module JsonbAccessor
  module Macro
    class << self
      def group_attributes(value_fields, typed_fields)
        value_fields_hash = process_value_fields(value_fields)

        typed_fields.each_with_object(nested: {}, typed: value_fields_hash) do |(attribute_name, type_or_nested), grouped_attributes|
          group = type_or_nested.is_a?(Hash) ? grouped_attributes[:nested] : grouped_attributes[:typed]
          group[attribute_name] = type_or_nested
        end
      end

      def process_value_fields(value_fields)
        value_fields.each_with_object({}) do |value_field, hash_for_value_fields|
          hash_for_value_fields[value_field] = :value
        end
      end

      def build_class_namespace(class_name)
        class_name = class_name.gsub(CONSTANT_SEPARATOR, "")
        if JsonbAccessor.constants.any? { |c| c.to_s == class_name }
          class_namespace = JsonbAccessor.const_get(class_name)
        else
          class_namespace = Module.new
          JsonbAccessor.const_set(class_name, class_namespace)
        end
        class_namespace
      end
    end

    module ClassMethods
      def jsonb_accessor(jsonb_attribute, *value_fields, **typed_fields)
        all_fields = Macro.group_attributes(value_fields, typed_fields)
        nested_fields, typed_fields = all_fields.values_at(:nested, :typed)

        class_namespace = Macro.build_class_namespace(name)
        attribute_namespace = Module.new
        class_namespace.const_set(jsonb_attribute.to_s.camelize, attribute_namespace)

        nested_classes = ClassBuilder.generate_nested_classes(attribute_namespace, nested_fields)

        singleton_class.send(:define_method, "#{jsonb_attribute}_classes") do
          nested_classes
        end

        delegate "#{jsonb_attribute}_classes", to: :class

        jsonb_attribute_initialization_method_name = "initialize_jsonb_attrs_for_#{jsonb_attribute}"

        define_method(jsonb_attribute_initialization_method_name) do
          jsonb_attribute_hash = send(jsonb_attribute) || {}
          (typed_fields.keys + nested_fields.keys).each do |field|
            send("#{field}=", jsonb_attribute_hash[field.to_s])
          end
        end

        after_initialize(jsonb_attribute_initialization_method_name)

        jsonb_accessor_methods = Module.new do
          define_method("#{jsonb_attribute}=") do |value|
            write_attribute(jsonb_attribute, value)
            send(jsonb_attribute_initialization_method_name)
          end

          define_method(:reload) do |*args, &block|
            super(*args, &block)
            send(jsonb_attribute_initialization_method_name)
            self
          end
        end

        typed_fields.each do |field, type|
          attribute(field.to_s, TypeHelper.fetch(type))

          jsonb_accessor_methods.instance_eval do
            define_method("#{field}=") do |value, *args, &block|
              super(value, *args, &block)
              new_jsonb_value = (send(jsonb_attribute) || {}).merge(field => attributes[field.to_s])
              write_attribute(jsonb_attribute, new_jsonb_value)
            end
          end
        end

        nested_fields.each do |field, nested_attributes|
          attribute(field.to_s, TypeHelper.fetch(:value))

          jsonb_accessor_methods.instance_eval do
            define_method("#{field}=") do |value|
              instance_class = nested_classes[field]

              case value
              when instance_class
                instance = instance_class.new(value.attributes)
              when Hash
                instance = instance_class.new(value)
              when nil
                instance = instance_class.new
              else
                raise UnknownValue, "unable to set value '#{value}' is not a hash, `nil`, or an instance of #{instance_class} in #{__method__}"
              end

              instance.parent = self
              new_jsonb_value = (send(jsonb_attribute) || {}).merge(field.to_s => instance.attributes)
              write_attribute(jsonb_attribute, new_jsonb_value)
              super(instance)
            end
          end
        end

        include jsonb_accessor_methods
      end
    end
  end
end