module ActiveAdminImport
  module DSL


    # Declares import functionality
    #
    # Options
    # +back+:: resource action to redirect after processing
    # +csv_options+:: hash to override default CSV options
    # +batch_size+:: integer value of max  record count inserted by 1 query/transaction
    # +batch_transaction+:: bool (false by default), if transaction is used when batch importing and works when :validate is set to true
    # +before_import+:: proc for before import action, hook called with  importer object
    # +after_import+:: proc for after import action, hook called with  importer object
    # +before_batch_import+:: proc for before each batch action, called with  importer object
    # +after_batch_import+:: proc for after each batch action, called with  importer object
    # +validate+:: true|false, means perform validations or not
    # +on_duplicate_key_update+:: an Array or Hash, tells activerecord-import to use MySQL's ON DUPLICATE KEY UPDATE ability.
    # +timestamps+::  true|false, tells activerecord-import to not add timestamps (if false) even if record timestamps is disabled in ActiveRecord::Base
    # +ignore+::  true|false, tells activerecord-import to use MySQL's INSERT IGNORE ability
    # +template+:: custom template rendering
    # +template_object+:: object passing to view
    # +resource_class+:: resource class name, override to import to another table (default config.resource_class)
    # +resource_label+:: resource label value (default config.resource_label)
    # +plural_resource_label+:: pluralized resource label value (default config.plural_resource_label)
    #


    DEFAULT_RESULT_PROC =  ->(result, options) do

      model_name = options[:resource_label].downcase
      plural_model_name = options[:plural_resource_label].downcase
      if result.empty?
        flash[:warning] = I18n.t('active_admin_import.file_empty_error')
      else
        if result.has_failed?
          flash[:error] = I18n.t('active_admin_import.failed', count: result.failed.count, model: model_name, plural_model: plural_model_name, message: result.failed_message(limit: 5))
          return if options[:batch_transaction]
        end
        if result.has_imported?
          flash[:notice] = I18n.t('active_admin_import.imported', count: result.imported_qty, model: model_name, plural_model: plural_model_name)
        end
      end
    end


    def active_admin_import(options = {}, &block)
      options.assert_valid_keys(*Options::VALID_OPTIONS)

      options = Options.options_for(config, options)
      params_key = ActiveModel::Naming.param_key(options[:template_object])

      collection_action :import, method: :get do
        authorize!(ActiveAdminImport::Auth::IMPORT, active_admin_config.resource_class)
        @active_admin_import_model = options[:template_object]
        render template: options[:template]
      end

      action_item :import, only: :index do
        if authorized?(ActiveAdminImport::Auth::IMPORT, active_admin_config.resource_class)
          link_to(I18n.t('active_admin_import.import_model', plural_model: options[:plural_resource_label]), action: :import)
        end
      end

      collection_action :do_import, method: :post do
        authorize!(ActiveAdminImport::Auth::IMPORT, active_admin_config.resource_class)

        @active_admin_import_model = options[:template_object]
        @active_admin_import_model.assign_attributes(params[params_key].try(:deep_symbolize_keys) || {})
        #go back to form
        return render template: options[:template] unless @active_admin_import_model.valid?
        @importer = Importer.new(options[:resource_class], @active_admin_import_model, options)
        begin
          result = @importer.import

          if block_given?
            instance_eval &block
          else
            instance_exec result, options, &DEFAULT_RESULT_PROC
          end
        rescue ActiveRecord::Import::MissingColumnError, NoMethodError, ActiveRecord::StatementInvalid => e
          Rails.logger.error(I18n.t('active_admin_import.file_error', message: e.message))
          flash[:error] = I18n.t('active_admin_import.file_error', message: e.message[0..200])
        end
        redirect_to options[:back]
      end

    end
  end
end