formatter.py

import html
import re
import base64


def format_content_html(content: str, allow_links: bool = False) -> str:
    # HTML-encode content

    def encode_codeblock(m):
        encoded = base64.b64encode(m.group(1).encode()).decode()
        return '\x1AM' + encoded + '\x1AM'

    # Encode multiline codeblocks (```text```)
    content = re.sub(r'```+((?:[^`]*?\n)?(?:[^`]+))\n?```+',
                     encode_codeblock,
                     content)

    content = html.escape(content)

    def encode_inline_codeblock(m):
        encoded = base64.b64encode(m.group(1).encode()).decode()
        return '\x1AI' + encoded + '\x1AI'

    # Encode inline codeblocks (`text`)
    content = re.sub(r'`([^`]+)`', encode_inline_codeblock, content)

    # Encode links
    if allow_links:
        def encode_link(m):
            encoded_1 = base64.b64encode(m.group(1).encode()).decode()
            encoded_2 = base64.b64encode(m.group(2).encode()).decode()
            return '\x1AL' + encoded_1 + '|' + encoded_2 + '\x1AL'

        content = re.sub(r'\[(.*?)\]\((.*?)\)', encode_link, content)

    def encode_url(m):
        encoded = base64.b64encode(m.group(1).encode()).decode()
        return '\x1AU' + encoded + '\x1AU'

    # Encode URLs
    content = re.sub(r'(\b(?:(?:https?|ftp|file)://|www\.|ftp\.)(?:\([-a-zA-Z0'
                     r'-9+&@#/%?=~_|!:,\.\[\];]*\)|[-a-zA-Z0-9+&@#/%?=~_|!:,\.'
                     r'\[\];])*(?:\([-a-zA-Z0-9+&@#/%?=~_|!:,\.\[\];]*\)|[-a-z'
                     r'A-Z0-9+&@#/%=~_|$]))', encode_url, content)

    # Process bold (**text**)
    content = re.sub(r'(\*\*)(?=\S)(.+?[*_]*)(?<=\S)\1', r'<b>\2</b>', content)

    # Process underline (__text__)
    content = re.sub(r'(__)(?=\S)(.+?)(?<=\S)\1', r'<u>\2</u>', content)

    # Process italic (*text* or _text_)
    content = re.sub(r'(\*|_)(?=\S)(.+?)(?<=\S)\1', r'<i>\2</i>', content)

    # Process strike through (~~text~~)
    content = re.sub(r'(~~)(?=\S)(.+?)(?<=\S)\1', r'<s>\2</s>', content)

    def decode_inline_codeblock(m):
        decoded = base64.b64decode(m.group(1).encode()).decode()
        return '<span class="pre pre--inline">' + decoded + '</span>'

    # Decode and process inline codeblocks
    content = re.sub('\x1AI(.*?)\x1AI', decode_inline_codeblock, content)

    # Decode and process links
    if allow_links:
        def decode_link(m):
            encoded_1 = base64.b64decode(m.group(1).encode()).decode()
            encoded_2 = base64.b64decode(m.group(2).encode()).decode()
            return '<a href="' + encoded_2 + '">' + encoded_1 + '</a>'

        # Potential bug, may need to change to: '\x1AL(.*?)\|(.*?)\x1AL'
        content = re.sub('\x1AL(.*?)\\|(.*?)\x1AL', decode_link, content)

    def decode_url(m):
        decoded = base64.b64decode(m.group(1).encode()).decode()
        return '<a href="' + decoded + '">' + decoded + '</a>'

    # Decode and process URLs
    content = re.sub('\x1AU(.*?)\x1AU', decode_url, content)

    # Process new lines
    content = content.replace('\n', '<br>')

    def decode_codeblock(m):
        decoded = base64.b64decode(m.group(1).encode()).decode()
        match = re.match('^([^`]*?\n)?([^`]+)$', decoded)
        lang = match.group(1) or ''
        if not lang.strip(' \n\r'):
            lang = 'plaintext'
        else:
            lang = lang.strip(' \n\r')

        result = html.escape(match.group(2))
        return (f'<div class="pre pre--multiline {lang}">{result}'
                '</div>')

    # Decode and process multiline codeblocks
    content = re.sub('\x1AM(.*?)\x1AM', decode_codeblock, content)

    # Meta mentions (@everyone)
    content = content.replace('@everyone',
                              '<span class="mention">@everyone</span>')

    # Meta mentions (@here)
    content = content.replace('@here', '<span class="mention">@here</span>')

    # User mentions (<@id> and <@!id>)
    content = re.sub(r'(&lt;@!?(\d+)&gt;)',
                     r'<span class="mention" title="\2">\1</span>', content)

    # Channel mentions (<#id>)
    content = re.sub(r'(&lt;#\d+&gt;)',
                     r'<span class="mention">\1</span>', content)

    # Role mentions (<@&id>)
    content = re.sub(r'(&lt;@&amp;(\d+)&gt;)',
                     r'<span class="mention">\1</span>', content)

    # Custom emojis (<:name:id>)
    is_jumboable = not re.sub(r'&lt;(:.*?:)(\d*)&gt;', '', content)
    emoji_class = 'emoji emoji--large' if is_jumboable else 'emoji'
    content = re.sub(r'&lt;(:.*?:)(\d*)&gt;',
                     r'<img class="' +
                     emoji_class +
                     r'" title="\1" src="https://cdn.discordapp.com/' +
                     r'emojis/\2.png" alt="\1">', content)

    # Custom animated emojis (<a:name:id>)
    is_jumboable_animated = not re.sub(r'&lt;(a:.*?:)(\d*)&gt;', '', content)
    emoji_class_animated = 'emoji emoji--large' \
        if is_jumboable_animated else 'emoji'
    content = re.sub(r'&lt;(a:.*?:)(\d*)&gt;',
                     r'<img class="' +
                     emoji_class_animated +
                     r'" title="\1" src="https://cdn.discordapp.com/' +
                     r'emojis/\2.gif" alt="\1">', content)

    return content