import bcrypt
from datetime import datetime, timedelta
from typing import Any, Union
from jose import jwt
from backend.app.core.config import settings

def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify if a plain text password matches its hashed bcrypt value."""
    if not hashed_password:
        return False
    try:
        return bcrypt.checkpw(
            plain_password.encode("utf-8"), 
            hashed_password.encode("utf-8")
        )
    except Exception:
        return False

def get_password_hash(password: str) -> str:
    """Generate a secure bcrypt hash of a plain text password."""
    # Generate salt and hash the password
    salt = bcrypt.gensalt()
    hashed = bcrypt.hashpw(password.encode("utf-8"), salt)
    return hashed.decode("utf-8")

def create_access_token(subject: Union[str, Any], expires_delta: timedelta = None) -> str:
    """Generate a JWT access token for a subject (usually user phone)."""
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode = {"exp": expire, "sub": str(subject)}
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt