DEV: improves speed of live reload css in core and plugins (#8161)

This corrects live refresh of CSS when working on plugins (and core) in many cases live refresh was not working.

lib/stylesheet/manager.rb

@@ -19,7 +19,15 @@ class Stylesheet::Manager
   end
 
   def self.clear_theme_cache!
-    cache.hash.keys.select { |k| k =~ /theme/ }.each { |k|cache.delete(k) }
+    cache.hash.keys.select { |k| k =~ /theme/ }.each { |k| cache.delete(k) }
+  end
+
+  def self.clear_core_cache!(targets)
+    cache.hash.keys.select { |k| k =~ /#{targets.join('|')}/ }.each { |k| cache.delete(k) }
+  end
+
+  def self.clear_plugin_cache!(plugin)
+    cache.hash.keys.select { |k| k =~ /#{plugin}/ }.each { |k| cache.delete(k) }
   end
 
   def self.stylesheet_data(target = :desktop, theme_ids = :missing)

lib/stylesheet/watcher.rb

@@ -56,10 +56,37 @@ module Stylesheet
       @paths.each do |watch|
         Thread.new do
           begin
+            plugins_paths = Dir.glob("#{Rails.root}/plugins/*").map do |file|
+              File.symlink?(file) ? File.readlink(file) : file
+            end.compact
+
             listener = Listen.to("#{root}/#{watch}", listener_opts) do |modified, added, _|
               paths = [modified, added].flatten
               paths.compact!
-              paths.map! { |long| long[(root.length + 1)..-1] }
+              paths.map! do |long|
+                plugin_name = nil
+                plugins_paths.each do |plugin_path|
+                  if long.include?(plugin_path)
+                    plugin_name = File.basename(plugin_path)
+                    break
+                  end
+                end
+
+                target = nil
+                if !plugin_name
+                  target_match = long.match(/admin|desktop|mobile/)
+                  if target_match&.length
+                    target = target_match[0]
+                  end
+                end
+
+                {
+                  basename: File.basename(long),
+                  target: target,
+                  plugin_name: plugin_name
+                }
+              end
+
               process_change(paths)
             end
           rescue => e
@@ -71,29 +98,41 @@ module Stylesheet
       end
     end
 
+    def core_assets_refresh(target)
+      targets = target ? [target] : ["desktop", "mobile", "admin"]
+      Stylesheet::Manager.clear_core_cache!(targets)
+      message = targets.map! do |name|
+        Stylesheet::Manager.stylesheet_data(name.to_sym, Stylesheet::Watcher.theme_id)
+      end.flatten!
+      MessageBus.publish '/file-change', message
+    end
+
+    def plugin_assets_refresh(plugin_name)
+      Stylesheet::Manager.clear_plugin_cache!(plugin_name)
+      message = Stylesheet::Manager.stylesheet_data(plugin_name.to_sym, Stylesheet::Watcher.theme_id)
+      MessageBus.publish '/file-change', message
+    end
+
     def worker_loop
-      @queue.pop
+      path = @queue.pop
+
       while @queue.length > 0
         @queue.pop
       end
 
-      Stylesheet::Manager.cache.clear
-
-      targets = ["desktop", "mobile", "admin"]
-      targets.append(*Discourse.find_plugin_css_assets(mobile_view: true, desktop_view: true))
-      message = targets.map do |name|
-        Stylesheet::Manager.stylesheet_data(name.to_sym, Stylesheet::Watcher.theme_id)
-      end.flatten
-      MessageBus.publish '/file-change', message
+      if path[:plugin_name]
+        plugin_assets_refresh(path[:plugin_name])
+      else
+        core_assets_refresh(path[:target])
+      end
     end
 
     def process_change(paths)
       paths.each do |path|
-        if path =~ /\.(css|scss)$/
+        if path[:basename] =~ /\.(css|scss)$/
           @queue.push path
         end
       end
     end
-
   end
 end