Get rules by id when editing branch protection rule (#22932)

When users rename an existing branch protection rule, a new rule with
the new name will be created and the old rule will still exist.

![image](https://user-images.githubusercontent.com/15528715/219276442-d3c001ad-e693-44ec-9ad2-b33f2666b49b.png)

---

![image](https://user-images.githubusercontent.com/15528715/219276478-547c3b93-b3f1-4292-a1ef-c1b7747fe1bb.png)

The reason is that the `SettingsProtectedBranchPost` function only get
branch protection rule by name before updating or creating a rule. When
the rule name changes, the function cannot find the existing rule so it
will create a new rule rather than update the existing rule. To fix the
bug, the function should get rule by id first.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

1 files changed, 30 insertions, 4 deletions

diff --git a/routers/web/repo/setting_protected_branch.go b/routers/web/repo/setting_protected_branch.go
index a54565c1f..0a8c39fef 100644
--- a/routers/web/repo/setting_protected_branch.go
+++ b/routers/web/repo/setting_protected_branch.go
@@ -166,10 +166,36 @@ func SettingsProtectedBranchPost(ctx *context.Context) {
 	}
 
 	var err error
-	protectBranch, err = git_model.GetProtectedBranchRuleByName(ctx, ctx.Repo.Repository.ID, f.RuleName)
-	if err != nil {
-		ctx.ServerError("GetProtectBranchOfRepoByName", err)
-		return
+	if f.RuleID > 0 {
+		// If the RuleID isn't 0, it must be an edit operation. So we get rule by id.
+		protectBranch, err = git_model.GetProtectedBranchRuleByID(ctx, ctx.Repo.Repository.ID, f.RuleID)
+		if err != nil {
+			ctx.ServerError("GetProtectBranchOfRepoByID", err)
+			return
+		}
+		if protectBranch != nil && protectBranch.RuleName != f.RuleName {
+			// RuleName changed. We need to check if there is a rule with the same name.
+			// If a rule with the same name exists, an error should be returned.
+			sameNameProtectBranch, err := git_model.GetProtectedBranchRuleByName(ctx, ctx.Repo.Repository.ID, f.RuleName)
+			if err != nil {
+				ctx.ServerError("GetProtectBranchOfRepoByName", err)
+				return
+			}
+			if sameNameProtectBranch != nil {
+				ctx.Flash.Error(ctx.Tr("repo.settings.protected_branch_duplicate_rule_name"))
+				ctx.Redirect(fmt.Sprintf("%s/settings/branches/edit?rule_name=%s", ctx.Repo.RepoLink, protectBranch.RuleName))
+				return
+			}
+		}
+	} else {
+		// FIXME: If a new ProtectBranch has a duplicate RuleName, an error should be returned.
+		// Currently, if a new ProtectBranch with a duplicate RuleName is created, the existing ProtectBranch will be updated.
+		// But we cannot modify this logic now because many unit tests rely on it.
+		protectBranch, err = git_model.GetProtectedBranchRuleByName(ctx, ctx.Repo.Repository.ID, f.RuleName)
+		if err != nil {
+			ctx.ServerError("GetProtectBranchOfRepoByName", err)
+			return
+		}
 	}
 	if protectBranch == nil {
 		// No options found, create defaults.