'''
lucky.py - both a joke and an implementation

The joke:

    New in Python X.X: Integrated Google search in urllib. Example:

    >>> import urllib
    >>> f = urllib.urlopen('miserable failure')
    >>> print f.geturl()
    http://www.whitehouse.gov/president/gwbbio.html

And for some reason, I decided to implement it:

    >>> import lucky
    >>> lucky.magic()
    >>> import urllib
    >>> f = urllib.urlopen('miserable failure')
    >>> print f.geturl()
    http://www.whitehouse.gov/president/gwbbio.html
'''

# lucky.py - Integrated Google search in urllib
# Copyright (C) 2006  Lenny Domnitser
# 
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor,
# Boston, MA 02110-1301, USA.


import httplib
import urllib
import urlparse


__author__ = 'Lenny Domnitser <http://domnit.org/>'
__license__ = 'GNU_GPL'
__version__ = '0.1' # 2006-09-11


__all__ = 'BadLuck', 'magic', 'unmagic', 'urlopen'


URL_TEMPLATE = 'http://www.google.com/search?btnI=&q=%s'


class BadLuck(IOError):
    '''No page matches keywords.'''
    pass


_normal_urlopen = urllib.urlopen


def magic():
    urllib.urlopen = urlopen
def unmagic():
    urllib.urlopen = _normal_urlopen


def urlopen(url, data = None, proxies = None):
    '''If url is not really a URL, then get the most likely matching web page.
    Otherwise works like urllib.urlopen'''
    if not data and not urlparse.urlparse(url)[0]:
        return lucky_open(url, proxies)
    else:
        return _normal_urlopen(url, data, proxies)


def lucky_open(keywords, proxies = None):
    url = URL_TEMPLATE % urllib.quote_plus(keywords)
    url_opener = urllib.URLopener(proxies)
    url_opener.addheaders = [('User-Agent', 'lucky.py/%s' % __version__)]
    try:
        # the opener will raise an error on 302 Found
        # if it doesn't raise an error, we do
        url_opener.open(url)
        raise BadLuck('No page matches keywords: %s' % keywords)
    except IOError, e:
        message = e[-1]
        if not isinstance(message, httplib.HTTPMessage):
            raise e
        location = message.get('Location')
        return _normal_urlopen(location, None, proxies)


if __name__ == '__main__':
    import sys
    print urlopen(' '.join(sys.argv[1:])).geturl()