Allow custom default merge message with .gitea/default_merge_message/<merge_style>_TEMPLATE.md (#18177)

* Allow custom default merge message with .gitea/MERGE_MESSAGE_<merge_style>_TEMPLATE.md

* Some improvements

* Follow some advices

* Fix bug

* Fix bug

* Fix lint

* Fix close comment

* Fix test

* Fix and docs

* Improve codes

* Update docs and remove unnecessary variables

* return error for GetDefaultMergeMessage

* Fix test

* improve code

* ignore unknow unit type

* return error for GetDefaultMergeMessage

* Update services/pull/merge.go

* Some improvements

* Follow some advices

* Fix bug

* Fix lint

* Improve codes

* Update docs and remove unnecessary variables

* return error for GetDefaultMergeMessage

* improve code

* Handle deleted HeadRepo in GetDefaultMergeMessage

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix test

* Fix test

Co-authored-by: zeripath <art27@cantab.net>

4 files changed, 162 insertions, 35 deletions

diff --git a/services/automerge/automerge.go b/services/automerge/automerge.go
index 389546ed57..e098f2cec0 100644
--- a/services/automerge/automerge.go
+++ b/services/automerge/automerge.go
@@ -234,7 +234,7 @@ func handlePull(pullID int64, sha string) {
 		defer baseGitRepo.Close()
 	}
 
-	if err := pull_service.Merge(pr, doer, baseGitRepo, scheduledPRM.MergeStyle, "", scheduledPRM.Message); err != nil {
+	if err := pull_service.Merge(ctx, pr, doer, baseGitRepo, scheduledPRM.MergeStyle, "", scheduledPRM.Message); err != nil {
 		log.Error("pull_service.Merge: %v", err)
 		return
 	}
diff --git a/services/forms/repo_form.go b/services/forms/repo_form.go
index bacee9a13c..6c61ed00ec 100644
--- a/services/forms/repo_form.go
+++ b/services/forms/repo_form.go
@@ -6,7 +6,6 @@
 package forms
 
 import (
-	stdContext "context"
 	"net/http"
 	"net/url"
 	"strings"
@@ -602,31 +601,6 @@ func (f *MergePullRequestForm) Validate(req *http.Request, errs binding.Errors)
 	return middleware.Validate(errs, ctx.Data, f, ctx.Locale)
 }
 
-// SetDefaults if not provided for mergestyle and commit message
-func (f *MergePullRequestForm) SetDefaults(ctx stdContext.Context, pr *models.PullRequest) (err error) {
-	if f.Do == "" {
-		f.Do = "merge"
-	}
-
-	f.MergeTitleField = strings.TrimSpace(f.MergeTitleField)
-	if len(f.MergeTitleField) == 0 {
-		switch f.Do {
-		case "merge", "rebase-merge":
-			f.MergeTitleField, err = pr.GetDefaultMergeMessage(ctx)
-		case "squash":
-			f.MergeTitleField, err = pr.GetDefaultSquashMessage(ctx)
-		}
-	}
-
-	f.MergeMessageField = strings.TrimSpace(f.MergeMessageField)
-	if len(f.MergeMessageField) > 0 {
-		f.MergeTitleField += "\n\n" + f.MergeMessageField
-		f.MergeMessageField = ""
-	}
-
-	return
-}
-
 // CodeCommentForm form for adding code comments for PRs
 type CodeCommentForm struct {
 	Origin         string `binding:"Required;In(timeline,diff)"`
diff --git a/services/pull/merge.go b/services/pull/merge.go
index 8cc4d88888..b14abcd780 100644
--- a/services/pull/merge.go
+++ b/services/pull/merge.go
@@ -13,6 +13,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
@@ -33,9 +34,101 @@ import (
 	issue_service "code.gitea.io/gitea/services/issue"
 )
 
+// GetDefaultMergeMessage returns default message used when merging pull request
+func GetDefaultMergeMessage(baseGitRepo *git.Repository, pr *models.PullRequest, mergeStyle repo_model.MergeStyle) (string, error) {
+	if err := pr.LoadHeadRepo(); err != nil {
+		return "", err
+	}
+	if err := pr.LoadBaseRepo(); err != nil {
+		return "", err
+	}
+	if pr.BaseRepo == nil {
+		return "", repo_model.ErrRepoNotExist{ID: pr.BaseRepoID}
+	}
+
+	if err := pr.LoadIssue(); err != nil {
+		return "", err
+	}
+
+	isExternalTracker := pr.BaseRepo.UnitEnabled(unit.TypeExternalTracker)
+	issueReference := "#"
+	if isExternalTracker {
+		issueReference = "!"
+	}
+
+	if mergeStyle != "" {
+		templateFilepath := fmt.Sprintf(".gitea/default_merge_message/%s_TEMPLATE.md", strings.ToUpper(string(mergeStyle)))
+		commit, err := baseGitRepo.GetBranchCommit(pr.BaseRepo.DefaultBranch)
+		if err != nil {
+			return "", err
+		}
+		templateContent, err := commit.GetFileContent(templateFilepath, setting.Repository.PullRequest.DefaultMergeMessageSize)
+		if err != nil {
+			if !git.IsErrNotExist(err) {
+				return "", err
+			}
+		} else {
+			vars := map[string]string{
+				"BaseRepoOwnerName":      pr.BaseRepo.OwnerName,
+				"BaseRepoName":           pr.BaseRepo.Name,
+				"BaseBranch":             pr.BaseBranch,
+				"HeadRepoOwnerName":      "",
+				"HeadRepoName":           "",
+				"HeadBranch":             pr.HeadBranch,
+				"PullRequestTitle":       pr.Issue.Title,
+				"PullRequestDescription": pr.Issue.Content,
+				"PullRequestPosterName":  pr.Issue.Poster.Name,
+				"PullRequestIndex":       strconv.FormatInt(pr.Index, 10),
+				"PullRequestReference":   fmt.Sprintf("%s%d", issueReference, pr.Index),
+			}
+			if pr.HeadRepo != nil {
+				vars["HeadRepoOwnerName"] = pr.HeadRepo.OwnerName
+				vars["HeadRepoName"] = pr.HeadRepo.Name
+			}
+			refs, err := pr.ResolveCrossReferences(baseGitRepo.Ctx)
+			if err == nil {
+				closeIssueIndexes := make([]string, 0, len(refs))
+				closeWord := "close"
+				if len(setting.Repository.PullRequest.CloseKeywords) > 0 {
+					closeWord = setting.Repository.PullRequest.CloseKeywords[0]
+				}
+				for _, ref := range refs {
+					if ref.RefAction == references.XRefActionCloses {
+						closeIssueIndexes = append(closeIssueIndexes, fmt.Sprintf("%s %s%d", closeWord, issueReference, ref.Issue.Index))
+					}
+				}
+				if len(closeIssueIndexes) > 0 {
+					vars["ClosingIssues"] = strings.Join(closeIssueIndexes, ", ")
+				} else {
+					vars["ClosingIssues"] = ""
+				}
+			}
+
+			return os.Expand(templateContent, func(s string) string {
+				return vars[s]
+			}), nil
+		}
+	}
+
+	// Squash merge has a different from other styles.
+	if mergeStyle == repo_model.MergeStyleSquash {
+		return fmt.Sprintf("%s (%s%d)", pr.Issue.Title, issueReference, pr.Issue.Index), nil
+	}
+
+	if pr.BaseRepoID == pr.HeadRepoID {
+		return fmt.Sprintf("Merge pull request '%s' (%s%d) from %s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadBranch, pr.BaseBranch), nil
+	}
+
+	if pr.HeadRepo == nil {
+		return fmt.Sprintf("Merge pull request '%s' (%s%d) from <deleted>:%s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadBranch, pr.BaseBranch), nil
+	}
+
+	return fmt.Sprintf("Merge pull request '%s' (%s%d) from %s:%s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseBranch), nil
+}
+
 // Merge merges pull request to base repository.
 // Caller should check PR is ready to be merged (review and status checks)
-func Merge(pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repository, mergeStyle repo_model.MergeStyle, expectedHeadCommitID, message string) error {
+func Merge(ctx context.Context, pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repository, mergeStyle repo_model.MergeStyle, expectedHeadCommitID, message string) error {
 	if err := pr.LoadHeadRepo(); err != nil {
 		log.Error("LoadHeadRepo: %v", err)
 		return fmt.Errorf("LoadHeadRepo: %v", err)
@@ -79,18 +172,18 @@ func Merge(pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repos
 	pr.Merger = doer
 	pr.MergerID = doer.ID
 
-	if _, err := pr.SetMerged(db.DefaultContext); err != nil {
+	if _, err := pr.SetMerged(ctx); err != nil {
 		log.Error("setMerged [%d]: %v", pr.ID, err)
 	}
 
-	if err := pr.LoadIssueCtx(db.DefaultContext); err != nil {
+	if err := pr.LoadIssueCtx(ctx); err != nil {
 		log.Error("loadIssue [%d]: %v", pr.ID, err)
 	}
 
-	if err := pr.Issue.LoadRepo(db.DefaultContext); err != nil {
+	if err := pr.Issue.LoadRepo(ctx); err != nil {
 		log.Error("loadRepo for issue [%d]: %v", pr.ID, err)
 	}
-	if err := pr.Issue.Repo.GetOwner(db.DefaultContext); err != nil {
+	if err := pr.Issue.Repo.GetOwner(ctx); err != nil {
 		log.Error("GetOwner for issue repo [%d]: %v", pr.ID, err)
 	}
 
@@ -100,17 +193,17 @@ func Merge(pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repos
 	cache.Remove(pr.Issue.Repo.GetCommitsCountCacheKey(pr.BaseBranch, true))
 
 	// Resolve cross references
-	refs, err := pr.ResolveCrossReferences(db.DefaultContext)
+	refs, err := pr.ResolveCrossReferences(ctx)
 	if err != nil {
 		log.Error("ResolveCrossReferences: %v", err)
 		return nil
 	}
 
 	for _, ref := range refs {
-		if err = ref.LoadIssueCtx(db.DefaultContext); err != nil {
+		if err = ref.LoadIssueCtx(ctx); err != nil {
 			return err
 		}
-		if err = ref.Issue.LoadRepo(db.DefaultContext); err != nil {
+		if err = ref.Issue.LoadRepo(ctx); err != nil {
 			return err
 		}
 		close := ref.RefAction == references.XRefActionCloses
diff --git a/services/pull/pull_test.go b/services/pull/pull_test.go
index 81627ebb77..09bae97780 100644
--- a/services/pull/pull_test.go
+++ b/services/pull/pull_test.go
@@ -8,6 +8,12 @@ package pull
 import (
 	"testing"
 
+	"code.gitea.io/gitea/models"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/git"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -29,3 +35,57 @@ func TestPullRequest_CommitMessageTrailersPattern(t *testing.T) {
 	assert.True(t, commitMessageTrailersPattern.MatchString("Additional whitespace is accepted.\n\nSigned-off-by \t :  \tBob   <bob@example.com>   "))
 	assert.True(t, commitMessageTrailersPattern.MatchString("Folded value.\n\nFolded-trailer: This is\n a folded\n   trailer value\nOther-Trailer: Value"))
 }
+
+func TestPullRequest_GetDefaultMergeMessage_InternalTracker(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	pr := unittest.AssertExistsAndLoadBean(t, &models.PullRequest{ID: 2}).(*models.PullRequest)
+
+	assert.NoError(t, pr.LoadBaseRepo())
+	gitRepo, err := git.OpenRepository(git.DefaultContext, pr.BaseRepo.RepoPath())
+	assert.NoError(t, err)
+	defer gitRepo.Close()
+
+	mergeMessage, err := GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from branch2 into master", mergeMessage)
+
+	pr.BaseRepoID = 1
+	pr.HeadRepoID = 2
+	mergeMessage, err = GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo1:branch2 into master", mergeMessage)
+}
+
+func TestPullRequest_GetDefaultMergeMessage_ExternalTracker(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	externalTracker := repo_model.RepoUnit{
+		Type: unit.TypeExternalTracker,
+		Config: &repo_model.ExternalTrackerConfig{
+			ExternalTrackerFormat: "https://someurl.com/{user}/{repo}/{issue}",
+		},
+	}
+	baseRepo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1}).(*repo_model.Repository)
+	baseRepo.Units = []*repo_model.RepoUnit{&externalTracker}
+
+	pr := unittest.AssertExistsAndLoadBean(t, &models.PullRequest{ID: 2, BaseRepo: baseRepo}).(*models.PullRequest)
+
+	assert.NoError(t, pr.LoadBaseRepo())
+	gitRepo, err := git.OpenRepository(git.DefaultContext, pr.BaseRepo.RepoPath())
+	assert.NoError(t, err)
+	defer gitRepo.Close()
+
+	mergeMessage, err := GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+
+	assert.Equal(t, "Merge pull request 'issue3' (!3) from branch2 into master", mergeMessage)
+
+	pr.BaseRepoID = 1
+	pr.HeadRepoID = 2
+	pr.BaseRepo = nil
+	pr.HeadRepo = nil
+	mergeMessage, err = GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo2:branch2 into master", mergeMessage)
+}