1 files changed, 99 insertions, 0 deletions
diff --git a/railties/lib/rails/command.rb b/railties/lib/rails/command.rb
new file mode 100644
index 0000000000..6065e78fd1
--- /dev/null
+++ b/railties/lib/rails/command.rb
@@ -0,0 +1,99 @@
+require "active_support"
+require "active_support/dependencies/autoload"
+require "active_support/core_ext/enumerable"
+require "active_support/core_ext/object/blank"
+require "active_support/core_ext/hash/transform_values"
+
+require "thor"
+
+module Rails
+  module Command
+    extend ActiveSupport::Autoload
+
+    autoload :Behavior
+    autoload :Base
+
+    include Behavior
+
+    class << self
+      def hidden_commands # :nodoc:
+        @hidden_commands ||= []
+      end
+
+      def environment # :nodoc:
+        ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "development"
+      end
+
+      # Receives a namespace, arguments and the behavior to invoke the command.
+      def invoke(namespace, args = [], **config)
+        namespace = namespace.to_s
+        namespace = "help" if namespace.blank? || Thor::HELP_MAPPINGS.include?(namespace)
+        namespace = "version" if %w( -v --version ).include? namespace
+
+        if command = find_by_namespace(namespace)
+          command.perform(namespace, args, config)
+        else
+          find_by_namespace("rake").perform(namespace, args, config)
+        end
+      end
+
+      # Rails finds namespaces similar to thor, it only adds one rule:
+      #
+      # Command names must end with "_command.rb". This is required because Rails
+      # looks in load paths and loads the command just before it's going to be used.
+      #
+      #   find_by_namespace :webrat, :rails, :integration
+      #
+      # Will search for the following commands:
+      #
+      #   "rails:webrat", "webrat:integration", "webrat"
+      #
+      # Notice that "rails:commands:webrat" could be loaded as well, what
+      # Rails looks for is the first and last parts of the namespace.
+      def find_by_namespace(name) # :nodoc:
+        lookups = [ name, "rails:#{name}" ]
+
+        lookup(lookups)
+
+        namespaces = subclasses.index_by(&:namespace)
+        namespaces[(lookups & namespaces.keys).first]
+      end
+
+      # Returns the root of the Rails engine or app running the command.
+      def root
+        if defined?(ENGINE_ROOT)
+          Pathname.new(ENGINE_ROOT)
+        elsif defined?(APP_PATH)
+          Pathname.new(File.expand_path("../..", APP_PATH))
+        end
+      end
+
+      def print_commands # :nodoc:
+        sorted_groups.each { |b, n| print_list(b, n) }
+      end
+
+      def sorted_groups # :nodoc:
+        lookup!
+
+        groups = (subclasses - hidden_commands).group_by { |c| c.namespace.split(":").first }
+        groups.transform_values! { |commands| commands.flat_map(&:printing_commands).sort }
+
+        rails = groups.delete("rails")
+        [[ "rails", rails ]] + groups.sort.to_a
+      end
+
+      protected
+        def command_type
+          @command_type ||= "command"
+        end
+
+        def lookup_paths
+          @lookup_paths ||= %w( rails/commands commands )
+        end
+
+        def file_lookup_paths
+          @file_lookup_paths ||= [ "{#{lookup_paths.join(',')}}", "**", "*_command.rb" ]
+        end
+    end
+  end
+end