Fix IRC to discord formatting nested styles

Author: rahatarmanahmed

lib/formatting.js

@@ -18,12 +18,30 @@ export function formatFromDiscordToIRC(text) {
 }
 
 export function formatFromIRCToDiscord(text) {
-  const blocks = ircFormatting.parse(text);
-  return blocks.map((block) => {
-    let mdText = block.text;
-    if (block.italic || block.reverse) mdText = `*${mdText}*`;
-    if (block.bold) mdText = `**${mdText}**`;
-    if (block.underline) mdText = `__${mdText}__`;
-    return mdText;
-  }).join('');
+  const blocks = ircFormatting.parse(text).map(block =>
+    // Consider reverse as italic, some IRC clients use that
+    _.assign({}, 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;
 }

test/formatting.test.js

@@ -55,5 +55,10 @@ describe('Formatting', () => {
       formatFromIRCToDiscord('\x02bold \x16italics\x16\x02')
       .should.equal('**bold *italics***');
     });
+
+    it('should convert nested IRC format', () => {
+      formatFromIRCToDiscord('\x02bold \x1funderline\x1f\x02')
+      .should.equal('**bold __underline__**');
+    });
   });
 });