allow reacting with remote custom emoji

lib/pleroma/web/activity_pub/builder.ex

@@ -55,29 +55,21 @@ def follow(follower, followed) do
     {:ok, data, []}
   end
 
-  defp unicode_emoji_react(object, data, emoji) do
+  defp unicode_emoji_react(_object, data, emoji) do
     data
     |> Map.put("content", emoji)
     |> Map.put("type", "EmojiReact")
   end
 
-  defp custom_emoji_react(object, data, emoji) do
-    if String.contains?("@") do
-      # Attempt to resolve remote emoji
-      [emoji_code, instance] = String.split(emoji, "@")
-    else
-      with %{} = emojo <- Emoji.get(emoji) do
-        path = emojo |> Map.get(:file)
-        url = "#{Endpoint.url()}#{path}"
-
+  defp add_emoji_content(data, emoji, url) do
     data
-        |> Map.put("content", emoji)
+    |> Map.put("content", Emoji.maybe_quote(emoji))
     |> Map.put("type", "EmojiReact")
     |> Map.put("tag", [
       %{}
       |> Map.put("id", url)
       |> Map.put("type", "Emoji")
-          |> Map.put("name", emojo.code)
+      |> Map.put("name", Emoji.maybe_quote(emoji))
       |> Map.put(
         "icon",
         %{}
@@ -85,10 +77,45 @@ defp custom_emoji_react(object, data, emoji) do
         |> Map.put("url", url)
       )
     ])
+  end
+
+  defp remote_custom_emoji_react(object, data, emoji) do
+    [emoji_code, instance] = String.split(Emoji.stripped_name(emoji), "@")
+    %{data: %{"reactions" => existing_reactions}} = object
+
+    matching_reaction =
+      Enum.find(
+        existing_reactions,
+        fn [name, _, url] ->
+          url = URI.parse(url)
+          url.host == instance && name == emoji_code
+        end
+      )
+
+    if matching_reaction do
+      [name, _, url] = matching_reaction
+      add_emoji_content(data, name, url)
+    else
+      {:error, "Could not react"}
+    end
+  end
+
+  defp local_custom_emoji_react(data, emoji) do
+    with %{} = emojo <- Emoji.get(emoji) do
+      path = emojo |> Map.get(:file)
+      url = "#{Endpoint.url()}#{path}"
+      add_emoji_content(data, emojo.code, url)
     else
       _ -> {:error, "Emoji does not exist"}
     end
   end
+
+  defp custom_emoji_react(object, data, emoji) do
+    if String.contains?(emoji, "@") do
+      remote_custom_emoji_react(object, data, emoji)
+    else
+      local_custom_emoji_react(data, emoji)
+    end
   end
 
   @spec emoji_react(User.t(), Object.t(), String.t()) :: {:ok, map(), keyword()}

lib/pleroma/web/activity_pub/object_validators/emoji_react_validator.ex

@@ -13,7 +13,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.EmojiReactValidator do
   import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
 
   @primary_key false
-  @emoji_regex ~r/:[A-Za-z0-9_-]+:/
+  @emoji_regex ~r/:[A-Za-z0-9_-]+(@.+)?:/
 
   embedded_schema do
     quote do

lib/pleroma/web/common_api.ex

@@ -209,7 +209,9 @@ def react_with_emoji(id, user, emoji) do
          {:ok, activity, _} <- Pipeline.common_pipeline(emoji_react, local: true) do
       {:ok, activity}
     else
-      _ -> {:error, dgettext("errors", "Could not add reaction emoji")}
+      e ->
+        IO.inspect(e)
+        {:error, dgettext("errors", "Could not add reaction emoji")}
     end
   end
 

lib/pleroma/web/mastodon_api/views/status_view.ex

@@ -587,7 +587,7 @@ defp pin_data(%Object{data: %{"id" => object_id}}, %User{pinned_objects: pinned_
 
   defp build_emoji_map(emoji, users, url, current_user) do
     %{
-      name: emoji,
+      name: Pleroma.Web.PleromaAPI.EmojiReactionView.emoji_name(emoji, url),
       count: length(users),
       url: MediaProxy.url(url),
       me: !!(current_user && current_user.ap_id in users),

lib/pleroma/web/pleroma_api/views/emoji_reaction_view.ex

@@ -8,6 +8,18 @@ defmodule Pleroma.Web.PleromaAPI.EmojiReactionView do
   alias Pleroma.Web.MastodonAPI.AccountView
   alias Pleroma.Web.MediaProxy
 
+  def emoji_name(emoji, nil), do: emoji
+
+  def emoji_name(emoji, url) do
+    url = URI.parse(url)
+
+    if url.host == Endpoint.host() do
+      emoji
+    else
+      "#{emoji}@#{url.host}"
+    end
+  end
+
   def render("index.json", %{emoji_reactions: emoji_reactions} = opts) do
     render_many(emoji_reactions, __MODULE__, "show.json", opts)
   end
@@ -16,7 +28,7 @@ def render("show.json", %{emoji_reaction: {emoji, user_ap_ids, url}, user: user}
     users = fetch_users(user_ap_ids)
 
     %{
-      name: emoji,
+      name: emoji_name(emoji, url),
       count: length(users),
       accounts: render(AccountView, "index.json", users: users, for: user),
       url: MediaProxy.url(url),