import re
#import urlparse 这个模块可以用来拼接网址
from bs4 import BeautifulSoup

class HtmlParser(object):
    def parser(self, page_url, html_cont):
        '''
        用来解析网页内容， 抽取url和数据
        :param page_url: 下载页面的url
        :param html_cont: 下载的网页内容
        :return: 返回url和数据
        '''
        if page_url is None or html_cont is None:
            return
        #'lxml'在书中是’html.parser'
        soup = BeautifulSoup(html_cont, 'lxml', from_encoding='utf-8' )
        #调用内部私有方法
        new_urls = self._get_new_urls(page_url, soup)
        new_data= self._get_new_data(page_url, soup)
        return new_urls, new_data


    def _get_new_urls(self, page_url, soup):
        '''
        抽取新的url集合
        :param self:
        :param page_url:
        :param soup:
        :return:
        '''
        new_urls = set()
        #抽取符合要求的a
        links = soup.find_all('a', href = re.compile(r'/item/.*'))
        for link in links:
            new_url = link['href']
            #拼接完成网址，注意修改
            new_full_url = page_url[0:-6] + new_url
            new_urls.add(new_full_url)
        return new_urls

    def _get_new_data(self, page_url, soup):
        '''
        抽取有效数据
        :param self:
        :param page_url: 下载页面的url
        :param soup:
        :return:
        '''
        data = {}
        data['url'] = page_url
        title = soup.find('dd', class_='lemmaWgt-lemmaTitle-title').find('h1')

        data['title'] = title.get_text()
        summary = soup.find('a', href =True)
        data['summary'] = summary.get_text()
        return data