"""
工具定义模块 - 纯函数工具，无依赖 AIAgent 类
"""

# 标准库
from pathlib import Path

# 第三方库
import pandas as pd
import pypdf
import requests
from bs4 import BeautifulSoup
from langchain_core.tools import tool

def _file_allow_check(filename: str) -> Path:
    """检查用户文件名是否位于允许目录 './user_docs' 下，防止路径遍历攻击。"""
    allowed_dir = Path("./user_docs").resolve()
    allowed_dir.mkdir(exist_ok=True)

    file_path = (allowed_dir / filename).resolve()
    if not str(file_path).startswith(str(allowed_dir)):
        raise ValueError("错误：非法文件路径。")

    if not file_path.exists():
        raise FileNotFoundError(f"错误：文件 '{filename}' 不存在。")

    return file_path

@tool
def get_current_temperature(location: str) -> str:
    """获取指定地点的当前温度。"""
    return f'当前{location}的温度为25℃'

@tool
def read_local_file(filename: str) -> str:
    """读取用户指定名称的本地文本文件内容并返回摘要。"""
    try:
        file_path = _file_allow_check(filename)
        with open(file_path, 'r', encoding='utf-8') as f:
            content = f.read()
        return f"文件 '{filename}' 的内容开头：\n{content[:1000]}..."
    except Exception as e:
        return f"读取文件时出错：{str(e)}"

@tool
def read_pdf_summary(filename: str) -> str:
    """读取PDF文件并返回内容文本摘要。"""
    try:
        file_path = _file_allow_check(filename)
        text = ""
        with open(file_path, 'rb') as f:
            reader = pypdf.PdfReader(f)
            for page in reader.pages[:3]:
                text += page.extract_text()
        return f"PDF文件 '{filename}' 的前几页内容：\n{text[:2000]}..."
    except Exception as e:
        return f"读取PDF出错：{e}"

@tool
def read_excel_as_markdown(filename: str) -> str:
    """读取Excel文件，并将其主要数据转换为Markdown表格格式。"""
    try:
        file_path = _file_allow_check(filename)
        df = pd.read_excel(file_path)
        markdown_table = df.head(10).to_markdown(index=False)
        return f"Excel文件 '{filename}' 的数据预览（前10行）：\n{markdown_table}"
    except Exception as e:
        return f"读取Excel出错：{e}"

@tool
def fetch_webpage_content(url: str) -> str:
    """抓取给定URL的网页正文内容，并返回清晰的纯文本。"""
    try:
        response = requests.get(url, timeout=10)
        response.raise_for_status()
        soup = BeautifulSoup(response.text, 'html.parser')
        for script in soup(["script", "style"]):
            script.decompose()
        text = soup.get_text()
        lines = (line.strip() for line in text.splitlines())
        chunks = (phrase.strip() for line in lines for phrase in line.split("  "))
        text = '\n'.join(chunk for chunk in chunks if chunk)
        return f"成功抓取网页 {url}，正文内容开头：\n{text[:1500]}..."
    except Exception as e:
        return f"抓取网页时出错：{str(e)}"

# 工具列表和映射（全局常量）
AVAILABLE_TOOLS = [
    get_current_temperature,
    read_local_file,
    fetch_webpage_content,
    read_pdf_summary,
    read_excel_as_markdown
]
TOOLS_BY_NAME = {tool.name: tool for tool in AVAILABLE_TOOLS}