1 files changed, 95 insertions, 0 deletions
diff --git a/lib/gitlab/github_gists_import/importer/gists_importer.rb b/lib/gitlab/github_gists_import/importer/gists_importer.rb
new file mode 100644
index 00000000000..08744dbaf5f
--- /dev/null
+++ b/lib/gitlab/github_gists_import/importer/gists_importer.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GithubGistsImport
+    module Importer
+      class GistsImporter
+        attr_reader :user, :client, :already_imported_cache_key
+
+        ALREADY_IMPORTED_CACHE_KEY = 'github-gists-importer/already-imported/%{user}'
+        RESULT_CONTEXT = Struct.new(:success?, :error, :waiter, :next_attempt_in, keyword_init: true)
+
+        def initialize(user, token)
+          @user = user
+          @client = Gitlab::GithubImport::Client.new(token, parallel: true)
+          @already_imported_cache_key = format(ALREADY_IMPORTED_CACHE_KEY, user: user.id)
+        end
+
+        def execute
+          waiter = spread_parallel_import
+
+          expire_already_imported_cache!
+
+          RESULT_CONTEXT.new(success?: true, waiter: waiter)
+        rescue Gitlab::GithubImport::RateLimitError => e
+          RESULT_CONTEXT.new(success?: false, error: e, next_attempt_in: client.rate_limit_resets_in)
+        rescue StandardError => e
+          RESULT_CONTEXT.new(success?: false, error: e)
+        end
+
+        private
+
+        def spread_parallel_import
+          waiter = JobWaiter.new
+          worker_arguments = fetch_gists_to_import.map { |gist_hash| [user.id, gist_hash, waiter.key] }
+          waiter.jobs_remaining = worker_arguments.size
+
+          schedule_bulk_perform(worker_arguments)
+          waiter
+        end
+
+        def fetch_gists_to_import
+          page_counter = Gitlab::GithubImport::PageCounter.new(user, :gists, 'github-gists-importer')
+          collection = []
+
+          client.each_page(:gists, nil, page: page_counter.current) do |page|
+            next unless page_counter.set(page.number)
+
+            collection += gists_from(page)
+          end
+
+          page_counter.expire!
+
+          collection
+        end
+
+        def gists_from(page)
+          page.objects.each.with_object([]) do |gist, page_collection|
+            gist = gist.to_h
+            next if already_imported?(gist)
+
+            page_collection << ::Gitlab::GithubGistsImport::Representation::Gist.from_api_response(gist).to_hash
+
+            mark_as_imported(gist)
+          end
+        end
+
+        def schedule_bulk_perform(worker_arguments)
+          # rubocop:disable Scalability/BulkPerformWithContext
+          Gitlab::ApplicationContext.with_context(user: user) do
+            Gitlab::GithubGistsImport::ImportGistWorker.bulk_perform_in(
+              1.second,
+              worker_arguments,
+              batch_size: 1000,
+              batch_delay: 1.minute
+            )
+          end
+          # rubocop:enable Scalability/BulkPerformWithContext
+        end
+
+        def already_imported?(gist)
+          Gitlab::Cache::Import::Caching.set_includes?(already_imported_cache_key, gist[:id])
+        end
+
+        def mark_as_imported(gist)
+          Gitlab::Cache::Import::Caching.set_add(already_imported_cache_key, gist[:id])
+        end
+
+        def expire_already_imported_cache!
+          Gitlab::Cache::Import::Caching
+            .expire(already_imported_cache_key, Gitlab::Cache::Import::Caching::SHORTER_TIMEOUT)
+        end
+      end
+    end
+  end
+end