import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
import * as path from "path";
import * as fs from "fs";

export interface McpClientManager {
  listTools(): Promise<any[]>;
  callTool(name: string, args: Record<string, any>, signal?: AbortSignal): Promise<any>;
  close(): Promise<void>;
}

function getPythonExecutable(): string {
  const pluginRoot = path.resolve(__dirname, "..");
  const maverickRoot = path.join(pluginRoot, "maverick-mcp");
  const venvDir = path.join(maverickRoot, ".venv");

  if (process.platform === "win32") {
    return path.join(venvDir, "Scripts", "python.exe");
  } else {
    return path.join(venvDir, "bin", "python");
  }
}

function getMaverickRoot(): string {
  return path.join(path.resolve(__dirname, ".."), "maverick-mcp");
}

class McpClientManagerImpl implements McpClientManager {
  private client: Client | null = null;
  private transport: StdioClientTransport | null = null;
  private initialized = false;
  private initPromise: Promise<void> | null = null;

  private async ensureInitialized(): Promise<void> {
    if (this.initialized) return;
    if (this.initPromise) return this.initPromise;

    this.initPromise = (async () => {
      const python = getPythonExecutable();
      const maverickRoot = getMaverickRoot();

      console.error(`[maverick-lms-mcp] Python path: ${python}`);
      console.error(`[maverick-lms-mcp] Maverick root: ${maverickRoot}`);

      // 確認 Python 存在
      if (!fs.existsSync(python)) {
        throw new Error(
          `Python venv not found at ${python}. ` +
          `Please ensure 'npm install' ran successfully.`
        );
      }

      // 確認 maverick-mcp 目錄存在
      if (!fs.existsSync(maverickRoot)) {
        throw new Error(
          `MaverickMCP directory not found at ${maverickRoot}. ` +
          `Please run 'npm install' to clone the repository.`
        );
      }

      console.error(`[maverick-lms-mcp] Starting Python MCP server...`);

      this.transport = new StdioClientTransport({
        command: python,
        args: ["-m", "maverick.server", "--transport", "stdio"],
        cwd: maverickRoot,
        stderr: "pipe", // 重要：捕捉 stderr
      });

      // 監聽 stderr 輸出以診斷問題
      this.transport.stderr?.on("data", (data: Buffer) => {
        const message = data.toString();
        console.error(`[maverick-mcp-stderr] ${message}`);
      });

      this.transport.stderr?.on("error", (err: Error) => {
        console.error(`[maverick-mcp-stderr-error] ${err.message}`);
      });

      this.client = new Client(
        { name: "maverick-lms-mcp", version: "1.0.0" },
        { capabilities: {} }
      );

      try {
        console.error(`[maverick-lms-mcp] Connecting to MCP server...`);
        await this.client.connect(this.transport);
        console.error(`[maverick-lms-mcp] Successfully connected to MCP server`);
        this.initialized = true;
      } catch (err: any) {
        console.error(`[maverick-lms-mcp] Failed to connect: ${err.message}`);
        console.error(`[maverick-lms-mcp] Stack: ${err.stack}`);
        throw err;
      }
    })();

    return this.initPromise;
  }

  async listTools(): Promise<any[]> {
    await this.ensureInitialized();
    if (!this.client) throw new Error("MCP client not initialized");
    
    try {
      console.error(`[maverick-lms-mcp] Listing tools...`);
      const result = await this.client.listTools();
      console.error(`[maverick-lms-mcp] Found ${result.tools?.length ?? 0} tools`);
      return result.tools ?? [];
    } catch (err: any) {
      console.error(`[maverick-lms-mcp] Failed to list tools: ${err.message}`);
      throw err;
    }
  }

  async callTool(name: string, args: Record<string, any>, signal?: AbortSignal): Promise<any> {
    await this.ensureInitialized();
    if (!this.client) throw new Error("MCP client not initialized");
    
    try {
      console.error(`[maverick-lms-mcp] Calling tool: ${name}`);
      const result = await this.client.callTool({ name, arguments: args });
      return result;
    } catch (err: any) {
      console.error(`[maverick-lms-mcp] Failed to call tool ${name}: ${err.message}`);
      throw err;
    }
  }

  async close(): Promise<void> {
    if (this.transport) {
      try {
        await this.transport.close();
      } catch {
        // ignore
      }
    }
    this.client = null;
    this.transport = null;
    this.initialized = false;
  }
}

let instance: McpClientManagerImpl | null = null;

export async function getMcpClient(): Promise<McpClientManager> {
  if (!instance) {
    instance = new McpClientManagerImpl();
  }
  return instance;
}

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
import * as path from "path";
import * as fs from "fs";

export interface McpClientManager {
  listTools(): Promise<any[]>;
  callTool(name: string, args: Record<string, any>, signal?: AbortSignal): Promise<any>;
  close(): Promise<void>;
}

function getPythonExecutable(): string {
  const pluginRoot = path.resolve(__dirname, "..");
  const maverickRoot = path.join(pluginRoot, "maverick-mcp");
  const venvDir = path.join(maverickRoot, ".venv");

  if (process.platform === "win32") {
    return path.join(venvDir, "Scripts", "python.exe");
  } else {
    return path.join(venvDir, "bin", "python");
  }
}

function getMaverickRoot(): string {
  return path.join(path.resolve(__dirname, ".."), "maverick-mcp");
}

class McpClientManagerImpl implements McpClientManager {
  private client: Client | null = null;
  private transport: StdioClientTransport | null = null;
  private initialized = false;
  private initPromise: Promise<void> | null = null;

  private async ensureInitialized(): Promise<void> {
    if (this.initialized) return;
    if (this.initPromise) return this.initPromise;

    this.initPromise = (async () => {
      const python = getPythonExecutable();
      const maverickRoot = getMaverickRoot();

      console.error(`[maverick-lms-mcp] Python path: ${python}`);
      console.error(`[maverick-lms-mcp] Maverick root: ${maverickRoot}`);

      // 確認 Python 存在
      if (!fs.existsSync(python)) {
        throw new Error(
          `Python venv not found at ${python}. ` +
          `Please ensure 'npm install' ran successfully.`
        );
      }

      // 確認 maverick-mcp 目錄存在
      if (!fs.existsSync(maverickRoot)) {
        throw new Error(
          `MaverickMCP directory not found at ${maverickRoot}. ` +
          `Please run 'npm install' to clone the repository.`
        );
      }

      console.error(`[maverick-lms-mcp] Starting Python MCP server...`);

      this.transport = new StdioClientTransport({
        command: python,
        args: ["-m", "maverick.server", "--transport", "stdio"],
        cwd: maverickRoot,
        stderr: "pipe", // 重要：捕捉 stderr
      });

      // 監聽 stderr 輸出以診斷問題
      this.transport.stderr?.on("data", (data: Buffer) => {
        const message = data.toString();
        console.error(`[maverick-mcp-stderr] ${message}`);
      });

      this.transport.stderr?.on("error", (err: Error) => {
        console.error(`[maverick-mcp-stderr-error] ${err.message}`);
      });

      this.client = new Client(
        { name: "maverick-lms-mcp", version: "1.0.0" },
        { capabilities: {} }
      );

      try {
        console.error(`[maverick-lms-mcp] Connecting to MCP server...`);
        await this.client.connect(this.transport);
        console.error(`[maverick-lms-mcp] Successfully connected to MCP server`);
        this.initialized = true;
      } catch (err: any) {
        console.error(`[maverick-lms-mcp] Failed to connect: ${err.message}`);
        console.error(`[maverick-lms-mcp] Stack: ${err.stack}`);
        throw err;
      }
    })();

    return this.initPromise;
  }

  async listTools(): Promise<any[]> {
    await this.ensureInitialized();
    if (!this.client) throw new Error("MCP client not initialized");
    
    try {
      console.error(`[maverick-lms-mcp] Listing tools...`);
      const result = await this.client.listTools();
      console.error(`[maverick-lms-mcp] Found ${result.tools?.length ?? 0} tools`);
      return result.tools ?? [];
    } catch (err: any) {
      console.error(`[maverick-lms-mcp] Failed to list tools: ${err.message}`);
      throw err;
    }
  }

  async callTool(name: string, args: Record<string, any>, signal?: AbortSignal): Promise<any> {
    await this.ensureInitialized();
    if (!this.client) throw new Error("MCP client not initialized");
    
    try {
      console.error(`[maverick-lms-mcp] Calling tool: ${name}`);
      const result = await this.client.callTool({ name, arguments: args });
      return result;
    } catch (err: any) {
      console.error(`[maverick-lms-mcp] Failed to call tool ${name}: ${err.message}`);
      throw err;
    }
  }

  async close(): Promise<void> {
    if (this.transport) {
      try {
        await this.transport.close();
      } catch {
        // ignore
      }
    }
    this.client = null;
    this.transport = null;
    this.initialized = false;
  }
}

let instance: McpClientManagerImpl | null = null;

export async function getMcpClient(): Promise<McpClientManager> {
  if (!instance) {
    instance = new McpClientManagerImpl();
  }
  return instance;
}