app_config.py

"""
app_config.py

Centralized configuration management for LinuxReport.
This module provides a single source of truth for all configuration values,
eliminating duplicate configuration loading across the application.

Features:
- Cached configuration loading with validation
- Fail-fast error handling for missing configuration
- Type-safe configuration access
- Centralized configuration validation
- No local dependencies (foundational module)

Author: LinuxReport System
License: See LICENSE file
"""

# =============================================================================
# STANDARD LIBRARY IMPORTS
# =============================================================================
import os
import socket
from functools import lru_cache
from pathlib import Path
from dataclasses import dataclass

import yaml
from Logging import g_logger as logging

# =============================================================================
# GLOBAL CONSTANTS AND CONFIGURATION
# =============================================================================

PATH = Path(__file__).parent
DEBUG = False
USE_TOR = True

# =============================================================================
# SHARED CONFIGURATION DICTIONARIES
# =============================================================================

# --- Shared Reddit Fetch Config ---
# Import here to avoid circular imports

@dataclass(frozen=True)
class FetchConfig:
    """
    Base class for fetch configurations.
    
    This immutable configuration class provides type safety for all fetch-related
    settings used across different sites and services.
    """
    needs_selenium: bool = False
    needs_tor: bool = False
    post_container: str = ""
    title_selector: str = ""
    link_selector: str = ""
    link_attr: str = "href"
    filter_pattern: str = None
    use_random_user_agent: bool = False
    published_selector: str = None

@dataclass(frozen=True)
class RedditFetchConfig(FetchConfig):
    """
    Reddit-specific fetch configuration.
    
    Inherits from FetchConfig with Reddit-specific defaults.
    """
    needs_selenium: bool = True
    needs_tor: bool = True
    post_container: str = "article"
    title_selector: str = "a[id^='post-title-']"
    link_selector: str = "a[id^='post-title-']"
    link_attr: str = "href"
    filter_pattern: str = None
    use_random_user_agent: bool = True

REDDIT_FETCH_CONFIG = RedditFetchConfig()

# =============================================================================
# CONFIGURATION MANAGER CLASS
# =============================================================================

class ConfigManager:
    """
    Centralized configuration manager with caching and validation.
    
    This class provides a single source of truth for all configuration values,
    eliminating duplicate configuration loading across the application.
    """
    
    _instance = None
    _config = None
    _validated = False
    
    def __new__(cls):
        """Singleton pattern to ensure only one configuration instance."""
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return cls._instance
    
    @classmethod
    def get_instance(cls):
        """Get the singleton instance of ConfigManager."""
        if cls._instance is None:
            cls._instance = ConfigManager()
        return cls._instance
    
    @lru_cache(maxsize=1)
    def load_config(self):
        """
        Load and cache configuration from config.yaml file.
        
        Returns:
            Dict[str, Any]: Configuration dictionary
            
        Raises:
            FileNotFoundError: If config.yaml is not found
            yaml.YAMLError: If config.yaml is malformed
            ValueError: If required configuration sections are missing
        """
        config_path = PATH / 'config.yaml'

        if not config_path.exists():
            raise FileNotFoundError(f"Configuration file not found: {config_path}")
        
        try:
            with open(config_path, 'r', encoding='utf-8') as f:
                config = yaml.safe_load(f)
            
            if not isinstance(config, dict):
                raise ValueError("Configuration file must contain a valid YAML dictionary")
            
            return config
            
        except yaml.YAMLError as e:
            raise ValueError(f"Malformed configuration file: {e}") from e
        except (IOError, OSError) as e:
            logging.error(f"Error reading config.yaml: {e}")
            raise
    
    def get_config(self):
        """
        Get the configuration dictionary, loading it if necessary.
        
        Returns:
            Dict[str, Any]: Configuration dictionary
        """
        if self._config is None:
            self._config = self.load_config()
            self._validate_config()
        return self._config
    
    def _validate_config(self):
        """
        Validate configuration if present. This is now permissive to avoid exceptions.
        """
        if self._validated:
            return

        # Just mark as validated without strict validation
        # Let the calling code handle missing config naturally
        self._validated = True
    
    def get(self, key_path, default=None):
        """
        Get a configuration value using dot notation.
        
        Args:
            key_path: Configuration key path (e.g., 'admin.password')
            default: Default value if key is not found
            
        Returns:
            Configuration value or default
        """
        config = self.get_config()
        keys = key_path.split('.')
        
        try:
            value = config
            for key in keys:
                value = value[key]
            return value
        except (KeyError, TypeError):
            return default
    
    def require(self, key_path):
        """
        Get a required configuration value, failing if not found.
        
        Args:
            key_path: Configuration key path (e.g., 'admin.password')
            
        Returns:
            Configuration value
            
        Raises:
            ValueError: If the configuration key is not found
        """
        value = self.get(key_path)
        if value is None:
            raise ValueError(f"Required configuration key not found: {key_path}")
        return value

    def reload(self):
        """
        Reload configuration from disk (useful for development).
        
        This clears the cache and forces a fresh load of the configuration file.
        """
        self._config = None
        self._validated = False
        self.load_config.cache_clear()

# =============================================================================
# GLOBAL CONFIGURATION INSTANCE
# =============================================================================

# Create global configuration manager instance
config_manager = ConfigManager.get_instance()

# =============================================================================
# UTILITY FUNCTIONS
# =============================================================================

def is_tor_running():
    """
    Check if Tor is running by attempting to connect to the SOCKS proxy port.
    
    Returns:
        bool: True if Tor is running, False otherwise
    """
    try:
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.settimeout(1)  # 1 second timeout
        result = sock.connect_ex(('127.0.0.1', 9050))
        sock.close()
        return result == 0
    except socket.error:
        return False

# Check if Tor is actually running and update USE_TOR accordingly
if USE_TOR and not is_tor_running():
    print("Tor is enabled but not running. Falling back to direct connection.")
    USE_TOR = False

# =============================================================================
# CONFIGURATION ACCESS FUNCTIONS
# =============================================================================

def load_config():
    """
    Load configuration from config.yaml file.
    
    This function is maintained for backward compatibility.
    New code should use the ConfigManager directly.
    
    Returns:
        Dict[str, Any]: Configuration dictionary
    """
    return config_manager.get_config()

def get_admin_password():
    """
    Get the admin password from configuration.

    Returns:
        Optional[str]: Admin password or None if not configured
    """
    return config_manager.get('admin.password')


def get_dashboard_credentials():
    """
    Get the dashboard credentials from configuration.

    Returns:
        Dict[str, str]: A dictionary with 'username' and 'password' keys.
    """
    return config_manager.get('admin.dashboard', {})

def get_secret_key():
    """
    Get the secret key from configuration.

    Returns:
        Optional[str]: Secret key or None if not configured
    """
    return config_manager.get('admin.secret_key')

def get_weather_api_key():
    """
    Get the weather API key from configuration.
    
    Returns:
        Optional[str]: Weather API key or None if not configured
    """
    return config_manager.get('admin.weather_api_key')

def get_storage_config():
    """
    Get the storage configuration.
    
    Returns:
        Dict[str, Any]: Storage configuration dictionary
    """
    return config_manager.get('storage', {})

def get_settings_config():
    """
    Get the settings configuration.
    
    Returns:
        Dict[str, Any]: Settings configuration dictionary
    """
    return config_manager.get('settings', {})

def get_allowed_domains():
    """
    Get the list of allowed domains for CSP and CORS.
    
    Returns:
        List[str]: List of allowed domains
    """
    return config_manager.get('settings.allowed_domains', [])

def get_allowed_requester_domains():
    """
    Get the list of domains allowed to make API requests.
    
    Returns:
        List[str]: List of allowed requester domains
    """
    return config_manager.get('settings.allowed_requester_domains', [])

def get_cdn_config():
    """
    Get the CDN configuration.
    
    Returns:
        Dict[str, Any]: CDN configuration dictionary
    """
    return config_manager.get('settings.cdn', {})

def get_object_store_config():
    """
    Get the object store configuration.
    
    Returns:
        Dict[str, Any]: Object store configuration dictionary
    """
    return config_manager.get('settings.object_store', {})

def get_welcome_html():
    """
    Get the welcome HTML message.
    
    Returns:
        str: Welcome HTML message
    """
    return config_manager.get('settings.welcome_html', '')

def get_reports_config():
    """
    Get the reports configuration.

    Returns:
        Dict[str, Any]: Reports configuration dictionary
    """
    return config_manager.get('reports', {})

def get_tor_password():
    """
    Get the Tor control port password from configuration.

    Returns:
        Optional[str]: Tor password or None if not configured
    """
    return config_manager.get('tor.password')

def is_storage_enabled():
    """
    Check if object storage is enabled.
    
    Returns:
        bool: True if storage is enabled, False otherwise
    """
    return config_manager.get('storage.enabled', False)

def is_cdn_enabled():
    """
    Check if CDN is enabled.
    
    Returns:
        bool: True if CDN is enabled, False otherwise
    """
    return config_manager.get('settings.cdn.enabled', False)

def is_object_store_enabled():
    """
    Check if object store feeds are enabled.
    
    Returns:
        bool: True if object store feeds are enabled, False otherwise
    """
    return config_manager.get('settings.object_store.enabled', False)

def get_proxy_config():
    """
    Get the proxy server configuration.
    
    Returns:
        Dict[str, Any]: Proxy configuration dictionary
    """
    return config_manager.get('proxy', {})

def get_proxy_server():
    """
    Get the proxy server address and port.
    
    Returns:
        Optional[str]: Proxy server address:port or None if not configured
    """
    return config_manager.get('proxy.server')

def get_proxy_username():
    """
    Get the proxy server username.
    
    Returns:
        Optional[str]: Proxy username or None if not configured
    """
    return config_manager.get('proxy.username')

def get_proxy_password():
    """
    Get the proxy server password.
    
    Returns:
        Optional[str]: Proxy password or None if not configured
    """
    return config_manager.get('proxy.password')

def get_reddit_username():
    """
    Get the Reddit username from configuration for user agent construction.
    
    Returns:
        str: Reddit username, defaults to "keithcu" if not configured
    """
    return config_manager.get('reddit.username', 'keithcu')


# =============================================================================
# CONFIGURATION VALIDATION
# =============================================================================

def validate_configuration():
    """
    Validate configuration if present. Now permissive to avoid exceptions.
    """
    try:
        # Just try to load config, don't validate strictly
        config_manager.get_config()
        print("Configuration loaded")
    except (FileNotFoundError, ValueError) as e:
        print(f"Configuration loading failed: {e}")

# =============================================================================
# CONFIGURATION RELOADING (for development)
# =============================================================================

def reload_configuration():
    """
    Reload configuration from disk (useful for development).
    
    This clears the cache and forces a fresh load of the configuration file.
    """
    config_manager.reload()
    print("Configuration reloaded successfully")

# =============================================================================
# INITIALIZATION
# =============================================================================

# Validate configuration on module import
try:
    validate_configuration()
except (FileNotFoundError, ValueError) as e:
    print(f"Warning: Configuration validation failed during import: {e}")
    # Don't raise here to allow the module to be imported for testing