import hashlib
from datetime import datetime, timedelta

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from sqlmodel import Session, select

from app.config import settings

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")

ALGORITHM = "HS256"


def create_access_token(subject: str) -> str:
    expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    return jwt.encode({"sub": subject, "exp": expire}, settings.SECRET_KEY, algorithm=ALGORITHM)


def hash_token(token: str) -> str:
    return hashlib.sha256(token.encode()).hexdigest()


def get_current_user(token: str = Depends(oauth2_scheme)) -> str:
    # Try JWT first
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED)
        return username
    except JWTError:
        pass

    # Fallback: check API token
    from app.db import get_session
    from app.models.models import APIToken

    token_hash = hash_token(token)
    with next(get_session()) as session:
        api_token = session.exec(
            select(APIToken).where(
                APIToken.token_hash == token_hash,
                APIToken.is_active == True,
            )
        ).first()
        if api_token:
            if api_token.expires_at and api_token.expires_at < datetime.utcnow():
                raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Token expired")
            return f"api:{api_token.name}"

    raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED)