FIX: Let users reset their homepage choice if custom homepage is from… (#26536)

Co-authored-by: Régis Hanol <regis@hanol.fr>

app/models/theme.rb

@@ -241,6 +241,19 @@ class Theme < ActiveRecord::Base
     end
   end
 
+  def self.enabled_theme_and_component_ids
+    get_set_cache "enabled_theme_and_component_ids" do
+      theme_ids = Theme.user_selectable.where(enabled: true).pluck(:id)
+      component_ids =
+        ChildTheme
+          .where(parent_theme_id: theme_ids)
+          .joins(:child_theme)
+          .where(themes: { enabled: true })
+          .pluck(:child_theme_id)
+      (theme_ids | component_ids)
+    end
+  end
+
   def self.allowed_remote_theme_ids
     return nil if GlobalSetting.allowed_theme_repos.blank?
 

app/serializers/user_serializer.rb

@@ -324,7 +324,7 @@ class UserSerializer < UserCardSerializer
   end
 
   def can_pick_theme_with_custom_homepage
-    ThemeModifierHelper.new(theme_ids: Theme.user_theme_ids).custom_homepage
+    ThemeModifierHelper.new(theme_ids: Theme.enabled_theme_and_component_ids).custom_homepage
   end
 
   private

spec/models/theme_spec.rb

@@ -466,6 +466,47 @@ HTML
     expect(Theme.user_theme_ids).to eq([])
   end
 
+  it "correctly caches enabled_theme_and_component_ids" do
+    Theme.destroy_all
+
+    theme2 = Fabricate(:theme)
+
+    expect(Theme.enabled_theme_and_component_ids).to eq([])
+
+    theme2.update!(user_selectable: true)
+
+    expect(Theme.enabled_theme_and_component_ids).to contain_exactly(theme2.id)
+
+    theme2.update!(user_selectable: false)
+    theme2.set_default!
+    expect(Theme.enabled_theme_and_component_ids).to contain_exactly(theme2.id)
+
+    child2 = Fabricate(:theme, component: true)
+    theme2.add_relative_theme!(:child, child2)
+    expect(Theme.enabled_theme_and_component_ids).to contain_exactly(theme2.id, child2.id)
+
+    child2.update!(enabled: false)
+    expect(Theme.enabled_theme_and_component_ids).to contain_exactly(theme2.id)
+
+    theme3 = Fabricate(:theme, user_selectable: true)
+    child2.update!(enabled: true)
+
+    expect(Theme.enabled_theme_and_component_ids).to contain_exactly(
+      theme2.id,
+      child2.id,
+      theme3.id,
+    )
+
+    theme3.update!(enabled: false)
+
+    expect(Theme.enabled_theme_and_component_ids).to contain_exactly(theme2.id, child2.id)
+
+    theme2.destroy
+    theme3.destroy
+
+    expect(Theme.enabled_theme_and_component_ids).to eq([])
+  end
+
   it "correctly caches user_themes template" do
     Theme.destroy_all
 

spec/system/homepage_spec.rb

@@ -5,7 +5,7 @@ describe "Homepage", type: :system do
   fab!(:user)
   fab!(:topics) { Fabricate.times(5, :post).map(&:topic) }
   let(:discovery) { PageObjects::Pages::Discovery.new }
-  let!(:theme) { Fabricate(:theme) }
+  fab!(:theme)
 
   before do
     # A workaround to avoid the global notice from interfering with the tests
@@ -76,23 +76,8 @@ describe "Homepage", type: :system do
       expect(page).to have_css(".alert-info")
     end
 
-    context "when the theme adds content to the [custom-homepage] connector" do
-      let!(:basic_html_field) do
-        Fabricate(
-          :theme_field,
-          theme: theme,
-          type_id: ThemeField.types[:html],
-          target_id: Theme.targets[:common],
-          name: "head_tag",
-          value: <<~HTML,
-            <script type="text/x-handlebars" data-template-name="/connectors/custom-homepage/new-home">
-              <div class="new-home">Hi friends!</div>
-            </script>
-          HTML
-        )
-      end
-
-      it "shows the custom homepage from the theme on the homepage" do
+    shared_examples "a custom homepage" do
+      it "shows the custom homepage component" do
         visit "/"
 
         expect(page).to have_css(".new-home", text: "Hi friends!")
@@ -148,5 +133,46 @@ describe "Homepage", type: :system do
         expect(page).to have_css(".new-home", text: "Hi friends!")
       end
     end
+
+    context "when the theme adds content to the [custom-homepage] connector" do
+      let!(:basic_html_field) do
+        Fabricate(
+          :theme_field,
+          theme: theme,
+          type_id: ThemeField.types[:html],
+          target_id: Theme.targets[:common],
+          name: "head_tag",
+          value: <<~HTML,
+            <script type="text/x-handlebars" data-template-name="/connectors/custom-homepage/new-home">
+              <div class="new-home">Hi friends!</div>
+            </script>
+          HTML
+        )
+      end
+
+      include_examples "a custom homepage"
+    end
+
+    context "when a theme component adds content to the [custom-homepage] connector" do
+      let!(:component) { Fabricate(:theme, component: true) }
+      let!(:component_html_field) do
+        Fabricate(
+          :theme_field,
+          theme: component,
+          type_id: ThemeField.types[:html],
+          target_id: Theme.targets[:common],
+          name: "head_tag",
+          value: <<~HTML,
+            <script type="text/x-handlebars" data-template-name="/connectors/custom-homepage/new-home">
+              <div class="new-home">Hi friends!</div>
+            </script>
+          HTML
+        )
+      end
+
+      before { theme.add_relative_theme!(:child, component) }
+
+      include_examples "a custom homepage"
+    end
   end
 end