implement unicode emoji replacements

app/assets/javascripts/pretty-text/engines/markdown-it/emoji.js.es6

@@ -171,13 +171,17 @@ function getEmojiTokenByTranslation(content, pos, state) {
   }
 }
 
-function applyEmoji(content, state) {
+function applyEmoji(content, state, emojiUnicodeReplacer) {
   let i;
   let result = null;
   let contentToken = null;
 
   let start = 0;
 
+  if (emojiUnicodeReplacer) {
+    content = emojiUnicodeReplacer(content);
+  }
+
   let endToken = content.length;
 
   for (i=0; i<content.length-1; i++) {
@@ -236,6 +240,8 @@ export function setup(helper) {
   });
 
   helper.registerPlugin((md)=>{
-    md.core.ruler.push('emoji', state => textReplace(state, applyEmoji));
+    md.core.ruler.push('emoji', state => textReplace(
+      state, (c,s)=>applyEmoji(c,s,md.options.discourse.emojiUnicodeReplacer))
+    );
   });
 }

app/assets/javascripts/pretty-text/pretty-text.js.es6

@@ -21,7 +21,8 @@ export function buildOptions(state) {
     userId,
     getCurrentUser,
     currentUser,
-    lookupAvatarByPostNumber
+    lookupAvatarByPostNumber,
+    emojiUnicodeReplacer
   } = state;
 
   if (!siteSettings.enable_experimental_markdown_it) {
@@ -53,6 +54,7 @@ export function buildOptions(state) {
     currentUser,
     lookupAvatarByPostNumber,
     mentionLookup: state.mentionLookup,
+    emojiUnicodeReplacer,
     allowedHrefSchemes: siteSettings.allowed_href_schemes ? siteSettings.allowed_href_schemes.split('|') : null,
     markdownIt: siteSettings.enable_experimental_markdown_it
   };