Simple Form: input with preview image / Concern per paperclip = seo friendly and easy remove file

attachment_concern.rb

#
#  save file: app/models/concerns/attachment_concern.rb
#
#  Example:
# -------------------------------------
#  add Model ------------
#  has_attached_file :picture, styles: {
#    medium: "600x315#",
#    thumb: "160x160>"
#  }
#  include AttachmentConcern
#
#
# add Controller ---------
# def permitted_params
#    params.permit(page: [ :picture, :remove_picture, ...]
# end
#
# Install image_preview_input.rb to make it easier to preview the image in the input, along with checkbox for deletion
# https://gist.github.com/mr4torr/1487e6bf19985b6f7b7c4b32977416e8

module AttachmentConcern
    extend ActiveSupport::Concern

    included do |base = nil, &block|

        attachments_keys = attachment_definitions.keys
        attachment_definitions.each do |key, val|

          attr_accessor :"remove_#{key}"

          before_validation { send(key).clear if send("remove_#{key}") == '1' }
          before_update  { send(:new_name_attached, attachments_keys) }
          after_update  { send(:new_filename_attached, attachments_keys) }

          define_method :"remove_#{key}=" do |value|
            instance_variable_set :"@remove_#{key}", value
            send("#{key}_file_name_will_change!")
          end

          content_type = val[:content_type] || Constant::CONTENT_TYPE_UPLOAD
          content_size = val[:content_size] || Constant::SIZE_UPLOAD

          validates key.to_sym, attachment_size: { in: content_size },
            attachment_content_type: { content_type: content_type }
        end


        def new_name_attached(attachments = [])
          return if self.try(:name) && !name_changed?
          return if self.try(:title) && !title_changed?

          get_name = self.try(:name) || self.try(:title)

          attachments.each do |key|
            _file_name = (key.to_s+"_file_name").to_sym

            _filename = self.send(key)
            _extension = Paperclip::Interpolations.extension(_filename, :original)
            self[_file_name] = get_name.parameterize + '.' + _extension
          end
        end

        def new_filename_attached(attachments = [])
          return if self.try(:name) && !name_changed?
          return if self.try(:title) && !title_changed?

          get_name_was = title_was if self.try(:title)
          get_name_was = name_was if self.try(:name)

          attachments.each do |key|

            _file_name = (key.to_s+"_file_name").to_sym
            _filename = self.send(key)
            _name = Paperclip::Interpolations.param(_filename, :original)
            _extension = Paperclip::Interpolations.extension(_filename, :original)
            _old_name = get_name_was.parameterize + '.' + _extension
            _new_name = _name + '.' + _extension

            (_filename.styles.keys+[:original]).each do |style|
              begin
                new_path = self.send(key).path(style)
                old_path = new_path.gsub(_new_name, _old_name)
                File.rename(old_path, new_path)
              rescue
                nil
              end
            end
          end
        end
    end
end

image_preview_input.rb

#
#  Install:
# -------------------------------------
#  save file: app/inputs/image_preview_input.rb
#  add file: config/application.rb ( config.autoload_paths += Dir[Rails.root.join('app', 'inputs').to_s] )
#  
#  Example:
# -------------------------------------
#
#  add View ------------
#  <%= form.input :picture, as: :image_preview %>
#
# -- params optional
#  <%= form.input :picture, as: :image_preview, input_html: { preview_version: :thumb, preview_width: 50, preview_height: 50 } %>
#
# 
# Install attachment_concern.rb to make it easier to delete with paperclip
# https://gist.github.com/mr4torr/1487e6bf19985b6f7b7c4b32977416e8
#

class ImagePreviewInput < SimpleForm::Inputs::FileInput
  def hint(wrapper_options = nil)
  end

  def input(wrapper_options)

    version = input_html_options[:preview_version].present? ? input_html_options.delete(:preview_version) : :thumb
    preview_width = input_html_options[:preview_width].present? ? input_html_options.delete(:preview_width) : nil
    preview_height = input_html_options[:preview_height].present? ? input_html_options.delete(:preview_height) : nil

    out = ActiveSupport::SafeBuffer.new

    if object.send("#{attribute_name}?")

      image_src = object.send(attribute_name).tap do |o|
          break o.url(version) if version
      end

      out << '<div class="d-block">'.html_safe
      out << template.image_tag(image_src, width: preview_width,  height: preview_height)
      out << @builder.input("remove_#{attribute_name}", as: :boolean,  :label => I18n.t('views.is_delete'))
      out << '</div>'.html_safe
    end

    input_html_options.merge!({ wrapper: :custom_file, label: I18n.t('views.send_file') })
    out << @builder.input(attribute_name, input_html_options)
  end
end