from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
import bcrypt
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session
import os

import models
from database import get_db

SECRET_KEY = os.environ.get(
    "SECRET_KEY", "insecure-default-key-change-in-production-use-env-var"
)
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 7  # 7 days

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


def verify_password(plain: str, hashed: str) -> bool:
    return bcrypt.checkpw(plain.encode("utf-8"), hashed.encode("utf-8"))


def get_password_hash(password: str) -> str:
    return bcrypt.hashpw(password.encode("utf-8"), bcrypt.gensalt()).decode("utf-8")


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + (
        expires_delta or timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    )
    to_encode["exp"] = expire
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)


def get_current_user(
    token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)
) -> models.User:
    exc = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if not username:
            raise exc
    except JWTError:
        raise exc
    user = db.query(models.User).filter(models.User.username == username).first()
    if not user:
        raise exc
    return user


def get_current_admin(
    current_user: models.User = Depends(get_current_user),
) -> models.User:
    if not current_user.is_admin:
        raise HTTPException(status_code=403, detail="Admin access required")
    return current_user