"""FluentGerman.ai — Authentication & authorization utilities."""

from datetime import datetime, timedelta, timezone

import bcrypt
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import get_settings
from app.database import get_db
from app.models import User

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")


def hash_password(password: str) -> str:
    return bcrypt.hashpw(password.encode(), bcrypt.gensalt()).decode()


def verify_password(plain: str, hashed: str) -> bool:
    return bcrypt.checkpw(plain.encode(), hashed.encode())


def create_access_token(data: dict) -> str:
    settings = get_settings()
    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.access_token_expire_minutes)
    to_encode = {**data, "exp": expire}
    return jwt.encode(to_encode, settings.secret_key, algorithm=settings.algorithm)


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_db),
) -> User:
    credentials_exc = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Invalid credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, get_settings().secret_key, algorithms=[get_settings().algorithm])
        user_id: int | None = payload.get("sub")
        if user_id is None:
            raise credentials_exc
    except JWTError:
        raise credentials_exc

    result = await db.execute(select(User).where(User.id == int(user_id)))
    user = result.scalar_one_or_none()
    if user is None or not user.is_active:
        raise credentials_exc
    return user


async def require_admin(user: User = Depends(get_current_user)) -> User:
    if not user.is_admin:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin access required")
    return user