bu

#!/usr/bin/env python3

# quick and dirty backup versions of the given file to a subdirectory named .bu
# revisions are copied to <filename>;<version_number> (retro throwback to vms)

import sys
import fnmatch
import os
import re
import shlex

DEBUG=False


def getHighestVersion(files):
    pattern = re.compile(r"^.+;(\d+)$")
    highestVersion = -1
    for filename in files:
        version = int(pattern.match(filename).group(1))
        if DEBUG:
            print("%s %d" % (filename, version))
        if (version > highestVersion):
            highestVersion = version
    return highestVersion


def cmd(s):
    if DEBUG:
        print("cmd: %s" % (s))
    os.system(s)

if __name__=='__main__':
    filepath = sys.argv[1]

    dirname = os.path.dirname(filepath)
    if (dirname==""):
        dirname="."
    backup_dirname = os.path.join(dirname,".bu")
    filename = os.path.basename(filepath)

    if (len(filename)==0):
        print("Cannot backup directories.... yet?")
        sys.exit(1)

    if (not os.path.exists(backup_dirname)):
        os.mkdir(backup_dirname)
        
    directoryListing = os.listdir(backup_dirname)
    if DEBUG:
        print("os.listdir(%s)=%s" % (backup_dirname, directoryListing))

    if (len(directoryListing)==0):
        version=0
        if DEBUG:
            print("no prior backups")
    else:
        versionFilenames = fnmatch.filter(directoryListing, "%s;*" % filename)
        if DEBUG:
            print("prior backups:%s" % versionFilenames)
        version = getHighestVersion(versionFilenames)+1

    backup_filepath = os.path.join(backup_dirname,filename)
    cmd("cp %s %s\;%d" % (shlex.quote(filepath), shlex.quote(backup_filepath), version))
    cmd("chmod a-w %s\;%d" % (shlex.quote(backup_filepath), version))

    backupFile = "%s;%d" % (backup_filepath, version)
    if (os.path.exists(backupFile)):
        print("%s backed up to %s" % (filepath, backupFile))
    else:
        print("*** Error copying file.  check existance of backup, change script variable Debug to True and try again")