10-12-2020 lesson

import argparse
import datetime
import os
import pathlib
import stat


class Singleton:
    def __init__(self):
        self.commands_dir = {}

    def __call__(self, func):
        self.commands_dir[func.__name__] = func

    @classmethod
    def get_instance(cls):
        if not hasattr(cls, 'instance'):
            cls.instance = cls()
        return cls.instance


@Singleton.get_instance()
def ls(command_args: tuple):
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "-l",
        dest="show_info",
        action="store_true",
        default=False
    )

    args = parser.parse_args(command_args)

    file_names = os.listdir()
    display_info = " ".join(file_names)

    # -l flag
    if args.show_info:
        files_info = []

        for file_name in file_names:
            file_stat = os.stat(file_name)

            file_mode = stat.filemode(file_stat.st_mode)
            file_hard_links_number = str(file_stat.st_nlink)
            file_size = str(file_stat.st_size)
            file_mod_date = str(
                datetime.datetime.fromtimestamp(file_stat.st_mtime)
            )

            files_info.append(
                " ".join(
                    [
                        file_mode,
                        file_hard_links_number,
                        file_size,
                        file_mod_date,
                        file_name
                    ]
                )
            )

        display_info = "\n".join(files_info)

    return display_info


@Singleton.get_instance()
def cat():
    pass


@Singleton.get_instance()
def cd(command_args: tuple):
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "string",
        metavar="dir_name",
        type=str,
        nargs="+"
    )

    args = parser.parse_args(command_args)

    if args.dir_name in ["..", "../"]:
        os.chdir(args.dir_name)


@Singleton.get_instance()
def rm():
    pass


@Singleton.get_instance()
def pwd():
    pass


@Singleton.get_instance()
def touch():
    pass


def main():
    while True:
        user_input = input(f"{pathlib.Path().absolute()}: ").split()

        if user_input[0] == "exit":
            break

        command = user_input[0]
        command_args = tuple(user_input[1::])

        print(Singleton.get_instance().commands_dir[command](command_args))


if __name__ == '__main__':
    main()