download a Qiita article and print program in code blocks

qiitacode.py

#!/usr/bin/env python3

"""
download a Qiita article and print program in code blocks

example:
    $ python3 qiitacode.py https://qiita.com/shiracamus/items/556ff8d916712a9f7055
    $ python3 qiitacode.py https://qiita.com/shiracamus/items/556ff8d916712a9f7055 c
    $ python3 qiitacode.py https://qiita.com/shiracamus/items/556ff8d916712a9f7055 py
"""

import sys
import re
import requests


def load_markdown(url):
    return requests.get(f'{url}.md').text.splitlines()


def markdown_code(lines, lang=''):
    lang_pattern = rf'(\s*{lang}(:.*)?|.*:.*\.{lang})' if lang else ''
    code_start = re.compile(rf'^\s*(```|~~~){lang_pattern}\s*$')
    code_end = re.compile(r'^\s*(```|~~~)\s*$')
    in_code_block = False
    for line in lines:
        if in_code_block:
            if code_end.match(line):
                in_code_block = False
                yield '\n'
            else:
                yield line
        else:
            if code_start.match(line):
                in_code_block = True


def main():
    if not 2 <= len(sys.argv) <= 3:
        print(f'Usage: {sys.argv[0]} QIITA_ARTICLE_URL LANGUAGE')
        exit(1)
    markdown = load_markdown(url=sys.argv[1])
    lang = sys.argv[2] if len(sys.argv) > 2 else ''
    for code in markdown_code(markdown, lang):
        print(code)


if __name__ == '__main__':
    main()