from typing import Annotated
from datetime import datetime, timedelta, timezone
from fastapi import Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer
from passlib.context import CryptContext
from sqlalchemy.orm import Session
from jose import JWTError, jwt


from app.config import ALGORITHM, SECRET_KEY
from app.db import get_db
from app.sql import models


pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")


def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)


def get_user(db: Session, username: str):
    return db.query(models.User).filter(models.User.username == username).first()


def authenticate_user(db: Session, username: str, password: str):
    user = get_user(db, username)
    if not user:
        return False
    if not verify_password(password, user.password):
        return False
    return user


def create_access_token(data: dict, expires_delta: timedelta | None = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)], db: Annotated[Session, Depends(get_db)]):
    credentials_exception = HTTPException(
        status_code=401, detail="Could not validate credentials")
    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
    user = get_user(db, username)
    if user is None:
        raise credentials_exception
    return user