"""User authentication and management system"""
import json
import os
import hashlib
import hmac
from datetime import datetime, timedelta
from typing import Optional, Dict
from passlib.context import CryptContext
import logging

logger = logging.getLogger(__name__)

# Password hashing context
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# JWT Secret key - SHOULD BE CONFIGURED VIA ENV
SECRET_KEY = os.getenv("JWT_SECRET_KEY", "dev-secret-change-in-production")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 7  # 7 days

# Users database file
USERS_DB_FILE = "config/users.json"


class UserManager:
    """Manages user storage and authentication"""

    def __init__(self, db_file: str = USERS_DB_FILE):
        self.db_file = db_file
        self.users: Dict[str, dict] = {}
        self._load_users()

    def _load_users(self):
        """Load users from JSON file"""
        try:
            if os.path.exists(self.db_file):
                with open(self.db_file, 'r', encoding='utf-8') as f:
                    self.users = json.load(f)
                logger.info(f"Loaded {len(self.users)} users from database")
        except Exception as e:
            logger.error(f"Error loading users: {e}")
            self.users = {}

    def _save_users(self):
        """Save users to JSON file"""
        try:
            os.makedirs(os.path.dirname(self.db_file), exist_ok=True)
            with open(self.db_file, 'w', encoding='utf-8') as f:
                json.dump(self.users, f, indent=2, ensure_ascii=False, default=str)
            logger.info(f"Saved {len(self.users)} users to database")
        except Exception as e:
            logger.error(f"Error saving users: {e}")

    def get_user(self, username: str) -> Optional[dict]:
        """Get user by username"""
        return self.users.get(username)

    def get_user_by_id(self, user_id: str) -> Optional[dict]:
        """Get user by ID"""
        for user in self.users.values():
            if user.get('id') == user_id:
                return user
        return None

    def create_user(self, username: str, password: str, email: str = None, full_name: str = None) -> dict:
        """Create a new user"""
        if username in self.users:
            raise ValueError(f"Username '{username}' already exists")

        # Truncate password to 72 bytes if necessary (bcrypt limitation)
        password_bytes = password.encode('utf-8')
        if len(password_bytes) > 72:
            password = password_bytes[:72].decode('utf-8', errors='ignore')

        # Hash password
        hashed_password = pwd_context.hash(password)

        # Create user
        user = {
            "id": hashlib.sha256(username.encode()).hexdigest()[:32],
            "username": username,
            "email": email,
            "full_name": full_name,
            "hashed_password": hashed_password,
            "is_active": True,
            "created_at": datetime.now().isoformat(),
            "last_login": None
        }

        self.users[username] = user
        self._save_users()

        logger.info(f"Created user: {username}")
        return user

    def authenticate_user(self, username: str, password: str) -> Optional[dict]:
        """Authenticate user with username and password"""
        user = self.get_user(username)
        if not user:
            return None

        if not pwd_context.verify(password, user["hashed_password"]):
            return None

        # Update last login
        user["last_login"] = datetime.now().isoformat()
        self._save_users()

        return user

    def update_last_login(self, username: str):
        """Update user's last login time"""
        user = self.get_user(username)
        if user:
            user["last_login"] = datetime.now().isoformat()
            self._save_users()


# Global user manager instance
user_manager = UserManager()


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a password against a hash"""
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password: str) -> str:
    """Hash a password for storage"""
    return pwd_context.hash(password)


def create_access_token(data: dict, expires_delta: timedelta = None) -> str:
    """Create JWT access token"""
    from jose import jwt

    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 verify_token(token: str) -> Optional[str]:
    """Verify JWT token and return username"""
    from jose import jwt
    from jose.exceptions import JWTError

    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            return None
        return username
    except JWTError:
        return None


def get_current_user(token: str) -> Optional[dict]:
    """Get current user from JWT token"""
    username = verify_token(token)
    if username:
        return user_manager.get_user(username)
    return None