"""Authentication utilities"""
from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select

from app.config import settings
from app.database import get_db
from app.models.user import User
from app.utils import utc_now

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

# OAuth2 scheme
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a password against a hash"""
    return pwd_context.verify(plain_password, hashed_password)


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


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    """Create a JWT access token"""
    to_encode = data.copy()
    if expires_delta:
        expire = utc_now() + expires_delta
    else:
        expire = utc_now() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)

    to_encode.update({"exp": expire, "type": "access"})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


def create_refresh_token(data: dict) -> str:
    """Create a JWT refresh token"""
    to_encode = data.copy()
    expire = utc_now() + timedelta(days=settings.REFRESH_TOKEN_EXPIRE_DAYS)
    to_encode.update({"exp": expire, "type": "refresh"})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_db)
) -> User:
    """Get the current authenticated user"""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        user_id: int = payload.get("user_id")
        if user_id is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception

    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()

    if user is None:
        raise credentials_exception

    return user


async def get_current_active_user(
    current_user: User = Depends(get_current_user)
) -> User:
    """Get the current active user"""
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


async def get_current_admin_user(
    current_user: User = Depends(get_current_active_user)
) -> User:
    """Get the current admin user"""
    if not current_user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions"
        )
    return current_user