from datetime import datetime, timedelta
from jose import JWTError, jwt
from fastapi import HTTPException, status, Depends
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.ext.asyncio import AsyncSession
from . import schemas, database, models
from sqlalchemy import select

SECRET_KEY = "a866319fb3f839e693191763019cf0dd3d78473d4d3d06d99afb3ef0b14bd0d5"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

def create_access_token(data: dict):
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

async def get_current_user(token: str = Depends(oauth2_scheme), db: AsyncSession = Depends(database.get_db)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    stmt = select(models.User).where(models.User.username == username)
    result = await db.execute(stmt)
    user = result.scalars().first()
    if user is None:
        raise credentials_exception
    return user