Changes in engine support due to review

README.md

@@ -23,7 +23,9 @@
   * [Using Tailwind plugins](#using-tailwind-plugins)
   * [Using with PostCSS](#using-with-postcss)
   * [Custom inputs or outputs](#custom-inputs-or-outputs)
+- [Rails Engines support](#rails-engines-support)
 - [Troubleshooting](#troubleshooting)
+  * [The `watch` command is hanging](#the-watch-command-is-hanging)
   * [Lost keystrokes or hanging when using terminal-based debugging tools (e.g. IRB, Pry, `ruby/debug`...etc.) with the Puma plugin](#lost-keystrokes-or-hanging-when-using-terminal-based-debugging-tools-eg-irb-pry-rubydebugetc-with-the-puma-plugin)
   * [Running in a docker container exits prematurely](#running-in-a-docker-container-exits-prematurely)
   * [Conflict with sassc-rails](#conflict-with-sassc-rails)
@@ -406,6 +408,14 @@ If you have Rails Engines in your application that use Tailwind CSS, they will b
 
 - The engine must have `tailwindcss-rails` as gem dependency.
 - The engine must have a `app/assets/tailwind/<engine_name>/application.css` file or your application must have overridden file in the same location of your application root.
+- The engine must register itself in Tailwindcss Rails:
+```ruby
+  initializer 'your_engine.tailwindcss' do |app|
+    ActiveSupport.on_load(:tailwindcss_rails) do
+      config.tailwindcss_rails.engines << Your::Engine.engine_name
+    end
+  end
+```
 
 ## Troubleshooting
 

lib/tailwindcss/commands.rb

@@ -3,13 +3,24 @@
 module Tailwindcss
   module Commands
     class << self
-      def compile_command(debug: false, **kwargs)
+      def rails_root
+        defined?(Rails) ? Rails.root : Pathname.new(Dir.pwd)
+      end
+
+      def remove_tempfile!
+        return unless class_variable_defined?(:@@tempfile) && @@tempfile
+
+        @@tempfile.close unless @@tempfile.closed?
+        @@tempfile.unlink if File.exist?(@@tempfile.path)
+        remove_class_variable(:@@tempfile)
+      end
+
+      def compile_command(input: application_css, debug: false, **kwargs)
         debug = ENV["TAILWINDCSS_DEBUG"].present? if ENV.key?("TAILWINDCSS_DEBUG")
-        rails_root = defined?(Rails) ? Rails.root : Pathname.new(Dir.pwd)
 
         command = [
           Tailwindcss::Ruby.executable(**kwargs),
-          "-i", rails_root.join("app/assets/tailwind/application.css").to_s,
+          "-i", input.to_s,
           "-o", rails_root.join("app/assets/builds/tailwind.css").to_s,
         ]
 
@@ -21,6 +32,22 @@ def compile_command(debug: false, **kwargs)
         command
       end
 
+      def application_css
+        return rails_root.join("app/assets/tailwind/application.css").to_s if engines_roots.empty?
+
+        @@tempfile = Tempfile.new("tailwind.application.css")
+
+        # Write content to tempfile
+        engines_roots.each do |root|
+          @@tempfile.write("@import \"#{root}\";\n")
+        end
+        @@tempfile.write("\n@import \"#{rails_root.join('app/assets/tailwind/application.css')}\";\n")
+        @@tempfile.flush
+        @@tempfile.close
+
+        @@tempfile.path
+      end
+
       def watch_command(always: false, poll: false, **kwargs)
         compile_command(**kwargs).tap do |command|
           command << "-w"
@@ -39,39 +66,19 @@ def rails_css_compressor?
         defined?(Rails) && Rails&.application&.config&.assets&.css_compressor.present?
       end
 
-      def engines_tailwindcss_roots
+      def engines_roots
         return [] unless defined?(Rails)
+        return [] unless Rails.application&.config&.tailwindcss_rails&.engines
 
-        Rails::Engine.subclasses.select do |engine|
-          begin
-            spec = Gem::Specification.find_by_name(engine.engine_name)
-            spec.dependencies.any? { |d| d.name == 'tailwindcss-rails' }
-          rescue Gem::MissingSpecError
-            false
-          end
+        Rails::Engine.descendants.select do |engine|
+          engine.engine_name.in?(Rails.application.config.tailwindcss_rails.engines)
         end.map do |engine|
           [
-            Rails.root.join("app/assets/tailwind/#{engine.engine_name}/application.css"),
+            rails_root.join("app/assets/tailwind/#{engine.engine_name}/application.css"),
             engine.root.join("app/assets/tailwind/#{engine.engine_name}/application.css")
           ].select(&:exist?).compact.first.to_s
         end.compact
       end
-
-      def enhance_command(command)
-        engine_roots = Tailwindcss::Commands.engines_tailwindcss_roots
-        if engine_roots.any?
-          Tempfile.create('tailwind.css') do |file|
-            file.write(engine_roots.map { |root| "@import \"#{root}\";" }.join("\n"))
-            file.write("\n@import \"#{Rails.root.join('app/assets/tailwind/application.css')}\";\n")
-            file.rewind
-            transformed_command = command.dup
-            transformed_command[2] = file.path
-            yield transformed_command if block_given?
-          end
-        else
-          yield command if block_given?
-        end
-      end
     end
   end
 end

lib/tailwindcss/engine.rb

@@ -2,6 +2,15 @@
 
 module Tailwindcss
   class Engine < ::Rails::Engine
+    config.before_configuration do |app|
+      app.config.tailwindcss_rails = ActiveSupport::OrderedOptions.new
+      app.config.tailwindcss_rails.engines = []
+    end
+
+    initializer 'tailwindcss.load_hook' do |app|
+      ActiveSupport.run_load_hooks(:tailwindcss_rails, app)
+    end
+
     initializer "tailwindcss.disable_generator_stylesheets" do
       Rails.application.config.generators.stylesheets = false
     end

lib/tasks/build.rake

@@ -5,12 +5,11 @@ namespace :tailwindcss do
     verbose = args.extras.include?("verbose")
 
     command = Tailwindcss::Commands.compile_command(debug: debug)
-    Tailwindcss::Commands.enhance_command(command) do |transformed_command|
-      env = Tailwindcss::Commands.command_env(verbose: verbose)
-      puts "Running: #{Shellwords.join(command)}" if verbose
+    env = Tailwindcss::Commands.command_env(verbose: verbose)
+    puts "Running: #{Shellwords.join(command)}" if verbose
 
-      system(env, *command, exception: true)
-    end
+    system(env, *command, exception: true)
+    Tailwindcss::Commands.remove_tempfile!
   end
 
   desc "Watch and build your Tailwind CSS on file changes"
@@ -21,14 +20,14 @@ namespace :tailwindcss do
     verbose = args.extras.include?("verbose")
 
     command = Tailwindcss::Commands.watch_command(always: always, debug: debug, poll: poll)
-    Tailwindcss::Commands.enhance_command(command) do |transformed_command|
-      env = Tailwindcss::Commands.command_env(verbose: verbose)
-      puts "Running: #{Shellwords.join(command)}" if verbose
+    env = Tailwindcss::Commands.command_env(verbose: verbose)
+    puts "Running: #{Shellwords.join(command)}" if verbose
 
-      system(env, *command)
-    end
+    system(env, *command)
   rescue Interrupt
     puts "Received interrupt, exiting tailwindcss:watch" if args.extras.include?("verbose")
+  ensure
+    Tailwindcss::Commands.remove_tempfile!
   end
 end