1 files changed, 34 insertions, 0 deletions
diff --git a/lib/gitlab/ci/cron_parser.rb b/lib/gitlab/ci/cron_parser.rb
new file mode 100644
index 00000000000..a3cc350ef22
--- /dev/null
+++ b/lib/gitlab/ci/cron_parser.rb
@@ -0,0 +1,34 @@
+module Gitlab
+  module Ci
+    class CronParser
+      VALID_SYNTAX_SAMPLE_TIME_ZONE = 'UTC'.freeze
+      VALID_SYNTAX_SAMPLE_CRON = '* * * * *'.freeze
+
+      def initialize(cron, cron_timezone = 'UTC')
+        @cron = cron
+        @cron_timezone = cron_timezone
+      end
+
+      def next_time_from(time)
+        @cron_line ||= try_parse_cron(@cron, @cron_timezone)
+        @cron_line.next_time(time).in_time_zone(Time.zone) if @cron_line.present?
+      end
+
+      def cron_valid?
+        try_parse_cron(@cron, VALID_SYNTAX_SAMPLE_TIME_ZONE).present?
+      end
+
+      def cron_timezone_valid?
+        try_parse_cron(VALID_SYNTAX_SAMPLE_CRON, @cron_timezone).present?
+      end
+
+      private
+
+      def try_parse_cron(cron, cron_timezone)
+        Rufus::Scheduler.parse("#{cron} #{cron_timezone}")
+      rescue
+        # noop
+      end
+    end
+  end
+end