PLT-1378 Initial version of emoji reactions (#4520)

* Refactored emoji.json to support multiple aliases and emoji categories

* Added custom category to emoji.jsx and stabilized all fields

* Removed conflicting aliases for :mattermost: and :ca:

* fixup after store changes

* Added emoji reactions

* Removed reactions for an emoji when that emoji is deleted

* Fixed incorrect test case

* Renamed ReactionList to ReactionListView

* Fixed 👍 and 👎 not showing up as possible reactions

* Removed text emoticons from emoji reaction autocomplete

* Changed emoji reactions to be sorted by the order that they were first created

* Set a maximum number of listeners for the ReactionStore

* Removed unused code from Textbox component

* Fixed reaction permissions

* Changed error code when trying to modify reactions for another user

* Fixed merge conflicts

* Properly applied theme colours to reactions

* Fixed ESLint and gofmt errors

* Fixed ReactionListContainer to properly update when its post prop changes

* Removed unnecessary escape characters from reaction regexes

* Shared reaction message pattern between CreatePost and CreateComment

* Removed an unnecessary select query when saving a reaction

* Changed reactions route to be under /reactions

* Fixed copyright dates on newly added files

* Removed debug code that prevented all unit tests from being ran

* Cleaned up unnecessary code for reactions

* Renamed ReactionStore.List to ReactionStore.GetForPost

api/emoji.go

@@ -209,11 +209,14 @@ func deleteEmoji(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	var emoji *model.Emoji
 	if result := <-Srv.Store.Emoji().Get(id); result.Err != nil {
 		c.Err = result.Err
 		return
 	} else {
-		if c.Session.UserId != result.Data.(*model.Emoji).CreatorId && !HasPermissionToContext(c, model.PERMISSION_MANAGE_SYSTEM) {
+		emoji = result.Data.(*model.Emoji)
+
+		if c.Session.UserId != emoji.CreatorId && !HasPermissionToContext(c, model.PERMISSION_MANAGE_SYSTEM) {
 			c.Err = model.NewLocAppError("deleteEmoji", "api.emoji.delete.permissions.app_error", nil, "user_id="+c.Session.UserId)
 			c.Err.StatusCode = http.StatusUnauthorized
 			return
@@ -226,6 +229,7 @@ func deleteEmoji(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 
 	go deleteEmojiImage(id)
+	go deleteReactionsForEmoji(emoji.Name)
 
 	ReturnStatusOK(w)
 }
@@ -236,6 +240,13 @@ func deleteEmojiImage(id string) {
 	}
 }
 
+func deleteReactionsForEmoji(emojiName string) {
+	if result := <-Srv.Store.Reaction().DeleteAllWithEmojiName(emojiName); result.Err != nil {
+		l4g.Warn(utils.T("api.emoji.delete.delete_reactions.app_error"), emojiName)
+		l4g.Warn(result.Err)
+	}
+}
+
 func getEmojiImage(c *Context, w http.ResponseWriter, r *http.Request) {
 	if !*utils.Cfg.ServiceSettings.EnableCustomEmoji {
 		c.Err = model.NewLocAppError("getEmojiImage", "api.emoji.disabled.app_error", nil, "")