Function Calling 与工具调用

const tools = [
  {
    type: 'function',
    function: {
      name: 'get_current_weather',
      description: '获取指定城市的当前天气信息',
      parameters: {
        type: 'object',
        properties: {
          location: {
            type: 'string',
            description: '城市名称，如 "北京" 或 "上海"',
          },
          unit: {
            type: 'string',
            enum: ['celsius', 'fahrenheit'],
            description: '温度单位',
          },
        },
        required: ['location'],
      },
    },
  },
  {
    type: 'function',
    function: {
      name: 'search_web',
      description: '在互联网上搜索信息',
      parameters: {
        type: 'object',
        properties: {
          query: {
            type: 'string',
            description: '搜索关键词',
          },
          max_results: {
            type: 'number',
            description: '最大返回结果数',
          },
        },
        required: ['query'],
      },
    },
  },
];

// server.ts
import express from 'express';
import axios from 'axios';
import { exec } from 'child_process';

const app = express();
app.use(express.json());

// 工具注册表
const toolHandlers: Record<string, (args: any) => Promise<string>> = {
  get_current_weather: async ({ location }) => {
    // 实际调用天气 API
    const res = await axios.get(`https://api.weather.com/v1/${location}`);
    return JSON.stringify(res.data);
  },
  run_shell_command: async ({ command }) => {
    return new Promise((resolve, reject) => {
      exec(command, (error, stdout) => {
        if (error) reject(error);
        else resolve(stdout);
      });
    });
  },
  search_web: async ({ query, max_results = 5 }) => {
    const res = await axios.get('https://api.search.com/search', {
      params: { q: query, limit: max_results },
    });
    return JSON.stringify(res.data.results);
  },
};

app.post('/chat', async (req, res) => {
  const { message } = req.body;
  const messages = [{ role: 'user', content: message }];

  // 工具调用循环（最多 5 轮）
  for (let i = 0; i < 5; i++) {
    const response = await axios.post(
      `${process.env.LLM_BASE_URL}/chat/completions`,
      {
        model: process.env.LLM_MODEL,
        messages,
        tools,
        tool_choice: 'auto',
      },
      {
        headers: { Authorization: `Bearer ${process.env.LLM_API_KEY}` },
      }
    );

    const choice = response.data.choices[0];

    // 如果模型直接回复文本，结束循环
    if (choice.finish_reason === 'stop') {
      return res.json({ reply: choice.message.content });
    }

    // 处理工具调用
    if (choice.finish_reason === 'tool_calls') {
      messages.push(choice.message); // 记录 assistant 的工具调用消息

      for (const toolCall of choice.message.tool_calls) {
        const { name, arguments: args } = toolCall.function;
        const handler = toolHandlers[name];

        let result: string;
        try {
          result = handler
            ? await handler(JSON.parse(args))
            : `Error: Unknown tool "${name}"`;
        } catch (e) {
          result = `Error: ${e.message}`;
        }

        // 回传工具结果
        messages.push({
          role: 'tool',
          tool_call_id: toolCall.id,
          content: result,
        });
      }
    }
  }

  res.json({ reply: '达到最大工具调用轮次限制' });
});

app.listen(3300);

// 使用 Ollama 的 OpenAI 兼容接口
const response = await axios.post(
  'http://localhost:11434/v1/chat/completions',
  {
    model: 'qwen3:1.7b',
    messages,
    tools,
    tool_choice: 'auto',
  }
);