#!/usr/bin/env python3

"""
Will break apart large files into smaller files
"""

import argparse
import time


def parse_args():
    argp = argparse.ArgumentParser(
            description="Will break a large file into smaller files"
    )

    argp.add_argument(
            'large_file',
            help="Full path for large file"
    )

    argp.add_argument(
            '--prefix', '-p',
            default='small',
            help="Prefix for the smaller files (default: %(default)s)"
    )

    argp.add_argument(
            '--extension', '-x',
            default='txt',
            help="Extension for the smaller files (default: %(default)s)"
    )

    argp.add_argument(
            '-s', '--size',
            default='10K',
            help="File size limits (5K, 10M, 2G)"
    )

    return argp.parse_args()


def main():
    args = parse_args()

    file_count = 0

    # get size for chunks
    size_value = args.size
    size_value_parts = re.match(r'(\d+)([BbKkMmGgTt]?)', size_value).groups()
    if size_value_parts[1]:
        factor = (
                (size_value_parts[1].lower() == 'k' and 1) or
                (size_value_parts[1].lower() == 'm' and 2) or
                (size_value_parts[1].lower() == 'g' and 3) or
                (size_value_parts[1].lower() == 't' and 4)
        )
        size_limit = int(size_value_parts[0]) * 1024**factor
    else:
        size_limit - int(size_value_parts[0])


    with open(args.large_file) as large_file:

        while chunk := large_file.read(size_limit):
            file_count = file_count + 1
            output_filename = f"{args.prefix}-{file_count}.{args.extension}"

            with open(output_filename, 'w') as small_file:
                small_file.write(chunk)


if __name__ == "__main__":
    main()