# Utility functions for the application
import logging
from functools import wraps
from flask import jsonify, request, session
from datetime import datetime

logger = logging.getLogger(__name__)


class APIError(Exception):
    """Custom exception for API errors"""
    def __init__(self, message, status_code=400, details=None):
        self.message = message
        self.status_code = status_code
        self.details = details or {}
        super().__init__(self.message)


def error_response(error_message, status_code=400, details=None):
    """Create a standardized error response"""
    response = {
        'success': False,
        'error': error_message,
        'timestamp': datetime.now().isoformat()
    }
    if details:
        response['details'] = details
    return jsonify(response), status_code


def success_response(data=None, message="Success", status_code=200):
    """Create a standardized success response"""
    response = {
        'success': True,
        'message': message,
        'timestamp': datetime.now().isoformat()
    }
    if data is not None:
        response['data'] = data
    return jsonify(response), status_code


def require_auth(f):
    """Decorator to require authentication"""
    @wraps(f)
    def decorated_function(*args, **kwargs):
        # Check for API key in headers
        api_key = request.headers.get('X-API-Key')
        from config import get_config
        config = get_config()
        
        if not api_key or api_key != config.API_KEY:
            logger.warning(f"Unauthorized access attempt from {request.remote_addr}")
            return error_response("Unauthorized", 401)
        
        return f(*args, **kwargs)
    return decorated_function


def require_session_auth(f):
    """Decorator to require session-based authentication"""
    @wraps(f)
    def decorated_function(*args, **kwargs):
        if 'user_id' not in session:
            return error_response("Authentication required", 401)
        return f(*args, **kwargs)
    return decorated_function


def log_request(f):
    """Decorator to log request details"""
    @wraps(f)
    def decorated_function(*args, **kwargs):
        logger.info(f"{request.method} {request.path} from {request.remote_addr}")
        try:
            return f(*args, **kwargs)
        except APIError as e:
            logger.error(f"API Error in {f.__name__}: {e.message}")
            return error_response(e.message, e.status_code, e.details)
        except Exception as e:
            logger.exception(f"Unexpected error in {f.__name__}")
            return error_response("Internal server error", 500)
    return decorated_function


def validate_required_fields(required_fields):
    """Decorator to validate required fields in JSON request"""
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            if not request.is_json:
                return error_response("Content-Type must be application/json", 400)
            
            data = request.get_json()
            missing_fields = [field for field in required_fields if field not in data or not data[field]]
            
            if missing_fields:
                return error_response(
                    "Missing required fields",
                    400,
                    {'missing_fields': missing_fields}
                )
            return f(*args, **kwargs)
        return decorated_function
    return decorator


def validate_ip_address(ip):
    """Validate IP address format"""
    import re
    pattern = r'^(\d{1,3}\.){3}\d{1,3}$'
    if not re.match(pattern, ip):
        return False
    parts = ip.split('.')
    return all(0 <= int(part) <= 255 for part in parts)


def sanitize_hostname(hostname):
    """Sanitize hostname to prevent injection"""
    import re
    # Allow alphanumeric, dash, and underscore
    if not re.match(r'^[a-zA-Z0-9_-]+$', hostname):
        raise APIError("Invalid hostname format", 400)
    if len(hostname) > 255:
        raise APIError("Hostname too long", 400)
    return hostname


def setup_logging(config):
    """Setup logging configuration"""
    import os
    from logging.handlers import RotatingFileHandler
    
    # Create logs directory if it doesn't exist
    log_dir = os.path.dirname(config.LOG_FILE)
    if log_dir and not os.path.exists(log_dir):
        os.makedirs(log_dir)
    
    # Create logger
    logger = logging.getLogger()
    logger.setLevel(getattr(logging, config.LOG_LEVEL))
    
    # File handler with rotation
    file_handler = RotatingFileHandler(
        config.LOG_FILE,
        maxBytes=config.LOG_MAX_BYTES,
        backupCount=config.LOG_BACKUP_COUNT
    )
    file_handler.setFormatter(logging.Formatter(
        '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
    ))
    
    # Console handler
    console_handler = logging.StreamHandler()
    console_handler.setFormatter(logging.Formatter(
        '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
    ))
    
    logger.addHandler(file_handler)
    logger.addHandler(console_handler)
    
    return logger