#!/usr/local/bin/python
# Poor man's feedreader
# public domain.
# written 2012 by Moritz Wilhelmy, mw at furnace wzff de
#
# contributors:
# - s4msung at exigen.org
#
# TODO:
# - lock the seen-file (done? do I care about ~ on NFS?)
# - improve error handling, i.e. if things fail between opening the seen-file
#   and finishing, have a backup file...
# - Fix Email storage
# - Do something about RSS feeds without GUIDs in entries

import os, sys, codecs, time, fcntl
import feedparser
import mailbox
import email.utils
from urllib import pathname2url as urlenc
from email.MIMEText import MIMEText
from email.utils    import formatdate, mktime_tz
from email.Header   import Header

try:
	import cPickle as pickle
except ImportError:
	import pickle

######
home   = os.getenv("HOME") or "."
base   = home + "/lib/feeds/"
furls  = base + "feeds" # textfile containing urls.
fseen  = base + "seen"  # things that have already been sent, just pickle it..
renderc= "/usr/local/bin/elinks -dump /dev/stdin"
# should also be possible to send them with sendmail if you need it..
mbox   = mailbox.Maildir(home + "/.Maildir/.feeds")
######

class Bug(Exception):
	pass

class Unreachable(Bug):
	pass

def render(html):
	i, o = os.popen2(renderc)
	i.write(html.encode("utf-8"))
	i.close()
	return o.read()

def time_convert(t):
	"""Workaround for feedparser discarding the timezone information from the
	input data. (RSS and Atom do have a timezone field in their date/time
	specification. Unfortunately, feedparser just drops it for no particular 
	reason). This means this reader might be some hours off with the timestamp."""
	return formatdate(mktime_tz(t[:] + (0,)))

with open(furls, "r") as u:
	feeds = filter(lambda(x): not x.strip().startswith("#"), u.read().splitlines())

seen = {}
try:
	with open(fseen, "r") as s:
		seen = pickle.load(s)
except IOError:
	pass

def create_feed_mail(author, title, body, date, id, link):
	for body_charset in ("US-ASCII", "ISO-8859-1", "UTF-8"):
		try:
			body.encode(body_charset)
		except UnicodeDecodeError:
			pass
		else:
			break
	#print body_charset

	mail = MIMEText(body, "plain", body_charset)

 	# FIXME: Escaping?
	if type(author) in (str, unicode):
		mail["From"] = '%s <>' % Header(author.encode("utf-8"), "utf-8").encode("utf-8")
	elif type(author) == feedparser.FeedParserDict: # FIXME: needs tweaking:
		mail["From"] = '%s <%s>' %(Header(author.get("name", u"Unknown"), "utf-8"), author.get("email", u"").encode("utf-8"))
	else:
		raise Unreachable, "Unknown author type. This shouldn't happen"
	# FIXME: Theoretically, there might be any mime type possible here:
	mail["Subject"] = Header(title.encode("utf-8"), "utf-8")
	if date: mail["Date"] = date.encode("utf-8")
	if id:   mail["Message-Id"] = '<%s@localhost>' % urlenc(id) # Helps filter duplicates
	if link: mail["To"] = ('<%s>' % link).encode("utf-8") # XXX: come up with a better header?
	return mail

for url in feeds:
	try:
		feed = feedparser.parse(url)
	except:
		print >> sys.stderr, "Error retrieving %s" % url
		continue
	fs = seen.get(url, set())

	for ent in feed.entries:
		if not ent.has_key("id"):
			print >> sys.stderr, "Feed '%s' currently does not work with cron-feed." % url
			break
		if ent["id"] in fs:
			continue
		title = ent.title_detail["value"] # XXX: take care of content types..
		summ = render(ent.summary) # pray that elinks autodetects text/plain...
		author = ent.get("author_detail") or ent.get("author") or\
			 feed.feed.get("author_detail") or feed.feed.get("author") or "Unknown"
		link = ent.get("link", None)
		try:
			date = time_convert(ent.get("updated_parsed", feed.feed.get("updated_parsed")))
		except:
			date = None
		mail = create_feed_mail(author, title, summ, date, ent["id"], link)
		mbox.add(mail)
		fs.add(ent["id"])

	seen[url] = fs

try:
	fd = open(fseen, "r+") # doesn't nuke the file ("w" does)
except:
	try:
		fd = open(fseen, "w")	
	except:
		print >> sys.stderr, "can't open %s for writing. Check permissions, rinse, repeat" % fseen
		sys.exit(1)
	
with fd as fd:
	fcntl.flock(fd, fcntl.LOCK_EX)
	pickle.dump(seen, fd, -1)
	fd.truncate()

# $Id: cron-feed,v 1.9 2012/05/07 18:08:00 mw Exp $