# frozen_string_literal: true

require "pakyow/support/extension"
require "pakyow/support/makeable"
require "pakyow/support/safe_string"

require "pakyow/helpers/app"
require "pakyow/helpers/connection"

module Pakyow
  module Helper
    extend Support::Makeable
  end

  module Behavior
    # Maintains a list of helper modules, with code for including helpers of a type into an object.
    #
    # Helpers are either global, passive, or active. Global helpers contain utility methods or
    # methods that need application-level state. Passive helpers can access state on the connection
    # but never change connection state, which active helpers are solely responsible for doing.
    #
    module Helpers
      extend Support::Extension

      apply_extension do
        class_state :__included_helpers, default: {}, inheritable: true

        setting :helpers,
                global: [
                  Pakyow::Helpers::App,
                  Support::SafeStringHelpers
                ],

                passive: [
                  Pakyow::Helpers::Connection
                ],

                active: []

        on "load" do
          # Helpers are loaded first so that other aspects inherit them.
          #
          load_aspect(:helpers)

          self.class.state(:helper).each do |helper|
            context = if helper.instance_variable_defined?(:@type)
              helper.instance_variable_get(:@type)
            else
              :global
            end

            self.class.register_helper(context, helper)
          end
        end

        # Define helpers as stateful after an app is made.
        #
        after "make", priority: :high do
          stateful :helper, Helper
        end
      end

      class_methods do
        # Registers a helper module to be loaded on defined endpoints.
        #
        def register_helper(context, helper_module)
          (config.helpers[context.to_sym] << helper_module).uniq!
        end

        # Includes helpers of a particular context into an object. Global helpers
        # will automatically be included into active and passive contexts, and
        # passive helpers will automatically be included into the active context.
        #
        def include_helpers(context, object)
          @__included_helpers[object] = context

          helpers(context.to_sym).each do |helper|
            object.include helper
          end
        end

        def helpers(context)
          case context.to_sym
          when :global
            config.helpers[:global]
          when :passive
            config.helpers[:global] + config.helpers[:passive]
          when :active
            config.helpers[:global] + config.helpers[:passive] + config.helpers[:active]
          else
            raise UnknownHelperContext.new_with_message(
              context: context
            )
          end
        end

        # @api private
        def included_helper_context(object)
          @__included_helpers.each_pair do |object_with_helpers, context|
            return context if object.is_a?(object_with_helpers)
          end

          nil
        end
      end
    end
  end
end