@clduab11/gemini-flow/extensions/vscode-gemini-flow/src/services/mcp-service.ts

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/**
 * MCP Service - Model Context Protocol implementation
 */

import * as vscode from 'vscode';
import { MCPServer } from '../types';
import { Logger } from '../utils/logger';

export class MCPService implements vscode.Disposable {
  private _servers = new Map<string, MCPConnection>();
  private _isInitialized = false;

  constructor(
    private readonly _serverConfigs: string[],
    private readonly _logger: Logger
  ) {}

  /**
   * Initialize MCP service
   */
  async initialize(): Promise<void> {
    try {
      this._logger.info('Initializing MCP service...');
      
      // Initialize connections to configured servers
      for (const serverConfig of this._serverConfigs) {
        await this.connectToServer(serverConfig);
      }
      
      this._isInitialized = true;
      this._logger.info('MCP service initialized successfully');
    } catch (error) {
      this._logger.error('Failed to initialize MCP service', error as Error);
      throw error;
    }
  }

  /**
   * Connect to an MCP server
   */
  async connectToServer(serverUrl: string): Promise<void> {
    try {
      this._logger.info(`Connecting to MCP server: ${serverUrl}`);
      
      if (this._servers.has(serverUrl)) {
        this._logger.warn(`Already connected to MCP server: ${serverUrl}`);
        return;
      }

      const connection = new MCPConnection(serverUrl, this._logger);
      await connection.connect();
      
      this._servers.set(serverUrl, connection);
      this._logger.info(`Successfully connected to MCP server: ${serverUrl}`);
    } catch (error) {
      this._logger.error(`Failed to connect to MCP server: ${serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * Disconnect from an MCP server
   */
  async disconnectFromServer(serverUrl: string): Promise<void> {
    try {
      this._logger.info(`Disconnecting from MCP server: ${serverUrl}`);
      
      const connection = this._servers.get(serverUrl);
      if (connection) {
        await connection.disconnect();
        this._servers.delete(serverUrl);
        this._logger.info(`Disconnected from MCP server: ${serverUrl}`);
      }
    } catch (error) {
      this._logger.error(`Failed to disconnect from MCP server: ${serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * List available tools from all connected servers
   */
  async listTools(): Promise<Array<{ server: string; tools: any[] }>> {
    const allTools: Array<{ server: string; tools: any[] }> = [];
    
    for (const [serverUrl, connection] of this._servers) {
      try {
        const tools = await connection.listTools();
        allTools.push({ server: serverUrl, tools });
      } catch (error) {
        this._logger.error(`Failed to list tools from server: ${serverUrl}`, error as Error);
      }
    }
    
    return allTools;
  }

  /**
   * Execute a tool on a specific server
   */
  async executeTool(
    serverUrl: string, 
    toolName: string, 
    args: any
  ): Promise<any> {
    const connection = this._servers.get(serverUrl);
    if (!connection) {
      throw new Error(`Not connected to server: ${serverUrl}`);
    }

    try {
      this._logger.debug(`Executing tool ${toolName} on server ${serverUrl}`, args);
      const result = await connection.executeTool(toolName, args);
      this._logger.debug(`Tool execution completed: ${toolName}`);
      return result;
    } catch (error) {
      this._logger.error(`Failed to execute tool ${toolName} on server ${serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * Get resources from a specific server
   */
  async getResources(serverUrl: string): Promise<any[]> {
    const connection = this._servers.get(serverUrl);
    if (!connection) {
      throw new Error(`Not connected to server: ${serverUrl}`);
    }

    try {
      return await connection.getResources();
    } catch (error) {
      this._logger.error(`Failed to get resources from server: ${serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * Read a resource from a specific server
   */
  async readResource(serverUrl: string, resourceUri: string): Promise<any> {
    const connection = this._servers.get(serverUrl);
    if (!connection) {
      throw new Error(`Not connected to server: ${serverUrl}`);
    }

    try {
      return await connection.readResource(resourceUri);
    } catch (error) {
      this._logger.error(`Failed to read resource ${resourceUri} from server: ${serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * Send context to all connected servers
   */
  async shareContext(context: any): Promise<void> {
    const promises: Promise<void>[] = [];
    
    for (const [serverUrl, connection] of this._servers) {
      promises.push(
        connection.sendContext(context).catch(error => {
          this._logger.error(`Failed to share context with server: ${serverUrl}`, error as Error);
        })
      );
    }
    
    await Promise.allSettled(promises);
  }

  /**
   * Get sampling configuration from servers
   */
  async getSamplingConfig(): Promise<any> {
    // Return sampling configuration from the first available server
    for (const [serverUrl, connection] of this._servers) {
      try {
        return await connection.getSamplingConfig();
      } catch (error) {
        this._logger.error(`Failed to get sampling config from server: ${serverUrl}`, error as Error);
      }
    }
    
    return null;
  }

  /**
   * Perform sampling with context
   */
  async performSampling(request: any): Promise<any> {
    // Use the first available server for sampling
    for (const [serverUrl, connection] of this._servers) {
      try {
        return await connection.performSampling(request);
      } catch (error) {
        this._logger.error(`Failed to perform sampling on server: ${serverUrl}`, error as Error);
      }
    }
    
    throw new Error('No available servers for sampling');
  }

  /**
   * Get connection status
   */
  getConnectionStatus(): Array<{ server: string; connected: boolean; tools: number }> {
    const status: Array<{ server: string; connected: boolean; tools: number }> = [];
    
    for (const [serverUrl, connection] of this._servers) {
      status.push({
        server: serverUrl,
        connected: connection.isConnected(),
        tools: connection.getToolCount()
      });
    }
    
    return status;
  }

  /**
   * Check if any servers are connected
   */
  hasConnections(): boolean {
    return this._servers.size > 0;
  }

  /**
   * Get connected server URLs
   */
  getConnectedServers(): string[] {
    return Array.from(this._servers.keys());
  }

  /**
   * Dispose of MCP service
   */
  dispose(): void {
    this._logger.info('Disposing MCP service...');
    
    const disconnectPromises: Promise<void>[] = [];
    
    for (const [serverUrl, connection] of this._servers) {
      disconnectPromises.push(
        connection.disconnect().catch(error => {
          this._logger.error(`Error disconnecting from server: ${serverUrl}`, error as Error);
        })
      );
    }
    
    Promise.allSettled(disconnectPromises).then(() => {
      this._servers.clear();
      this._logger.info('MCP service disposed');
    });
  }
}

/**
 * Individual MCP server connection
 */
class MCPConnection {
  private _isConnected = false;
  private _tools = new Map<string, any>();
  private _resources = new Map<string, any>();

  constructor(
    private readonly _serverUrl: string,
    private readonly _logger: Logger
  ) {}

  /**
   * Connect to the MCP server
   */
  async connect(): Promise<void> {
    try {
      // This is a simplified implementation
      // In a real implementation, you would use the MCP SDK to establish connections
      // based on the transport type (stdio, SSE, WebSocket)
      
      this._logger.debug(`Establishing MCP connection to: ${this._serverUrl}`);
      
      // Simulate connection establishment
      await this.simulateConnection();
      
      // Initialize server capabilities
      await this.initializeCapabilities();
      
      this._isConnected = true;
      this._logger.debug(`MCP connection established: ${this._serverUrl}`);
    } catch (error) {
      this._logger.error(`Failed to connect to MCP server: ${this._serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * Disconnect from the MCP server
   */
  async disconnect(): Promise<void> {
    try {
      this._logger.debug(`Disconnecting from MCP server: ${this._serverUrl}`);
      
      // Clean up resources
      this._tools.clear();
      this._resources.clear();
      this._isConnected = false;
      
      this._logger.debug(`Disconnected from MCP server: ${this._serverUrl}`);
    } catch (error) {
      this._logger.error(`Error during MCP disconnection: ${this._serverUrl}`, error as Error);
      throw error;
    }
  }

  /**
   * List available tools
   */
  async listTools(): Promise<any[]> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    return Array.from(this._tools.values());
  }

  /**
   * Execute a tool
   */
  async executeTool(toolName: string, args: any): Promise<any> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    const tool = this._tools.get(toolName);
    if (!tool) {
      throw new Error(`Tool not found: ${toolName}`);
    }

    // Simulate tool execution
    this._logger.debug(`Executing MCP tool: ${toolName}`, args);
    
    // In a real implementation, this would send an MCP tool execution request
    return {
      result: `Tool ${toolName} executed successfully`,
      args,
      timestamp: new Date().toISOString()
    };
  }

  /**
   * Get available resources
   */
  async getResources(): Promise<any[]> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    return Array.from(this._resources.values());
  }

  /**
   * Read a specific resource
   */
  async readResource(resourceUri: string): Promise<any> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    const resource = this._resources.get(resourceUri);
    if (!resource) {
      throw new Error(`Resource not found: ${resourceUri}`);
    }

    // In a real implementation, this would send an MCP resource read request
    return {
      uri: resourceUri,
      content: resource.content,
      mimeType: resource.mimeType
    };
  }

  /**
   * Send context to the server
   */
  async sendContext(context: any): Promise<void> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    // In a real implementation, this would send context via MCP notifications
    this._logger.debug(`Sending context to MCP server: ${this._serverUrl}`);
  }

  /**
   * Get sampling configuration
   */
  async getSamplingConfig(): Promise<any> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    // Return default sampling configuration
    return {
      maxTokens: 4096,
      temperature: 0.7,
      topP: 0.9
    };
  }

  /**
   * Perform sampling request
   */
  async performSampling(request: any): Promise<any> {
    if (!this._isConnected) {
      throw new Error('Not connected to MCP server');
    }

    // In a real implementation, this would send an MCP sampling request
    this._logger.debug(`Performing sampling on MCP server: ${this._serverUrl}`);
    
    return {
      content: 'Sampled response from MCP server',
      model: 'mcp-model',
      usage: {
        inputTokens: 100,
        outputTokens: 50
      }
    };
  }

  /**
   * Check if connected
   */
  isConnected(): boolean {
    return this._isConnected;
  }

  /**
   * Get tool count
   */
  getToolCount(): number {
    return this._tools.size;
  }

  /**
   * Simulate connection establishment
   */
  private async simulateConnection(): Promise<void> {
    // Simulate network delay
    await new Promise(resolve => setTimeout(resolve, 100));
    
    // In a real implementation, you would:
    // 1. Parse the server URL to determine transport type
    // 2. Establish the appropriate connection (stdio, SSE, WebSocket)
    // 3. Perform MCP handshake
    // 4. Exchange capabilities
  }

  /**
   * Initialize server capabilities
   */
  private async initializeCapabilities(): Promise<void> {
    // Simulate server capabilities discovery
    // In a real implementation, this would query the server for its capabilities
    
    // Add some example tools
    this._tools.set('search', {
      name: 'search',
      description: 'Search for information',
      inputSchema: {
        type: 'object',
        properties: {
          query: { type: 'string' }
        }
      }
    });

    this._tools.set('calculate', {
      name: 'calculate',
      description: 'Perform calculations',
      inputSchema: {
        type: 'object',
        properties: {
          expression: { type: 'string' }
        }
      }
    });

    // Add some example resources
    this._resources.set('file://example.txt', {
      uri: 'file://example.txt',
      name: 'Example Text File',
      mimeType: 'text/plain',
      content: 'This is an example text file content'
    });
  }
}