"""Säkerhetsfunktioner: lösenordshashning, JWT-hantering, roller."""
from datetime import datetime, timedelta
from typing import Optional, Union
from uuid import UUID

from jose import jwt, JWTError
from passlib.context import CryptContext

from app.config import get_settings
from app.models import UserRole

settings = get_settings()

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


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


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


def create_access_token(subject: Union[str, UUID], expires_delta: Optional[timedelta] = None) -> str:
    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), "type": "access"}
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


def create_refresh_token(subject: Union[str, UUID]) -> str:
    expire = datetime.utcnow() + timedelta(days=settings.REFRESH_TOKEN_EXPIRE_DAYS)
    to_encode = {"exp": expire, "sub": str(subject), "type": "refresh"}
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


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


# ─── Role-based access helpers ────────────────────────

ROLE_HIERARCHY = {
    UserRole.VIEWER: 0,
    UserRole.ANALYST: 1,
    UserRole.MANAGER: 2,
    UserRole.ADMIN: 3,
}


def role_level(role: UserRole) -> int:
    return ROLE_HIERARCHY.get(role, 0)


def can_manage(manager_role: UserRole, target_role: UserRole) -> bool:
    """Returnerar True om manager_role har högre eller lika nivå som target_role."""
    return role_level(manager_role) >= role_level(target_role)


def require_role(min_role: UserRole):
    """Factory för roll-krav. Används i dependency-kedjan."""
    from fastapi import HTTPException, status

    def checker(current_user_role: UserRole):
        if role_level(current_user_role) < role_level(min_role):
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail=f"Requires role {min_role.value} or higher",
            )
        return True

    return checker