#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# GuessIt - A library for guessing information from filenames
# Copyright (c) 2011 Nicolas Wack <wackou@gmail.com>
#
# GuessIt is free software; you can redistribute it and/or modify it under
# the terms of the Lesser GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# GuessIt 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
# Lesser GNU General Public License for more details.
#
# You should have received a copy of the Lesser GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

from guessit import Guess
import struct, os

def hash_file(filename):
    """This function is taken from:
    http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes
    and is licensed under the GPL."""

    longlongformat = 'q'  # long long
    bytesize = struct.calcsize(longlongformat)

    f = open(filename, "rb")

    filesize = os.path.getsize(filename)
    hash = filesize

    if filesize < 65536 * 2:
        raise Exception, "SizeError: size is %d, should be > 132K..." % filesize

    for x in range(65536/bytesize):
        buffer = f.read(bytesize)
        (l_value,)= struct.unpack(longlongformat, buffer)
        hash += l_value
        hash = hash & 0xFFFFFFFFFFFFFFFF #to remain as 64bit number


    f.seek(max(0,filesize-65536),0)
    for x in range(65536/bytesize):
        buffer = f.read(bytesize)
        (l_value,)= struct.unpack(longlongformat, buffer)
        hash += l_value
        hash = hash & 0xFFFFFFFFFFFFFFFF

    f.close()
    returnedhash =  "%016x" % hash
    return returnedhash