Convert to Zeitwerk for code loading (#402)

- Add zeitwerk to the gemspec
- Add `lib/hanami-controller.rb` so the gem follows a conventional structure
- Set up the Zeitwerk loader inside `lib/hanami/action.rb` (call it `.gem_loader` instead of `.loader` like we have done in other gems, since `Hanami::Action` is a class with other responsibilities, and `loader` is too generic a term)
- Move conditional requires below the `gem_loader.setup` line to ensure any internal autoloader work
- Remove all now-unneeded manual requires for files inside the gem

hanami-controller.gemspec

@@ -20,9 +20,10 @@ Gem::Specification.new do |spec|
   spec.metadata["rubygems_mfa_required"] = "true"
   spec.required_ruby_version = ">= 3.0"
 
-  spec.add_dependency "rack",         "~> 2.0"
+  spec.add_dependency "rack", "~> 2.0"
   spec.add_dependency "hanami-utils", "~> 2.0.0.rc1"
   spec.add_dependency "dry-configurable", "~> 1.0", "< 2"
+  spec.add_dependency "zeitwerk", "~> 2.6"
 
   spec.add_development_dependency "bundler",   ">= 1.6", "< 3"
   spec.add_development_dependency "rack-test", "~> 2.0"

lib/hanami-controller.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require_relative "hanami/controller"

lib/hanami/action.rb

@@ -1,29 +1,15 @@
 # frozen_string_literal: true
 
-begin
-  require "dry/core"
-  require "dry/types"
-  require "hanami/validations"
-  require "hanami/action/validatable"
-rescue LoadError # rubocop:disable Lint/SuppressedException
-end
-
 require "dry/configurable"
-require "hanami/utils/callbacks"
 require "hanami/utils"
-require "hanami/utils/string"
+require "hanami/utils/callbacks"
 require "hanami/utils/kernel"
+require "hanami/utils/string"
 require "rack"
 require "rack/utils"
+require "zeitwerk"
 
-require_relative "action/config"
 require_relative "action/constants"
-require_relative "action/base_params"
-require_relative "action/halt"
-require_relative "action/mime"
-require_relative "action/rack/file"
-require_relative "action/request"
-require_relative "action/response"
 require_relative "action/errors"
 
 module Hanami
@@ -42,6 +28,32 @@ module Hanami
   #
   # @api public
   class Action
+    # @since 2.0.0
+    # @api private
+    def self.gem_loader
+      @gem_loader ||= Zeitwerk::Loader.new.tap do |loader|
+        root = File.expand_path("..", __dir__)
+        loader.tag = "hanami-controller"
+        loader.inflector = Zeitwerk::GemInflector.new("#{root}/hanami-controller.rb")
+        loader.push_dir(root)
+        loader.ignore(
+          "#{root}/hanami-controller.rb",
+          "#{root}/hanami/controller/version.rb",
+          "#{root}/hanami/action/{constants,errors,params,validatable}.rb"
+        )
+        loader.inflector.inflect("csrf_protection" => "CSRFProtection")
+      end
+    end
+
+    gem_loader.setup
+
+    # Make conditional requires after Zeitwerk setup so any internal autoloading works as expected
+    begin
+      require "hanami/validations"
+      require_relative "action/validatable"
+    rescue LoadError # rubocop:disable Lint/SuppressedException
+    end
+
     extend Dry::Configurable(config_class: Config)
 
     # See {Config} for individual setting accessor API docs

lib/hanami/action/cache.rb

@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/cache/cache_control"
-require "hanami/action/cache/expires"
-require "hanami/action/cache/conditional_get"
-
 module Hanami
   class Action
     # Cache type API

lib/hanami/action/cache/cache_control.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/cache/directives"
-
 module Hanami
   class Action
     module Cache

lib/hanami/action/cache/expires.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/cache/cache_control"
-
 module Hanami
   class Action
     module Cache

lib/hanami/action/config.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "dry/configurable"
-require_relative "mime"
 
 module Hanami
   class Action

lib/hanami/action/params.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/base_params"
 require "hanami/validations/form"
 
 module Hanami

lib/hanami/action/request.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/flash"
 require "rack/mime"
 require "rack/request"
 require "rack/utils"

lib/hanami/action/response.rb

@@ -3,11 +3,6 @@
 require "rack"
 require "rack/response"
 require "hanami/utils/kernel"
-require "hanami/action/halt"
-require "hanami/action/cookie_jar"
-require "hanami/action/cache/cache_control"
-require "hanami/action/cache/expires"
-require "hanami/action/cache/conditional_get"
 require_relative "errors"
 
 module Hanami

lib/hanami/action/session.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/flash"
-
 module Hanami
   class Action
     # Session support for actions.

lib/hanami/action/validatable.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "hanami/action/params"
+require_relative "params"
 
 module Hanami
   class Action

lib/hanami/controller.rb

@@ -9,22 +9,10 @@ require "hanami/controller/version"
 module Hanami
   # A set of logically grouped actions
   #
-  # @since 0.1.0
-  #
   # @see Hanami::Action
   #
-  # @example
-  #   require "hanami/controller"
-  #
-  #   module Articles
-  #     class Index < Hanami::Action
-  #       # ...
-  #     end
-  #
-  #     class Show < Hanami::Action
-  #       # ...
-  #     end
-  #   end
+  # @since 0.1.0
+  # @api public
   module Controller
   end
 end

lib/hanami/controller/version.rb

@@ -2,6 +2,11 @@
 
 module Hanami
   module Controller
+    # The current hanami-controller version.
+    #
+    # @return [String]
+    #
+    # @since 0.1.0
     # @api public
     VERSION = "2.0.0.rc1"
   end

spec/integration/hanami/controller/cache_spec.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "hanami/router"
-require "hanami/action/cache"
 
 module CacheControl
   class Default < Hanami::Action

spec/spec_helper.rb

@@ -3,8 +3,6 @@
 $LOAD_PATH.unshift "lib"
 require "hanami/utils"
 require "hanami/devtools/unit"
-require "hanami/controller"
-require "hanami/action/cookies"
-require "hanami/action/session"
+require "hanami/action"
 
 Hanami::Utils.require!("spec/support")

spec/support/fixtures.rb

@@ -5,10 +5,6 @@ require "digest/md5"
 require "hanami/router"
 require "hanami/middleware/body_parser"
 require "hanami/utils/escape"
-require "hanami/action/params"
-require "hanami/action/cookies"
-require "hanami/action/session"
-require "hanami/action/cache"
 require_relative "./renderer"
 
 require_relative "./validations"

spec/unit/hanami/action/csrf_protection_spec.rb

@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action"
-require "hanami/action/csrf_protection"
-
 RSpec.describe Hanami::Action::CSRFProtection do
   subject(:action) {
     Class.new(Hanami::Action) {

spec/unit/hanami/action/flash_spec.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/flash"
-
 RSpec.describe Hanami::Action::Flash do
   let(:flash) { described_class.new(input_hash) }
   let(:input_hash) { {} }

spec/unit/hanami/action/request_spec.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/request"
-
 RSpec.describe Hanami::Action::Request do
   describe "#body" do
     it "exposes the raw body of the request" do

spec/unit/hanami/action/response/session_spec.rb

@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require "hanami/action/response"
-require "hanami/action/request"
-
 RSpec.describe Hanami::Action::Response, "session features" do
   subject(:response) {
     described_class.new(