FIX: Improvements to like button for archived topics (#17951)

* FIX: Do not allow to remove like if topic is archived

* FIX: Always show like button

The like button used to be hidden if the topic was archived and it had
no likes. This commit changes that to always show the like button, but
with a not-allowed cursor if the topic is archived.

app/assets/javascripts/discourse/app/lib/transform-post.js

@@ -255,12 +255,10 @@ export default function transformPost(
   if (likeAction) {
     postAtts.liked = likeAction.acted;
     postAtts.canToggleLike = likeAction.get("canToggle");
-    postAtts.showLike = postAtts.liked || postAtts.canToggleLike;
+    postAtts.showLike = true;
     postAtts.likeCount = likeAction.count;
-  }
-
-  if (!currentUser) {
-    postAtts.showLike = !topic.archived;
+  } else if (!currentUser) {
+    postAtts.showLike = true;
   }
 
   if (postAtts.post_number === 1) {

app/assets/javascripts/discourse/app/widgets/post-menu.js

@@ -147,7 +147,9 @@ function likeCount(attrs, state) {
 
 registerButton("like-count", likeCount);
 
-registerButton("like", (attrs) => {
+registerButton(
+  "like",
+  (attrs, _state, _siteSettings, _settings, currentUser) => {
     if (!attrs.showLike) {
       return likeCount(attrs);
     }
@@ -173,15 +175,17 @@ registerButton("like", (attrs) => {
     // this is important for accessibility.
     if (attrs.liked && !attrs.canToggleLike) {
       button.title = "post.controls.has_liked";
-    button.disabled = true;
     } else {
       button.title = attrs.liked
         ? "post.controls.undo_like"
         : "post.controls.like";
     }
-
+    if (currentUser && !attrs.canToggleLike) {
+      button.disabled = true;
+    }
     return button;
-});
+  }
+);
 
 registerButton("flag-count", (attrs) => {
   let className = "button-count";

app/serializers/post_serializer.rb

@@ -315,7 +315,8 @@ class PostSerializer < BasicPostSerializer
       summary.delete(:count) if summary[:count] == 0
 
       # Only include it if the user can do it or it has a count
-      if summary[:can_act] || summary[:count]
+      # If it is a like, we want to show it always (even for archived topic)
+      if summary[:can_act] || summary[:count] || (sym == :like && object.user_id != scope.user&.id)
         result << summary
       end
     end

lib/guardian/post_guardian.rb

@@ -232,7 +232,7 @@ module PostGuardian
   def can_delete_post_action?(post_action)
     return false unless is_my_own?(post_action) && !post_action.is_private_message?
 
-    post_action.created_at > SiteSetting.post_undo_action_window_mins.minutes.ago
+    post_action.created_at > SiteSetting.post_undo_action_window_mins.minutes.ago && !post_action.post.topic&.archived?
   end
 
   def can_see_post?(post)

spec/lib/guardian_spec.rb

@@ -2235,6 +2235,12 @@ RSpec.describe Guardian do
         expect(Guardian.new(user).can_delete?(post_action)).to be_falsey
       end
 
+      it "returns false if topic is archived" do
+        post.topic.update!(archived: true)
+
+        expect(Guardian.new(user).can_delete?(post_action)).to be_falsey
+      end
+
       it "returns true if it's yours" do
         expect(Guardian.new(user).can_delete?(post_action)).to be_truthy
       end

spec/serializers/post_serializer_spec.rb

@@ -55,6 +55,14 @@ RSpec.describe PostSerializer do
 
       expect(notify_user_action).to eq(nil)
     end
+
+    it "shows like for archived topics even if user cannot act" do
+      post = Fabricate(:post)
+      post.topic.update!(archived: true)
+
+      serializer = PostSerializer.new(post, scope: Guardian.new(actor), root: false)
+      expect(serializer.as_json[:actions_summary].map { |a| a[:id] }).to include(PostActionType.types[:like])
+    end
   end
 
   context "with a post with reviewable content" do