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


class UserRole(str, enum.Enum):
    USER = "USER"
    PATIENT = "PATIENT"
    DOCTOR = "DOCTOR"
    ADMIN = "ADMIN"


def verify_password(plain_password: str, hashed_password: str) -> bool:
    try:
        pwd_bytes = plain_password.encode("utf-8")[:72]
        hash_bytes = hashed_password.encode("utf-8")
        return bcrypt.checkpw(pwd_bytes, hash_bytes)
    except Exception:
        return False


def get_password_hash(password: str) -> str:
    pwd_bytes = password.encode("utf-8")[:72]
    salt = bcrypt.gensalt()
    return bcrypt.hashpw(pwd_bytes, salt).decode("utf-8")


def create_access_token(
    subject: Union[str, Any],
    role: str = UserRole.PATIENT.value,
    expires_delta: Optional[timedelta] = None,
) -> str:
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(
            minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
        )

    to_encode = {
        "sub": str(subject),
        "role": role,
        "type": "access",
        "exp": expire,
        "iat": datetime.now(timezone.utc),
    }
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


def create_refresh_token(
    subject: Union[str, Any],
    role: str = UserRole.PATIENT.value,
    expires_delta: Optional[timedelta] = None,
) -> str:
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(
            days=settings.REFRESH_TOKEN_EXPIRE_DAYS
        )

    to_encode = {
        "sub": str(subject),
        "role": role,
        "type": "refresh",
        "exp": expire,
        "iat": datetime.now(timezone.utc),
    }
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


def decode_token(token: str) -> Optional[dict]:
    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM]
        )
        return payload
    except JWTError:
        return None