1 files changed, 131 insertions, 0 deletions
diff --git a/lib/gitlab/chat/responder/mattermost.rb b/lib/gitlab/chat/responder/mattermost.rb
new file mode 100644
index 00000000000..0488c98e422
--- /dev/null
+++ b/lib/gitlab/chat/responder/mattermost.rb
@@ -0,0 +1,131 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Chat
+    module Responder
+      class Mattermost < Responder::Base
+        SUCCESS_COLOR = '#00c100'
+        FAILURE_COLOR = '#e40303'
+
+        # 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 Mattermost
+        #
+        # body - The message payload to send back to Mattermost, as a Hash.
+        def send_response(body)
+          Gitlab::HTTP.post(
+            pipeline.chat_data.response_url,
+            {
+              headers: { 'Content-Type': 'application/json' },
+              body: body.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(
+            response_type: :in_channel,
+            attachments: [
+              {
+                color: SUCCESS_COLOR,
+                text: "ChatOps job started by #{user_ref} completed successfully",
+                fields: [
+                  {
+                    short: true,
+                    title: "ID",
+                    value: "#{build_ref}"
+                  },
+                  {
+                    short: true,
+                    title: "Name",
+                    value: build.name
+                  },
+                  {
+                    short: false,
+                    title: "Output",
+                    value: success_message(output)
+                  }
+                ]
+              }
+            ]
+          )
+        end
+
+        # Sends the output for a build that failed.
+        def failure
+          send_response(
+            response_type: :in_channel,
+            attachments: [
+              {
+                color: FAILURE_COLOR,
+                text: "ChatOps job started by #{user_ref} failed!",
+                fields: [
+                  {
+                    short: true,
+                    title: "ID",
+                    value: "#{build_ref}"
+                  },
+                  {
+                    short: true,
+                    title: "Name",
+                    value: build.name
+                  }
+                ]
+              }
+            ]
+          )
+        end
+
+        # Returns the output to send back after a command has been scheduled.
+        def scheduled_output
+          {
+            response_type: :ephemeral,
+            text: "Your ChatOps job #{build_ref} has been created!"
+          }
+        end
+
+        private
+
+        def success_message(output)
+          <<~HEREDOC.chomp
+            ```shell
+            #{strip_ansi_colorcodes(limit_output(output))}
+            ```
+          HEREDOC
+        end
+
+        def limit_output(output)
+          if output.bytesize <= MESSAGE_SIZE_LIMIT
+            output
+          else
+            "The output is too large to be sent back directly!"
+          end
+        end
+
+        def strip_ansi_colorcodes(output)
+          output.gsub(/\x1b\[[0-9;]*m/, '')
+        end
+
+        def user_ref
+          user = pipeline.chat_data.chat_name.user
+          user_url = ::Gitlab::Routing.url_helpers.user_url(user)
+
+          "[#{user.name}](#{user_url})"
+        end
+
+        def build_ref
+          build_url = ::Gitlab::Routing.url_helpers.project_build_url(project, build)
+
+          "[##{build.id}](#{build_url})"
+        end
+      end
+    end
+  end
+end