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

from database.models import User
from database.session import get_db

# Security configuration
SECRET_KEY = os.getenv("SECRET_KEY", "auranexus-secret-key-change-in-production")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# For demo purposes, using a simple hash function
# In production, use proper password hashing like bcrypt
security = HTTPBearer()

def verify_password(plain_password: str, hashed_password: str) -> bool:
    # Simple hash comparison for demo purposes
    return get_password_hash(plain_password) == hashed_password

def get_password_hash(password: str) -> str:
    # Simple hash for demo purposes
    return hashlib.sha256(password.encode()).hexdigest()

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db)
) -> User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(credentials.credentials, SECRET_KEY, algorithms=[ALGORITHM])
        user_id: str = payload.get("sub")
        if user_id is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    
    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise credentials_exception
    return user