quality-mcp/src/core/plugin-manager.js

An MCP server that analyzes to your codebase, with plugin support for DCD and Simian. 🏍️ "The only Zen you find on the tops of mountains is the Zen you bring up there."

/**
 * Plugin Manager
 * Handles registration, lifecycle, and communication between MCP server and analysis plugins
 */

import { EventEmitter } from 'events';
import { createLogger } from '../utils/logger.js';
import {
  CallToolRequestSchema,
  ReadResourceRequestSchema,
  GetPromptRequestSchema,
  ListToolsRequestSchema,
  ListResourcesRequestSchema,
  ListResourceTemplatesRequestSchema,
  ListPromptsRequestSchema,
} from '@modelcontextprotocol/sdk/types.js';

const logger = createLogger('plugin-manager');

/**
 * Dependency injection function for plugin manager
 * @returns {Object} Dependencies object
 */
export function getDeps() {
  return {
    logger,
  };
}

/**
 * Abstract base class for analysis plugins
 */
export class AnalysisPlugin {
  constructor(name, config = {}) {
    this.name = name;
    this.config = config;
    this.enabled = true;
  }

  /**
   * Initialize the plugin
   * @returns {Promise<void>}
   */
  async initialize() {
    throw new Error('initialize() must be implemented by plugin');
  }

  /**
   * Get the tools this plugin provides
   * @returns {Array<Object>} Array of MCP tool definitions
   */
  getTools() {
    return [];
  }

  /**
   * Get the resources this plugin provides
   * @returns {Array<Object>} Array of MCP resource definitions
   */
  getResources() {
    return [];
  }

  /**
   * Get the prompts this plugin provides
   * @returns {Array<Object>} Array of MCP prompt definitions
   */
  getPrompts() {
    return [];
  }

  /**
   * Execute a tool
   * @param {string} toolName - Name of the tool to execute
   * @param {Object} _params - Tool parameters
   * @returns {Promise<Object>} Tool execution result
   */
  async executeTool(toolName, _params) {
    throw new Error(`Tool ${toolName} not implemented by plugin ${this.name}`);
  }

  /**
   * Get a resource
   * @param {string} resourceUri - URI of the resource to get
   * @returns {Promise<Object>} Resource data
   */
  async getResource(resourceUri) {
    throw new Error(`Resource ${resourceUri} not implemented by plugin ${this.name}`);
  }

  /**
   * Get a prompt
   * @param {string} promptName - Name of the prompt to get
   * @param {Object} _params - Prompt parameters
   * @returns {Promise<Object>} Prompt data
   */
  async getPrompt(promptName, _params) {
    throw new Error(`Prompt ${promptName} not implemented by plugin ${this.name}`);
  }

  /**
   * Shutdown the plugin
   * @returns {Promise<void>}
   */
  async shutdown() {
    logger.info(`Shutting down plugin: ${this.name}`);
  }
}

/**
 * Plugin Manager - orchestrates multiple analysis plugins
 */
export class PluginManager extends EventEmitter {
  constructor(server, _getDeps = getDeps) {
    super();
    this.server = server;
    this.plugins = new Map();
    this.toolRegistry = new Map();
    this.resourceRegistry = new Map();
    this.promptRegistry = new Map();

    this.setupServerHandlers();
  }

  /**
   * Set up MCP server request handlers
   */
  setupServerHandlers(_getDeps = getDeps) {
    const { logger } = _getDeps();

    try {
      // Register the get_plugin_status tool
      this.toolRegistry.set('get_plugin_status', {
        plugin: this,
        definition: {
          name: 'get_plugin_status',
          description: 'Check the status and availability of all plugins and their tools',
          inputSchema: {
            type: 'object',
            properties: {
              plugin: {
                type: 'string',
                description:
                  'Specific plugin to check (optional - if not provided, checks all plugins)',
                enum: ['dcd', 'simian', 'all'],
                default: 'all',
              },
            },
            required: [],
          },
        },
      });

      logger.debug('Plugin manager handlers setup completed');
    } catch (error) {
      logger.error('Failed to setup plugin manager handlers:', error);
      throw error;
    }

    // Handle tool execution requests
    this.server.setRequestHandler(CallToolRequestSchema, async request => {
      try {
        const { name, arguments: args = {} } = request.params;

        if (!this.toolRegistry.has(name)) {
          throw new Error(`Unknown tool: ${name}`);
        }

        const { plugin } = this.toolRegistry.get(name);

        // Special handling for get_plugin_status tool
        if (name === 'get_plugin_status') {
          const result = await this.getPluginStatus();

          // Return result in proper MCP format without double serialization
          return this.formatToolResponse(result, name);
        }

        const result = await plugin.executeTool(name, args);

        // Return result in proper MCP format without double serialization
        return this.formatToolResponse(result, name);
      } catch (error) {
        logger.error('Tool execution error:', error);
        throw error;
      }
    });

    // Handle resource requests
    this.server.setRequestHandler(ReadResourceRequestSchema, async request => {
      try {
        const { uri } = request.params;

        if (!this.resourceRegistry.has(uri)) {
          throw new Error(`Unknown resource: ${uri}`);
        }

        const { plugin } = this.resourceRegistry.get(uri);
        const result = await plugin.getResource(uri);

        // Return response in proper MCP format using the same pattern as tools
        return {
          contents: [
            {
              uri,
              mimeType: result.mimeType || 'application/json',
              text: this.formatResourceResponse(result.data, uri),
            },
          ],
        };
      } catch (error) {
        logger.error('Resource read error:', error);
        throw error;
      }
    });

    // Handle prompt requests
    this.server.setRequestHandler(GetPromptRequestSchema, async request => {
      try {
        const { name, arguments: args = {} } = request.params;

        if (!this.promptRegistry.has(name)) {
          throw new Error(`Unknown prompt: ${name}`);
        }

        const { plugin } = this.promptRegistry.get(name);
        const result = await plugin.getPrompt(name, args);

        return result;
      } catch (error) {
        logger.error('Prompt get error:', error);
        throw error;
      }
    });

    // Handle tools list requests
    this.server.setRequestHandler(ListToolsRequestSchema, async () => {
      try {
        logger.debug('Handling ListToolsRequest');
        const tools = [];
        for (const { definition } of this.toolRegistry.values()) {
          tools.push(definition);
        }
        logger.debug(`Returning ${tools.length} tools`);
        return { tools };
      } catch (error) {
        logger.error('Error in ListToolsRequest handler:', error);
        throw error;
      }
    });

    // Handle resources list requests
    this.server.setRequestHandler(ListResourcesRequestSchema, async () => {
      try {
        logger.debug('Handling ListResourcesRequest');
        const resources = [];
        for (const { definition } of this.resourceRegistry.values()) {
          resources.push(definition);
        }
        logger.debug(`Returning ${resources.length} resources`);
        return { resources };
      } catch (error) {
        logger.error('Error in ListResourcesRequest handler:', error);
        throw error;
      }
    });

    // Handle resource templates list requests (none defined yet)
    this.server.setRequestHandler(ListResourceTemplatesRequestSchema, async () => {
      try {
        logger.debug('Handling ListResourceTemplatesRequest');
        return { resourceTemplates: [] };
      } catch (error) {
        logger.error('Error in ListResourceTemplatesRequest handler:', error);
        throw error;
      }
    });

    // Handle prompts list requests
    this.server.setRequestHandler(ListPromptsRequestSchema, async () => {
      try {
        logger.debug('Handling ListPromptsRequest');
        const prompts = [];
        for (const { definition } of this.promptRegistry.values()) {
          prompts.push(definition);
        }
        logger.debug(`Returning ${prompts.length} prompts`);
        return { prompts };
      } catch (error) {
        logger.error('Error in ListPromptsRequest handler:', error);
        throw error;
      }
    });
  }

  /**
   * Format tool response in proper MCP format without double serialization
   * @param {any} result - Tool execution result
   * @param {string} toolName - Name of the tool for logging
   * @returns {Object} Properly formatted MCP response
   */
  formatToolResponse(result, toolName, _getDeps = getDeps) {
    const { logger } = _getDeps();

    // Handle different result types appropriately
    let responseText;

    if (typeof result === 'string') {
      // If result is already a string, use it directly
      responseText = result;
    } else if (result === null || result === undefined) {
      // Handle null/undefined gracefully
      responseText = '{}';
    } else {
      // For objects, arrays, etc., serialize to JSON
      try {
        responseText = JSON.stringify(result, null, 2);
      } catch (jsonError) {
        logger.warn(`Failed to stringify tool result for ${toolName}, using fallback:`, jsonError);
        responseText = JSON.stringify({
          error: 'Failed to serialize result',
          originalResult: String(result),
          toolName,
        });
      }
    }

    // Return in proper MCP format
    return {
      content: [
        {
          type: 'text',
          text: responseText,
        },
      ],
    };
  }

  /**
   * Format resource response in proper MCP format without double serialization
   * @param {any} data - Resource data
   * @param {string} uri - Resource URI for logging
   * @returns {string} Properly formatted response text
   */
  formatResourceResponse(data, uri, _getDeps = getDeps) {
    const { logger } = _getDeps();

    // Handle different data types appropriately
    if (typeof data === 'string') {
      // If data is already a string, use it directly
      return data;
    } else if (data === null || data === undefined) {
      // Handle null/undefined gracefully
      return '{}';
    } else {
      // For objects, arrays, etc., serialize to JSON
      try {
        return JSON.stringify(data, null, 2);
      } catch (jsonError) {
        logger.warn(`Failed to stringify resource data for ${uri}, using fallback:`, jsonError);
        return JSON.stringify({
          error: 'Failed to serialize resource data',
          originalData: String(data),
          uri,
        });
      }
    }
  }

  /**
   * Register a plugin
   * @param {string} name - Plugin name
   * @param {AnalysisPlugin} plugin - Plugin instance
   * @returns {Promise<void>}
   */
  async register(name, plugin) {
    logger.info(`Registering plugin: ${name}`);

    try {
      // Initialize the plugin
      await plugin.initialize();

      // Store plugin
      this.plugins.set(name, plugin);

      // Register plugin's capabilities
      this.registerPluginTools(name, plugin);
      this.registerPluginResources(name, plugin);
      this.registerPluginPrompts(name, plugin);

      logger.info(`Plugin registered successfully: ${name}`);
      this.emit('pluginRegistered', name, plugin);
    } catch (error) {
      logger.error(`Failed to register plugin ${name}:`, error);
      this.emit('error', name, error);
      throw error;
    }
  }

  /**
   * Register tools from a plugin
   */
  registerPluginTools(pluginName, plugin) {
    const tools = plugin.getTools();

    for (const tool of tools) {
      const toolName = tool.name;

      if (this.toolRegistry.has(toolName)) {
        logger.warn(`Tool ${toolName} already registered, skipping`);
        continue;
      }

      this.toolRegistry.set(toolName, {
        plugin,
        definition: tool,
      });

      logger.debug(`Registered tool: ${toolName} from plugin: ${pluginName}`);
    }
  }

  /**
   * Register resources from a plugin
   */
  registerPluginResources(pluginName, plugin) {
    const resources = plugin.getResources();

    for (const resource of resources) {
      const resourceUri = resource.uri;

      if (this.resourceRegistry.has(resourceUri)) {
        logger.warn(`Resource ${resourceUri} already registered, skipping`);
        continue;
      }

      this.resourceRegistry.set(resourceUri, {
        plugin,
        definition: resource,
      });

      logger.debug(`Registered resource: ${resourceUri} from plugin: ${pluginName}`);
    }
  }

  /**
   * Register prompts from a plugin
   */
  registerPluginPrompts(pluginName, plugin) {
    const prompts = plugin.getPrompts();

    for (const prompt of prompts) {
      const promptName = prompt.name;

      if (this.promptRegistry.has(promptName)) {
        logger.warn(`Prompt ${promptName} already registered, skipping`);
        continue;
      }

      this.promptRegistry.set(promptName, {
        plugin,
        definition: prompt,
      });

      logger.debug(`Registered prompt: ${promptName} from plugin: ${pluginName}`);
    }
  }

  /**
   * Get a plugin by name
   * @param {string} name - Plugin name
   * @returns {AnalysisPlugin|null}
   */
  getPlugin(name) {
    return this.plugins.get(name) || null;
  }

  /**
   * Get all registered plugins
   * @returns {Map<string, AnalysisPlugin>}
   */
  getPlugins() {
    return new Map(this.plugins);
  }

  /**
   * Check if a plugin is registered
   * @param {string} name - Plugin name
   * @returns {boolean}
   */
  hasPlugin(name) {
    return this.plugins.has(name);
  }

  /**
   * Shutdown all plugins
   * @returns {Promise<void>}
   */
  async shutdown(_getDeps = getDeps) {
    const { logger } = _getDeps();
    logger.info('Shutting down all plugins...');

    const shutdownPromises = Array.from(this.plugins.values()).map(async plugin => {
      try {
        await plugin.shutdown();
      } catch (error) {
        logger.error(`Error shutting down plugin ${plugin.name}:`, error);
      }
    });

    await Promise.all(shutdownPromises);

    // Clear registries
    this.plugins.clear();
    this.toolRegistry.clear();
    this.resourceRegistry.clear();
    this.promptRegistry.clear();

    logger.info('All plugins shutdown complete');
  }

  /**
   * Get comprehensive status of all plugins
   * @returns {Object} Status information for all plugins
   */
  async getPluginStatus(_getDeps = getDeps) {
    const { logger } = _getDeps();
    logger.debug('Getting plugin status');

    const available = [];
    const unavailable = [];
    let totalTools = 0;

    for (const [pluginName, plugin] of this.plugins) {
      try {
        const status = await plugin.getPluginStatus();

        if (status.tools && status.tools.length > 0) {
          available.push(status);
          totalTools += status.tools.length;
        } else {
          unavailable.push(status);
        }
      } catch (error) {
        logger.warn(`Failed to get status for plugin ${pluginName}:`, error);
        unavailable.push({
          plugin: pluginName,
          name: pluginName,
          message: `Failed to get status: ${error.message}`,
        });
      }
    }

    const recommendations = [];
    if (unavailable.length > 0) {
      for (const plugin of unavailable) {
        if (plugin.installation) {
          if (plugin.plugin === 'dcd') {
            recommendations.push(`Install DCD: ${plugin.installation.command}`);
          } else if (plugin.plugin === 'simian') {
            recommendations.push(
              `Install Simian: ${plugin.installation.description} (requires commercial license)`
            );
          }
        }
      }
    }

    return {
      available,
      unavailable,
      summary: {
        totalPlugins: this.plugins.size,
        availablePlugins: available.length,
        totalTools,
        recommendations,
      },
    };
  }
}