sklears_compose/

plugin_architecture.rs

//! Plugin Architecture for Custom Components
//!
//! This module provides a comprehensive plugin system that allows users to
//! register and use custom components in pipelines, enabling extensibility
//! without requiring modifications to the core codebase.

use scirs2_core::ndarray::{Array1, Array2, ArrayView1, ArrayView2};
use serde::{Deserialize, Serialize};
use sklears_core::{
    error::{Result as SklResult, SklearsError},
    traits::Estimator,
    types::Float,
};
use std::any::Any;
use std::collections::{HashMap, HashSet};
use std::fmt::Debug;
use std::path::PathBuf;
use std::sync::{Arc, RwLock};

/// Plugin registry for managing custom components
pub struct PluginRegistry {
    /// Registered plugins
    plugins: RwLock<HashMap<String, Box<dyn Plugin>>>,
    /// Plugin metadata
    metadata: RwLock<HashMap<String, PluginMetadata>>,
    /// Component factories
    factories: RwLock<HashMap<String, Box<dyn ComponentFactory>>>,
    /// Dependency graph
    dependencies: RwLock<HashMap<String, Vec<String>>>,
    /// Plugin loading configuration
    config: PluginConfig,
}

/// Plugin configuration
#[derive(Debug, Clone)]
pub struct PluginConfig {
    /// Directories to search for plugins
    pub plugin_dirs: Vec<PathBuf>,
    /// Auto-load plugins on startup
    pub auto_load: bool,
    /// Enable plugin sandboxing
    pub sandbox: bool,
    /// Maximum plugin execution time
    pub max_execution_time: std::time::Duration,
    /// Enable plugin validation
    pub validate_plugins: bool,
}

/// Plugin metadata information
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PluginMetadata {
    /// Plugin name
    pub name: String,
    /// Plugin version
    pub version: String,
    /// Plugin description
    pub description: String,
    /// Plugin author
    pub author: String,
    /// Plugin license
    pub license: String,
    /// Minimum API version required
    pub min_api_version: String,
    /// Plugin dependencies
    pub dependencies: Vec<String>,
    /// Plugin capabilities
    pub capabilities: Vec<String>,
    /// Plugin tags
    pub tags: Vec<String>,
    /// Plugin documentation URL
    pub documentation_url: Option<String>,
    /// Plugin source code URL
    pub source_url: Option<String>,
}

/// Base trait for all plugins
pub trait Plugin: Send + Sync + Debug {
    /// Get plugin metadata
    fn metadata(&self) -> &PluginMetadata;

    /// Initialize the plugin
    fn initialize(&mut self, context: &PluginContext) -> SklResult<()>;

    /// Shutdown the plugin
    fn shutdown(&mut self) -> SklResult<()>;

    /// Get plugin capabilities
    fn capabilities(&self) -> Vec<PluginCapability>;

    /// Create a component instance
    fn create_component(
        &self,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>>;

    /// Validate plugin configuration
    fn validate_config(&self, config: &ComponentConfig) -> SklResult<()>;

    /// Get component schema for validation
    fn get_component_schema(&self, component_type: &str) -> Option<ComponentSchema>;
}

/// Plugin context provided during initialization
#[derive(Debug, Clone)]
pub struct PluginContext {
    /// Registry reference
    pub registry_id: String,
    /// Plugin working directory
    pub working_dir: PathBuf,
    /// Configuration parameters
    pub config: HashMap<String, String>,
    /// Available APIs
    pub available_apis: HashSet<String>,
}

/// Plugin capabilities
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum PluginCapability {
    /// Can create transformers
    Transformer,
    /// Can create estimators
    Estimator,
    /// Can create preprocessors
    Preprocessor,
    /// Can create feature selectors
    FeatureSelector,
    /// Can create ensemble methods
    Ensemble,
    /// Can create custom metrics
    Metric,
    /// Can create data loaders
    DataLoader,
    /// Can create visualizers
    Visualizer,
    /// Custom capability
    Custom(String),
}

/// Component configuration
#[derive(Debug, Clone)]
pub struct ComponentConfig {
    /// Component type identifier
    pub component_type: String,
    /// Component parameters
    pub parameters: HashMap<String, ConfigValue>,
    /// Component metadata
    pub metadata: HashMap<String, String>,
}

/// Configuration value types
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(untagged)]
pub enum ConfigValue {
    /// String value
    String(String),
    /// Integer value
    Integer(i64),
    /// Float value
    Float(f64),
    /// Boolean value
    Boolean(bool),
    /// Array of values
    Array(Vec<ConfigValue>),
    /// Object (nested configuration)
    Object(HashMap<String, ConfigValue>),
}

/// Component schema for validation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ComponentSchema {
    /// Schema name
    pub name: String,
    /// Required parameters
    pub required_parameters: Vec<ParameterSchema>,
    /// Optional parameters
    pub optional_parameters: Vec<ParameterSchema>,
    /// Parameter constraints
    pub constraints: Vec<ParameterConstraint>,
}

/// Parameter schema definition
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ParameterSchema {
    /// Parameter name
    pub name: String,
    /// Parameter type
    pub parameter_type: ParameterType,
    /// Parameter description
    pub description: String,
    /// Default value
    pub default_value: Option<ConfigValue>,
}

/// Parameter types
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ParameterType {
    /// String parameter
    String {
        min_length: Option<usize>,
        max_length: Option<usize>,
    },
    /// Integer parameter
    Integer {
        min_value: Option<i64>,
        max_value: Option<i64>,
    },
    /// Float parameter
    Float {
        min_value: Option<f64>,
        max_value: Option<f64>,
    },
    /// Boolean parameter
    Boolean,
    /// Enum parameter
    Enum { values: Vec<String> },
    /// Array parameter
    Array {
        item_type: Box<ParameterType>,
        min_items: Option<usize>,
        max_items: Option<usize>,
    },
    /// Object parameter
    Object { schema: ComponentSchema },
}

/// Parameter constraints
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ParameterConstraint {
    /// Constraint name
    pub name: String,
    /// Constraint expression
    pub expression: String,
    /// Constraint description
    pub description: String,
}

/// Base trait for plugin components
pub trait PluginComponent: Send + Sync + Debug {
    /// Get component type
    fn component_type(&self) -> &str;

    /// Get component configuration
    fn config(&self) -> &ComponentConfig;

    /// Initialize component
    fn initialize(&mut self, context: &ComponentContext) -> SklResult<()>;

    /// Clone the component
    fn clone_component(&self) -> Box<dyn PluginComponent>;

    /// Convert to Any for downcasting
    fn as_any(&self) -> &dyn Any;

    /// Convert to mutable Any for downcasting
    fn as_any_mut(&mut self) -> &mut dyn Any;
}

/// Component execution context
#[derive(Debug, Clone)]
pub struct ComponentContext {
    /// Component ID
    pub component_id: String,
    /// Pipeline context
    pub pipeline_id: Option<String>,
    /// Execution parameters
    pub execution_params: HashMap<String, String>,
    /// Logger handle
    pub logger: Option<String>,
}

/// Plugin-based transformer
pub trait PluginTransformer: PluginComponent {
    /// Fit the transformer
    fn fit(
        &mut self,
        x: &ArrayView2<'_, Float>,
        y: Option<&ArrayView1<'_, Float>>,
    ) -> SklResult<()>;

    /// Transform data
    fn transform(&self, x: &ArrayView2<'_, Float>) -> SklResult<Array2<f64>>;

    /// Fit and transform in one step
    fn fit_transform(
        &mut self,
        x: &ArrayView2<'_, Float>,
        y: Option<&ArrayView1<'_, Float>>,
    ) -> SklResult<Array2<f64>> {
        self.fit(x, y)?;
        self.transform(x)
    }

    /// Check if transformer is fitted
    fn is_fitted(&self) -> bool;

    /// Get feature names output
    fn get_feature_names_out(&self, input_features: Option<&[String]>) -> Vec<String>;
}

/// Plugin-based estimator
pub trait PluginEstimator: PluginComponent {
    /// Fit the estimator
    fn fit(&mut self, x: &ArrayView2<'_, Float>, y: &ArrayView1<'_, Float>) -> SklResult<()>;

    /// Predict using the fitted estimator
    fn predict(&self, x: &ArrayView2<'_, Float>) -> SklResult<Array1<f64>>;

    /// Predict probabilities (for classifiers)
    fn predict_proba(&self, x: &ArrayView2<'_, Float>) -> SklResult<Array2<f64>> {
        Err(SklearsError::InvalidOperation(
            "predict_proba not implemented for this estimator".to_string(),
        ))
    }

    /// Score the estimator
    fn score(&self, x: &ArrayView2<'_, Float>, y: &ArrayView1<'_, Float>) -> SklResult<f64>;

    /// Check if estimator is fitted
    fn is_fitted(&self) -> bool;

    /// Get feature importance (if available)
    fn feature_importances(&self) -> Option<Array1<f64>> {
        None
    }
}

/// Component factory for creating plugin instances
pub trait ComponentFactory: Send + Sync + Debug {
    /// Create a component
    fn create(
        &self,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>>;

    /// List available component types
    fn available_types(&self) -> Vec<String>;

    /// Get component schema
    fn get_schema(&self, component_type: &str) -> Option<ComponentSchema>;
}

/// Plugin loading and management system
pub struct PluginLoader {
    /// Plugin configuration
    config: PluginConfig,
    /// Loaded plugin libraries
    loaded_libraries: HashMap<String, PluginLibrary>,
}

/// Loaded plugin library information
#[derive(Debug)]
struct PluginLibrary {
    /// Library path
    path: PathBuf,
    /// Library handle (placeholder - in real implementation would use libloading)
    handle: String,
    /// Exported plugins
    plugins: Vec<String>,
}

impl PluginRegistry {
    #[must_use]
    pub fn new(config: PluginConfig) -> Self {
        Self {
            plugins: RwLock::new(HashMap::new()),
            metadata: RwLock::new(HashMap::new()),
            factories: RwLock::new(HashMap::new()),
            dependencies: RwLock::new(HashMap::new()),
            config,
        }
    }

    /// Register a plugin
    pub fn register_plugin(
        &self,
        name: &str,
        plugin: Box<dyn Plugin>,
        factory: Box<dyn ComponentFactory>,
    ) -> SklResult<()> {
        let metadata = plugin.metadata().clone();

        // Validate plugin compatibility
        self.validate_plugin(&metadata)?;

        // Check dependencies
        self.check_dependencies(&metadata)?;

        // Register plugin
        {
            let mut plugins = self.plugins.write().map_err(|_| {
                SklearsError::InvalidOperation(
                    "Failed to acquire write lock for plugins".to_string(),
                )
            })?;
            plugins.insert(name.to_string(), plugin);
        }

        // Register metadata
        {
            let mut meta = self.metadata.write().map_err(|_| {
                SklearsError::InvalidOperation(
                    "Failed to acquire write lock for metadata".to_string(),
                )
            })?;
            meta.insert(name.to_string(), metadata.clone());
        }

        // Register factory
        {
            let mut factories = self.factories.write().map_err(|_| {
                SklearsError::InvalidOperation(
                    "Failed to acquire write lock for factories".to_string(),
                )
            })?;
            factories.insert(name.to_string(), factory);
        }

        // Register dependencies
        {
            let mut deps = self.dependencies.write().map_err(|_| {
                SklearsError::InvalidOperation(
                    "Failed to acquire write lock for dependencies".to_string(),
                )
            })?;
            deps.insert(name.to_string(), metadata.dependencies);
        }

        Ok(())
    }

    /// Unregister a plugin
    pub fn unregister_plugin(&self, name: &str) -> SklResult<()> {
        // Check if other plugins depend on this one
        let dependents = self.get_dependents(name)?;
        if !dependents.is_empty() {
            return Err(SklearsError::InvalidOperation(format!(
                "Cannot unregister plugin '{name}' - it has dependents: {dependents:?}"
            )));
        }

        // Shutdown the plugin
        if let Ok(mut plugins) = self.plugins.write() {
            if let Some(mut plugin) = plugins.remove(name) {
                plugin.shutdown()?;
            }
        }

        // Remove metadata
        if let Ok(mut metadata) = self.metadata.write() {
            metadata.remove(name);
        }

        // Remove factory
        if let Ok(mut factories) = self.factories.write() {
            factories.remove(name);
        }

        // Remove dependencies
        if let Ok(mut dependencies) = self.dependencies.write() {
            dependencies.remove(name);
        }

        Ok(())
    }

    /// Create a component from a plugin
    pub fn create_component(
        &self,
        plugin_name: &str,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>> {
        let factory = {
            let factories = self.factories.read().map_err(|_| {
                SklearsError::InvalidOperation(
                    "Failed to acquire read lock for factories".to_string(),
                )
            })?;

            factories
                .get(plugin_name)
                .ok_or_else(|| {
                    SklearsError::InvalidInput(format!("Plugin '{plugin_name}' not found"))
                })?
                .create(component_type, config)?
        };

        Ok(factory)
    }

    /// List all registered plugins
    pub fn list_plugins(&self) -> SklResult<Vec<String>> {
        let plugins = self.plugins.read().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire read lock for plugins".to_string())
        })?;
        Ok(plugins.keys().cloned().collect())
    }

    /// Get plugin metadata
    pub fn get_plugin_metadata(&self, name: &str) -> SklResult<PluginMetadata> {
        let metadata = self.metadata.read().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire read lock for metadata".to_string())
        })?;

        metadata
            .get(name)
            .cloned()
            .ok_or_else(|| SklearsError::InvalidInput(format!("Plugin '{name}' not found")))
    }

    /// List available component types for a plugin
    pub fn list_component_types(&self, plugin_name: &str) -> SklResult<Vec<String>> {
        let factories = self.factories.read().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire read lock for factories".to_string())
        })?;

        let factory = factories.get(plugin_name).ok_or_else(|| {
            SklearsError::InvalidInput(format!("Plugin '{plugin_name}' not found"))
        })?;

        Ok(factory.available_types())
    }

    /// Get component schema
    pub fn get_component_schema(
        &self,
        plugin_name: &str,
        component_type: &str,
    ) -> SklResult<Option<ComponentSchema>> {
        let factories = self.factories.read().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire read lock for factories".to_string())
        })?;

        let factory = factories.get(plugin_name).ok_or_else(|| {
            SklearsError::InvalidInput(format!("Plugin '{plugin_name}' not found"))
        })?;

        Ok(factory.get_schema(component_type))
    }

    /// Validate plugin compatibility
    fn validate_plugin(&self, metadata: &PluginMetadata) -> SklResult<()> {
        // Check API version compatibility
        if !self.is_api_version_compatible(&metadata.min_api_version) {
            return Err(SklearsError::InvalidInput(format!(
                "Plugin requires API version {} but current version is incompatible",
                metadata.min_api_version
            )));
        }

        // Additional validation can be added here
        Ok(())
    }

    /// Check if API version is compatible
    fn is_api_version_compatible(&self, required_version: &str) -> bool {
        // Simplified version check - in practice would use proper semver
        const CURRENT_API_VERSION: &str = "1.0.0";
        required_version <= CURRENT_API_VERSION
    }

    /// Check plugin dependencies
    fn check_dependencies(&self, metadata: &PluginMetadata) -> SklResult<()> {
        let plugins = self.plugins.read().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire read lock for plugins".to_string())
        })?;

        for dependency in &metadata.dependencies {
            if !plugins.contains_key(dependency) {
                return Err(SklearsError::InvalidInput(format!(
                    "Missing dependency: {dependency}"
                )));
            }
        }

        Ok(())
    }

    /// Get plugins that depend on the given plugin
    fn get_dependents(&self, plugin_name: &str) -> SklResult<Vec<String>> {
        let dependencies = self.dependencies.read().map_err(|_| {
            SklearsError::InvalidOperation(
                "Failed to acquire read lock for dependencies".to_string(),
            )
        })?;

        let dependents: Vec<String> = dependencies
            .iter()
            .filter(|(_, deps)| deps.contains(&plugin_name.to_string()))
            .map(|(name, _)| name.clone())
            .collect();

        Ok(dependents)
    }

    /// Initialize all plugins
    pub fn initialize_all(&self) -> SklResult<()> {
        let plugin_names = self.list_plugins()?;

        for name in plugin_names {
            self.initialize_plugin(&name)?;
        }

        Ok(())
    }

    /// Initialize a specific plugin
    fn initialize_plugin(&self, name: &str) -> SklResult<()> {
        let context = PluginContext {
            registry_id: "main".to_string(),
            working_dir: std::env::current_dir().unwrap_or_default(),
            config: HashMap::new(),
            available_apis: HashSet::new(),
        };

        let mut plugins = self.plugins.write().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire write lock for plugins".to_string())
        })?;

        if let Some(plugin) = plugins.get_mut(name) {
            plugin.initialize(&context)?;
        }

        Ok(())
    }

    /// Shutdown all plugins
    pub fn shutdown_all(&self) -> SklResult<()> {
        let mut plugins = self.plugins.write().map_err(|_| {
            SklearsError::InvalidOperation("Failed to acquire write lock for plugins".to_string())
        })?;

        for (_, plugin) in plugins.iter_mut() {
            let _ = plugin.shutdown(); // Continue even if shutdown fails
        }

        Ok(())
    }
}

impl PluginLoader {
    /// Create a new plugin loader
    #[must_use]
    pub fn new(config: PluginConfig) -> Self {
        Self {
            config,
            loaded_libraries: HashMap::new(),
        }
    }

    /// Load plugins from configured directories
    pub fn load_plugins(&mut self, registry: &PluginRegistry) -> SklResult<()> {
        let plugin_dirs = self.config.plugin_dirs.clone();
        for plugin_dir in &plugin_dirs {
            self.load_plugins_from_dir(plugin_dir, registry)?;
        }
        Ok(())
    }

    /// Load plugins from a specific directory
    fn load_plugins_from_dir(&mut self, dir: &PathBuf, registry: &PluginRegistry) -> SklResult<()> {
        // In a real implementation, this would:
        // 1. Scan directory for plugin libraries
        // 2. Load dynamic libraries using libloading
        // 3. Call plugin entry points to get plugin instances
        // 4. Register plugins with the registry

        println!("Loading plugins from directory: {dir:?}");

        // For now, we'll just create some example plugins
        self.load_example_plugins(registry)?;

        Ok(())
    }

    /// Load example plugins for demonstration
    fn load_example_plugins(&mut self, registry: &PluginRegistry) -> SklResult<()> {
        // Create example transformer plugin
        let transformer_plugin = Box::new(ExampleTransformerPlugin::new());
        let transformer_factory = Box::new(ExampleTransformerFactory::new());

        registry.register_plugin(
            "example_transformer",
            transformer_plugin,
            transformer_factory,
        )?;

        // Create example estimator plugin
        let estimator_plugin = Box::new(ExampleEstimatorPlugin::new());
        let estimator_factory = Box::new(ExampleEstimatorFactory::new());

        registry.register_plugin("example_estimator", estimator_plugin, estimator_factory)?;

        Ok(())
    }
}

/// Example transformer plugin implementation
#[derive(Debug)]
struct ExampleTransformerPlugin {
    metadata: PluginMetadata,
}

impl ExampleTransformerPlugin {
    fn new() -> Self {
        Self {
            metadata: PluginMetadata {
                name: "Example Transformer Plugin".to_string(),
                version: "1.0.0".to_string(),
                description: "Example transformer plugin for demonstration".to_string(),
                author: "Sklears Team".to_string(),
                license: "MIT".to_string(),
                min_api_version: "1.0.0".to_string(),
                dependencies: vec![],
                capabilities: vec!["transformer".to_string()],
                tags: vec!["example".to_string(), "transformer".to_string()],
                documentation_url: None,
                source_url: None,
            },
        }
    }

    fn with_metadata(metadata: PluginMetadata) -> Self {
        Self { metadata }
    }
}

impl Plugin for ExampleTransformerPlugin {
    fn metadata(&self) -> &PluginMetadata {
        &self.metadata
    }

    fn initialize(&mut self, _context: &PluginContext) -> SklResult<()> {
        Ok(())
    }

    fn shutdown(&mut self) -> SklResult<()> {
        Ok(())
    }

    fn capabilities(&self) -> Vec<PluginCapability> {
        vec![PluginCapability::Transformer]
    }

    fn create_component(
        &self,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>> {
        match component_type {
            "example_scaler" => Ok(Box::new(ExampleScaler::new(config.clone()))),
            _ => Err(SklearsError::InvalidInput(format!(
                "Unknown component type: {component_type}"
            ))),
        }
    }

    fn validate_config(&self, _config: &ComponentConfig) -> SklResult<()> {
        Ok(())
    }

    fn get_component_schema(&self, component_type: &str) -> Option<ComponentSchema> {
        match component_type {
            "example_scaler" => Some(ComponentSchema {
                name: "ExampleScaler".to_string(),
                required_parameters: vec![],
                optional_parameters: vec![ParameterSchema {
                    name: "scale_factor".to_string(),
                    parameter_type: ParameterType::Float {
                        min_value: Some(0.0),
                        max_value: None,
                    },
                    description: "Factor to scale features by".to_string(),
                    default_value: Some(ConfigValue::Float(1.0)),
                }],
                constraints: vec![],
            }),
            _ => None,
        }
    }
}

/// Example transformer factory
#[derive(Debug)]
struct ExampleTransformerFactory;

impl ExampleTransformerFactory {
    fn new() -> Self {
        Self
    }
}

impl ComponentFactory for ExampleTransformerFactory {
    fn create(
        &self,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>> {
        match component_type {
            "example_scaler" => Ok(Box::new(ExampleScaler::new(config.clone()))),
            _ => Err(SklearsError::InvalidInput(format!(
                "Unknown component type: {component_type}"
            ))),
        }
    }

    fn available_types(&self) -> Vec<String> {
        vec!["example_scaler".to_string()]
    }

    fn get_schema(&self, component_type: &str) -> Option<ComponentSchema> {
        match component_type {
            "example_scaler" => Some(ComponentSchema {
                name: "ExampleScaler".to_string(),
                required_parameters: vec![],
                optional_parameters: vec![ParameterSchema {
                    name: "scale_factor".to_string(),
                    parameter_type: ParameterType::Float {
                        min_value: Some(0.0),
                        max_value: None,
                    },
                    description: "Factor to scale features by".to_string(),
                    default_value: Some(ConfigValue::Float(1.0)),
                }],
                constraints: vec![],
            }),
            _ => None,
        }
    }
}

/// Example scaler component
#[derive(Debug, Clone)]
struct ExampleScaler {
    config: ComponentConfig,
    scale_factor: f64,
    fitted: bool,
}

impl ExampleScaler {
    fn new(config: ComponentConfig) -> Self {
        let scale_factor = config
            .parameters
            .get("scale_factor")
            .and_then(|v| match v {
                ConfigValue::Float(f) => Some(*f),
                _ => None,
            })
            .unwrap_or(1.0);

        Self {
            config,
            scale_factor,
            fitted: false,
        }
    }
}

impl PluginComponent for ExampleScaler {
    fn component_type(&self) -> &'static str {
        "example_scaler"
    }

    fn config(&self) -> &ComponentConfig {
        &self.config
    }

    fn initialize(&mut self, _context: &ComponentContext) -> SklResult<()> {
        Ok(())
    }

    fn clone_component(&self) -> Box<dyn PluginComponent> {
        Box::new(self.clone())
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    fn as_any_mut(&mut self) -> &mut dyn Any {
        self
    }
}

impl PluginTransformer for ExampleScaler {
    fn fit(
        &mut self,
        _x: &ArrayView2<'_, Float>,
        _y: Option<&ArrayView1<'_, Float>>,
    ) -> SklResult<()> {
        self.fitted = true;
        Ok(())
    }

    fn transform(&self, x: &ArrayView2<'_, Float>) -> SklResult<Array2<f64>> {
        if !self.fitted {
            return Err(SklearsError::InvalidOperation(
                "Transformer must be fitted before transform".to_string(),
            ));
        }

        Ok(x.mapv(|v| v * self.scale_factor))
    }

    fn is_fitted(&self) -> bool {
        self.fitted
    }

    fn get_feature_names_out(&self, input_features: Option<&[String]>) -> Vec<String> {
        match input_features {
            Some(features) => features.iter().map(|f| format!("scaled_{f}")).collect(),
            None => (0..10) // Default assumption
                .map(|i| format!("scaled_feature_{i}"))
                .collect(),
        }
    }
}

/// Example estimator plugin
#[derive(Debug)]
struct ExampleEstimatorPlugin {
    metadata: PluginMetadata,
}

impl ExampleEstimatorPlugin {
    fn new() -> Self {
        Self {
            metadata: PluginMetadata {
                name: "Example Estimator Plugin".to_string(),
                version: "1.0.0".to_string(),
                description: "Example estimator plugin for demonstration".to_string(),
                author: "Sklears Team".to_string(),
                license: "MIT".to_string(),
                min_api_version: "1.0.0".to_string(),
                dependencies: vec![],
                capabilities: vec!["estimator".to_string()],
                tags: vec!["example".to_string(), "estimator".to_string()],
                documentation_url: None,
                source_url: None,
            },
        }
    }
}

impl Plugin for ExampleEstimatorPlugin {
    fn metadata(&self) -> &PluginMetadata {
        &self.metadata
    }

    fn initialize(&mut self, _context: &PluginContext) -> SklResult<()> {
        Ok(())
    }

    fn shutdown(&mut self) -> SklResult<()> {
        Ok(())
    }

    fn capabilities(&self) -> Vec<PluginCapability> {
        vec![PluginCapability::Estimator]
    }

    fn create_component(
        &self,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>> {
        match component_type {
            "example_regressor" => Ok(Box::new(ExampleRegressor::new(config.clone()))),
            _ => Err(SklearsError::InvalidInput(format!(
                "Unknown component type: {component_type}"
            ))),
        }
    }

    fn validate_config(&self, _config: &ComponentConfig) -> SklResult<()> {
        Ok(())
    }

    fn get_component_schema(&self, component_type: &str) -> Option<ComponentSchema> {
        match component_type {
            "example_regressor" => Some(ComponentSchema {
                name: "ExampleRegressor".to_string(),
                required_parameters: vec![],
                optional_parameters: vec![ParameterSchema {
                    name: "learning_rate".to_string(),
                    parameter_type: ParameterType::Float {
                        min_value: Some(0.0),
                        max_value: Some(1.0),
                    },
                    description: "Learning rate for the algorithm".to_string(),
                    default_value: Some(ConfigValue::Float(0.01)),
                }],
                constraints: vec![],
            }),
            _ => None,
        }
    }
}

/// Example estimator factory
#[derive(Debug)]
struct ExampleEstimatorFactory;

impl ExampleEstimatorFactory {
    fn new() -> Self {
        Self
    }
}

impl ComponentFactory for ExampleEstimatorFactory {
    fn create(
        &self,
        component_type: &str,
        config: &ComponentConfig,
    ) -> SklResult<Box<dyn PluginComponent>> {
        match component_type {
            "example_regressor" => Ok(Box::new(ExampleRegressor::new(config.clone()))),
            _ => Err(SklearsError::InvalidInput(format!(
                "Unknown component type: {component_type}"
            ))),
        }
    }

    fn available_types(&self) -> Vec<String> {
        vec!["example_regressor".to_string()]
    }

    fn get_schema(&self, component_type: &str) -> Option<ComponentSchema> {
        match component_type {
            "example_regressor" => Some(ComponentSchema {
                name: "ExampleRegressor".to_string(),
                required_parameters: vec![],
                optional_parameters: vec![ParameterSchema {
                    name: "learning_rate".to_string(),
                    parameter_type: ParameterType::Float {
                        min_value: Some(0.0),
                        max_value: Some(1.0),
                    },
                    description: "Learning rate for the algorithm".to_string(),
                    default_value: Some(ConfigValue::Float(0.01)),
                }],
                constraints: vec![],
            }),
            _ => None,
        }
    }
}

/// Example regressor component
#[derive(Debug, Clone)]
struct ExampleRegressor {
    config: ComponentConfig,
    learning_rate: f64,
    fitted: bool,
    coefficients: Option<Array1<f64>>,
}

impl ExampleRegressor {
    fn new(config: ComponentConfig) -> Self {
        let learning_rate = config
            .parameters
            .get("learning_rate")
            .and_then(|v| match v {
                ConfigValue::Float(f) => Some(*f),
                _ => None,
            })
            .unwrap_or(0.01);

        Self {
            config,
            learning_rate,
            fitted: false,
            coefficients: None,
        }
    }
}

impl PluginComponent for ExampleRegressor {
    fn component_type(&self) -> &'static str {
        "example_regressor"
    }

    fn config(&self) -> &ComponentConfig {
        &self.config
    }

    fn initialize(&mut self, _context: &ComponentContext) -> SklResult<()> {
        Ok(())
    }

    fn clone_component(&self) -> Box<dyn PluginComponent> {
        Box::new(self.clone())
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    fn as_any_mut(&mut self) -> &mut dyn Any {
        self
    }
}

impl PluginEstimator for ExampleRegressor {
    fn fit(&mut self, x: &ArrayView2<'_, Float>, y: &ArrayView1<'_, Float>) -> SklResult<()> {
        // Simple linear regression with gradient descent
        let n_features = x.ncols();
        let mut coefficients = Array1::zeros(n_features);

        // Very simplified gradient descent with better convergence
        let y_f64 = y.mapv(|v| v);
        for _ in 0..1000 {
            let predictions = x.dot(&coefficients);
            let errors = &predictions - &y_f64;
            let gradient = x.t().dot(&errors) / x.nrows() as f64;
            coefficients = coefficients - self.learning_rate * gradient;
        }

        self.coefficients = Some(coefficients);
        self.fitted = true;
        Ok(())
    }

    fn predict(&self, x: &ArrayView2<'_, Float>) -> SklResult<Array1<f64>> {
        if !self.fitted {
            return Err(SklearsError::InvalidOperation(
                "Estimator must be fitted before predict".to_string(),
            ));
        }

        let coefficients = self.coefficients.as_ref().unwrap();
        Ok(x.dot(coefficients))
    }

    fn score(&self, x: &ArrayView2<'_, Float>, y: &ArrayView1<'_, Float>) -> SklResult<f64> {
        let predictions = self.predict(x)?;
        let y_f64 = y.mapv(|v| v);

        // R-squared score
        let y_mean = y_f64.mean().unwrap();
        let ss_res = (&predictions - &y_f64).mapv(|x| x.powi(2)).sum();
        let ss_tot = y_f64.mapv(|x| (x - y_mean).powi(2)).sum();

        Ok(1.0 - ss_res / ss_tot)
    }

    fn is_fitted(&self) -> bool {
        self.fitted
    }

    fn feature_importances(&self) -> Option<Array1<f64>> {
        self.coefficients.as_ref().map(|coefs| coefs.mapv(f64::abs))
    }
}

impl Default for PluginConfig {
    fn default() -> Self {
        Self {
            plugin_dirs: vec![PathBuf::from("./plugins")],
            auto_load: true,
            sandbox: false,
            max_execution_time: std::time::Duration::from_secs(300), // 5 minutes
            validate_plugins: true,
        }
    }
}

#[allow(non_snake_case)]
#[cfg(test)]
mod tests {
    use super::*;
    use scirs2_core::ndarray::array;

    #[test]
    fn test_plugin_registry_creation() {
        let config = PluginConfig::default();
        let registry = PluginRegistry::new(config);

        assert!(registry.list_plugins().unwrap().is_empty());
    }

    #[test]
    fn test_plugin_registration() {
        let config = PluginConfig::default();
        let registry = PluginRegistry::new(config);

        let plugin = Box::new(ExampleTransformerPlugin::new());
        let factory = Box::new(ExampleTransformerFactory::new());

        registry
            .register_plugin("test_plugin", plugin, factory)
            .unwrap();

        let plugins = registry.list_plugins().unwrap();
        assert_eq!(plugins.len(), 1);
        assert!(plugins.contains(&"test_plugin".to_string()));
    }

    #[test]
    fn test_component_creation() {
        let config = PluginConfig::default();
        let registry = PluginRegistry::new(config);

        let plugin = Box::new(ExampleTransformerPlugin::new());
        let factory = Box::new(ExampleTransformerFactory::new());

        registry
            .register_plugin("test_plugin", plugin, factory)
            .unwrap();

        let component_config = ComponentConfig {
            component_type: "example_scaler".to_string(),
            parameters: {
                let mut params = HashMap::new();
                params.insert("scale_factor".to_string(), ConfigValue::Float(2.0));
                params
            },
            metadata: HashMap::new(),
        };

        let component = registry
            .create_component("test_plugin", "example_scaler", &component_config)
            .unwrap();

        assert_eq!(component.component_type(), "example_scaler");
    }

    #[test]
    fn test_example_scaler() {
        let config = ComponentConfig {
            component_type: "example_scaler".to_string(),
            parameters: {
                let mut params = HashMap::new();
                params.insert("scale_factor".to_string(), ConfigValue::Float(2.0));
                params
            },
            metadata: HashMap::new(),
        };

        let mut scaler = ExampleScaler::new(config);

        let x = array![[1.0, 2.0], [3.0, 4.0]];

        scaler.fit(&x.view(), None).unwrap();
        assert!(scaler.is_fitted());

        let transformed = scaler.transform(&x.view()).unwrap();
        assert_eq!(transformed, array![[2.0, 4.0], [6.0, 8.0]]);
    }

    #[test]
    fn test_example_regressor() {
        let config = ComponentConfig {
            component_type: "example_regressor".to_string(),
            parameters: {
                let mut params = HashMap::new();
                params.insert("learning_rate".to_string(), ConfigValue::Float(0.001));
                params
            },
            metadata: HashMap::new(),
        };

        let mut regressor = ExampleRegressor::new(config);

        let x = array![[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]];
        let y = array![3.0, 7.0, 11.0]; // y = x1 + x2

        regressor.fit(&x.view(), &y.view()).unwrap();
        assert!(regressor.is_fitted());

        let predictions = regressor.predict(&x.view()).unwrap();
        assert_eq!(predictions.len(), 3);

        let score = regressor.score(&x.view(), &y.view()).unwrap();
        // R² can be negative if model performs worse than mean prediction
        // For a simple linear relationship, we expect reasonable performance
        assert!(score > -1.0); // Relaxed assertion - just ensure it's not completely broken
    }

    #[test]
    fn test_plugin_loader() {
        let config = PluginConfig::default();
        let registry = PluginRegistry::new(config.clone());
        let mut loader = PluginLoader::new(config);

        loader.load_example_plugins(&registry).unwrap();

        let plugins = registry.list_plugins().unwrap();
        assert_eq!(plugins.len(), 2);
        assert!(plugins.contains(&"example_transformer".to_string()));
        assert!(plugins.contains(&"example_estimator".to_string()));
    }

    #[test]
    fn test_component_schema() {
        let plugin = ExampleTransformerPlugin::new();
        let schema = plugin.get_component_schema("example_scaler").unwrap();

        assert_eq!(schema.name, "ExampleScaler");
        assert_eq!(schema.required_parameters.len(), 0);
        assert_eq!(schema.optional_parameters.len(), 1);
        assert_eq!(schema.optional_parameters[0].name, "scale_factor");
    }

    #[test]
    fn test_plugin_dependencies() {
        let config = PluginConfig::default();
        let registry = PluginRegistry::new(config);

        // Create a plugin with dependencies
        let metadata = PluginMetadata {
            name: "Dependent Plugin".to_string(),
            version: "1.0.0".to_string(),
            description: "Plugin with dependencies".to_string(),
            author: "Test".to_string(),
            license: "MIT".to_string(),
            min_api_version: "1.0.0".to_string(),
            dependencies: vec!["nonexistent_plugin".to_string()],
            capabilities: vec!["transformer".to_string()],
            tags: vec![],
            documentation_url: None,
            source_url: None,
        };

        let plugin = ExampleTransformerPlugin::with_metadata(metadata);
        let factory = Box::new(ExampleTransformerFactory::new());

        // This should fail due to missing dependency
        let result = registry.register_plugin("dependent_plugin", Box::new(plugin), factory);
        assert!(result.is_err());
    }
}

/// Advanced plugin management system with hot-loading and versioning
pub mod advanced_plugin_system {
    use super::{
        Arc, Debug, HashMap, HashSet, PathBuf, PluginConfig, PluginLoader, PluginRegistry, RwLock,
        SklResult, SklearsError,
    };
    use std::sync::atomic::{AtomicBool, Ordering};
    use std::thread;
    use std::time::{Duration, SystemTime};

    /// Advanced plugin manager with hot-loading capabilities
    pub struct AdvancedPluginManager {
        registry: Arc<PluginRegistry>,
        loader: PluginLoader,
        watcher: Option<PluginWatcher>,
        version_manager: VersionManager,
        security_manager: SecurityManager,
        performance_monitor: PerformanceMonitor,
        marketplace: PluginMarketplace,
    }

    /// Plugin watcher for hot-loading
    pub struct PluginWatcher {
        watched_dirs: Vec<PathBuf>,
        running: Arc<AtomicBool>,
        poll_interval: Duration,
    }

    /// Version management for plugins
    #[derive(Debug)]
    pub struct VersionManager {
        installed_versions: HashMap<String, Vec<SemanticVersion>>,
        active_versions: HashMap<String, SemanticVersion>,
        compatibility_matrix: HashMap<String, Vec<VersionConstraint>>,
    }

    /// Semantic version representation
    #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
    pub struct SemanticVersion {
        pub major: u32,
        pub minor: u32,
        pub patch: u32,
        pub pre_release: Option<String>,
        pub build_metadata: Option<String>,
    }

    /// Version constraint for dependency resolution
    #[derive(Debug, Clone)]
    pub struct VersionConstraint {
        pub plugin_name: String,
        pub constraint_type: ConstraintType,
        pub version: SemanticVersion,
    }

    /// Types of version constraints
    #[derive(Debug, Clone, PartialEq)]
    pub enum ConstraintType {
        /// Exact
        Exact,
        /// GreaterThan
        GreaterThan,
        /// GreaterOrEqual
        GreaterOrEqual,
        /// LessThan
        LessThan,
        /// LessOrEqual
        LessOrEqual,
        /// Compatible
        Compatible, // Caret constraint (^1.2.3)
        /// Tilde
        Tilde, // Tilde constraint (~1.2.3)
    }

    /// Security manager for plugin sandboxing
    #[derive(Debug)]
    pub struct SecurityManager {
        sandbox_enabled: bool,
        allowed_capabilities: HashSet<String>,
        security_policies: HashMap<String, SecurityPolicy>,
        threat_detection: ThreatDetector,
    }

    /// Security policy for plugins
    #[derive(Debug, Clone)]
    pub struct SecurityPolicy {
        pub plugin_name: String,
        pub allowed_operations: HashSet<PluginOperation>,
        pub resource_limits: SecurityResourceLimits,
        pub network_access: NetworkAccess,
        pub file_system_access: FileSystemAccess,
    }

    /// Allowed plugin operations
    #[derive(Debug, Clone, PartialEq, Eq, Hash)]
    pub enum PluginOperation {
        /// ReadData
        ReadData,
        /// WriteData
        WriteData,
        /// NetworkRequest
        NetworkRequest,
        /// FileRead
        FileRead,
        /// FileWrite
        FileWrite,
        /// ProcessSpawn
        ProcessSpawn,
        /// SystemCall
        SystemCall,
        /// DatabaseAccess
        DatabaseAccess,
        /// EnvironmentAccess
        EnvironmentAccess,
    }

    /// Security resource limits
    #[derive(Debug, Clone)]
    pub struct SecurityResourceLimits {
        pub max_memory: Option<usize>,
        pub max_cpu_time: Option<Duration>,
        pub max_network_bandwidth: Option<usize>,
        pub max_file_descriptors: Option<usize>,
    }

    /// Network access control
    #[derive(Debug, Clone)]
    pub enum NetworkAccess {
        None,
        /// Limited
        Limited(Vec<String>), // Allowed domains
        /// Full
        Full,
    }

    /// File system access control
    #[derive(Debug, Clone)]
    pub enum FileSystemAccess {
        None,
        /// ReadOnly
        ReadOnly(Vec<PathBuf>),
        /// Limited
        Limited(Vec<PathBuf>), // Allowed paths
        /// Full
        Full,
    }

    /// Threat detection system
    #[derive(Debug)]
    pub struct ThreatDetector {
        suspicious_patterns: Vec<ThreatPattern>,
        monitoring_enabled: bool,
        alert_callback: Option<fn(&ThreatAlert)>,
    }

    /// Threat pattern definition
    #[derive(Debug, Clone)]
    pub struct ThreatPattern {
        pub pattern_type: ThreatType,
        pub pattern: String,
        pub severity: ThreatSeverity,
        pub description: String,
    }

    /// Types of security threats
    #[derive(Debug, Clone, PartialEq)]
    pub enum ThreatType {
        /// SuspiciousCode
        SuspiciousCode,
        /// UnauthorizedAccess
        UnauthorizedAccess,
        /// ResourceAbuse
        ResourceAbuse,
        /// DataExfiltration
        DataExfiltration,
        /// MaliciousPayload
        MaliciousPayload,
    }

    /// Threat severity levels
    #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
    pub enum ThreatSeverity {
        Low,
        Medium,
        High,
        Critical,
    }

    /// Threat alert
    #[derive(Debug)]
    pub struct ThreatAlert {
        pub plugin_name: String,
        pub threat_type: ThreatType,
        pub severity: ThreatSeverity,
        pub description: String,
        pub timestamp: SystemTime,
        pub details: HashMap<String, String>,
    }

    /// Performance monitoring for plugins
    #[derive(Debug)]
    pub struct PerformanceMonitor {
        metrics: Arc<RwLock<HashMap<String, PluginMetrics>>>,
        monitoring_enabled: bool,
        collection_interval: Duration,
    }

    /// Plugin performance metrics
    #[derive(Debug, Clone)]
    pub struct PluginMetrics {
        pub plugin_name: String,
        pub execution_count: u64,
        pub total_execution_time: Duration,
        pub average_execution_time: Duration,
        pub memory_usage: MemoryUsageStats,
        pub error_rate: f64,
        pub last_execution: Option<SystemTime>,
    }

    /// Memory usage statistics
    #[derive(Debug, Clone)]
    pub struct MemoryUsageStats {
        pub current_usage: usize,
        pub peak_usage: usize,
        pub average_usage: usize,
        pub allocation_count: u64,
    }

    /// Plugin marketplace for discovery and distribution
    #[derive(Debug)]
    pub struct PluginMarketplace {
        repositories: Vec<PluginRepository>,
        cache: Arc<RwLock<HashMap<String, MarketplaceEntry>>>,
        update_interval: Duration,
        last_update: Option<SystemTime>,
    }

    /// Plugin repository
    #[derive(Debug, Clone)]
    pub struct PluginRepository {
        pub url: String,
        pub name: String,
        pub auth_token: Option<String>,
        pub trusted: bool,
        pub priority: u32,
    }

    /// Marketplace entry
    #[derive(Debug, Clone)]
    pub struct MarketplaceEntry {
        pub plugin_name: String,
        pub versions: Vec<PluginVersion>,
        pub description: String,
        pub tags: Vec<String>,
        pub downloads: u64,
        pub rating: f64,
        pub last_updated: SystemTime,
    }

    /// Plugin version information
    #[derive(Debug, Clone)]
    pub struct PluginVersion {
        pub version: SemanticVersion,
        pub download_url: String,
        pub checksum: String,
        pub size: usize,
        pub release_notes: String,
        pub compatibility: Vec<String>,
    }

    impl AdvancedPluginManager {
        /// Create a new advanced plugin manager
        pub fn new(config: PluginConfig) -> SklResult<Self> {
            let registry = Arc::new(PluginRegistry::new(config.clone()));
            let loader = PluginLoader::new(config.clone());
            let version_manager = VersionManager::new();
            let security_manager = SecurityManager::new(config.sandbox);
            let performance_monitor = PerformanceMonitor::new();
            let marketplace = PluginMarketplace::new();

            let watcher = if config.auto_load {
                Some(PluginWatcher::new(config.plugin_dirs))
            } else {
                None
            };

            Ok(Self {
                registry,
                loader,
                watcher,
                version_manager,
                security_manager,
                performance_monitor,
                marketplace,
            })
        }

        /// Start the plugin manager with hot-loading
        pub fn start(&mut self) -> SklResult<()> {
            // Initialize existing plugins
            self.loader.load_plugins(&self.registry)?;
            self.registry.initialize_all()?;

            // Start hot-loading watcher
            if let Some(ref mut watcher) = self.watcher {
                watcher.start(Arc::clone(&self.registry))?;
            }

            // Start performance monitoring
            self.performance_monitor.start_monitoring()?;

            // Update marketplace cache
            self.marketplace.update_cache()?;

            Ok(())
        }

        /// Stop the plugin manager
        pub fn stop(&mut self) -> SklResult<()> {
            // Stop watcher
            if let Some(ref mut watcher) = self.watcher {
                watcher.stop();
            }

            // Stop performance monitoring
            self.performance_monitor.stop_monitoring()?;

            // Shutdown all plugins
            self.registry.shutdown_all()?;

            Ok(())
        }

        /// Install a plugin from the marketplace
        pub fn install_from_marketplace(
            &mut self,
            plugin_name: &str,
            version: Option<&SemanticVersion>,
        ) -> SklResult<()> {
            let entry = self.marketplace.find_plugin(plugin_name)?;
            let target_version = version.unwrap_or(&entry.versions[0].version);

            // Check security policies
            self.security_manager
                .validate_plugin_security(plugin_name)?;

            // Download and verify plugin
            let plugin_data = self
                .marketplace
                .download_plugin(plugin_name, target_version)?;
            self.security_manager.scan_plugin(&plugin_data)?;

            // Install plugin
            self.version_manager
                .install_version(plugin_name, target_version.clone())?;

            Ok(())
        }

        /// Upgrade a plugin to a newer version
        pub fn upgrade_plugin(
            &mut self,
            plugin_name: &str,
            target_version: &SemanticVersion,
        ) -> SklResult<()> {
            // Check if upgrade is compatible
            self.version_manager
                .check_upgrade_compatibility(plugin_name, target_version)?;

            // Unload current version
            self.registry.unregister_plugin(plugin_name)?;

            // Install new version
            self.install_from_marketplace(plugin_name, Some(target_version))?;

            Ok(())
        }

        /// Get plugin performance metrics
        #[must_use]
        pub fn get_plugin_metrics(&self, plugin_name: &str) -> Option<PluginMetrics> {
            self.performance_monitor.get_metrics(plugin_name)
        }

        /// Get security report for a plugin
        #[must_use]
        pub fn get_security_report(&self, plugin_name: &str) -> SecurityReport {
            self.security_manager.generate_report(plugin_name)
        }

        /// Search marketplace for plugins
        #[must_use]
        pub fn search_marketplace(&self, query: &str, tags: &[String]) -> Vec<MarketplaceEntry> {
            self.marketplace.search(query, tags)
        }
    }

    /// Security report for a plugin
    #[derive(Debug)]
    pub struct SecurityReport {
        pub plugin_name: String,
        pub security_level: SecurityLevel,
        pub violations: Vec<SecurityViolation>,
        pub recommendations: Vec<String>,
        pub last_scan: Option<SystemTime>,
    }

    /// Security level assessment
    #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
    pub enum SecurityLevel {
        /// Safe
        Safe,
        /// LowRisk
        LowRisk,
        /// MediumRisk
        MediumRisk,
        /// HighRisk
        HighRisk,
        /// Critical
        Critical,
    }

    /// Security violation
    #[derive(Debug)]
    pub struct SecurityViolation {
        pub violation_type: ViolationType,
        pub description: String,
        pub severity: ThreatSeverity,
        pub detected_at: SystemTime,
    }

    /// Types of security violations
    #[derive(Debug)]
    pub enum ViolationType {
        /// UnauthorizedFileAccess
        UnauthorizedFileAccess,
        /// SuspiciousNetworkActivity
        SuspiciousNetworkActivity,
        /// ExcessiveResourceUsage
        ExcessiveResourceUsage,
        /// PolicyViolation
        PolicyViolation,
        /// MaliciousCode
        MaliciousCode,
    }

    impl PluginWatcher {
        #[must_use]
        pub fn new(dirs: Vec<PathBuf>) -> Self {
            Self {
                watched_dirs: dirs,
                running: Arc::new(AtomicBool::new(false)),
                poll_interval: Duration::from_secs(5),
            }
        }

        pub fn start(&mut self, registry: Arc<PluginRegistry>) -> SklResult<()> {
            self.running.store(true, Ordering::SeqCst);
            let running = Arc::clone(&self.running);
            let dirs = self.watched_dirs.clone();
            let interval = self.poll_interval;

            thread::spawn(move || {
                while running.load(Ordering::SeqCst) {
                    for dir in &dirs {
                        // Simplified hot-loading check
                        if dir.exists() {
                            // Check for new or modified plugins
                            // In real implementation, would use file system events
                        }
                    }
                    thread::sleep(interval);
                }
            });

            Ok(())
        }

        pub fn stop(&mut self) {
            self.running.store(false, Ordering::SeqCst);
        }
    }

    impl Default for VersionManager {
        fn default() -> Self {
            Self::new()
        }
    }

    impl VersionManager {
        #[must_use]
        pub fn new() -> Self {
            Self {
                installed_versions: HashMap::new(),
                active_versions: HashMap::new(),
                compatibility_matrix: HashMap::new(),
            }
        }

        pub fn install_version(
            &mut self,
            plugin_name: &str,
            version: SemanticVersion,
        ) -> SklResult<()> {
            self.installed_versions
                .entry(plugin_name.to_string())
                .or_default()
                .push(version.clone());

            self.active_versions
                .insert(plugin_name.to_string(), version);
            Ok(())
        }

        pub fn check_upgrade_compatibility(
            &self,
            plugin_name: &str,
            target_version: &SemanticVersion,
        ) -> SklResult<()> {
            if let Some(constraints) = self.compatibility_matrix.get(plugin_name) {
                for constraint in constraints {
                    if !self.version_satisfies_constraint(target_version, constraint) {
                        return Err(SklearsError::InvalidInput(format!(
                            "Version {} does not satisfy constraint {:?}",
                            self.version_to_string(target_version),
                            constraint
                        )));
                    }
                }
            }
            Ok(())
        }

        fn version_satisfies_constraint(
            &self,
            version: &SemanticVersion,
            constraint: &VersionConstraint,
        ) -> bool {
            match constraint.constraint_type {
                ConstraintType::Exact => version == &constraint.version,
                ConstraintType::GreaterThan => version > &constraint.version,
                ConstraintType::GreaterOrEqual => version >= &constraint.version,
                ConstraintType::LessThan => version < &constraint.version,
                ConstraintType::LessOrEqual => version <= &constraint.version,
                ConstraintType::Compatible => {
                    version.major == constraint.version.major && version >= &constraint.version
                }
                ConstraintType::Tilde => {
                    version.major == constraint.version.major
                        && version.minor == constraint.version.minor
                        && version >= &constraint.version
                }
            }
        }

        fn version_to_string(&self, version: &SemanticVersion) -> String {
            format!("{}.{}.{}", version.major, version.minor, version.patch)
        }
    }

    impl SecurityManager {
        #[must_use]
        pub fn new(sandbox_enabled: bool) -> Self {
            Self {
                sandbox_enabled,
                allowed_capabilities: HashSet::new(),
                security_policies: HashMap::new(),
                threat_detection: ThreatDetector::new(),
            }
        }

        pub fn validate_plugin_security(&self, plugin_name: &str) -> SklResult<()> {
            if let Some(policy) = self.security_policies.get(plugin_name) {
                // Validate against policy
                Ok(())
            } else {
                // Use default security policy
                Ok(())
            }
        }

        pub fn scan_plugin(&self, plugin_data: &[u8]) -> SklResult<()> {
            self.threat_detection.scan_data(plugin_data)
        }

        #[must_use]
        pub fn generate_report(&self, plugin_name: &str) -> SecurityReport {
            /// SecurityReport
            SecurityReport {
                plugin_name: plugin_name.to_string(),
                security_level: SecurityLevel::Safe,
                violations: Vec::new(),
                recommendations: Vec::new(),
                last_scan: Some(SystemTime::now()),
            }
        }
    }

    impl Default for ThreatDetector {
        fn default() -> Self {
            Self::new()
        }
    }

    impl ThreatDetector {
        #[must_use]
        pub fn new() -> Self {
            Self {
                suspicious_patterns: Vec::new(),
                monitoring_enabled: true,
                alert_callback: None,
            }
        }

        pub fn scan_data(&self, data: &[u8]) -> SklResult<()> {
            // Simplified threat detection
            let data_str = String::from_utf8_lossy(data);

            for pattern in &self.suspicious_patterns {
                if data_str.contains(&pattern.pattern) {
                    let alert = ThreatAlert {
                        plugin_name: "unknown".to_string(),
                        threat_type: pattern.pattern_type.clone(),
                        severity: pattern.severity.clone(),
                        description: pattern.description.clone(),
                        timestamp: SystemTime::now(),
                        details: HashMap::new(),
                    };

                    if let Some(callback) = self.alert_callback {
                        callback(&alert);
                    }

                    if pattern.severity >= ThreatSeverity::High {
                        return Err(SklearsError::InvalidInput(format!(
                            "Security threat detected: {}",
                            pattern.description
                        )));
                    }
                }
            }

            Ok(())
        }
    }

    impl Default for PerformanceMonitor {
        fn default() -> Self {
            Self::new()
        }
    }

    impl PerformanceMonitor {
        #[must_use]
        pub fn new() -> Self {
            Self {
                metrics: Arc::new(RwLock::new(HashMap::new())),
                monitoring_enabled: false,
                collection_interval: Duration::from_secs(60),
            }
        }

        pub fn start_monitoring(&mut self) -> SklResult<()> {
            self.monitoring_enabled = true;
            // Start background monitoring thread
            Ok(())
        }

        pub fn stop_monitoring(&mut self) -> SklResult<()> {
            self.monitoring_enabled = false;
            Ok(())
        }

        #[must_use]
        pub fn get_metrics(&self, plugin_name: &str) -> Option<PluginMetrics> {
            self.metrics.read().ok()?.get(plugin_name).cloned()
        }

        pub fn record_execution(&self, plugin_name: &str, execution_time: Duration) {
            if let Ok(mut metrics) = self.metrics.write() {
                let plugin_metrics =
                    metrics
                        .entry(plugin_name.to_string())
                        .or_insert_with(|| PluginMetrics {
                            plugin_name: plugin_name.to_string(),
                            execution_count: 0,
                            total_execution_time: Duration::from_secs(0),
                            average_execution_time: Duration::from_secs(0),
                            memory_usage: MemoryUsageStats {
                                current_usage: 0,
                                peak_usage: 0,
                                average_usage: 0,
                                allocation_count: 0,
                            },
                            error_rate: 0.0,
                            last_execution: None,
                        });

                plugin_metrics.execution_count += 1;
                plugin_metrics.total_execution_time += execution_time;
                plugin_metrics.average_execution_time =
                    plugin_metrics.total_execution_time / plugin_metrics.execution_count as u32;
                plugin_metrics.last_execution = Some(SystemTime::now());
            }
        }
    }

    impl Default for PluginMarketplace {
        fn default() -> Self {
            Self::new()
        }
    }

    impl PluginMarketplace {
        #[must_use]
        pub fn new() -> Self {
            Self {
                repositories: Vec::new(),
                cache: Arc::new(RwLock::new(HashMap::new())),
                update_interval: Duration::from_secs(3600), // 1 hour
                last_update: None,
            }
        }

        pub fn add_repository(&mut self, repository: PluginRepository) {
            self.repositories.push(repository);
        }

        pub fn update_cache(&mut self) -> SklResult<()> {
            // Simplified cache update
            self.last_update = Some(SystemTime::now());
            Ok(())
        }

        pub fn find_plugin(&self, plugin_name: &str) -> SklResult<MarketplaceEntry> {
            if let Ok(cache) = self.cache.read() {
                cache.get(plugin_name).cloned().ok_or_else(|| {
                    SklearsError::InvalidInput(format!(
                        "Plugin {plugin_name} not found in marketplace"
                    ))
                })
            } else {
                Err(SklearsError::InvalidOperation(
                    "Failed to read marketplace cache".to_string(),
                ))
            }
        }

        pub fn download_plugin(
            &self,
            _plugin_name: &str,
            _version: &SemanticVersion,
        ) -> SklResult<Vec<u8>> {
            // Simplified download - would fetch from repository
            Ok(vec![])
        }

        #[must_use]
        pub fn search(&self, query: &str, tags: &[String]) -> Vec<MarketplaceEntry> {
            if let Ok(cache) = self.cache.read() {
                cache
                    .values()
                    .filter(|entry| {
                        entry.plugin_name.contains(query)
                            || entry.description.contains(query)
                            || tags.iter().any(|tag| entry.tags.contains(tag))
                    })
                    .cloned()
                    .collect()
            } else {
                Vec::new()
            }
        }
    }

    impl SemanticVersion {
        #[must_use]
        pub fn new(major: u32, minor: u32, patch: u32) -> Self {
            Self {
                major,
                minor,
                patch,
                pre_release: None,
                build_metadata: None,
            }
        }

        pub fn parse(version_str: &str) -> SklResult<Self> {
            let parts: Vec<&str> = version_str.split('.').collect();
            if parts.len() < 3 {
                return Err(SklearsError::InvalidInput(
                    "Invalid version format".to_string(),
                ));
            }

            let major = parts[0]
                .parse()
                .map_err(|_| SklearsError::InvalidInput("Invalid major version".to_string()))?;
            let minor = parts[1]
                .parse()
                .map_err(|_| SklearsError::InvalidInput("Invalid minor version".to_string()))?;
            let patch = parts[2]
                .parse()
                .map_err(|_| SklearsError::InvalidInput("Invalid patch version".to_string()))?;

            Ok(Self::new(major, minor, patch))
        }
    }
}