import { Client } from '@modelcontextprotocol/sdk/client/index.js';
import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js';
import type { FastifyBaseLogger } from 'fastify';

export interface MCPClientConfig {
  userId: string;
  mcpServerUrl: string;
  platformJWT?: string;
  logger: FastifyBaseLogger;
}

/**
 * MCP client connector for user's container
 * Manages connection to user-specific MCP server
 */
export class MCPClientConnector {
  private client: Client | null = null;
  private connected = false;
  private config: MCPClientConfig;

  constructor(config: MCPClientConfig) {
    this.config = config;
  }

  /**
   * Connect to user's MCP server
   * TODO: Implement HTTP/SSE transport instead of stdio for container communication
   */
  async connect(): Promise<void> {
    if (this.connected) {
      return;
    }

    try {
      this.config.logger.info(
        { userId: this.config.userId, url: this.config.mcpServerUrl },
        'Connecting to user MCP server'
      );

      this.client = new Client(
        {
          name: 'dexorder-gateway',
          version: '0.1.0',
        },
        {
          capabilities: {
            tools: {},
            resources: {},
          },
        }
      );

      // TODO: Replace with HTTP transport when user containers are ready
      // For now, this is a placeholder structure
      // const transport = new HTTPTransport(this.config.mcpServerUrl, {
      //   headers: {
      //     'Authorization': `Bearer ${this.config.platformJWT}`
      //   }
      // });

      // Placeholder: will be replaced with actual container transport
      this.config.logger.warn(
        'MCP transport not yet implemented - using placeholder'
      );

      this.connected = true;
      this.config.logger.info('Connected to user MCP server');
    } catch (error) {
      this.config.logger.error(
        { error, userId: this.config.userId },
        'Failed to connect to user MCP server'
      );
      throw error;
    }
  }

  /**
   * Call a tool on the user's MCP server
   */
  async callTool(name: string, args: Record<string, unknown>): Promise<unknown> {
    if (!this.client || !this.connected) {
      throw new Error('MCP client not connected');
    }

    try {
      this.config.logger.debug({ tool: name, args }, 'Calling MCP tool');

      // TODO: Implement when MCP client is connected
      // const result = await this.client.callTool({ name, arguments: args });
      // return result;

      // Placeholder response
      return { success: true, message: 'MCP tool call placeholder' };
    } catch (error) {
      this.config.logger.error({ error, tool: name }, 'MCP tool call failed');
      throw error;
    }
  }

  /**
   * List available tools from user's MCP server
   */
  async listTools(): Promise<Array<{ name: string; description?: string }>> {
    if (!this.client || !this.connected) {
      throw new Error('MCP client not connected');
    }

    try {
      // TODO: Implement when MCP client is connected
      // const tools = await this.client.listTools();
      // return tools;

      // Placeholder tools (actions only, not context)
      return [
        { name: 'save_message', description: 'Save message to conversation history' },
        { name: 'list_strategies', description: 'List user strategies' },
        { name: 'read_strategy', description: 'Read strategy code' },
        { name: 'write_strategy', description: 'Write strategy code' },
        { name: 'run_backtest', description: 'Run backtest on strategy' },
        { name: 'get_watchlist', description: 'Get user watchlist' },
        { name: 'execute_trade', description: 'Execute trade' },
      ];
    } catch (error) {
      this.config.logger.error({ error }, 'Failed to list MCP tools');
      throw error;
    }
  }

  /**
   * List available resources from user's MCP server
   */
  async listResources(): Promise<Array<{ uri: string; name: string; description?: string; mimeType?: string }>> {
    if (!this.client || !this.connected) {
      throw new Error('MCP client not connected');
    }

    try {
      // TODO: Implement when MCP client is connected
      // const resources = await this.client.listResources();
      // return resources;

      // Placeholder resources for user context
      return [
        {
          uri: 'context://user-profile',
          name: 'User Profile',
          description: 'User trading style, preferences, and background',
          mimeType: 'text/plain',
        },
        {
          uri: 'context://conversation-summary',
          name: 'Conversation Summary',
          description: 'Semantic summary of recent conversation history with RAG',
          mimeType: 'text/plain',
        },
        {
          uri: 'context://workspace-state',
          name: 'Workspace State',
          description: 'Current chart, watchlist, and open positions',
          mimeType: 'application/json',
        },
        {
          uri: 'context://system-prompt',
          name: 'Custom System Prompt',
          description: 'User custom instructions for the assistant',
          mimeType: 'text/plain',
        },
      ];
    } catch (error) {
      this.config.logger.error({ error }, 'Failed to list MCP resources');
      throw error;
    }
  }

  /**
   * Read a resource from user's MCP server
   */
  async readResource(uri: string): Promise<{ uri: string; mimeType?: string; text?: string; blob?: string }> {
    if (!this.client || !this.connected) {
      throw new Error('MCP client not connected');
    }

    try {
      this.config.logger.debug({ uri }, 'Reading MCP resource');

      // TODO: Implement when MCP client is connected
      // const resource = await this.client.readResource({ uri });
      // return resource;

      // Placeholder resource content
      if (uri === 'context://user-profile') {
        return {
          uri,
          mimeType: 'text/plain',
          text: `User Profile:
- Trading experience: Intermediate
- Preferred timeframes: 1h, 4h, 1d
- Risk tolerance: Medium
- Focus: Swing trading with technical indicators`,
        };
      } else if (uri === 'context://conversation-summary') {
        return {
          uri,
          mimeType: 'text/plain',
          text: `Recent Conversation Summary:
[RAG-generated summary would go here]

User recently discussed:
- Moving average crossover strategies
- Backtesting on BTC/USDT
- Risk management techniques`,
        };
      } else if (uri === 'context://workspace-state') {
        return {
          uri,
          mimeType: 'application/json',
          text: JSON.stringify({
            currentChart: { ticker: 'BINANCE:BTC/USDT', timeframe: '1h' },
            watchlist: ['BTC/USDT', 'ETH/USDT', 'SOL/USDT'],
            openPositions: [],
          }, null, 2),
        };
      } else if (uri === 'context://system-prompt') {
        return {
          uri,
          mimeType: 'text/plain',
          text: `Custom Instructions:
- Be concise and data-driven
- Always show risk/reward ratios
- Prefer simple strategies over complex ones`,
        };
      }

      return { uri, text: '' };
    } catch (error) {
      this.config.logger.error({ error, uri }, 'MCP resource read failed');
      throw error;
    }
  }

  /**
   * Disconnect from MCP server
   */
  async disconnect(): Promise<void> {
    if (this.client && this.connected) {
      try {
        await this.client.close();
        this.connected = false;
        this.config.logger.info('Disconnected from user MCP server');
      } catch (error) {
        this.config.logger.error({ error }, 'Error disconnecting from MCP server');
      }
    }
  }

  isConnected(): boolean {
    return this.connected;
  }
}
