plugins/loader.py

"""
Plugin Loader

Dynamically loads and manages plugins.
"""

import importlib
import inspect
from pathlib import Path
from typing import Dict, List, Type, Optional, Any
from loguru import logger

from plugins.base import BasePlugin, PluginMetadata
from core.exceptions import PluginError, PluginLoadError


class PluginLoader:
    """
    Load and manage plugins dynamically.
    
    Discovers, loads, and manages plugin lifecycle.
    """
    
    def __init__(self, plugin_dir: Optional[Path] = None):
        """
        Initialize PluginLoader.
        
        Args:
            plugin_dir: Directory containing plugin modules
        """
        if plugin_dir is None:
            plugin_dir = Path(__file__).parent
        
        self.plugin_dir = Path(plugin_dir)
        self.plugins: Dict[str, BasePlugin] = {}
        self.plugin_classes: Dict[str, Type[BasePlugin]] = {}
        
        logger.info(f"PluginLoader initialized with directory: {plugin_dir}")
    
    def discover_plugins(self) -> List[str]:
        """
        Discover available plugins in the plugin directory.
        
        Returns:
            List of discovered plugin module names
        """
        discovered = []
        
        # Look for Python files in the plugin directory
        for file_path in self.plugin_dir.glob("*.py"):
            # Skip __init__.py, base.py, loader.py
            if file_path.stem in ["__init__", "base", "loader"]:
                continue
            
            module_name = file_path.stem
            discovered.append(module_name)
            logger.debug(f"Discovered plugin module: {module_name}")
        
        logger.info(f"Discovered {len(discovered)} plugin modules")
        return discovered
    
    def load_plugin_class(self, module_name: str) -> Optional[Type[BasePlugin]]:
        """
        Load a plugin class from a module.
        
        Args:
            module_name: Name of the module to load
            
        Returns:
            Plugin class or None if not found
        """
        try:
            # Import the module
            module = importlib.import_module(f"plugins.{module_name}")
            
            # Find all classes that inherit from BasePlugin
            for name, obj in inspect.getmembers(module, inspect.isclass):
                if (issubclass(obj, BasePlugin) and 
                    obj is not BasePlugin and
                    obj.__module__ == module.__name__):
                    
                    logger.info(f"Loaded plugin class: {name} from {module_name}")
                    return obj
            
            logger.warning(f"No plugin class found in module: {module_name}")
            return None
            
        except Exception as e:
            logger.error(f"Failed to load plugin module {module_name}: {e}")
            raise PluginLoadError(
                f"Cannot load plugin module {module_name}: {str(e)}",
                {"module": module_name, "error": str(e)}
            )
    
    def load_plugin(
        self,
        plugin_name: str,
        auto_initialize: bool = True
    ) -> BasePlugin:
        """
        Load and optionally initialize a plugin.
        
        Args:
            plugin_name: Name of the plugin module
            auto_initialize: Whether to automatically initialize the plugin
            
        Returns:
            Loaded plugin instance
        """
        try:
            # Check if already loaded
            if plugin_name in self.plugins:
                logger.info(f"Plugin {plugin_name} already loaded")
                return self.plugins[plugin_name]
            
            # Load plugin class
            plugin_class = self.load_plugin_class(plugin_name)
            
            if plugin_class is None:
                raise PluginLoadError(
                    f"No plugin class found in {plugin_name}",
                    {"plugin": plugin_name}
                )
            
            # Store plugin class
            self.plugin_classes[plugin_name] = plugin_class
            
            # Create instance
            plugin_instance = plugin_class()
            
            # Initialize if requested
            if auto_initialize:
                plugin_instance.initialize()
                plugin_instance._initialized = True
            
            # Store instance
            self.plugins[plugin_instance.metadata.name] = plugin_instance
            
            logger.info(
                f"Plugin loaded: {plugin_instance.metadata.name} "
                f"v{plugin_instance.metadata.version}"
            )
            
            return plugin_instance
            
        except Exception as e:
            logger.error(f"Failed to load plugin {plugin_name}: {e}")
            raise PluginLoadError(
                f"Cannot load plugin {plugin_name}: {str(e)}",
                {"plugin": plugin_name, "error": str(e)}
            )
    
    def load_all_plugins(self, auto_initialize: bool = True) -> Dict[str, BasePlugin]:
        """
        Discover and load all available plugins.
        
        Args:
            auto_initialize: Whether to automatically initialize plugins
            
        Returns:
            Dictionary of loaded plugins
        """
        discovered = self.discover_plugins()
        
        for module_name in discovered:
            try:
                self.load_plugin(module_name, auto_initialize=auto_initialize)
            except Exception as e:
                logger.error(f"Failed to load plugin {module_name}: {e}")
                # Continue loading other plugins
                continue
        
        logger.info(f"Loaded {len(self.plugins)} plugins")
        return self.plugins
    
    def unload_plugin(self, plugin_name: str) -> None:
        """
        Unload a plugin and clean up resources.
        
        Args:
            plugin_name: Name of the plugin to unload
        """
        if plugin_name not in self.plugins:
            logger.warning(f"Plugin {plugin_name} not loaded")
            return
        
        plugin = self.plugins[plugin_name]
        
        # Clean up resources
        try:
            plugin.cleanup()
        except Exception as e:
            logger.error(f"Error during plugin cleanup: {e}")
        
        # Remove from loaded plugins
        del self.plugins[plugin_name]
        
        logger.info(f"Plugin unloaded: {plugin_name}")
    
    def unload_all_plugins(self) -> None:
        """Unload all plugins."""
        plugin_names = list(self.plugins.keys())
        
        for plugin_name in plugin_names:
            self.unload_plugin(plugin_name)
        
        logger.info("All plugins unloaded")
    
    def get_plugin(self, plugin_name: str) -> Optional[BasePlugin]:
        """
        Get a loaded plugin by name.
        
        Args:
            plugin_name: Name of the plugin
            
        Returns:
            Plugin instance or None
        """
        return self.plugins.get(plugin_name)
    
    def list_plugins(self) -> List[PluginMetadata]:
        """
        List all loaded plugins.
        
        Returns:
            List of plugin metadata
        """
        return [plugin.metadata for plugin in self.plugins.values()]
    
    def reload_plugin(self, plugin_name: str) -> BasePlugin:
        """
        Reload a plugin (unload then load).
        
        Args:
            plugin_name: Name of the plugin to reload
            
        Returns:
            Reloaded plugin instance
        """
        logger.info(f"Reloading plugin: {plugin_name}")
        
        # Find the module name
        module_name = None
        for name, plugin in self.plugins.items():
            if name == plugin_name:
                module_name = plugin.__class__.__module__.split(".")[-1]
                break
        
        if module_name is None:
            raise PluginError(
                f"Plugin {plugin_name} not found",
                {"plugin": plugin_name}
            )
        
        # Unload
        self.unload_plugin(plugin_name)
        
        # Reload module
        importlib.reload(
            importlib.import_module(f"plugins.{module_name}")
        )
        
        # Load again
        return self.load_plugin(module_name)
    
    def get_plugins_by_category(self, category: str) -> List[BasePlugin]:
        """
        Get all plugins in a specific category.
        
        Args:
            category: Plugin category
            
        Returns:
            List of plugins in the category
        """
        return [
            plugin for plugin in self.plugins.values()
            if plugin.metadata.category == category
        ]
    
    def get_enabled_plugins(self) -> List[BasePlugin]:
        """
        Get all enabled plugins.
        
        Returns:
            List of enabled plugins
        """
        return [
            plugin for plugin in self.plugins.values()
            if plugin.is_enabled()
        ]
    
    def get_plugin_info(self) -> Dict[str, Dict[str, Any]]:
        """
        Get information about all loaded plugins.
        
        Returns:
            Dictionary with plugin information
        """
        info = {}
        
        for name, plugin in self.plugins.items():
            info[name] = {
                "name": plugin.metadata.name,
                "version": plugin.metadata.version,
                "description": plugin.metadata.description,
                "author": plugin.metadata.author,
                "category": plugin.metadata.category,
                "enabled": plugin.is_enabled(),
                "initialized": plugin.is_initialized(),
                "priority": plugin.metadata.priority,
            }
        
        return info
    
    def __repr__(self) -> str:
        """String representation."""
        return f"PluginLoader(plugins={len(self.plugins)})"