#!/usr/bin/env python3

from functools import partial
from pathlib import Path
import os
import sys

def ensure_path(p):
    return p if isinstance(p, Path) else Path(p)

def include_all(*args):
    return True

class File:
    def __init__(self, path):
        self.path = ensure_path(path)
        self.stat = os.stat(self.path)

    @property
    def name(self):
        return self.path.name

    def size(self):
        return self.stat.st_size

def get(values, *, existing=set()):
    for val in values:
        if val in existing:
            continue
        if val.size() == 0:
            continue
        yield val

def by_size(x, *, filter=None):
    return x.size(filter=filter)

def by_name(x):
    return x.name

class Directory:
    def __init__(self, base_dir):
        self.base = ensure_path(base_dir)
        self.files = {}
        self.dirs = {}

    @property
    def name(self):
        return self.base

    def list_by_size(self, *, files=None):
        files = set() if files is None else files

        while True:
            dirs = get(self.dirs.values(), existing=files)
            without_file = lambda x: x not in files
            filtered_by_size = partial(by_size, filter=without_file)
            dirs_by_size = sorted(dirs, key=filtered_by_size, reverse=True)
            if len(dirs_by_size):
                largest_dir = dirs_by_size[0]
                current_file = next(largest_dir.list_by_size(files=files))
                files.add(current_file)
                yield current_file
                continue

            files_by_name = sorted(get(self.files.values(), existing=files),
                                   key=by_name)
            if len(files_by_name):
                current_file = files_by_name[0]
                files.add(current_file)
                yield current_file
                continue
            return

    def size(self, *, filter=None):
        filter = include_all if filter is None else filter

        total = 0
        for node in self.files.values():
            if filter(node):
                total += node.size()

        for node in self.dirs.values():
            total += node.size(filter=filter)

        return total

    def directory(self, *parts):
        if len(parts) == 0:
            return self

        part, *rest = parts
        node = self.dirs.get(part)
        if node is None:
            node = Directory(part)
            self.dirs[part] = node

        return node.directory(*rest)

    def add_file(self, path):
        node = self.directory(*path.parent.parts)
        node.files[path.name] = File(path)
        return node.files[path.name]

def main(base_dir):
    tree = Directory(base_dir)
    for root, dirs, files in os.walk(base_dir):
        for f in files:
            tree.add_file(Path(root) / f)

    for f in tree.list_by_size():
        print("{}/{}".format(base_dir, f.path))

if __name__ == '__main__':
    from argparse import ArgumentParser
    parser = ArgumentParser()
    parser.add_argument('-o', '--output', default='.')
    parser.add_argument('-d', '--directory', default=Path('.'), type=Path)
    args = parser.parse_args()
    main(args.directory)