#! /usr/bin/python

import sre as RX
import os as OS
import time as T
import socket as S
from getopt import getopt, GetoptError
from sys import stdin, stdout, stderr, argv, exit
from cStringIO import StringIO
env = OS.environ

prog = argv[0]

def bad(msg):
  print >>stderr, '%s (fatal): %s' % (prog, msg)
  exit(100)
def die(msg):
  print >>stderr, '%s: %s' % (prog, msg)
  exit(111)
def usage():
  print >>stderr, \
    ('Usage: %s [-d DIST] [-h HOST] [-r REMOTE] [-p PATH] GROUP <MESSAGE' %
     prog)
  exit(111)

def headers(file):
  h = None
  while True:
    line = file.next()
    if line == '' or line == '\n':
      break
    if line[0].isspace():
      if h is None:
        bad('unexpected continuation')
      h += line
    else:
      if h: yield h
      h = line
  if h: yield h

def hdrsplit(h):
  v = h.split(':', 1)
  if len(v) != 2:
    bad('failed to parse header')
  return v[0].strip().lower(), v[1].strip()

remote = ('localhost', 119)
approved = None
try:
  host = OS.popen('hostname -f').read().strip()
except:
  host = 'localhost'
dist = 'mail'
path = 'newsgate'
sender = env.get('SENDER')
recip = env.get('RECIPIENT')
group = None

def opts():
  global approved, remote, host, dist, path, group, sender, recip
  try:
    opts, args = getopt(argv[1:], 'a:d:h:r:p:S:R:',
                        ['approved=', 'distribution=',
                         'sender=', 'recipient=',
                         'hostname=', 'remote=', 'path='])
  except GetoptError:
    usage()
  for o, a in opts:
    if o in ('-a', '--approved'):
      approved = a
    elif o in ('-d', '--distribution'):
      dist = a
    elif o in ('-h', '--hostname'):
      host = a
    elif o in ('-r', '--remote'):
      remote = (lambda addr, port = 119: (addr, int(port)))(*a.split(':'))
    elif o in ('-R', '--recipient'):
      recip = a
    elif o in ('-S', '--sender'):
      sender = a
  if len(args) != 1:
    usage()
  group, = args

rx_msgid = RX.compile(r'^\<\S+@\S+\>$')

class NNTP (object):
  def __init__(me, addr):
    me.sk = S.socket(S.AF_INET, S.SOCK_STREAM)
    me.sk.connect(remote)
    me.f = me.sk.makefile()
    rc, msg = me.reply()
    if rc != '200':
      die('unable to contact server: %s %s' % (rc, msg))
  def write(me, stuff):
    me.f.write(stuff)
  def flush(me):
    me.f.flush()
  def cmd(me, stuff):
    me.f.write(stuff + '\r\n')
    me.f.flush()
  def reply(me):
    rc, msg = (lambda rc, msg = '.': (rc, msg.strip())) \
                (*me.f.readline().split(None, 1))
    if rc.startswith('5'):
      die('server hated me: %s %s' % (rc, msg))
    return rc, msg.strip()

def send():
  hdr = StringIO()
  body = StringIO()
  hdr.write('Path: newsgate\r\n'
            'Distribution: mail\r\n'
            'Newsgroups: %s\r\n'
            % group)
  if approved: hdr.write('Approved: %s\r\n' % approved)
  if sender: hdr.write('Return-Path: <%s>\r\n' % sender)
  if recip: hdr.write('Delivered-To: %s\r\n' % recip)
  xify = {}
  for h in '''
    lines xref newsgroups path distribution approved received
  '''.split():
    xify[h] = 1
  seen = {}
  for h in headers(stdin):
    n, c = hdrsplit(h)
    if n in xify:
      h = 'X-Newsgate-' + h
    elif h.startswith('.'):
      h = '.' + h
    seen[n] = c
    if h.endswith('\r\n'):
      pass
    elif h.endswith('\n'):
      h = h[:-1] + '\r\n'
    else:
      h += '\r\n'
    hdr.write(h)
  if 'message-id' not in seen:
    seen['message-id'] = ('<newsgate-%s@%s>'
                          % (OS.popen('gorp 128').read().strip(),
                             host))
    hdr.write('Message-ID: %s\r\n' % seen['message-id'])
  if 'date' not in seen:
    hdr.write('Date: %s\r\n'
              % (T.strftime('%a, %d %b %Y %H:%M:%S %Z')))
  if 'subject' not in seen:
    hdr.write('Subject: (no subject)\r\n')

  msgid = seen['message-id']
  if not rx_msgid.match(msgid):
    bad('invalid message-id %s' % msgid)

  nntp = NNTP(remote)
  nntp.cmd('IHAVE %s' % msgid)
  rc, msg = nntp.reply()
  if rc == '335':
    n = 0
    for i in stdin:
      if i.startswith('.'):
        i = '.' + i
      if i.endswith('\r\n'):
        pass
      elif i.endswith('\n'):
        i = i[:-1] + '\r\n'
      else:
        i = i + '\r\n'
      body.write(i)
      n += 1
    hdr.write('Lines: %d\r\n' % n)
    hdr.write('\r\n')
    nntp.write(hdr.getvalue())
    nntp.write(body.getvalue())
    nntp.write('.\r\n')
    nntp.flush()
    rc, msg = nntp.reply()
  if rc == '435':
    ## doesn't want my article; pretend all is fine: I don't care
    pass
  elif rc == '436':
    die('failed to send article: %s %s' % (rc, msg))
  elif rc == '437':
    bad('server rejected article: %s %s' % (rc, msg))
  elif not rc.startswith('2'):
    die('unexpected response from server: %s %s' % (rc, msg))
  nntp.cmd('QUIT')
  nntp.reply()

def main():
  try:
    opts()
    send()
  except SystemExit:
    raise
#  except Exception, exc:
#    die('unhandled exception: %s, %s' % (exc.__class__.__name__,
#                                         exc.args))
main()