feat: notify doers of a merge when automerging (#21553)

I found myself wondering whether a PR I scheduled for automerge was
actually merged. It was, but I didn't receive a mail notification for it
- that makes sense considering I am the doer and usually don't want to
receive such notifications. But ideally I want to receive a notification
when a PR was merged because I scheduled it for automerge.

This PR implements exactly that.

The implementation works, but I wonder if there's a way to avoid passing
the "This PR was automerged" state down so much. I tried solving this
via the database (checking if there's an automerge scheduled for this PR
when sending the notification) but that did not work reliably, probably
because sending the notification happens async and the entry might have
already been deleted. My implementation might be the most
straightforward but maybe not the most elegant.

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

18 files changed, 87 insertions, 27 deletions

diff --git a/models/activities/action.go b/models/activities/action.go
index 147511edec..cad3263c2d 100644
--- a/models/activities/action.go
+++ b/models/activities/action.go
@@ -64,6 +64,7 @@ const (
 	ActionPublishRelease                                  // 24
 	ActionPullReviewDismissed                             // 25
 	ActionPullRequestReadyForReview                       // 26
+	ActionAutoMergePullRequest                            // 27
 )
 
 // Action represents user operation type and other information to
@@ -550,7 +551,7 @@ func notifyWatchers(ctx context.Context, actions ...*Action) error {
 				if !permIssue[i] {
 					continue
 				}
-			case ActionCreatePullRequest, ActionCommentPull, ActionMergePullRequest, ActionClosePullRequest, ActionReopenPullRequest:
+			case ActionCreatePullRequest, ActionCommentPull, ActionMergePullRequest, ActionClosePullRequest, ActionReopenPullRequest, ActionAutoMergePullRequest:
 				if !permPR[i] {
 					continue
 				}
diff --git a/modules/notification/action/action.go b/modules/notification/action/action.go
index d3ff8b156e..44d115f3d7 100644
--- a/modules/notification/action/action.go
+++ b/modules/notification/action/action.go
@@ -283,6 +283,20 @@ func (*actionNotifier) NotifyMergePullRequest(pr *issues_model.PullRequest, doer
 	}
 }
 
+func (*actionNotifier) NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
+	if err := activities_model.NotifyWatchers(&activities_model.Action{
+		ActUserID: doer.ID,
+		ActUser:   doer,
+		OpType:    activities_model.ActionAutoMergePullRequest,
+		Content:   fmt.Sprintf("%d|%s", pr.Issue.Index, pr.Issue.Title),
+		RepoID:    pr.Issue.Repo.ID,
+		Repo:      pr.Issue.Repo,
+		IsPrivate: pr.Issue.Repo.IsPrivate,
+	}); err != nil {
+		log.Error("NotifyWatchers [%d]: %v", pr.ID, err)
+	}
+}
+
 func (*actionNotifier) NotifyPullRevieweDismiss(doer *user_model.User, review *issues_model.Review, comment *issues_model.Comment) {
 	reviewerName := review.Reviewer.Name
 	if len(review.OriginalAuthor) > 0 {
diff --git a/modules/notification/base/notifier.go b/modules/notification/base/notifier.go
index d6cec92e19..9edab8213f 100644
--- a/modules/notification/base/notifier.go
+++ b/modules/notification/base/notifier.go
@@ -34,7 +34,8 @@ type Notifier interface {
 	NotifyIssueChangeLabels(doer *user_model.User, issue *issues_model.Issue,
 		addedLabels, removedLabels []*issues_model.Label)
 	NotifyNewPullRequest(pr *issues_model.PullRequest, mentions []*user_model.User)
-	NotifyMergePullRequest(*issues_model.PullRequest, *user_model.User)
+	NotifyMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User)
+	NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User)
 	NotifyPullRequestSynchronized(doer *user_model.User, pr *issues_model.PullRequest)
 	NotifyPullRequestReview(pr *issues_model.PullRequest, review *issues_model.Review, comment *issues_model.Comment, mentions []*user_model.User)
 	NotifyPullRequestCodeComment(pr *issues_model.PullRequest, comment *issues_model.Comment, mentions []*user_model.User)
diff --git a/modules/notification/base/null.go b/modules/notification/base/null.go
index b113ae79e1..f051fbc26f 100644
--- a/modules/notification/base/null.go
+++ b/modules/notification/base/null.go
@@ -54,6 +54,10 @@ func (*NullNotifier) NotifyPullRequestCodeComment(pr *issues_model.PullRequest,
 func (*NullNotifier) NotifyMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
 }
 
+// NotifyAutoMergePullRequest places a place holder function
+func (*NullNotifier) NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
+}
+
 // NotifyPullRequestSynchronized places a place holder function
 func (*NullNotifier) NotifyPullRequestSynchronized(doer *user_model.User, pr *issues_model.PullRequest) {
 }
diff --git a/modules/notification/mail/mail.go b/modules/notification/mail/mail.go
index 100b4eb36f..54f561839d 100644
--- a/modules/notification/mail/mail.go
+++ b/modules/notification/mail/mail.go
@@ -153,6 +153,16 @@ func (m *mailNotifier) NotifyMergePullRequest(pr *issues_model.PullRequest, doer
 	}
 }
 
+func (m *mailNotifier) NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
+	if err := pr.LoadIssue(); err != nil {
+		log.Error("pr.LoadIssue: %v", err)
+		return
+	}
+	if err := mailer.MailParticipants(pr.Issue, doer, activities_model.ActionAutoMergePullRequest, nil); err != nil {
+		log.Error("MailParticipants: %v", err)
+	}
+}
+
 func (m *mailNotifier) NotifyPullRequestPushCommits(doer *user_model.User, pr *issues_model.PullRequest, comment *issues_model.Comment) {
 	ctx, _, finished := process.GetManager().AddContext(graceful.GetManager().HammerContext(), fmt.Sprintf("mailNotifier.NotifyPullRequestPushCommits Pull[%d] #%d in [%d]", pr.ID, pr.Index, pr.BaseRepoID))
 	defer finished()
diff --git a/modules/notification/notification.go b/modules/notification/notification.go
index 693c7f5c22..7bdc0a04c4 100644
--- a/modules/notification/notification.go
+++ b/modules/notification/notification.go
@@ -98,6 +98,13 @@ func NotifyMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User)
 	}
 }
 
+// NotifyAutoMergePullRequest notifies merge pull request to notifiers
+func NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
+	for _, notifier := range notifiers {
+		notifier.NotifyAutoMergePullRequest(pr, doer)
+	}
+}
+
 // NotifyNewPullRequest notifies new pull request to notifiers
 func NotifyNewPullRequest(pr *issues_model.PullRequest, mentions []*user_model.User) {
 	for _, notifier := range notifiers {
diff --git a/modules/notification/ui/ui.go b/modules/notification/ui/ui.go
index 4d96a6b0ed..0e2b3e67c7 100644
--- a/modules/notification/ui/ui.go
+++ b/modules/notification/ui/ui.go
@@ -119,6 +119,10 @@ func (ns *notificationService) NotifyMergePullRequest(pr *issues_model.PullReque
 	})
 }
 
+func (ns *notificationService) NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
+	ns.NotifyMergePullRequest(pr, doer)
+}
+
 func (ns *notificationService) NotifyNewPullRequest(pr *issues_model.PullRequest, mentions []*user_model.User) {
 	if err := pr.LoadIssue(); err != nil {
 		log.Error("Unable to load issue: %d for pr: %d: Error: %v", pr.IssueID, pr.ID, err)
diff --git a/modules/notification/webhook/webhook.go b/modules/notification/webhook/webhook.go
index 630b565984..c591e1e34d 100644
--- a/modules/notification/webhook/webhook.go
+++ b/modules/notification/webhook/webhook.go
@@ -632,6 +632,11 @@ func (m *webhookNotifier) NotifyPushCommits(pusher *user_model.User, repo *repo_
 	}
 }
 
+func (m *webhookNotifier) NotifyAutoMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
+	// just redirect to the NotifyMergePullRequest
+	m.NotifyMergePullRequest(pr, doer)
+}
+
 func (*webhookNotifier) NotifyMergePullRequest(pr *issues_model.PullRequest, doer *user_model.User) {
 	ctx, _, finished := process.GetManager().AddContext(graceful.GetManager().HammerContext(), fmt.Sprintf("webhook.NotifyMergePullRequest Pull[%d] #%d in [%d]", pr.ID, pr.Index, pr.BaseRepoID))
 	defer finished()
diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index a723291440..a127b98dc2 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -905,7 +905,7 @@ func ActionIcon(opType activities_model.ActionType) string {
 		return "git-pull-request"
 	case activities_model.ActionCommentIssue, activities_model.ActionCommentPull:
 		return "comment-discussion"
-	case activities_model.ActionMergePullRequest:
+	case activities_model.ActionMergePullRequest, activities_model.ActionAutoMergePullRequest:
 		return "git-merge"
 	case activities_model.ActionCloseIssue, activities_model.ActionClosePullRequest:
 		return "issue-closed"
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index ac2b2ecc99..8ffb7a5b20 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -3003,6 +3003,7 @@ reopen_pull_request = `reopened pull request <a href="%[1]s">%[3]s#%[2]s</a>`
 comment_issue = `commented on issue <a href="%[1]s">%[3]s#%[2]s</a>`
 comment_pull = `commented on pull request <a href="%[1]s">%[3]s#%[2]s</a>`
 merge_pull_request = `merged pull request <a href="%[1]s">%[3]s#%[2]s</a>`
+auto_merge_pull_request = `automatically merged pull request <a href="%[1]s">%[3]s#%[2]s</a>`
 transfer_repo = transferred repository <code>%s</code> to <a href="%s">%s</a>
 push_tag = pushed tag <a href="%[2]s">%[3]s</a> to <a href="%[1]s">%[4]s</a>
 delete_tag = deleted tag %[2]s from <a href="%[1]s">%[3]s</a>
diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index ebb9c0f261..f7e82dab37 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -839,7 +839,7 @@ func MergePullRequest(ctx *context.APIContext) {
 		}
 	}
 
-	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message); err != nil {
+	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message, false); err != nil {
 		if models.IsErrInvalidMergeStyle(err) {
 			ctx.Error(http.StatusMethodNotAllowed, "Invalid merge style", fmt.Errorf("%s is not allowed an allowed merge style for this repository", repo_model.MergeStyle(form.Do)))
 		} else if models.IsErrMergeConflicts(err) {
diff --git a/routers/web/feed/convert.go b/routers/web/feed/convert.go
index 306ecf7d6a..c6fc352b64 100644
--- a/routers/web/feed/convert.go
+++ b/routers/web/feed/convert.go
@@ -115,6 +115,12 @@ func feedActionsToFeedItems(ctx *context.Context, actions activities_model.Actio
 				link.Href = pullLink
 			}
 			title += ctx.TrHTMLEscapeArgs("action.merge_pull_request", pullLink, act.GetIssueInfos()[0], act.ShortRepoPath())
+		case activities_model.ActionAutoMergePullRequest:
+			pullLink := toPullLink(act)
+			if link.Href == "#" {
+				link.Href = pullLink
+			}
+			title += ctx.TrHTMLEscapeArgs("action.auto_merge_pull_request", pullLink, act.GetIssueInfos()[0], act.ShortRepoPath())
 		case activities_model.ActionCloseIssue:
 			issueLink := toIssueLink(act)
 			if link.Href == "#" {
@@ -221,7 +227,7 @@ func feedActionsToFeedItems(ctx *context.Context, actions activities_model.Actio
 				if len(comment) != 0 {
 					desc += "\n\n" + renderMarkdown(ctx, act, comment)
 				}
-			case activities_model.ActionMergePullRequest:
+			case activities_model.ActionMergePullRequest, activities_model.ActionAutoMergePullRequest:
 				desc = act.GetIssueInfos()[1]
 			case activities_model.ActionCloseIssue, activities_model.ActionReopenIssue, activities_model.ActionClosePullRequest, activities_model.ActionReopenPullRequest:
 				desc = act.GetIssueTitle()
diff --git a/routers/web/repo/pull.go b/routers/web/repo/pull.go
index fc95bbf240..41eac7cc39 100644
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@@ -1002,7 +1002,7 @@ func MergePullRequest(ctx *context.Context) {
 		}
 	}
 
-	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message); err != nil {
+	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message, false); err != nil {
 		if models.IsErrInvalidMergeStyle(err) {
 			ctx.Flash.Error(ctx.Tr("repo.pulls.invalid_merge_option"))
 			ctx.Redirect(issue.Link())
diff --git a/services/automerge/automerge.go b/services/automerge/automerge.go
index ca008ebfe6..3ee8af2344 100644
--- a/services/automerge/automerge.go
+++ b/services/automerge/automerge.go
@@ -257,7 +257,7 @@ func handlePull(pullID int64, sha string) {
 		defer baseGitRepo.Close()
 	}
 
-	if err := pull_service.Merge(ctx, pr, doer, baseGitRepo, scheduledPRM.MergeStyle, "", scheduledPRM.Message); err != nil {
+	if err := pull_service.Merge(ctx, pr, doer, baseGitRepo, scheduledPRM.MergeStyle, "", scheduledPRM.Message, true); err != nil {
 		log.Error("pull_service.Merge: %v", err)
 		return
 	}
diff --git a/services/mailer/mail.go b/services/mailer/mail.go
index a5bfa496f9..85a7d107e5 100644
--- a/services/mailer/mail.go
+++ b/services/mailer/mail.go
@@ -340,7 +340,7 @@ func createReference(issue *issues_model.Issue, comment *issues_model.Comment, a
 			extra = fmt.Sprintf("/close/%d", time.Now().UnixNano()/1e6)
 		case activities_model.ActionReopenIssue, activities_model.ActionReopenPullRequest:
 			extra = fmt.Sprintf("/reopen/%d", time.Now().UnixNano()/1e6)
-		case activities_model.ActionMergePullRequest:
+		case activities_model.ActionMergePullRequest, activities_model.ActionAutoMergePullRequest:
 			extra = fmt.Sprintf("/merge/%d", time.Now().UnixNano()/1e6)
 		case activities_model.ActionPullRequestReadyForReview:
 			extra = fmt.Sprintf("/ready/%d", time.Now().UnixNano()/1e6)
@@ -451,7 +451,7 @@ func actionToTemplate(issue *issues_model.Issue, actionType activities_model.Act
 		name = "close"
 	case activities_model.ActionReopenIssue, activities_model.ActionReopenPullRequest:
 		name = "reopen"
-	case activities_model.ActionMergePullRequest:
+	case activities_model.ActionMergePullRequest, activities_model.ActionAutoMergePullRequest:
 		name = "merge"
 	case activities_model.ActionPullReviewDismissed:
 		name = "review_dismissed"
diff --git a/services/mailer/mail_issue.go b/services/mailer/mail_issue.go
index 33a20694e8..61e276805d 100644
--- a/services/mailer/mail_issue.go
+++ b/services/mailer/mail_issue.go
@@ -25,11 +25,12 @@ func fallbackMailSubject(issue *issues_model.Issue) string {
 
 type mailCommentContext struct {
 	context.Context
-	Issue      *issues_model.Issue
-	Doer       *user_model.User
-	ActionType activities_model.ActionType
-	Content    string
-	Comment    *issues_model.Comment
+	Issue                 *issues_model.Issue
+	Doer                  *user_model.User
+	ActionType            activities_model.ActionType
+	Content               string
+	Comment               *issues_model.Comment
+	ForceDoerNotification bool
 }
 
 const (
@@ -93,7 +94,7 @@ func mailIssueCommentToParticipants(ctx *mailCommentContext, mentions []*user_mo
 	visited := make(container.Set[int64], len(unfiltered)+len(mentions)+1)
 
 	// Avoid mailing the doer
-	if ctx.Doer.EmailNotificationsPreference != user_model.EmailNotificationsAndYourOwn {
+	if ctx.Doer.EmailNotificationsPreference != user_model.EmailNotificationsAndYourOwn && !ctx.ForceDoerNotification {
 		visited.Add(ctx.Doer.ID)
 	}
 
@@ -181,17 +182,19 @@ func MailParticipants(issue *issues_model.Issue, doer *user_model.User, opType a
 	content := issue.Content
 	if opType == activities_model.ActionCloseIssue || opType == activities_model.ActionClosePullRequest ||
 		opType == activities_model.ActionReopenIssue || opType == activities_model.ActionReopenPullRequest ||
-		opType == activities_model.ActionMergePullRequest {
+		opType == activities_model.ActionMergePullRequest || opType == activities_model.ActionAutoMergePullRequest {
 		content = ""
 	}
+	forceDoerNotification := opType == activities_model.ActionAutoMergePullRequest
 	if err := mailIssueCommentToParticipants(
 		&mailCommentContext{
-			Context:    context.TODO(), // TODO: use a correct context
-			Issue:      issue,
-			Doer:       doer,
-			ActionType: opType,
-			Content:    content,
-			Comment:    nil,
+			Context:               context.TODO(), // TODO: use a correct context
+			Issue:                 issue,
+			Doer:                  doer,
+			ActionType:            opType,
+			Content:               content,
+			Comment:               nil,
+			ForceDoerNotification: forceDoerNotification,
 		}, mentions); err != nil {
 		log.Error("mailIssueCommentToParticipants: %v", err)
 	}
diff --git a/services/pull/merge.go b/services/pull/merge.go
index 0ca3730183..56ee9c9a73 100644
--- a/services/pull/merge.go
+++ b/services/pull/merge.go
@@ -133,7 +133,7 @@ func GetDefaultMergeMessage(baseGitRepo *git.Repository, pr *issues_model.PullRe
 
 // Merge merges pull request to base repository.
 // Caller should check PR is ready to be merged (review and status checks)
-func Merge(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User, baseGitRepo *git.Repository, mergeStyle repo_model.MergeStyle, expectedHeadCommitID, message string) error {
+func Merge(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User, baseGitRepo *git.Repository, mergeStyle repo_model.MergeStyle, expectedHeadCommitID, message string, wasAutoMerged bool) error {
 	if err := pr.LoadHeadRepo(); err != nil {
 		log.Error("LoadHeadRepo: %v", err)
 		return fmt.Errorf("LoadHeadRepo: %w", err)
@@ -193,7 +193,11 @@ func Merge(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.U
 		log.Error("GetOwner for issue repo [%d]: %v", pr.ID, err)
 	}
 
-	notification.NotifyMergePullRequest(pr, doer)
+	if wasAutoMerged {
+		notification.NotifyAutoMergePullRequest(pr, doer)
+	} else {
+		notification.NotifyMergePullRequest(pr, doer)
+	}
 
 	// Reset cached commit count
 	cache.Remove(pr.Issue.Repo.GetCommitsCountCacheKey(pr.BaseBranch, true))
diff --git a/tests/integration/pull_merge_test.go b/tests/integration/pull_merge_test.go
index 9bd430084d..bec85e8a8d 100644
--- a/tests/integration/pull_merge_test.go
+++ b/tests/integration/pull_merge_test.go
@@ -245,11 +245,11 @@ func TestCantMergeConflict(t *testing.T) {
 		gitRepo, err := git.OpenRepository(git.DefaultContext, repo_model.RepoPath(user1.Name, repo1.Name))
 		assert.NoError(t, err)
 
-		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "CONFLICT")
+		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "CONFLICT", false)
 		assert.Error(t, err, "Merge should return an error due to conflict")
 		assert.True(t, models.IsErrMergeConflicts(err), "Merge error is not a conflict error")
 
-		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleRebase, "", "CONFLICT")
+		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleRebase, "", "CONFLICT", false)
 		assert.Error(t, err, "Merge should return an error due to conflict")
 		assert.True(t, models.IsErrRebaseConflicts(err), "Merge error is not a conflict error")
 		gitRepo.Close()
@@ -344,7 +344,7 @@ func TestCantMergeUnrelated(t *testing.T) {
 			BaseBranch: "base",
 		})
 
-		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "UNRELATED")
+		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "UNRELATED", false)
 		assert.Error(t, err, "Merge should return an error due to unrelated")
 		assert.True(t, models.IsErrMergeUnrelatedHistories(err), "Merge error is not a unrelated histories error")
 		gitRepo.Close()