#!/usr/bin/env python3

"""Scan the files in a directory sub-tree and set directory modification times
to be the modification time of the newest non directory file within the
sub-tree. This is work around the Office 2016 practice of creating a temporary
file in the same directory as each file when opening that file (which of
course updates the directory modification time."""

import argparse, os, sys, time

loglevel = 1

def scan_directory(dirpath, mtimes={}, level=0):
    """Scan directory sub-tree...

    dirpath: root of directory sub-tree
    mtimes: dictionary...
    level: indentation level (used only for reporting)"""

    mtime0 = os.stat(dirpath).st_mtime
    mtimes[dirpath] = {"mtime0": mtime0, "mtime": 0.0}

    for direntry in os.scandir(dirpath):
        name = direntry.name
        path = direntry.path
        is_file = direntry.is_file()
        is_dir = direntry.is_dir()
        is_symlink = direntry.is_symlink()

        if loglevel > 2:
            print("%s%s %s" % (level * "  ", name,
                               time.ctime(direntry.stat().st_mtime)))

        if not is_file and not is_dir:
            continue

        if is_dir and name == ".git":
            continue

        if is_dir and not is_symlink:
            mtime = scan_directory(path, level=level+1, mtimes=mtimes)
        else:
            mtime = direntry.stat().st_mtime

        if mtime > mtimes[dirpath]["mtime"]:
            mtimes[dirpath]["mtime"] = mtime

    return mtimes[dirpath]["mtime"]

def main(argv=None):
    """Main program."""

    if argv is None: argv = sys.argv

    # XXX might be better to use positional argument for directory?
    global loglevel
    parser = argparse.ArgumentParser(
        prog=argv[0], description="update directory modification time")
    parser.add_argument("-d", "--directory",
        help="root of directory sub-tree; default is current directory")
    parser.add_argument("-l", "--loglevel", type=int,
        help="logging level; default: %d" % loglevel)
    parser.add_argument("-n", "--dryrun", action="store_true",
        help="dry run; report what would have been done but don't do it")

    args = parser.parse_args(argv[1:])

    directory = args.directory if args.directory else os.getcwd()
    dryrun = args.dryrun
    if args.loglevel is not None: loglevel = args.loglevel

    mtimes = {}
    scan_directory(directory, mtimes)

    for dirname in sorted(mtimes.keys()):
        mtime0 = mtimes[dirname]["mtime0"]
        mtime = mtimes[dirname]["mtime"]
        if mtime > 0 and mtime < mtime0:

            if loglevel > 0:
                print("%s: %s -> %s" % (dirname, time.ctime(mtime0),
                                        time.ctime(mtime)))

            if dryrun or loglevel > 1:
                print("os.utime(\"%s\", (%d, %d))" % (dirname, mtime, mtime))

            if not dryrun:
                os.utime(dirname, (mtime, mtime))

if __name__ == "__main__":
    sys.exit(main())