#!/usr/bin/env python
"""ln_s.py: Use the ln-s.net URL redirector
Mark Matienzo - October 2007"""

import getopt, re, sys, urllib, urllib2

_api_url = 'http://ln-s.net/home/api.jsp'
_help_msg = 'For help, use, -h or --help'
_invalid_url = 'Invalid URL (must start with either "http://" or "https://")'

def main():
  """usage: ln_s.py <url>"""
  try:
    opts, args = getopt.getopt(sys.argv[1:], "h", ["help"])
  except getopt.error, e:
    print e
    print _help_msg
    sys.exit(2)
  for o, a in opts:
    if o in ("-h", "--help"):
      print main.__doc__
      sys.exit(0)
  try:
    print shorten(sys.argv[1])
    sys.exit(1)
  except IndexError, e:
    raise IOError, 'Missing URL - %s' % _help_msg
    sys.exit(2)

def shorten(url_to_shorten):
  """shorten(): Creates shortened redirect using ln-s.net's API
  
  Returns a string or throws an exception. For more information on
  the ln-s.net API, see http://ln-s.net/home/apidoc.jsp.
  N.B.: ln-s.net doesn't return proper HTTP error codes (just 200).
  """
  try:
    params = urllib.urlencode({'url': url_to_shorten.strip()})
    shorten_req = urllib2.Request(url=_api_url, data=params)
    opened = urllib2.urlopen(shorten_req)
    result = opened.read().strip()
    if result.startswith('200 '):
      return result[4:]
    else:
      raise IOError, result
  except (AttributeError, TypeError), e:
    raise TypeError, '%s\n%s' % (e, _invalid_url)

if __name__ == "__main__":
    sys.exit(main())