Implement update branch API (#32433)

Resolves #22526.

Builds upon #23061.

---------

Co-authored-by: sillyguodong <33891828+sillyguodong@users.noreply.github.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
(cherry picked from commit 01b1896bf5eacfd7f4f64d9ebb0ad165e3e60a5c)

Conflicts:
	routers/api/v1/api.go
  context conflict + s/PathParam/Params/
	templates/swagger/v1_json.tmpl
  make generate-swagger

3 files changed, 74 insertions, 0 deletions

diff --git a/routers/api/v1/api.go b/routers/api/v1/api.go
index c028a5a32d..4928c9ff58 100644
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@@ -1153,6 +1153,7 @@ func Routes() *web.Route {
 					m.Get("/*", repo.GetBranch)
 					m.Delete("/*", reqToken(), reqRepoWriter(unit.TypeCode), mustNotBeArchived, repo.DeleteBranch)
 					m.Post("", reqToken(), reqRepoWriter(unit.TypeCode), mustNotBeArchived, bind(api.CreateBranchRepoOption{}), context.EnforceQuotaAPI(quota_model.LimitSubjectSizeGitAll, context.QuotaTargetRepo), repo.CreateBranch)
+					m.Patch("/*", reqToken(), reqRepoWriter(unit.TypeCode), mustNotBeArchived, bind(api.UpdateBranchRepoOption{}), repo.UpdateBranch)
 				}, context.ReferencesGitRepo(), reqRepoReader(unit.TypeCode))
 				m.Group("/branch_protections", func() {
 					m.Get("", repo.ListBranchProtections)
diff --git a/routers/api/v1/repo/branch.go b/routers/api/v1/repo/branch.go
index e3e6efa781..3ca97f7770 100644
--- a/routers/api/v1/repo/branch.go
+++ b/routers/api/v1/repo/branch.go
@@ -393,6 +393,77 @@ func ListBranches(ctx *context.APIContext) {
 	ctx.JSON(http.StatusOK, apiBranches)
 }
 
+// UpdateBranch updates a repository's branch.
+func UpdateBranch(ctx *context.APIContext) {
+	// swagger:operation PATCH /repos/{owner}/{repo}/branches/{branch} repository repoUpdateBranch
+	// ---
+	// summary: Update a branch
+	// consumes:
+	// - application/json
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: branch
+	//   in: path
+	//   description: name of the branch
+	//   type: string
+	//   required: true
+	// - name: body
+	//   in: body
+	//   schema:
+	//     "$ref": "#/definitions/UpdateBranchRepoOption"
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+
+	opt := web.GetForm(ctx).(*api.UpdateBranchRepoOption)
+
+	oldName := ctx.Params("*")
+	repo := ctx.Repo.Repository
+
+	if repo.IsEmpty {
+		ctx.Error(http.StatusNotFound, "", "Git Repository is empty.")
+		return
+	}
+
+	if repo.IsMirror {
+		ctx.Error(http.StatusForbidden, "", "Git Repository is a mirror.")
+		return
+	}
+
+	msg, err := repo_service.RenameBranch(ctx, repo, ctx.Doer, ctx.Repo.GitRepo, oldName, opt.Name)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "RenameBranch", err)
+		return
+	}
+	if msg == "target_exist" {
+		ctx.Error(http.StatusUnprocessableEntity, "", "Cannot rename a branch using the same name or rename to a branch that already exists.")
+		return
+	}
+	if msg == "from_not_exist" {
+		ctx.Error(http.StatusNotFound, "", "Branch doesn't exist.")
+		return
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
+
 // GetBranchProtection gets a branch protection
 func GetBranchProtection(ctx *context.APIContext) {
 	// swagger:operation GET /repos/{owner}/{repo}/branch_protections/{name} repository repoGetBranchProtection
diff --git a/routers/api/v1/swagger/options.go b/routers/api/v1/swagger/options.go
index 1dccf92d82..432e42d4e7 100644
--- a/routers/api/v1/swagger/options.go
+++ b/routers/api/v1/swagger/options.go
@@ -101,6 +101,8 @@ type swaggerParameterBodies struct {
 	// in:body
 	EditRepoOption api.EditRepoOption
 	// in:body
+	UpdateBranchRepoOption api.UpdateBranchRepoOption
+	// in:body
 	TransferRepoOption api.TransferRepoOption
 	// in:body
 	CreateForkOption api.CreateForkOption