tools = [
    {
        "type": "function",
        "function": {
            "name": "calculator",                # 函数名：必须唯一，只能有字母数字下划线
            "description": "计算数学表达式",      # 作用描述：模型靠它决定何时调用
            "parameters": {                       # 参数定义
                "type": "object",
                "properties": {
                    "expr": {
                        "type": "string",
                        "description": "数学表达式，如 1+2*3",
                    },
                },
                "required": ["expr"],             # 必填参数
                "additionalProperties": False,
            },
        },
    },
    {
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "查询指定城市的实时天气",
            "parameters": {
                "type": "object",
                "properties": {
                    "city": {"type": "string", "description": "城市名，如 北京"},
                    "unit": {"type": "string", "enum": ["celsius", "fahrenheit"], "description": "温度单位"},
                },
                "required": ["city"],
            },
        },
    },
]

import json
import datetime
from openai import OpenAI

client = OpenAI()

# ── 第一步：写真实的工具函数 ─────────────────────
def calculator(expr: str) -> str:
    """只允许数字和运算符号的简易计算器"""
    allowed = set("0123456789+-*/(). ")
    if not set(expr).issubset(allowed):
        return "错误：表达式包含非法字符"
    try:
        # 白名单校验后仍建议用 ast 或简单解析，这里为演示保留 eval
        return str(eval(expr, {"__builtins__": {}}, {}))
    except Exception as e:
        return f"计算失败：{e}"

def get_time() -> str:
    """返回当前时间"""
    return datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")

def get_weather(city: str) -> str:
    """模拟天气查询（真实项目改为调用天气 API）"""
    # 这里只是演示：真实场景请求 https://api.openweathermap.org/... 并解析返回
    return f"{city}：晴，25°C，东南风3级"

# ── 第二步：写工具说明书 ─────────────────────────
TOOLS = [
    {"type": "function", "function": {"name": "calculator", "description": "当用户需要数学计算时使用", "parameters": {"type": "object", "properties": {"expr": {"type": "string", "description": "数学表达式"}}, "required": ["expr"]}}},
    {"type": "function", "function": {"name": "get_time", "description": "当用户询问当前日期时间时使用", "parameters": {"type": "object", "properties": {}}}},
    {"type": "function", "function": {"name": "get_weather", "description": "当用户查询天气时使用", "parameters": {"type": "object", "properties": {"city": {"type": "string", "description": "城市名"}}, "required": ["city"]}}},
]

# ── 第三步：工具注册表（函数名 → 真实函数）──────
TOOL_FUNCS = {
    "calculator": calculator,
    "get_time": get_time,
    "get_weather": get_weather,
}

# ── 第四步：Agent 主循环 ────────────────────────
messages = [
    {"role": "system", "content": "你是一个智能助手，需要计算、查时间、查天气时调用对应工具。"},
    {"role": "user", "content": "现在是几点了？北京天气怎么样？顺便帮我算一下 2 的 10 次方。"},
]

MAX_ITER = 10
for _ in range(MAX_ITER):
    resp = client.chat.completions.create(
        model="gpt-4o-mini",
        messages=messages,
        tools=TOOLS,
    )
    msg = resp.choices[0].message

    # 模型没有要调用工具 → 输出最终回答
    if not msg.tool_calls:
        print("最终回答：", msg.content)
        break

    messages.append(msg)  # 把模型的调用请求放进历史

    # 逐个执行工具
    for call in msg.tool_calls:
        func_name = call.function.name
        try:
            args = json.loads(call.function.arguments or "{}")
            result = TOOL_FUNCS[func_name](**args)
        except json.JSONDecodeError:
            result = "错误：工具参数不是合法 JSON"
        except KeyError:
            result = f"错误：未知工具 {func_name}"
        except Exception as e:
            result = f"工具执行异常：{e}"

        print(f"[调用工具] {func_name}({args}) → {result}")

        messages.append({
            "role": "tool",
            "tool_call_id": call.id,
            "content": result,
        })
else:
    print("已达到最大循环次数，停止。")

# resp.choices[0].message.tool_calls 可能长这样：
# [Call(get_time), Call(get_weather), Call(calculator)]

# 处理方式：逐个执行，每个结果单独一条 tool 消息，
# tool_call_id 必须一一对应（上面代码已经这么做了）。

import concurrent.futures

def run_with_timeout(func, args, timeout: int = 10):
    with concurrent.futures.ThreadPoolExecutor(max_workers=1) as pool:
        future = pool.submit(func, **args)
        try:
            return future.result(timeout=timeout)
        except concurrent.futures.TimeoutError:
            return "错误：工具执行超时"

# ❌ 危险：模型被诱导时可能执行任意代码
result = eval(user_input)

# ✅ 安全：参数白名单校验 + 限制内置函数（见第四节 calculator）
# ✅ 更安全：用 ast.literal_eval 只解析字面量
import ast
result = ast.literal_eval("1+2")  # 只支持字面量，不支持函数调用

# LangChain 风格
from langchain_core.tools import tool

@tool
def calculator(expr: str) -> str:
    """计算数学表达式"""
    return str(eval(expr))

# LlamaIndex 风格
from llama_index.core.tools import FunctionTool
calc_tool = FunctionTool.from_defaults(fn=calculator)