import os
import getpass


class GlobalPath:
    SELF_PATH = __file__[:__file__.rfind('\\')]
    visible_path = ''


def ls(path: str = 'DEFAULT') -> str:
    if path != 'DEFAULT':
        files = os.listdir(path)
    else:
        files = os.listdir(GlobalPath.SELF_PATH)

    res = ''

    for offset, file in enumerate(files):
        res += file + '\t'

        if offset % 6 == 0 and offset != 0:
            res += '\n'

    return res


def cat(*files) -> str:
    res = ''

    for file in files:
        with open(file=f'{GlobalPath.SELF_PATH}\\{file}', mode='r', encoding='utf-8') as f:
            for line in f:
                res += line

    return res


def pwd() -> str:
    return GlobalPath.SELF_PATH


def cd(path: str):
    if path == '..':
        GlobalPath.SELF_PATH = generate_new_path(GlobalPath.SELF_PATH)

        path = generate_new_path(GlobalPath.visible_path).replace('\\\\', '')

        GlobalPath.visible_path = path
    else:
        if os.path.exists(GlobalPath.SELF_PATH + f'\\{path}'):
            GlobalPath.SELF_PATH += f'\\{path}'
            GlobalPath.visible_path += f'\\{path}'


def convert_path_to_list(visible_path: str) -> list:
    return visible_path.split('\\')


def generate_new_path(path):
    tmp = convert_path_to_list(path)
    tmp.pop()

    path = ''

    for offset, file in enumerate(tmp):
        if offset != 0:
            path += f'\\{file}'
        else:
            path += f'{file}'

    return path


def run():
    commands = {
        'ls': ls,
        'cat': cat,
        'pwd': pwd,
        'cd': cd,
    }

    while True:
        user_name = f'{getpass.getuser()}@ubuntu:{GlobalPath.visible_path if GlobalPath.visible_path else "~"}$ '
        enter_command = input(user_name).split(' ')
        command, args = enter_command[0], enter_command[1:]

        if not commands.get(command):
            continue

        try:
            res = commands[command](*args)
        except Exception as e:
            print(e)
            continue

        if res:
            print(res)


if __name__ == '__main__':
    run()