#!/usr/bin/python
##########################################################
# join all part files in a dir created by split.py.  
# This is roughly like a 'cat fromdir/* > tofile' command
# on unix, but is a bit more portable and configurable,
# and exports the join operation as a reusable function.
# Relies on sort order of file names: must be same length.
# Could extend split/join to popup Tkinter file selectors.
##########################################################

import os, sys
readsize = 1024

def join(fromdir, tofile):
    output = open(tofile, 'wb')
    parts  = os.listdir(fromdir)
    parts.sort()
    for filename in parts:
        filepath = os.path.join(fromdir, filename)
        fileobj  = open(filepath, 'rb')
        while 1:
            filebytes = fileobj.read(readsize)
            if not filebytes: break
            output.write(filebytes)
        fileobj.close()
    output.close()

if __name__ == '__main__':
    if len(sys.argv) == 2 and sys.argv[1] == '-help':
        print 'Use: join.py [from-dir-name to-file-name]'
    else:
        if len(sys.argv) != 3:
            interactive = 1
            fromdir = raw_input('Directory containing part files? ')
            tofile  = raw_input('Name of file to be recreated? ')
        else:
            interactive = 0
            fromdir, tofile = sys.argv[1:]
        absfrom, absto = map(os.path.abspath, [fromdir, tofile])
        print 'Joining', absfrom, 'to make', absto

        try:
            join(fromdir, tofile)
        except:
            print 'Error joining files:'
            print sys.exc_type, sys.exc_value
        else:
           print 'Join complete: see', absto
        if interactive: raw_input('Press Enter key') # pause if clicked