Convert text styles between IRC/Discord

lib/bot.js

@@ -4,6 +4,7 @@ import logger from 'winston';
 import discord from 'discord.js';
 import { ConfigurationError } from './errors';
 import { validateChannelMapping } from './validators';
+import { formatFromDiscordToIRC, formatFromIRCToDiscord } from './formatting';
 
 const REQUIRED_FIELDS = ['server', 'nickname', 'channelMapping', 'discordToken'];
 const NICK_COLORS = ['light_blue', 'dark_blue', 'light_red', 'dark_red', 'light_green',
@@ -173,6 +174,9 @@ class Bot {
         this.ircClient.say(ircChannel, text);
       } else {
         if (text !== '') {
+          // Convert formatting
+          text = formatFromDiscordToIRC(text);
+
           text = `<${displayUsername}> ${text}`;
           logger.debug('Sending message to IRC', ircChannel, text);
           this.ircClient.say(ircChannel, text);
@@ -203,7 +207,10 @@ class Bot {
         return;
       }
 
-      const withMentions = text.replace(/@[^\s]+\b/g, (match) => {
+      // Convert text formatting (bold, italics, underscore)
+      const withFormat = formatFromIRCToDiscord(text);
+
+      const withMentions = withFormat.replace(/@[^\s]+\b/g, (match) => {
         const search = match.substring(1);
         const guild = discordChannel.guild;
         const nickUser = guild.members.find('nickname', search);

lib/formatting.js

@@ -0,0 +1,47 @@
+import ircFormatting from 'irc-formatting';
+import SimpleMarkdown from 'simple-markdown';
+import colors from 'irc-colors';
+
+function mdNodeToIRC(node) {
+  let content = node.content;
+  if (Array.isArray(content)) content = content.map(mdNodeToIRC).join('');
+  if (node.type === 'em') return colors.italic(content);
+  if (node.type === 'strong') return colors.bold(content);
+  if (node.type === 'u') return colors.underline(content);
+  return content;
+}
+
+export function formatFromDiscordToIRC(text) {
+  const markdownAST = SimpleMarkdown.defaultInlineParse(text);
+  return markdownAST.map(mdNodeToIRC).join('');
+}
+
+export function formatFromIRCToDiscord(text) {
+  const blocks = ircFormatting.parse(text).map(block => ({
+    // Consider reverse as italic, some IRC clients use that
+    ...block,
+    italic: block.italic || block.reverse
+  }));
+  let mdText = '';
+
+  for (let i = 0; i <= blocks.length; i += 1) {
+    // Default to unstyled blocks when index out of range
+    const block = blocks[i] || {};
+    const prevBlock = blocks[i - 1] || {};
+
+    // Add start markers when style turns from false to true
+    if (!prevBlock.italic && block.italic) mdText += '*';
+    if (!prevBlock.bold && block.bold) mdText += '**';
+    if (!prevBlock.underline && block.underline) mdText += '__';
+
+    // Add end markers when style turns from true to false
+    // (and apply in reverse order to maintain nesting)
+    if (prevBlock.underline && !block.underline) mdText += '__';
+    if (prevBlock.bold && !block.bold) mdText += '**';
+    if (prevBlock.italic && !block.italic) mdText += '*';
+
+    mdText += block.text || '';
+  }
+
+  return mdText;
+}

package.json

@@ -40,7 +40,10 @@
     "commander": "2.9.0",
     "discord.js": "11.0.0",
     "irc": "0.5.2",
+    "irc-colors": "^1.3.2",
+    "irc-formatting": "^1.0.0-rc3",
     "lodash": "^4.17.4",
+    "simple-markdown": "^0.2.1",
     "strip-json-comments": "2.0.1",
     "winston": "2.3.1"
   },

test/formatting.test.js

@@ -0,0 +1,64 @@
+/* eslint-disable prefer-arrow-callback */
+
+import chai from 'chai';
+import { formatFromDiscordToIRC, formatFromIRCToDiscord } from '../lib/formatting';
+
+chai.should();
+
+describe('Formatting', () => {
+  describe('Discord to IRC', () => {
+    it('should convert bold markdown', () => {
+      formatFromDiscordToIRC('**text**').should.equal('\x02text\x02');
+    });
+
+    it('should convert italic markdown', () => {
+      formatFromDiscordToIRC('*text*').should.equal('\x16text\x16');
+      formatFromDiscordToIRC('_text_').should.equal('\x16text\x16');
+    });
+
+    it('should convert underline markdown', () => {
+      formatFromDiscordToIRC('__text__').should.equal('\x1ftext\x1f');
+    });
+
+    it('should ignore strikethrough markdown', () => {
+      formatFromDiscordToIRC('~~text~~').should.equal('text');
+    });
+
+    it('should convert nested markdown', () => {
+      formatFromDiscordToIRC('**bold *italics***')
+      .should.equal('\x02bold \x16italics\x16\x02');
+    });
+  });
+
+  describe('IRC to Discord', () => {
+    it('should convert bold IRC format', () => {
+      formatFromIRCToDiscord('\x02text\x02').should.equal('**text**');
+    });
+
+    it('should convert reverse IRC format', () => {
+      formatFromIRCToDiscord('\x16text\x16').should.equal('*text*');
+    });
+
+    it('should convert italic IRC format', () => {
+      formatFromIRCToDiscord('\x1dtext\x1d').should.equal('*text*');
+    });
+
+    it('should convert underline IRC format', () => {
+      formatFromIRCToDiscord('\x1ftext\x1f').should.equal('__text__');
+    });
+
+    it('should ignore color IRC format', () => {
+      formatFromIRCToDiscord('\x0306,08text\x03').should.equal('text');
+    });
+
+    it('should convert nested IRC format', () => {
+      formatFromIRCToDiscord('\x02bold \x16italics\x16\x02')
+      .should.equal('**bold *italics***');
+    });
+
+    it('should convert nested IRC format', () => {
+      formatFromIRCToDiscord('\x02bold \x1funderline\x1f\x02')
+      .should.equal('**bold __underline__**');
+    });
+  });
+});