1 files changed, 80 insertions, 0 deletions
diff --git a/lib/gitlab/chat/responder/slack.rb b/lib/gitlab/chat/responder/slack.rb
new file mode 100644
index 00000000000..0cf02c92a67
--- /dev/null
+++ b/lib/gitlab/chat/responder/slack.rb
@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Chat
+    module Responder
+      class Slack < Responder::Base
+        SUCCESS_COLOR = '#B3ED8E'
+        FAILURE_COLOR = '#FF5640'
+        RESPONSE_TYPE = :in_channel
+
+        # Slack breaks messages apart if they're around 4 KB in size. We use a
+        # slightly smaller limit here to account for user mentions.
+        MESSAGE_SIZE_LIMIT = 3.5.kilobytes
+
+        # Sends a response back to Slack
+        #
+        # output - The output to send back to Slack, as a Hash.
+        def send_response(output)
+          Gitlab::HTTP.post(
+            pipeline.chat_data.response_url,
+            {
+              headers: { Accept: 'application/json' },
+              body: output.to_json
+            }
+          )
+        end
+
+        # Sends the output for a build that completed successfully.
+        #
+        # output - The output produced by the chat command.
+        def success(output)
+          return if output.empty?
+
+          send_response(
+            text: message_text(limit_output(output)),
+            response_type: RESPONSE_TYPE
+          )
+        end
+
+        # Sends the output for a build that failed.
+        def failure
+          send_response(
+            text: message_text("<#{build_url}|Sorry, the build failed!>"),
+            response_type: RESPONSE_TYPE
+          )
+        end
+
+        # Returns the output to send back after a command has been scheduled.
+        def scheduled_output
+          # We return an empty message so that Slack still shows the input
+          # command, without polluting the channel with standard "The job has
+          # been scheduled" (or similar) responses.
+          { text: '' }
+        end
+
+        private
+
+        def limit_output(output)
+          if output.bytesize <= MESSAGE_SIZE_LIMIT
+            output
+          else
+            "<#{build_url}|The output is too large to be sent back directly!>"
+          end
+        end
+
+        def mention_user
+          "<@#{pipeline.chat_data.chat_name.chat_id}>"
+        end
+
+        def message_text(output)
+          "#{mention_user}: #{output}"
+        end
+
+        def build_url
+          ::Gitlab::Routing.url_helpers.project_build_url(project, build)
+        end
+      end
+    end
+  end
+end