from datetime import datetime, timedelta, timezone
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import HTTPException, status, Depends
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from dotenv import load_dotenv
import os

load_dotenv()

SECRET_KEY = os.getenv("SECRET_KEY", "change-this-secret-key-in-production")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_HOURS = 24

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


def hash_password(password: str) -> str:
    return pwd_context.hash(password)


def verify_password(plain: str, hashed: str) -> bool:
    return pwd_context.verify(plain, hashed)


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + (
        expires_delta or timedelta(hours=ACCESS_TOKEN_EXPIRE_HOURS)
    )
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)


def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(bearer_scheme),
) -> str:
    token = credentials.credentials
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Invalid or expired token",
        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
        return username
    except JWTError:
        raise credentials_exception