mr_edit: Support (un)marking merge requests as draft

Gitlab supports marking a merge request as draft to indicate that it is
not ready to be merged. This is supported in the web UI (actions to mark
as draft/ready, disabled merge button in draft MRs), but not explicitly
exposed in the API: Drafts are simply indicated by prefixing the MR title
with "Draft:", "[Draft]" or "(Draft)" (or previously "WIP)[0].

lab therefore kind of supports the feature already, but it still seems
reasonable to export the feature explicitly rather than via manipulating
the title (although that's of course what the implementation does under
the hood).

[0] https://docs.gitlab.com/ee/user/project/merge_requests/work_in_progress_merge_requests.html

cmd/mr_edit.go

@@ -98,6 +98,20 @@ lab MR edit <id>:<comment_id>                   # update a comment on MR`,
 			log.Fatal(err)
 		}
 
+		draft, err := cmd.Flags().GetBool("draft")
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		ready, err := cmd.Flags().GetBool("ready")
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if draft && ready {
+			log.Fatal("--draft and --ready cannot be used together")
+		}
+
 		currentAssignees := mrGetCurrentAssignees(mr)
 		assigneeIDs, assigneesChanged, err := getUpdateAssignees(currentAssignees, assignees, unassignees)
 		if err != nil {
@@ -118,6 +132,29 @@ lab MR edit <id>:<comment_id>                   # update a comment on MR`,
 			log.Fatal("aborting: empty mr title")
 		}
 
+		isWIP := strings.EqualFold(title[0:4], "wip:")
+		isDraft := strings.EqualFold(title[0:6], "draft:") ||
+			strings.EqualFold(title[0:7], "[draft]") ||
+			strings.EqualFold(title[0:7], "(draft)")
+
+		if ready {
+			if isWIP {
+				title = strings.TrimPrefix(title, title[0:4])
+			} else if isDraft {
+				if title[0] == '(' || title[0] == '[' {
+					title = strings.TrimPrefix(title, title[0:7])
+				} else {
+					title = strings.TrimPrefix(title, title[0:6])
+				}
+			}
+		}
+
+		if draft {
+			if !isWIP && !isDraft {
+				title = "Draft: " + title
+			}
+		}
+
 		abortUpdate := title == mr.Title && body == mr.Description && !labelsChanged && !assigneesChanged
 		if abortUpdate {
 			log.Fatal("aborting: no changes")
@@ -167,6 +204,8 @@ func init() {
 	mrEditCmd.Flags().StringSliceP("assign", "a", []string{}, "add an assignee by username")
 	mrEditCmd.Flags().StringSliceP("unassign", "", []string{}, "remove an assignee by username")
 	mrEditCmd.Flags().Bool("force-linebreak", false, "append 2 spaces to the end of each line to force markdown linebreaks")
+	mrEditCmd.Flags().Bool("draft", false, "mark the merge request as draft")
+	mrEditCmd.Flags().Bool("ready", false, "mark the merge request as ready")
 
 	mrCmd.AddCommand(mrEditCmd)
 	carapace.Gen(mrEditCmd).PositionalCompletion(