1 files changed, 101 insertions, 0 deletions
diff --git a/app/services/packages/nuget/search_service.rb b/app/services/packages/nuget/search_service.rb
new file mode 100644
index 00000000000..f7e09e11819
--- /dev/null
+++ b/app/services/packages/nuget/search_service.rb
@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+module Packages
+  module Nuget
+    class SearchService < BaseService
+      include Gitlab::Utils::StrongMemoize
+      include ActiveRecord::ConnectionAdapters::Quoting
+
+      MAX_PER_PAGE = 30
+      MAX_VERSIONS_PER_PACKAGE = 10
+      PRE_RELEASE_VERSION_MATCHING_TERM = '%-%'
+
+      DEFAULT_OPTIONS = {
+        include_prerelease_versions: true,
+        per_page: Kaminari.config.default_per_page,
+        padding: 0
+      }.freeze
+
+      def initialize(project, search_term, options = {})
+        @project = project
+        @search_term = search_term
+        @options = DEFAULT_OPTIONS.merge(options)
+
+        raise ArgumentError, 'negative per_page' if per_page.negative?
+        raise ArgumentError, 'negative padding' if padding.negative?
+      end
+
+      def execute
+        OpenStruct.new(
+          total_count: package_names.total_count,
+          results: search_packages
+        )
+      end
+
+      private
+
+      def search_packages
+        # custom query to get package names and versions as expected from the nuget search api
+        # See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/24182#technical-notes
+        # and https://docs.microsoft.com/en-us/nuget/api/search-query-service-resource
+        subquery_name = :partition_subquery
+        arel_table = Arel::Table.new(:partition_subquery)
+        column_names = Packages::Package.column_names.map do |cn|
+          "#{subquery_name}.#{quote_column_name(cn)}"
+        end
+
+        # rubocop: disable CodeReuse/ActiveRecord
+        pkgs = Packages::Package.select(column_names.join(','))
+                                .from(package_names_partition, subquery_name)
+                                .where(arel_table[:row_number].lteq(MAX_VERSIONS_PER_PACKAGE))
+
+        return pkgs if include_prerelease_versions?
+
+        # we can't use pkgs.without_version_like since we have a custom from
+        pkgs.where.not(arel_table[:version].matches(PRE_RELEASE_VERSION_MATCHING_TERM))
+      end
+
+      def package_names_partition
+        table_name = quote_table_name(Packages::Package.table_name)
+        name_column = "#{table_name}.#{quote_column_name('name')}"
+        created_at_column = "#{table_name}.#{quote_column_name('created_at')}"
+        select_sql = "ROW_NUMBER() OVER (PARTITION BY #{name_column} ORDER BY #{created_at_column} DESC) AS row_number, #{table_name}.*"
+
+        @project.packages
+                .select(select_sql)
+                .nuget
+                .has_version
+                .without_nuget_temporary_name
+                .with_name(package_names)
+      end
+
+      def package_names
+        strong_memoize(:package_names) do
+          pkgs = @project.packages
+                         .nuget
+                         .has_version
+                         .without_nuget_temporary_name
+                         .order_name
+                         .select_distinct_name
+          pkgs = pkgs.without_version_like(PRE_RELEASE_VERSION_MATCHING_TERM) unless include_prerelease_versions?
+          pkgs = pkgs.search_by_name(@search_term) if @search_term.present?
+          pkgs.page(0) # we're using a padding
+              .per(per_page)
+              .padding(padding)
+        end
+      end
+
+      def include_prerelease_versions?
+        @options[:include_prerelease_versions]
+      end
+
+      def padding
+        @options[:padding]
+      end
+
+      def per_page
+        [@options[:per_page], MAX_PER_PAGE].min
+      end
+    end
+  end
+end