# Copyright 2017 Deluxe Entertainment Services Group Inc. and its subsidiaries
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

module QuickClone
  class Cloner
    ATTRIBUTE_CLASSES = %w(String Symbol).freeze

    ABSOLUTE_EXCLUDE = [
      :id,
      :created_at,
      :updated_at
    ].freeze

    SINGULAR_ASSOCIATIONS = [
      :has_one,
      :belongs_to
    ].freeze

    def self.clone_from(original_object, filter)
      new(original_object, filter).clone
    end

    def initialize(original_object, filter)
      @filter = filter

      @original_object = original_object
      @new_object = original_object.class.new
    end

    def clone
      determine_clone(@original_object, @new_object, @filter)
      @new_object
    end

    private

    def determine_clone(original_object, new_object, filter)
      filter.each do |field|
        if ATTRIBUTE_CLASSES.include? field.class.name
          next if ABSOLUTE_EXCLUDE.include?(field.to_sym)
          copy_attribute(original_object, new_object, field)
        elsif field.is_a? Hash
          field.each do |association_name, association_filter|
            copy_association(original_object, new_object, association_name, association_filter)
          end
        end
      end
    end

    def copy_attribute(original_object, new_object, field)
      new_object.send("#{field}=", original_object.send(field))
    end

    def copy_association(original_object, new_object, association_name, association_filter)
      if SINGULAR_ASSOCIATIONS.include?(original_object.class.reflect_on_association(association_name).macro)
        determine_clone(original_object.send(association_name),
                        new_object.send("build_#{association_name}"),
                        association_filter)
      else
        original_object.send(association_name).each do |association_original_object|
          determine_clone(association_original_object, new_object.send(association_name).build, association_filter)
        end
      end
    end
  end
end