Fix emojify() by generating a mapping to existing Twemoji files (#5080)

A new rake task emojis:generate downloads a full list of valid
unicode sequences from unicode.org and checks it against existing
Twemoji files, finally generating a map from each sequence to the
existing file (e.g. when there's multiple ways an emoji can be
expressed). The map is dumped into app/javascript/mastodon/emoji_map.json

That file is loaded by emojione_light.js (now a misnomer) which
decorates it further with shortcodes taken from emoji-mart's index.

app/javascript/mastodon/emojione_light.js

@@ -1,13 +1,38 @@
 // @preval
-// Force tree shaking on emojione by exposing just a subset of its functionality
+// http://www.unicode.org/Public/emoji/5.0/emoji-test.txt
 
-const emojione = require('emojione');
+const emojis         = require('./emoji_map.json');
+const { emojiIndex } = require('emoji-mart');
+const excluded       = ['®', '©', '™'];
+const skins          = ['🏻', '🏼', '🏽', '🏾', '🏿'];
+const shortcodeMap   = {};
 
-const mappedUnicode = emojione.mapUnicodeToShort();
-const excluded = ['®', '©', '™'];
+Object.keys(emojiIndex.emojis).forEach(key => {
+  shortcodeMap[emojiIndex.emojis[key].native] = emojiIndex.emojis[key].id;
+});
 
-module.exports.unicodeMapping = Object.keys(emojione.jsEscapeMap)
-  .filter(c => !excluded.includes(c))
-  .map(unicodeStr => [unicodeStr, mappedUnicode[emojione.jsEscapeMap[unicodeStr]]])
-  .map(([unicodeStr, shortCode]) => ({ [unicodeStr]: [emojione.emojioneList[shortCode].fname.replace(/^0+/g, ''), shortCode.slice(1, shortCode.length - 1)] }))
-  .reduce((x, y) => Object.assign(x, y), { });
+const stripModifiers = unicode => {
+  skins.forEach(tone => {
+    unicode = unicode.replace(tone, '');
+  });
+
+  return unicode;
+};
+
+Object.keys(emojis).forEach(key => {
+  if (excluded.includes(key)) {
+    delete emojis[key];
+    return;
+  }
+
+  const normalizedKey = stripModifiers(key);
+  let shortcode       = shortcodeMap[normalizedKey];
+
+  if (!shortcode) {
+    shortcode = shortcodeMap[normalizedKey + '\uFE0F'];
+  }
+
+  emojis[key] = [emojis[key], shortcode];
+});
+
+module.exports.unicodeMapping = emojis;

lib/tasks/emojis.rake

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+def codepoints_to_filename(codepoints)
+  codepoints.downcase.gsub(/\A[0]+/, '').tr(' ', '-')
+end
+
+def codepoints_to_unicode(codepoints)
+  if codepoints.include?(' ')
+    codepoints.split(' ').map(&:hex).pack('U*')
+  else
+    [codepoints.hex].pack('U')
+  end
+end
+
+namespace :emojis do
+  desc 'Generate a unicode to filename mapping'
+  task :generate do
+    source = 'http://www.unicode.org/Public/emoji/5.0/emoji-test.txt'
+    codes  = []
+    dest   = Rails.root.join('app', 'javascript', 'mastodon', 'emoji_map.json')
+
+    puts "Downloading emojos from source... (#{source})"
+
+    HTTP.get(source).to_s.split("\n").each do |line|
+      next if line.start_with? '#'
+      parts = line.split(';').map(&:strip)
+      next if parts.size < 2
+      codes << [parts[0], parts[1].start_with?('fully-qualified')]
+    end
+
+    grouped_codes = codes.reduce([]) do |agg, current|
+      if current[1]
+        agg << [current[0]]
+      else
+        agg.last << current[0]
+        agg
+      end
+    end
+
+    existence_maps = grouped_codes.map { |c| c.map { |cc| [cc, File.exist?(Rails.root.join('public', 'emoji', codepoints_to_filename(cc) + '.svg'))] }.to_h }
+    map = {}
+
+    existence_maps.each do |group|
+      existing_one = group.key(true)
+
+      group.each_key do |key|
+        map[codepoints_to_unicode(key)] = codepoints_to_filename(existing_one)
+      end
+    end
+
+    map = map.sort { |a, b| a[0].size <=> b[0].size }.to_h
+
+    File.write(dest, Oj.dump(map))
+    puts "Wrote emojo to destination! (#{dest})"
+  end
+end

spec/javascript/components/emojify.test.js

@@ -22,10 +22,10 @@ describe('emojify', () => {
 
   it('does unicode', () => {
     expect(emojify('\uD83D\uDC69\u200D\uD83D\uDC69\u200D\uD83D\uDC66\u200D\uD83D\uDC66')).to.equal(
-      '<img draggable="false" class="emojione" alt="👩‍👩‍👦‍👦" title=":family_wwbb:" src="/emoji/1f469-1f469-1f466-1f466.svg" />');
-    expect(emojify('\uD83D\uDC68\uD83D\uDC69\uD83D\uDC67\uD83D\uDC67')).to.equal(
-      '<img draggable="false" class="emojione" alt="👨👩👧👧" title=":family_mwgg:" src="/emoji/1f468-1f469-1f467-1f467.svg" />');
-    expect(emojify('\uD83D\uDC69\uD83D\uDC69\uD83D\uDC66')).to.equal('<img draggable="false" class="emojione" alt="👩👩👦" title=":family_wwb:" src="/emoji/1f469-1f469-1f466.svg" />');
+      '<img draggable="false" class="emojione" alt="👩‍👩‍👦‍👦" title=":woman-woman-boy-boy:" src="/emoji/1f469-200d-1f469-200d-1f466-200d-1f466.svg" />');
+    expect(emojify('👨‍👩‍👧‍👧')).to.equal(
+      '<img draggable="false" class="emojione" alt="👨‍👩‍👧‍👧" title=":man-woman-girl-girl:" src="/emoji/1f468-200d-1f469-200d-1f467-200d-1f467.svg" />');
+    expect(emojify('👩‍👩‍👦')).to.equal('<img draggable="false" class="emojione" alt="👩‍👩‍👦" title=":woman-woman-boy:" src="/emoji/1f469-200d-1f469-200d-1f466.svg" />');
     expect(emojify('\u2757')).to.equal(
       '<img draggable="false" class="emojione" alt="❗" title=":exclamation:" src="/emoji/2757.svg" />');
   });