import argparse
import collections
import os
import shutil
import sys

from voussoirkit import passwordy
from voussoirkit import pathclass
from voussoirkit import pipeable
from voussoirkit import spinal
from voussoirkit import vlogging
from voussoirkit import winglob

log = vlogging.getLogger(__name__, 'sole_subdir_lift')

def main(argv):
    argv = vlogging.set_level_by_argv(log, argv)

def sole_lift_argparse(args):
    starting = pathclass.Path(args.starting)
    queue = collections.deque()
    queue.extend(spinal.walk(starting, yield_files=False, yield_directories=True))
    while len(queue) > 0:
        directory = queue.popleft()

        if not directory.exists:
            log.debug('%s no longer exists.', directory)
            continue

        if directory not in starting:
            log.debug('%s is outside of starting.', directory)
            continue

        children = directory.listdir()
        child_count = len(children)
        if child_count != 1:
            log.debug('%s has %d children.', directory, child_count)
            continue

        child = children[0]

        if not child.is_dir:
            log.debug('%s contains a file, not a dir.', directory)
            continue

        log.info('Lifting contents of %s.', child.absolute_path)
        # child is renamed to random hex so that the grandchildren we are about
        # to lift don't have name conflicts with the child dir itself.
        # Consider .\abc\abc where the grandchild can't be moved.
        temp_dir = directory.with_child(passwordy.urandom_hex(32))
        os.rename(child.absolute_path, temp_dir.absolute_path)
        for grandchild in temp_dir.listdir():
            shutil.move(grandchild.absolute_path, directory.absolute_path)

        if temp_dir.listdir():
            raise Exception()

        os.rmdir(temp_dir.absolute_path)
        queue.append(directory.parent)

def main(argv):
    argv = vlogging.set_level_by_argv(log, argv)

    parser = argparse.ArgumentParser(description=__doc__)

    parser.add_argument('starting', nargs='?', default='.')
    parser.set_defaults(func=sole_lift_argparse)

    args = parser.parse_args(argv)
    return args.func(args)

if __name__ == '__main__':
    raise SystemExit(main(sys.argv[1:]))