regulated_reader.py

from bs4 import BeautifulSoup
import requests, PyRSS2Gen
import json, time, datetime, sys, os

def _print_usage():
	sys.stderr.write('Usage: \n')
	sys.stderr.write(sys.argv[0]+" init [URL] - set up the RSS feed\n")
	sys.stderr.write(sys.argv[0]+" - Generate an RSS feed with the next item\n")
	sys.exit(1)

class RegulatedReader():
	def add_item(self, feed, next_url):
		feed_item = self.getinfo(self.get_soup(next_url))
		feed_item['link'] = next_url
		feed_item['pubDate'] = time.time()
		
		feed.append(feed_item)
		
		with open(self.name+'.rss', 'w') as f:
			self.compose_pyrss2_tree(feed).write_xml(f)
		
		with open(self.name+'.json', 'w') as f:
			json.dump(feed, f)
		
	def build(self):
		if len(sys.argv) == 1: # Build the RSS feed
			with open(self.name+'.json') as f:
				feed=json.load(f)
			next_url = self.getnext(self.get_soup(feed[-1]['link']))
		elif len(sys.argv) == 3 and sys.argv[1] == 'init':
			if os.path.exists(self.name+'.json'):
				sys.stderr.write('That feed has already been initialized. Please delete '+self.name+'.json if you wish to start over.\n')
				sys.exit(2)
			feed = []
			next_url = sys.argv[2]
		else:
			_print_usage()
		
		self.add_item(feed, next_url)
	
	def get_soup(self, url):
		r = requests.get(url)
		r.raise_for_status()
		return BeautifulSoup(r.text)

	def compose_pyrss2_tree(self, feed):
		items = []
		for item in feed:
			items.append(PyRSS2Gen.RSSItem(
				title = item['title'],
				link  = item['link'],
				description = item['description'],
				guid = PyRSS2Gen.Guid(item['link']),
				pubDate = datetime.datetime.fromtimestamp(item['pubDate']),
			))
		
		return PyRSS2Gen.RSS2(
			title = self.title,
			link = self.link,
			description = self.description,
			lastBuildDate = datetime.datetime.now(),
			items = items,
		)