raen79/fie

module Fie
  module Track
    def track_changes_in_objects(object)
      if object.is_a?(Array)
        track_changes_in_array(object)
      elsif object.is_a?(Hash)
        track_changes_in_hash(object)
      elsif !object.duplicable? || object.is_a?(String) || object.is_a?(Time)
        nil
      else
        track_changes_in_object(object)
      end
    end

    def untrack_changes_in_objects(object)
      if object.is_a? Hash
        untrack_changes_in_hash(object)
      elsif object.is_a? Array
        untrack_changes_in_array(object)
      elsif !object.duplicable? || object.is_a?(String) || object.is_a?(Time)
        nil
      else
        untrack_changes_in_object(object)
      end
    end

    private
      def track_changes_in_array(object)
        state = self

        unless object.frozen?
          object.class_eval do
            alias_method('previous_[]=', '[]=')
            alias_method('previous_<<', '<<')
            alias_method('previous_push', 'push')
            alias_method('previous_delete_at', 'delete_at')
            alias_method('previous_delete', 'delete')

            define_method('[]=') do |key, value|
              send('previous_[]=', key, value)
              state.permeate
            end

            define_method('<<') do |value|
              send('previous_<<', value)
              state.permeate
            end


            define_method('push') do |value|
              send('previous_push', value)
              state.permeate
            end

            define_method('delete_at') do |value|
              send('previous_delete_at', value)
              state.permeate
            end

            define_method('delete') do |value|
              send('previous_delete', value)
              state.permeate
            end
          end
        end

        object.each do |value|
          track_changes_in_objects(value)
        end
      end

      def track_changes_in_hash(object)
        state = self

        unless object.frozen?
          object.class_eval do
            alias_method('previous_[]=', '[]=')
            alias_method('previous_delete', 'delete')

            define_method('[]=') do |key, value|
              send('previous_[]=', key, value)
              state.permeate
            end

            define_method('delete') do |value|
              send('previous_delete', value)
              state.permeate
            end
          end
        end

        object.each do |value|
          track_changes_in_objects(value)
        end
      end

      def track_changes_in_object(object)
        state = self
        is_untracked = !object.instance_variable_defined?('@fie_tracked')

        if is_untracked
          object.methods.each do |attribute_name, attribute_value|
            is_setter = attribute_name.to_s.ends_with?('=') && attribute_name.to_s.match(/[A-Za-z]/)

            if is_setter
              unless object.frozen?
                object.class_eval do
                  alias_method("previous_#{ attribute_name }", attribute_name)

                  define_method(attribute_name) do |setter_value|
                    send("previous_#{ attribute_name }", setter_value)
                    state.permeate
                  end
                end

                object.instance_variable_set('@fie_tracked', true)
              end

              getter_name = attribute_name.to_s.chomp('=').to_sym
              object_has_getter = object.methods.include?(getter_name)
              if object_has_getter
                track_changes_in_objects object.send(getter_name)
              end
            end
          end
        end
      end

      def untrack_changes_in_hash(hash)
        unless hash.frozen?
          hash.class_eval do
            begin
              ['[]=', 'delete'].each do |method_name|
                remove_method method_name
                remove_method "previous_#{ method_name }"
              end
            rescue
            end
          end
        end

        hash.each do |key, value|
          untrack_changes_in_objects(value)
        end
      end

      def untrack_changes_in_array(array)
        unless array.frozen?
          array.class_eval do
            begin
              ['[]=', '<<', 'push', 'delete_at', 'delete'].each do |method_name|
                remove_method method_name
                remove_method "previous_#{ method_name }"
              end
            rescue
            end
          end
        end

        array.each do |value|
          untrack_changes_in_objects(value)
        end
      end

      def untrack_changes_in_object(object)
        is_tracked = object.instance_variable_defined?('@fie_tracked')

        if is_tracked
          object.methods.each do |attribute_name, attribute_value|
            is_setter = attribute_name.to_s.ends_with?('=') &&
              attribute_name.to_s.match(/[A-Za-z]/) &&
              !attribute_name.to_s.start_with?('previous_')

            if is_setter
              remove_tracked_object_methods(object, attribute_name) unless object.frozen?

              getter_name = attribute_name.to_s.chomp('=').to_sym
              object_has_getter = object.methods.include?(getter_name)

              untrack_changes_in_objects object.send(getter_name) if object_has_getter
            end
          end
        end
      end

      def remove_tracked_object_methods(object, attribute_name)
        object.remove_instance_variable('@fie_tracked') if object.instance_variable_defined?('@fie_tracked')
        object.class_eval do
          begin
            remove_method attribute_name
            remove_method "previous_#{ attribute_name }"
          rescue
          end
        end
      end
  end
end