Allow import/export of instance-level domain blocks/allows (#1754)

* Allow import/export of instance-level domain blocks/allows.
Fixes #15095

* Pacify circleci

* Address simple code review feedback

* Add headers to exported CSV

* Extract common import/export functionality to
AdminExportControllerConcern

* Add additional fields to instance-blocked domain export

* Address review feedback

* Split instance domain block/allow import/export into separate pages/controllers

* Address code review feedback

* Pacify DeepSource

* Work around Paperclip::HasAttachmentFile for Rails 6

* Fix deprecated API warning in export tests

* Remove after_commit workaround

app/controllers/admin/export_domain_allows_controller.rb

@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require 'csv'
+
+module Admin
+  class ExportDomainAllowsController < BaseController
+    include AdminExportControllerConcern
+
+    before_action :set_dummy_import!, only: [:new]
+
+    ROWS_PROCESSING_LIMIT = 20_000
+
+    def new
+      authorize :domain_allow, :create?
+    end
+
+    def export
+      authorize :instance, :index?
+      send_export_file
+    end
+
+    def import
+      authorize :domain_allow, :create?
+      begin
+        @import = Admin::Import.new(import_params)
+        parse_import_data!(export_headers)
+
+        @data.take(ROWS_PROCESSING_LIMIT).each do |row|
+          domain = row['#domain'].strip
+          next if DomainAllow.allowed?(domain)
+
+          domain_allow = DomainAllow.new(domain: domain)
+          log_action :create, domain_allow if domain_allow.save
+        end
+        flash[:notice] = I18n.t('admin.domain_allows.created_msg')
+      rescue ActionController::ParameterMissing
+        flash[:error] = I18n.t('admin.export_domain_allows.no_file')
+      end
+      redirect_to admin_instances_path
+    end
+
+    private
+
+    def export_filename
+      'domain_allows.csv'
+    end
+
+    def export_headers
+      %w(#domain)
+    end
+
+    def export_data
+      CSV.generate(headers: export_headers, write_headers: true) do |content|
+        DomainAllow.allowed_domains.each do |instance|
+          content << [instance.domain]
+        end
+      end
+    end
+  end
+end

app/controllers/admin/export_domain_blocks_controller.rb

@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require 'csv'
+
+module Admin
+  class ExportDomainBlocksController < BaseController
+    include AdminExportControllerConcern
+
+    before_action :set_dummy_import!, only: [:new]
+
+    ROWS_PROCESSING_LIMIT = 20_000
+
+    def new
+      authorize :domain_block, :create?
+    end
+
+    def export
+      authorize :instance, :index?
+      send_export_file
+    end
+
+    def import
+      authorize :domain_block, :create?
+      begin
+        @import = Admin::Import.new(import_params)
+        parse_import_data!(export_headers)
+
+        @data.take(ROWS_PROCESSING_LIMIT).each do |row|
+          domain = row['#domain'].strip
+          next if DomainBlock.rule_for(domain).present?
+
+          domain_block = DomainBlock.new(domain: domain,
+                                         severity: row['#severity'].strip,
+                                         reject_media: row['#reject_media'].strip,
+                                         reject_reports: row['#reject_reports'].strip,
+                                         public_comment: row['#public_comment'].strip,
+                                         obfuscate: row['#obfuscate'].strip)
+          if domain_block.save
+            DomainBlockWorker.perform_async(domain_block.id)
+            log_action :create, domain_block
+          end
+        end
+        flash[:notice] = I18n.t('admin.domain_blocks.created_msg')
+      rescue ActionController::ParameterMissing
+        flash[:error] = I18n.t('admin.export_domain_blocks.no_file')
+      end
+      redirect_to admin_instances_path(limited: '1')
+    end
+
+    private
+
+    def export_filename
+      'domain_blocks.csv'
+    end
+
+    def export_headers
+      %w(#domain #severity #reject_media #reject_reports #public_comment #obfuscate)
+    end
+
+    def export_data
+      CSV.generate(headers: export_headers, write_headers: true) do |content|
+        DomainBlock.with_user_facing_limitations.each do |instance|
+          content << [instance.domain, instance.severity, instance.reject_media, instance.reject_reports, instance.public_comment, instance.obfuscate]
+        end
+      end
+    end
+  end
+end

app/controllers/concerns/admin_export_controller_concern.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module AdminExportControllerConcern
+  extend ActiveSupport::Concern
+
+  private
+
+  def send_export_file
+    respond_to do |format|
+      format.csv { send_data export_data, filename: export_filename }
+    end
+  end
+
+  def export_data
+    raise 'Override in controller'
+  end
+
+  def export_filename
+    raise 'Override in controller'
+  end
+
+  def set_dummy_import!
+    @import = Admin::Import.new
+  end
+
+  def import_params
+    params.require(:admin_import).permit(:data)
+  end
+
+  def import_data
+    Paperclip.io_adapters.for(@import.data).read
+  end
+
+  def parse_import_data!(default_headers)
+    data = CSV.parse(import_data, headers: true)
+    data = CSV.parse(import_data, headers: default_headers) unless data.headers&.first&.strip&.include?(default_headers[0])
+    @data = data.reject(&:blank?)
+  end
+end