#第 16 章：MCP 工具协议与自定义集成

// index.js
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";

// 创建 MCP Server 实例
const server = new McpServer({
  name: "weather-server",
  version: "1.0.0",
  description: "提供天气查询能力的 MCP Server",
});

// 定义工具：获取当前天气
server.tool(
  "get_weather",
  "获取指定城市的当前天气信息",
  {
    city: z.string().describe("城市名称，如 '北京'、'上海'"),
    unit: z
      .enum(["celsius", "fahrenheit"])
      .optional()
      .default("celsius")
      .describe("温度单位"),
  },
  async ({ city, unit }) => {
    // 实际项目中，这里应调用真实的天气 API
    // 此处用模拟数据做演示
    const apiKey = process.env.WEATHER_API_KEY;
    const response = await fetch(
      `https://api.weatherapi.com/v1/current.json?key=${apiKey}&q=${encodeURIComponent(city)}&lang=zh`
    );

    if (!response.ok) {
      return {
        content: [
          {
            type: "text",
            text: ` 查询失败：无法获取 ${city} 的天气信息（HTTP ${response.status}）`,
          },
        ],
        isError: true,
      };
    }

    const data = await response.json();
    const temp =
      unit === "fahrenheit" ? data.current.temp_f : data.current.temp_c;
    const unitLabel = unit === "fahrenheit" ? "°F" : "°C";

    return {
      content: [
        {
          type: "text",
          text: [
            `📍 ${data.location.name}（${data.location.country}）`,
            `🌡️ 温度：${temp}${unitLabel}`,
            `🌤️ 天气：${data.current.condition.text}`,
            `💨 风速：${data.current.wind_kph} km/h`,
            `💧 湿度：${data.current.humidity}%`,
            `🕐 更新时间：${data.current.last_updated}`,
          ].join("\n"),
        },
      ],
    };
  }
);

// 定义工具：获取天气预报
server.tool(
  "get_forecast",
  "获取指定城市未来几天的天气预报",
  {
    city: z.string().describe("城市名称"),
    days: z
      .number()
      .min(1)
      .max(7)
      .default(3)
      .describe("预报天数，1-7 天"),
  },
  async ({ city, days }) => {
    const apiKey = process.env.WEATHER_API_KEY;
    const response = await fetch(
      `https://api.weatherapi.com/v1/forecast.json?key=${apiKey}&q=${encodeURIComponent(city)}&days=${days}&lang=zh`
    );

    if (!response.ok) {
      return {
        content: [{ type: "text", text: ` 查询失败（HTTP ${response.status}）` }],
        isError: true,
      };
    }

    const data = await response.json();
    const forecastLines = data.forecast.forecastday.map((day) => {
      return `📅 ${day.date} | ${day.day.condition.text} | ${day.day.mintemp_c}°C ~ ${day.day.maxtemp_c}°C | 降雨概率 ${day.day.daily_chance_of_rain}%`;
    });

    return {
      content: [
        {
          type: "text",
          text: `📍 ${data.location.name} 未来 ${days} 天天气预报：\n\n${forecastLines.join("\n")}`,
        },
      ],
    };
  }
);

// 启动 Server（使用 stdio 传输）
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("Weather MCP Server 已启动（stdio 模式）");

// ✅ 好的描述
server.tool(
  "search_products",
  "在电商平台搜索商品。支持按名称、品类、价格区间筛选。返回商品列表包含名称、价格、销量和评分。",
  { /* schema */ },
  handler
);

// ❌ 差的描述
server.tool(
  "search",
  "搜索功能",
  { /* schema */ },
  handler
);

// Node.js 示例
server.resource(
  "config",                           // 资源名称
  "config://app/settings",            // 资源 URI
  "应用配置信息，包含版本号和功能开关", // 描述
  async () => ({
    contents: [{
      uri: "config://app/settings",
      mimeType: "application/json",
      text: JSON.stringify({
        version: "2.1.0",
        features: { darkMode: true, betaFeatures: false }
      })
    }]
  })
);

server.prompt(
  "weather_report",
  "生成城市天气报告的提示模板",
  { city: z.string().describe("城市名称") },
  async ({ city }) => ({
    messages: [{
      role: "user",
      content: {
        type: "text",
        text: ` 请为 ${city} 编写一份详细的天气分析报告，包含当前天气、未来趋势和出行建议。`
      }
    }]
  })
);

// test/weather-server.test.js
import { describe, it, expect, beforeAll, afterAll } from "vitest";
import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";

describe("Weather MCP Server", () => {
  let client;

  beforeAll(async () => {
    const transport = new StdioClientTransport({
      command: "node",
      args: ["./index.js"],
      env: { ...process.env, WEATHER_API_KEY: "test-key" },
    });
    client = new Client({ name: "test-client", version: "1.0.0" });
    await client.connect(transport);
  });

  afterAll(async () => {
    await client.close();
  });

  it("应列出所有工具", async () => {
    const result = await client.listTools();
    expect(result.tools).toHaveLength(2);
    expect(result.tools.map((t) => t.name)).toContain("get_weather");
    expect(result.tools.map((t) => t.name)).toContain("get_forecast");
  });

  it("get_weather 应返回天气信息", async () => {
    const result = await client.callTool({
      name: "get_weather",
      arguments: { city: "北京" },
    });
    expect(result.content[0].type).toBe("text");
    expect(result.content[0].text).toContain("温度");
    expect(result.isError).toBeFalsy();
  });

  it("无效城市应返回错误", async () => {
    const result = await client.callTool({
      name: "get_weather",
      arguments: { city: "不存在的城市 xyz" },
    });
    expect(result.isError).toBe(true);
  });

  it("get_forecast 天数应在 1-7 之间", async () => {
    const result = await client.callTool({
      name: "get_forecast",
      arguments: { city: "上海", days: 5 },
    });
    expect(result.content[0].text).toContain("未来 5 天");
  });
});

// todo-mcp-server/index.js
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";
import fs from "fs/promises";

const server = new McpServer({
  name: "todo-server",
  version: "1.0.0",
});

const TODO_FILE = "/tmp/mcp-todos.json";

// 辅助函数：读取待办列表
async function loadTodos() {
  try {
    const data = await fs.readFile(TODO_FILE, "utf-8");
    return JSON.parse(data);
  } catch {
    return [];
  }
}

// 辅助函数：保存待办列表
async function saveTodos(todos) {
  await fs.writeFile(TODO_FILE, JSON.stringify(todos, null, 2));
}

server.tool(
  "add_todo",
  "添加一条新的待办事项",
  {
    title: z.string().describe("待办事项标题"),
    priority: z.enum(["low", "medium", "high"]).default("medium").describe("优先级"),
  },
  async ({ title, priority }) => {
    const todos = await loadTodos();
    const newTodo = {
      id: Date.now().toString(),
      title,
      priority,
      completed: false,
      createdAt: new Date().toISOString(),
    };
    todos.push(newTodo);
    await saveTodos(todos);
    return {
      content: [{ type: "text", text: `✅ 已添加待办：「${title}」（优先级：${priority}）` }],

    };
  }
);

server.tool(
  "list_todos",
  "列出所有待办事项，可按状态筛选",
  {
    status: z.enum(["all", "pending", "completed"]).default("all").describe("筛选状态"),
  },
  async ({ status }) => {
    let todos = await loadTodos();
    if (status === "pending") todos = todos.filter((t) => !t.completed);
    if (status === "completed") todos = todos.filter((t) => t.completed);

    if (todos.length === 0) {
      return { content: [{ type: "text", text: "📋 暂无待办事项" }] };
    }

    const lines = todos.map(
      (t) =>
        `${t.completed ? "✅" : "⬜"} [${t.priority}] ${t.title} (ID: ${t.id})`
    );
    return {
      content: [{ type: "text", text: `📋 待办列表：\n${lines.join("\n")}` }],
    };
  }
);

// TODO: 实现 complete_todo 和 delete_todo ...

const transport = new StdioServerTransport();
await server.connect(transport);