From 7878e5007aa96f21a23320cfdc2cda5c5ad081d6 Mon Sep 17 00:00:00 2001
From: David Taylor <david@taylorhq.com>
Date: Tue, 19 Feb 2019 15:55:59 +0000
Subject: [PATCH] FIX: Refactor to prevent themes affecting core stylesheets
 (#7029)

If a theme setting contained invalid SCSS, it would cause an error 500 on the site, with no way to recover. This commit stops loading theme settings in the core stylesheets, and instead only loads the color scheme variables. This change also makes `common/foundation/variables.scss` available to themes without an explicit import.
---
 app/assets/stylesheets/common/foundation/variables.scss | 2 +-
 app/models/theme_field.rb                               | 2 +-
 lib/stylesheet/compiler.rb                              | 2 +-
 lib/stylesheet/importer.rb                              | 9 ++++++++-
 spec/models/theme_spec.rb                               | 2 +-
 5 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/app/assets/stylesheets/common/foundation/variables.scss b/app/assets/stylesheets/common/foundation/variables.scss
index 29e1ebbba47..41afa8dad82 100644
--- a/app/assets/stylesheets/common/foundation/variables.scss
+++ b/app/assets/stylesheets/common/foundation/variables.scss
@@ -64,7 +64,7 @@ $line-height-large: 1.4; // Normal or small text
 // These files don't actually exist. They're injected by Stylesheet::Compiler.
 // --------------------------------------------------
 
-@import "theme_variables";
+@import "theme_colors";
 @import "plugins_variables";
 @import "common/foundation/math";
 
diff --git a/app/models/theme_field.rb b/app/models/theme_field.rb
index 4064cabf162..9d62dc27610 100644
--- a/app/models/theme_field.rb
+++ b/app/models/theme_field.rb
@@ -261,7 +261,7 @@ class ThemeField < ActiveRecord::Base
   def ensure_scss_compiles!
     if ThemeField.scss_fields.include?(self.name)
       begin
-        Stylesheet::Compiler.compile("@import \"theme_variables\"; @import \"theme_field\";",
+        Stylesheet::Compiler.compile("@import \"common/foundation/variables\"; @import \"theme_variables\"; @import \"theme_field\";",
                                      "theme.scss",
                                      theme_field: self.value.dup,
                                      theme: self.theme
diff --git a/lib/stylesheet/compiler.rb b/lib/stylesheet/compiler.rb
index 9f7b3b9bb0b..1c2a165e3b5 100644
--- a/lib/stylesheet/compiler.rb
+++ b/lib/stylesheet/compiler.rb
@@ -10,7 +10,7 @@ module Stylesheet
 
       if Importer.special_imports[asset.to_s]
         filename = "theme.scss"
-        file = "@import \"theme_variables\"; @import \"#{asset}\";"
+        file = "@import \"common/foundation/variables\"; @import \"theme_variables\"; @import \"#{asset}\";"
       else
         filename = "#{asset}.scss"
         path = "#{ASSET_ROOT}/#{filename}"
diff --git a/lib/stylesheet/importer.rb b/lib/stylesheet/importer.rb
index 635645c5c79..49ff26d8e70 100644
--- a/lib/stylesheet/importer.rb
+++ b/lib/stylesheet/importer.rb
@@ -33,12 +33,19 @@ module Stylesheet
       import_files(DiscoursePluginRegistry.sass_variables)
     end
 
-    register_import "theme_variables" do
+    register_import "theme_colors" do
       contents = ""
       colors = (@theme_id && theme.color_scheme) ? theme.color_scheme.resolved_colors : ColorScheme.base_colors
       colors.each do |n, hex|
         contents << "$#{n}: ##{hex} !default;\n"
       end
+      contents
+
+      Import.new("theme_colors.scss", source: contents)
+    end
+
+    register_import "theme_variables" do
+      contents = ""
 
       theme&.all_theme_variables&.each do |field|
         if field.type_id == ThemeField.types[:theme_upload_var]
diff --git a/spec/models/theme_spec.rb b/spec/models/theme_spec.rb
index a799ac0306b..0b4a332c9a7 100644
--- a/spec/models/theme_spec.rb
+++ b/spec/models/theme_spec.rb
@@ -290,7 +290,7 @@ HTML
       theme.reload
       expect(theme.theme_fields.find_by(name: :scss).error).to eq(nil)
 
-      scss, _map = Stylesheet::Compiler.compile('@import "theme_variables"; @import "desktop_theme"; ', "theme.scss", theme_id: theme.id)
+      scss, _map = Stylesheet::Compiler.compile('@import "common/foundation/variables"; @import "theme_variables"; @import "desktop_theme"; ', "theme.scss", theme_id: theme.id)
       expect(scss).to include(upload.url)
     end
   end