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 HTTPBearer, HTTPAuthorizationCredentials
import os

# JWT Configuration
SECRET_KEY = os.getenv("JWT_SECRET_KEY", "your-secret-key-change-this-in-production")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 7  # 7 days

# HTTP Bearer token scheme
security = HTTPBearer()


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a password against its hash"""
    return bcrypt.checkpw(plain_password.encode('utf-8'), hashed_password.encode('utf-8'))


def get_password_hash(password: str) -> str:
    """Hash a password using bcrypt"""
    salt = bcrypt.gensalt()
    hashed = bcrypt.hashpw(password.encode('utf-8'), salt)
    return hashed.decode('utf-8')


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 = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


def decode_access_token(token: str) -> dict:
    """Decode and verify a JWT token"""
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        return payload
    except JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )


async def get_current_user(credentials: HTTPAuthorizationCredentials = Depends(security)) -> dict:
    """Dependency to get the current authenticated user from JWT token"""
    try:
        token = credentials.credentials
        payload = decode_access_token(token)
        
        user_id = payload.get("sub")
        if user_id is None:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Could not validate credentials - no user_id",
                headers={"WWW-Authenticate": "Bearer"},
            )
        
        # Convert to int if it's a string
        if isinstance(user_id, str):
            user_id = int(user_id)
        
        return {"user_id": user_id, "username": payload.get("username")}
    except Exception as e:
        print(f"Auth error: {e}")
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail=f"Could not validate credentials: {str(e)}",
            headers={"WWW-Authenticate": "Bearer"},
        )