DEV: Allow us to use Ember CLI assets in production

This adds an optional ENV variable, `EMBER_CLI_PROD_ASSETS`. If truthy,
compiling production assets will be done via Ember CLI and will replace
the assets Rails would otherwise use.

lib/tasks/assets.rake

@@ -18,9 +18,7 @@ task 'assets:precompile:before' do
   # is recompiled
   Emoji.clear_cache
 
-  if !`which terser`.empty? && !ENV['SKIP_NODE_UGLIFY']
-    $node_uglify = true
-  end
+  $node_compress = `which terser`.present? && !ENV['SKIP_NODE_UGLIFY']
 
   unless ENV['USE_SPROCKETS_UGLIFY']
     $bypass_sprockets_uglify = true
@@ -36,6 +34,15 @@ task 'assets:precompile:before' do
 
   require 'sprockets'
   require 'digest/sha1'
+
+  if ENV['EMBER_CLI_PROD_ASSETS']
+    # Remove the assets that Ember CLI will handle for us
+    Rails.configuration.assets.precompile.reject! do |asset|
+      asset.is_a?(String) &&
+        (%w(application.js admin.js ember_jquery.js pretty-text-bundle.js start-discourse.js vendor.js).include?(asset) ||
+          asset.start_with?("discourse/tests"))
+    end
+  end
 end
 
 task 'assets:precompile:css' => 'environment' do
@@ -165,7 +172,7 @@ def max_compress?(path, locales)
 end
 
 def compress(from, to)
-  if $node_uglify
+  if $node_compress
     compress_node(from, to)
   else
     compress_ruby(from, to)
@@ -216,8 +223,66 @@ def copy_maxmind(from_path, to_path)
   end
 end
 
+def copy_ember_cli_assets
+  ember_dir = "app/assets/javascripts/discourse"
+  ember_cli_assets = "#{ember_dir}/dist/assets/"
+  assets = {}
+  files = {}
+
+  system("yarn --cwd #{ember_dir} run ember build -prod")
+
+  # Copy assets and generate manifest data
+  Dir["#{ember_cli_assets}**/*"].each do |f|
+    if f !~ /test/ && File.file?(f)
+      rel_file = f.sub(ember_cli_assets, "")
+      digest = f.scan(/\-([a-f0-9]+)\./)[0][0]
+
+      dest = "public/assets"
+      dest_sub = dest
+      if rel_file =~ /^([a-z\-\_]+)\//
+        dest_sub = "#{dest}/#{Regexp.last_match[1]}"
+      end
+
+      FileUtils.mkdir_p(dest_sub) unless Dir.exists?(dest_sub)
+      log_file = File.basename(rel_file).sub("-#{digest}", "")
+
+      # It's simpler to serve the file as `application.js`
+      if log_file == "discourse.js"
+        log_file = "application.js"
+        rel_file.sub!(/^discourse/, "application")
+      end
+
+      res = FileUtils.cp(f, "#{dest}/#{rel_file}")
+
+      assets[log_file] = rel_file
+      files[rel_file] = {
+        "logical_path" => log_file,
+        "mtime" => File.mtime(f).iso8601(9),
+        "size" => File.size(f),
+        "digest" => digest,
+        "integrity" => "sha384-#{Base64.encode64(Digest::SHA384.digest(File.read(f))).chomp}"
+      }
+    end
+  end
+
+  # Update manifest file
+  manifest_result = Dir["public/assets/.sprockets-manifest-*.json"]
+  if manifest_result && manifest_result.size == 1
+    json = JSON.parse(File.read(manifest_result[0]))
+    json['files'].merge!(files)
+    json['assets'].merge!(assets)
+    File.write(manifest_result[0], json.to_json)
+  end
+end
+
+task 'test_ember_cli_copy' do
+  copy_ember_cli_assets
+end
+
 task 'assets:precompile' => 'assets:precompile:before' do
 
+  copy_ember_cli_assets if ENV['EMBER_CLI_PROD_ASSETS']
+
   refresh_days = GlobalSetting.refresh_maxmind_db_during_precompile_days
 
   if refresh_days.to_i > 0
@@ -261,6 +326,7 @@ task 'assets:precompile' => 'assets:precompile:before' do
     puts "Compressing Javascript and Generating Source Maps"
     startAll = Process.clock_gettime(Process::CLOCK_MONOTONIC)
     manifest = Sprockets::Manifest.new(assets_path)
+
     locales = Set.new(["en"])
 
     RailsMultisite::ConnectionManagement.each_connection do |db|