From 6986b36985fa242cb3d346b05f84d3878573c354 Mon Sep 17 00:00:00 2001
From: Alan Guo Xiang Tan <gxtan1990@gmail.com>
Date: Wed, 30 Jun 2021 16:06:13 +0800
Subject: [PATCH] FIX: Child themes being precompiled multiple times.

---
 lib/stylesheet/manager.rb                  | 43 ++++++++++------------
 spec/components/stylesheet/manager_spec.rb |  8 +++-
 2 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/lib/stylesheet/manager.rb b/lib/stylesheet/manager.rb
index b3749e48939..ec48eee3b7f 100644
--- a/lib/stylesheet/manager.rb
+++ b/lib/stylesheet/manager.rb
@@ -46,54 +46,49 @@ class Stylesheet::Manager
     targets += Discourse.find_plugin_css_assets(include_disabled: true, mobile_view: true, desktop_view: true)
 
     targets.each do |target|
-      STDERR.puts "precompile target: #{target}"
+      $stderr.puts "precompile target: #{target}"
 
       Stylesheet::Manager::Builder.new(target: target, manager: nil).compile(force: true)
     end
   end
 
   def self.precompile_theme_css
-    themes = Theme.where('user_selectable OR id = ?', SiteSetting.default_theme_id).pluck(:id, :name, :color_scheme_id)
-    themes << nil
+    themes = Theme.where('user_selectable OR id = ?', SiteSetting.default_theme_id).pluck(:id, :color_scheme_id)
 
     color_schemes = ColorScheme.where(user_selectable: true).to_a
     color_schemes << ColorScheme.find_by(id: SiteSetting.default_dark_mode_color_scheme_id)
+    color_schemes << ColorScheme.base
     color_schemes = color_schemes.compact.uniq
 
     targets = [:desktop_theme, :mobile_theme]
+    compiled = Set.new
 
-    themes.each do |id, name, color_scheme_id|
-      theme_id = id || SiteSetting.default_theme_id
+    themes.each do |theme_id, color_scheme_id|
       manager = self.new(theme_id: theme_id)
 
       targets.each do |target|
-        if target =~ THEME_REGEX
-          next if theme_id == -1
+        next if theme_id == -1
 
-          scss_checker = ScssChecker.new(target, manager.theme_ids)
+        scss_checker = ScssChecker.new(target, manager.theme_ids)
 
-          manager.load_themes(manager.theme_ids).each do |theme|
-            builder = Stylesheet::Manager::Builder.new(
-              target: target, theme: theme, manager: manager
-            )
+        manager.load_themes(manager.theme_ids).each do |theme|
+          next if compiled.include?("#{target}_#{theme.id}")
 
-            STDERR.puts "precompile target: #{target} #{builder.theme.name}"
-            next if theme.component && !scss_checker.has_scss(theme.id)
-            builder.compile(force: true)
-          end
-        else
-          STDERR.puts "precompile target: #{target} #{name}"
+          builder = Stylesheet::Manager::Builder.new(
+            target: target, theme: theme, manager: manager
+          )
 
-          Stylesheet::Manager::Builder.new(
-            target: target, theme: manager.get_theme(theme_id), manager: manager
-          ).compile(force: true)
+          $stderr.puts "precompile target: #{target} #{theme.name}"
+          next if theme.component && !scss_checker.has_scss(theme.id)
+          builder.compile(force: true)
+          compiled << "#{target}_#{theme.id}"
         end
       end
 
-      theme_color_scheme = ColorScheme.find_by_id(color_scheme_id) || ColorScheme.base
+      theme_color_scheme = ColorScheme.find_by_id(color_scheme_id)
 
-      [theme_color_scheme, *color_schemes].uniq.each do |scheme|
-        STDERR.puts "precompile target: #{COLOR_SCHEME_STYLESHEET} #{name} (#{scheme.name})"
+      [theme_color_scheme, *color_schemes].compact.uniq.each do |scheme|
+        $stderr.puts "precompile target: #{COLOR_SCHEME_STYLESHEET} #{name} (#{scheme.name})"
 
         Stylesheet::Manager::Builder.new(
           target: COLOR_SCHEME_STYLESHEET,
diff --git a/spec/components/stylesheet/manager_spec.rb b/spec/components/stylesheet/manager_spec.rb
index 0287c2bf635..51ffcc04608 100644
--- a/spec/components/stylesheet/manager_spec.rb
+++ b/spec/components/stylesheet/manager_spec.rb
@@ -654,6 +654,7 @@ describe Stylesheet::Manager do
         t.save!
 
         user_theme.add_relative_theme!(:child, t)
+        default_theme.add_relative_theme!(:child, t)
       end
 
       default_theme.set_default!
@@ -668,7 +669,12 @@ describe Stylesheet::Manager do
       StylesheetCache.destroy_all
 
       # only themes
-      Stylesheet::Manager.precompile_theme_css
+      output = capture_output(:stderr) do
+        Stylesheet::Manager.precompile_theme_css
+      end
+
+      # Ensure we force compile each theme only once
+      expect(output.scan(/#{child_theme_with_css.name}/).length).to eq(2)
       results = StylesheetCache.pluck(:target)
       expect(results.size).to eq(12) # (2 themes * 2 targets) + (one child theme * 2 targets) + 6 color schemes (2 custom, 4 base schemes)