import re

from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule


class PingSpider(CrawlSpider):
    name = 'ping'

    def __init__(self, start_url):
        self.start_urls = [start_url]
        self.rules = (
            Rule(LinkExtractor(allow='^'+re.escape(start_url))),
            Rule(LinkExtractor(tags='img', attrs='src', deny_extensions=set())),
            Rule(LinkExtractor(tags='link', attrs='href', deny_extensions=set())),
        )
        super(PingSpider, self).__init__()