app.get("/")
def read_root():
    return {"status": "Volatile Backend is running!", "database": "SQLite connected"}

# Example route to test saving a message to SQLite
@app.post("/test-message")
def create_test_message(sender: str, content: str, db: Session = Depends(get_db)):
    new_msg = Message(sender=sender, content=content)
    db.add(new_msg)
    db.commit()
    db.refresh(new_msg)
    return {"message": "Saved to Volatile memory", "data": new_msg}

# --- WEBSOCKETS ---
@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    try:
        while True:
            data = await websocket.receive_text()
            await websocket.send_text(f"Echo from Volatile Server: {data}")
    except WebSocketDisconnect:
        print("Client disconnected")