Make manual merge autodetection optional and add manual merge as merge method (#12543)

* Make auto check manual merge as a chooseable mod and add manual merge way on ui

as title, Before this pr, we use same way with GH to check manually merge.
It good, but in some special cases, misjudgments can occur. and it's hard
to fix this bug. So I add option to allow repo manager block "auto check manual merge"
function, Then it will have same style like gitlab(allow empty pr). and to compensate for
not being able to detect THE PR merge automatically, I added a manual approach.

Signed-off-by: a1012112796 <1012112796@qq.com>

* make swager

* api support

* ping ci

* fix TestPullCreate_EmptyChangesWithCommits

* Apply suggestions from code review

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

* Apply review suggestions and add test

* Apply suggestions from code review

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

* fix build

* test error message

* make fmt

* Fix indentation issues identified by @silverwind

Co-authored-by: silverwind <me@silverwind.io>

* Fix tests and make manually merged disabled error on API the same

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

* a small nit

* fix wrong commit id error

* fix bug

* simple test

* fix test

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

4 files changed, 56 insertions, 6 deletions

diff --git a/routers/repo/compare.go b/routers/repo/compare.go
index 2eef20f5ff..a8f4f8add8 100644
--- a/routers/repo/compare.go
+++ b/routers/repo/compare.go
@@ -429,6 +429,14 @@ func PrepareCompareDiff(
 
 	if headCommitID == compareInfo.MergeBase {
 		ctx.Data["IsNothingToCompare"] = true
+		if unit, err := repo.GetUnit(models.UnitTypePullRequests); err == nil {
+			config := unit.PullRequestsConfig()
+			if !config.AutodetectManualMerge {
+				ctx.Data["AllowEmptyPr"] = !(baseBranch == headBranch && ctx.Repo.Repository.Name == headRepo.Name)
+			} else {
+				ctx.Data["AllowEmptyPr"] = false
+			}
+		}
 		return true
 	}
 
diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index a9459a10ed..99df9db183 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -1491,6 +1491,8 @@ func ViewIssue(ctx *context.Context) {
 				ctx.Data["MergeStyle"] = models.MergeStyleRebaseMerge
 			} else if prConfig.AllowSquash {
 				ctx.Data["MergeStyle"] = models.MergeStyleSquash
+			} else if prConfig.AllowManualMerge {
+				ctx.Data["MergeStyle"] = models.MergeStyleManuallyMerged
 			} else {
 				ctx.Data["MergeStyle"] = ""
 			}
@@ -1531,6 +1533,22 @@ func ViewIssue(ctx *context.Context) {
 			pull.HeadRepo != nil &&
 			git.IsBranchExist(pull.HeadRepo.RepoPath(), pull.HeadBranch) &&
 			(!pull.HasMerged || ctx.Data["HeadBranchCommitID"] == ctx.Data["PullHeadCommitID"])
+
+		stillCanManualMerge := func() bool {
+			if pull.HasMerged || issue.IsClosed || !ctx.IsSigned {
+				return false
+			}
+			if pull.CanAutoMerge() || pull.IsWorkInProgress() || pull.IsChecking() {
+				return false
+			}
+			if (ctx.User.IsAdmin || ctx.Repo.IsAdmin()) && prConfig.AllowManualMerge {
+				return true
+			}
+
+			return false
+		}
+
+		ctx.Data["StillCanManualMerge"] = stillCanManualMerge()
 	}
 
 	// Get Dependencies
diff --git a/routers/repo/pull.go b/routers/repo/pull.go
index 15af2a2a3f..2ed47605f8 100644
--- a/routers/repo/pull.go
+++ b/routers/repo/pull.go
@@ -33,6 +33,7 @@ import (
 	"code.gitea.io/gitea/services/gitdiff"
 	pull_service "code.gitea.io/gitea/services/pull"
 	repo_service "code.gitea.io/gitea/services/repository"
+	"github.com/unknwon/com"
 )
 
 const (
@@ -794,15 +795,36 @@ func MergePullRequest(ctx *context.Context) {
 		return
 	}
 
-	if !pr.CanAutoMerge() {
-		ctx.Flash.Error(ctx.Tr("repo.pulls.no_merge_not_ready"))
-		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + fmt.Sprint(issue.Index))
+	if pr.HasMerged {
+		ctx.Flash.Error(ctx.Tr("repo.pulls.has_merged"))
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
 		return
 	}
 
-	if pr.HasMerged {
-		ctx.Flash.Error(ctx.Tr("repo.pulls.has_merged"))
-		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + fmt.Sprint(issue.Index))
+	// handle manually-merged mark
+	if models.MergeStyle(form.Do) == models.MergeStyleManuallyMerged {
+		if err = pull_service.MergedManually(pr, ctx.User, ctx.Repo.GitRepo, form.MergeCommitID); err != nil {
+			if models.IsErrInvalidMergeStyle(err) {
+				ctx.Flash.Error(ctx.Tr("repo.pulls.invalid_merge_option"))
+				ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+				return
+			} else if strings.Contains(err.Error(), "Wrong commit ID") {
+				ctx.Flash.Error(ctx.Tr("repo.pulls.wrong_commit_id"))
+				ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+				return
+			}
+
+			ctx.ServerError("MergedManually", err)
+			return
+		}
+
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+		return
+	}
+
+	if !pr.CanAutoMerge() {
+		ctx.Flash.Error(ctx.Tr("repo.pulls.no_merge_not_ready"))
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
 		return
 	}
 
diff --git a/routers/repo/setting.go b/routers/repo/setting.go
index b35828d7b1..692d65b44c 100644
--- a/routers/repo/setting.go
+++ b/routers/repo/setting.go
@@ -321,6 +321,8 @@ func SettingsPost(ctx *context.Context) {
 					AllowRebase:               form.PullsAllowRebase,
 					AllowRebaseMerge:          form.PullsAllowRebaseMerge,
 					AllowSquash:               form.PullsAllowSquash,
+					AllowManualMerge:          form.PullsAllowManualMerge,
+					AutodetectManualMerge:     form.EnableAutodetectManualMerge,
 				},
 			})
 		} else if !models.UnitTypePullRequests.UnitGlobalDisabled() {