#! /usr/local/bin/python
# -*- coding: utf-8 -*-

# Stéganô - Stéganô is a basic Python Steganography module.
# Copyright (C) 2010  Cédric Bonhomme - http://cedric.bonhomme.free.fr/
#
# For more information : http://bitbucket.org/cedricbonhomme/stegano/
#
# 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 3 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, see <http://www.gnu.org/licenses/>

__author__ = "Cedric Bonhomme"
__version__ = "$Revision: 0.1 $"
__date__ = "$Date: 2010/10/01 $"
__license__ = "GPLv3"

def a2bits(chars):
    """
    Converts a string to its bits representation as a string of 0's and 1's.

    >>> a2bits("Hello World!")
    '010010000110010101101100011011000110111100100000010101110110111101110010011011000110010000100001'
    """
    return bin(reduce(lambda x, y : (x<<8)+y, (ord(c) for c in chars), 1))[3:]

def a2bits_list(chars):
    """
    Convert a string to its bits representation as a list of 0's and 1's.

    >>>  a2bits_list("Hello World!")
    ['01001000',
    '01100101',
    '01101100',
    '01101100',
    '01101111',
    '00100000',
    '01010111',
    '01101111',
    '01110010',
    '01101100',
    '01100100',
    '00100001']
    >>> "".join(a2bits_list("Hello World!"))
    '010010000110010101101100011011000110111100100000010101110110111101110010011011000110010000100001'
    """
    return [bin(ord(x))[2:].rjust(8,"0") for x in chars]

def bs(s):
    """
    Converts an int to its bits representation as a string of 0's and 1's.
    """
    return str(s) if s<=1 else bs(s>>1) + str(s&1)

def setlsb(component, bit):
    """
    Set Least Significant Bit of a colour component.
    """
    return component & ~1 | int(bit)

def n_at_a_time(items, n, fillvalue):
    """
    Returns an iterator which groups n items at a time.
    Any final partial tuple will be padded with the fillvalue

    >>> list(n_at_a_time([1, 2, 3, 4, 5], 2, 'X'))
    [(1, 2), (3, 4), (5, 'X')]
    """
    it = iter(items)
    return its.izip_longest(*[it] * n, fillvalue=fillvalue)

def binary2base64(binary_file, output_file):
    """
    Convert a binary file (OGG, executable, etc.) to a
    printable file.
    """
    # Use mode = "rb" to read binary file
    fin = open(binary_file, "rb")
    binary_data = fin.read()
    fin.close()

    # Encode binary to base64 string (printable)
    b64_data = base64.b64encode(binary_data)

    fout = open(output_file, "w")
    fout.write(b64_data)
    fout.close

def base642binary(b64_fname):
    """
    Convert a printable file to a binary file.
    """
    # Read base64 string
    fin = open(b64_fname, "r")
    b64_str = fin.read()
    fin.close()
    # Decode base64 string to original binary sound object
    return base64.b64decode(b64_str)