"""
Will either compute a passwordmaker style key from `sha256(mp + site +
username)` or open a symmetrically keyed gpg file and lookup a specific
site-key for the username and password. The keyfile must follow the following
format::

   foobar.com:
       username: johnuser
       password: megaleet

"""

from argparse import ArgumentParser
import getpass
import hashlib
import math

import gnupg
import yaml

CHARSET = ("ABCDEFGHIJKLMNOPQRSTUVWXYZ"
           "abcdefghijklmnopqrstuvwxyz"
           "0123456789`~!@#$%^&*()_-+={}|[]\\:\";\'<>?,./")


# `copy_url` from lodgeit.py
# :license: 3-Clause BSD
# :authors: 2007-2008 Georg Brandl <georg@python.org>,
#           2006 Armin Ronacher <armin.ronacher@active-4.com>,
#           2006 Matt Good <matt@matt-good.net>,
#           2005 Raphael Slinckx <raphael@slinckx.net>
def clipboard_copy(item):
    """Copy the item into the clipboard."""
    # try windows first
    try:
        import win32clipboard
    except ImportError:
        # then give pbcopy a try.  do that before gtk because
        # gtk might be installed on os x but nobody is interested
        # in the X11 clipboard there.
        from subprocess import Popen, PIPE
        for prog in 'pbcopy', 'xclip':
            try:
                client = Popen([prog], stdin=PIPE)
            except OSError:
                continue
            else:
                client.stdin.write(item)
                client.stdin.close()
                client.wait()
                break
        else:
            try:
                import pygtk
                pygtk.require('2.0')
                import gtk
                import gobject
            except ImportError:
                return
            gtk.clipboard_get(gtk.gdk.SELECTION_CLIPBOARD).set_text(item)
            gobject.idle_add(gtk.main_quit)
            gtk.main()
    else:
        win32clipboard.OpenClipboard()
        win32clipboard.EmptyClipboard()
        win32clipboard.SetClipboardText(item)
        win32clipboard.CloseClipboard()


def rstr2any(input, encoding, trim=True):
    """Convert a raw string to an arbitrary string encoding. Set trim
    to false for keeping leading zeros

    """
    divisor = len(encoding)
    remainders = []

    # Convert to an array of 16-bit big-endian values, forming the dividend
    dividend = []
    # pad this
    while len(dividend) < math.ceil(len(input) / 2):
        dividend.append(0)
    for i in range(len(dividend)):
        dividend[i] = (ord(input[i * 2]) << 8) | ord(input[i * 2 + 1])
    # Repeatedly perform a long division. The binary array forms the dividend,
    # the length of the encoding is the divisor. Once computed, the quotient
    # forms the dividend for the next step. We stop when the dividend is zero.
    # All remainders are stored for later use.
    while len(dividend) > 0:
        quotient = []
        x = 0
        for i in range(len(dividend)):
            x = (int(x) << 16) + dividend[i]
            q = math.floor(x / divisor)
            x -= q * divisor
            if len(quotient) > 0 or q > 0:
                quotient.append(q)
        remainders.append(x)
        dividend = quotient

    # Convert the remainders to the output string
    output = ""
    for i in range(len(remainders) - 1, 0, -1):
        output += encoding[int(remainders[i])]
    return output


def main():
    parser = ArgumentParser()
    parser.add_argument('-f', '--file',
                        help='GPG file to use for looking up keys',
                        type=file)
    parser.add_argument('-u', '--user',
                        help='Username default',
                        default=getpass.getuser())
    mutex_group = parser.add_mutually_exclusive_group()
    mutex_group.add_argument('-l', '--list', action='store_true')
    mutex_group.add_argument('-g', '--generate')
    mutex_group.add_argument('-s', '--select')
    namespace = parser.parse_args()

    if namespace.list or namespace.select:
        symmetric_phrase = getpass.getpass('passphrase: ')
        gpg = gnupg.GPG()
        crypt = gpg.decrypt_file(namespace.file, passphrase=symmetric_phrase)
        key_data = yaml.load(crypt.data)
        if namespace.list:
            print key_data.keys()
            return
        elif namespace.select:
            # TODO:dc: check for the key in key_data
            username = key_data[namespace.select].get('username', '')
            pass_ = key_data[namespace.select].get('password', '')
    else:
        mp = getpass.getpass('master key: ')
        site = raw_input('site: ')
        username = namespace.user
        hash_ = hashlib.sha256(mp + site + username).digest()
        pass_ = rstr2any(hash_, CHARSET)[:20]

    clipboard_copy(pass_)
    print username

if __name__ == '__main__':
    main()