import time
import random
from typing import Tuple, Union
import requests
from requests import Response
from requests.exceptions import SSLError, RequestException
from bs4 import BeautifulSoup

from qwen_agent.tools.base import BaseTool, register_tool

DEFAULT_MAX_CHARS = 10000

# 模拟真实浏览器请求头，防止 GitHub 等网站返回 429
COMMON_HEADERS = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8',
    'Accept-Language': 'zh-CN,zh;q=0.9,en;q=0.8',
    'Accept-Encoding': 'gzip, deflate, br',
    'Connection': 'keep-alive'
}

def _normalize_text(text: str) -> str:
    lines = [line.strip() for line in text.splitlines()]
    lines = [line for line in lines if line]
    return '\n'.join(lines)

def _fetch_page(url: str, timeout: int = 30, retries: int = 2) -> Tuple[Union[Response, str], bool]:
    """带有重试机制和伪装头的抓取函数"""
    for i in range(retries + 1):
        try:
            if i > 0:
                time.sleep(2 + random.uniform(1, 2) * i)
            
            response = requests.get(url, headers=COMMON_HEADERS, timeout=timeout, verify=True)
            
            if response.status_code == 429:
                if i < retries: continue
                return f"错误：目标网站限制了请求频率 (429)。请稍后再试，禁止读取本地无关文件。", False
            
            response.raise_for_status()
            return response, False
            
        except SSLError:
            try:
                response = requests.get(url, headers=COMMON_HEADERS, timeout=timeout, verify=False)
                response.raise_for_status()
                return response, True
            except Exception as e:
                return f"SSL 错误且备选方案失败: {str(e)}", False
        except RequestException as e:
            if i < retries: continue
            return f"网络抓取失败: {str(e)}", False
    
    return "未知抓取错误", False

def _extract_page_text(html: str, max_chars: int) -> Tuple[str, str]:
    soup = BeautifulSoup(html, 'html.parser')
    for tag in soup(['script', 'style', 'noscript', 'header', 'footer', 'nav']):
        tag.decompose()
    title = soup.title.string.strip() if soup.title and soup.title.string else '无标题'
    body_text = _normalize_text(soup.get_text(separator='\n'))
    return title, body_text[:max_chars]

@register_tool('web_fetch', allow_overwrite=True)
class WebFetchTool(BaseTool):
    description = '抓取网页正文并返回可读文本。'
    parameters = {
        'type': 'object',
        'properties': {
            'url': {'type': 'string', 'description': '网页链接'},
            'max_chars': {'type': 'integer', 'description': '返回最大字符数', 'default': DEFAULT_MAX_CHARS}
        },
        'required': ['url'],
    }

    def call(self, params: Union[str, dict], **kwargs) -> str:
        params = self._verify_json_format_args(params)
        url = params['url'].strip()
        max_chars = int(params.get('max_chars', DEFAULT_MAX_CHARS))

        result, insecure = _fetch_page(url)
        if isinstance(result, str):
            return result

        title, body_text = _extract_page_text(result.text, max_chars)
        insecure_note = '（注意：使用了非安全连接）\n' if insecure else ''
        return f'标题: {title}\n链接: {url}\n{insecure_note}\n{body_text}'

@register_tool('web_extractor', allow_overwrite=True)
class WebExtractorTool(BaseTool):
    description = '提取单个网页正文。'
    parameters = {
        'type': 'object',
        'properties': {
            'url': {'type': 'string', 'description': '网页链接'},
            'max_chars': {'type': 'integer', 'description': '返回最大字符数', 'default': DEFAULT_MAX_CHARS}
        },
        'required': ['url'],
    }

    def call(self, params: Union[str, dict], **kwargs) -> str:
        # 复用 WebFetchTool 的逻辑，但作为独立的类注册
        fetcher = WebFetchTool(self.cfg)
        return fetcher.call(params, **kwargs)