FEATURE: Native theme support

This feature introduces the concept of themes. Themes are an evolution
of site customizations.

Themes introduce two very big conceptual changes:

- A theme may include other "child themes", children can include grand
children and so on.

- A theme may specify a color scheme

The change does away with the idea of "enabled" color schemes.

It also adds a bunch of big niceties like

- You can source a theme from a git repo

- History for themes is much improved

- You can only have a single enabled theme. Themes can be selected by
    users, if you opt for it.

On a technical level this change comes with a whole bunch of goodies

- All CSS is now compiled using a custom pipeline that uses libsass
    see /lib/stylesheet

- There is a single pipeline for css compilation (in the past we used
    one for customizations and another one for the rest of the app

- The stylesheet pipeline is now divorced of sprockets, there is no
   reliance on sprockets for CSS bundling

- CSS is generated with source maps everywhere (including themes) this
    makes debugging much easier

- Our "live reloader" is smarter and avoid a flash of unstyled content
   we run a file watcher in "puma" in dev so you no longer need to run
   rake autospec to watch for CSS changes

app/services/color_scheme_revisor.rb

@@ -9,63 +9,26 @@ class ColorSchemeRevisor
     self.new(color_scheme, params).revise
   end
 
-  def self.revert(color_scheme)
-    self.new(color_scheme).revert
-  end
-
   def revise
     ColorScheme.transaction do
-      if @params[:enabled]
-        ColorScheme.where('id != ?', @color_scheme.id).update_all enabled: false
-      end
 
       @color_scheme.name    = @params[:name]    if @params.has_key?(:name)
-      @color_scheme.enabled = @params[:enabled] if @params.has_key?(:enabled)
-      @color_scheme.theme_id = @params[:theme_id] if @params.has_key?(:theme_id)
-      new_version = false
+      @color_scheme.base_scheme_id = @params[:base_scheme_id] if @params.has_key?(:base_scheme_id)
+      has_colors = @params[:colors]
 
-      if @params[:colors]
-        new_version = @params[:colors].any? do |c|
-          (existing = @color_scheme.colors_by_name[c[:name]]).nil? or existing.hex != c[:hex]
-        end
-      end
-
-      if new_version
-        ColorScheme.create(
-          name: @color_scheme.name,
-          enabled: false,
-          colors: @color_scheme.colors_hashes,
-          versioned_id: @color_scheme.id,
-          version: @color_scheme.version)
-        @color_scheme.version += 1
-      end
-
-      if @params[:colors]
+      if has_colors
         @params[:colors].each do |c|
           if existing = @color_scheme.colors_by_name[c[:name]]
             existing.update_attributes(c)
+          else
+            @color_scheme.color_scheme_colors << ColorSchemeColor.new(name: c[:name], hex: c[:hex])
           end
         end
-      end
-
-      @color_scheme.save
-      @color_scheme.clear_colors_cache
-    end
-    @color_scheme
-  end
-
-  def revert
-    ColorScheme.transaction do
-      if prev = @color_scheme.previous_version
-        @color_scheme.version = prev.version
-        @color_scheme.colors.clear
-        prev.colors.update_all(color_scheme_id: @color_scheme.id)
-        prev.destroy
-        @color_scheme.save!
         @color_scheme.clear_colors_cache
       end
-    end
 
+      @color_scheme.save if has_colors || @color_scheme.name_changed? || @color_scheme.base_scheme_id_changed?
+    end
     @color_scheme
   end
 

app/services/staff_action_logger.rb

@@ -113,34 +113,49 @@ class StaffActionLogger
     }))
   end
 
-  SITE_CUSTOMIZATION_LOGGED_ATTRS = [
-    'stylesheet', 'mobile_stylesheet',
-    'header', 'mobile_header',
-    'top', 'mobile_top',
-    'footer', 'mobile_footer',
-    'head_tag',
-    'body_tag',
-    'position',
-    'enabled',
-    'key'
-  ]
+  def theme_json(theme)
+    ThemeSerializer.new(theme, root:false).to_json
+  end
+
+  def strip_duplicates(old,cur)
+    return [old,cur] unless old && cur
+
+    old = JSON.parse(old)
+    cur = JSON.parse(cur)
+
+    old.each do |k, v|
+      next if k == "name"
+      next if k == "id"
+      if (v == cur[k])
+        cur.delete(k)
+        old.delete(k)
+      end
+    end
+
+    [old.to_json, cur.to_json]
+  end
+
+  def log_theme_change(old_json, new_theme, opts={})
+    raise Discourse::InvalidParameters.new(:new_theme) unless new_theme
+
+    new_json = theme_json(new_theme)
+
+    old_json,new_json = strip_duplicates(old_json,new_json)
 
-  def log_site_customization_change(old_record, site_customization_params, opts={})
-    raise Discourse::InvalidParameters.new(:site_customization_params) unless site_customization_params
     UserHistory.create( params(opts).merge({
-      action: UserHistory.actions[:change_site_customization],
-      subject: site_customization_params[:name],
-      previous_value: old_record ? old_record.attributes.slice(*SITE_CUSTOMIZATION_LOGGED_ATTRS).to_json : nil,
-      new_value: site_customization_params.slice(*(SITE_CUSTOMIZATION_LOGGED_ATTRS.map(&:to_sym))).to_json
+      action: UserHistory.actions[:change_theme],
+      subject: new_theme.name,
+      previous_value: old_json,
+      new_value: new_json
     }))
   end
 
-  def log_site_customization_destroy(site_customization, opts={})
-    raise Discourse::InvalidParameters.new(:site_customization) unless site_customization
+  def log_theme_destroy(theme, opts={})
+    raise Discourse::InvalidParameters.new(:theme) unless theme
     UserHistory.create( params(opts).merge({
-      action: UserHistory.actions[:delete_site_customization],
-      subject: site_customization.name,
-      previous_value: site_customization.attributes.slice(*SITE_CUSTOMIZATION_LOGGED_ATTRS).to_json
+      action: UserHistory.actions[:delete_theme],
+      subject: theme.name,
+      previous_value: theme_json(theme)
     }))
   end