#!/usr/bin/python -S
#
# python script to genereate a hash for a video file in MythVideo
#
# @url       $$
# @date      $$
# @version   $$
# @author    $$
#

import os, struct, sys

def hashFile(filename):
    '''Create metadata hash values for mythvideo files
    return a hash value
    return u'' if the was an error with the video file or the video file length was zero bytes
    '''
    # generate a hash for a file on the local system
    # For original code: http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes#Python
    try:
        longlongformat = 'q'  # long long
        bytesize = struct.calcsize(longlongformat)
        f = open(filename, "rb")
        filesize = os.path.getsize(filename)
        hash = filesize
        if filesize < 65536 * 2:    # Video file is too small
               return u''
        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

    except(IOError):    # Accessing to this video file caused and error
        return u''
# end hashFile()

print hashFile(sys.argv[1])