"""a tutorial example of A CLI module using argparse to find all files in a directory tree
"""

from argparse import ArgumentParser
from sys import argv, stderr, stdout
from os import _exit, scandir
from os.path import exists

__VERSION__ = "1.0.0"


def find_all_the_files(path):
    """a recursive function to take a path on a disk and find all the files in a complicated directory tree

    :param str path: a directory path that is on disk

    :rtype generator
    """
    # call a for to iterate through the output of scandir
    # this does a flat ls of the directory contents whether
    # each content is a file or a directory or a symbolic link
    for n_item in scandir(path):
        # have to check if the item in hand is a directory
        if n_item.is_dir():
            # if it is a directory have to call the function
            # with the path of the new item
            yield from find_all_the_files(n_item.path)
        # check if the item is a regular file
        elif n_item.is_file():
            # if it is a regular file add this to the generator
            yield n_item.path
        else:
            # if the item is neither a directory nor a file then
            # something is wierd about this directory
            # and you need to know so that you can deal with it
            stderr.write("{} cannot be recognized.\n".format(n_item.path))


def main():
    """a main method for the module. takes parameters passed

    :rtype int
    """
    arguments = ArgumentParser(description="A tool to find all regular files in a complex directory tree",
                               epilog="Copyright verbalhanglider, version " + __VERSION__)
    arguments.add_argument("a_directory", action="store",
                           type=str, help="An absolute directory path")
    parsed_args = arguments.parse_args()
    try:
        if exists(parsed_args.a_directory):
            a_generator = find_all_the_files(parsed_args.a_directory)
            for a_file in a_generator:
                stdout.write("{}\n".format(a_file))
        else:
            stderr.write("{} does not exist on this machine!")
         # if this completes return proper code to terminal to indicate that program
        # completed everything it needed to complete
        return 0
    except KeyboardInterrupt:
        # if user hits Ctrl-C return proper code to terminal to interrupt
        return 131


if __name__ == "__main__":
    _exit(main())