from contextlib import asynccontextmanager
from fastapi import FastAPI, Depends, HTTPException, status
from fastapi.middleware.cors import CORSMiddleware
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from database import engine, get_db, Base
from models import Counter, User
from auth import (
    UserCreate,
    UserLogin,
    UserResponse,
    TokenResponse,
    get_password_hash,
    get_user_by_email,
    authenticate_user,
    create_access_token,
    get_current_user,
)


@asynccontextmanager
async def lifespan(app: FastAPI):
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
    yield


app = FastAPI(lifespan=lifespan)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["http://localhost:3000"],
    allow_methods=["*"],
    allow_headers=["*"],
    allow_credentials=True,
)


# Auth endpoints
@app.post("/api/auth/register", response_model=TokenResponse)
async def register(user_data: UserCreate, db: AsyncSession = Depends(get_db)):
    existing_user = await get_user_by_email(db, user_data.email)
    if existing_user:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered",
        )
    
    user = User(
        email=user_data.email,
        hashed_password=get_password_hash(user_data.password),
    )
    db.add(user)
    await db.commit()
    await db.refresh(user)
    
    access_token = create_access_token(data={"sub": str(user.id)})
    return TokenResponse(
        access_token=access_token,
        token_type="bearer",
        user=UserResponse(id=user.id, email=user.email),
    )


@app.post("/api/auth/login", response_model=TokenResponse)
async def login(user_data: UserLogin, db: AsyncSession = Depends(get_db)):
    user = await authenticate_user(db, user_data.email, user_data.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect email or password",
        )
    
    access_token = create_access_token(data={"sub": str(user.id)})
    return TokenResponse(
        access_token=access_token,
        token_type="bearer",
        user=UserResponse(id=user.id, email=user.email),
    )


@app.get("/api/auth/me", response_model=UserResponse)
async def get_me(current_user: User = Depends(get_current_user)):
    return UserResponse(id=current_user.id, email=current_user.email)


# Counter endpoints
async def get_or_create_counter(db: AsyncSession) -> Counter:
    result = await db.execute(select(Counter).where(Counter.id == 1))
    counter = result.scalar_one_or_none()
    if not counter:
        counter = Counter(id=1, value=0)
        db.add(counter)
        await db.commit()
        await db.refresh(counter)
    return counter


@app.get("/api/counter")
async def get_counter(
    db: AsyncSession = Depends(get_db),
    _current_user: User = Depends(get_current_user),
):
    counter = await get_or_create_counter(db)
    return {"value": counter.value}


@app.post("/api/counter/increment")
async def increment_counter(
    db: AsyncSession = Depends(get_db),
    _current_user: User = Depends(get_current_user),
):
    counter = await get_or_create_counter(db)
    counter.value += 1
    await db.commit()
    return {"value": counter.value}