Add "Update Branch" button to Pull Requests (#9784)

* add Divergence

* add Update Button

* first working version

* re-use code

* split raw merge commands and db-change functions (notify, cache, ...)

* use rawMerge (remove redundant code)

* own function to get Diverging of PRs

* use FlashError

* correct Error Msg

* hook is triggerd ... so remove comment

* add "branch2" to "user2/repo1" because it unit-test "TestPullView_ReviewerMissed" use it but dont exist jet :/

* move GetPerm to IsUserAllowedToUpdate

* add Flash Success MSG

* imprufe code
- remove useless js chage

* fix-lint

* TEST: add PullRequest ID:5
Repo: user2/repo1
Base: branch1
Head: pr-to-update

* correct comments

* make PR5 outdated

* fix Tests

* WIP: add pull update test

* update revs

* update locales

* working TEST

* update UI

* misspell

* change style

* add 1s delay so rev exist

* move row up (before merge row)

* fix lint nit

* UI remove divider

* Update style

* nits

* do it right

* introduce IsSameRepo

* remove useless check

Co-authored-by: Lauris BH <lauris@nix.lv>

routers/repo/pull.go

@@ -14,6 +14,7 @@ import (
 	"net/http"
 	"path"
 	"strings"
+	"time"
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/auth"
@@ -342,8 +343,21 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 
 	setMergeTarget(ctx, pull)
 
+	divergence, err := pull_service.GetDiverging(pull)
+	if err != nil {
+		ctx.ServerError("GetDiverging", err)
+		return nil
+	}
+	ctx.Data["Divergence"] = divergence
+	allowUpdate, err := pull_service.IsUserAllowedToUpdate(pull, ctx.User)
+	if err != nil {
+		ctx.ServerError("GetDiverging", err)
+		return nil
+	}
+	ctx.Data["UpdateAllowed"] = allowUpdate
+
 	if err := pull.LoadProtectedBranch(); err != nil {
-		ctx.ServerError("GetLatestCommitStatus", err)
+		ctx.ServerError("LoadProtectedBranch", err)
 		return nil
 	}
 	ctx.Data["EnableStatusCheck"] = pull.ProtectedBranch != nil && pull.ProtectedBranch.EnableStatusCheck
@@ -587,6 +601,72 @@ func ViewPullFiles(ctx *context.Context) {
 	ctx.HTML(200, tplPullFiles)
 }
 
+// UpdatePullRequest merge master into PR
+func UpdatePullRequest(ctx *context.Context) {
+	issue := checkPullInfo(ctx)
+	if ctx.Written() {
+		return
+	}
+	if issue.IsClosed {
+		ctx.NotFound("MergePullRequest", nil)
+		return
+	}
+	if issue.PullRequest.HasMerged {
+		ctx.NotFound("MergePullRequest", nil)
+		return
+	}
+
+	if err := issue.PullRequest.LoadBaseRepo(); err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+	if err := issue.PullRequest.LoadHeadRepo(); err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+
+	allowedUpdate, err := pull_service.IsUserAllowedToUpdate(issue.PullRequest, ctx.User)
+	if err != nil {
+		ctx.ServerError("IsUserAllowedToMerge", err)
+		return
+	}
+
+	// ToDo: add check if maintainers are allowed to change branch ... (need migration & co)
+	if !allowedUpdate {
+		ctx.Flash.Error(ctx.Tr("repo.pulls.update_not_allowed"))
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+		return
+	}
+
+	// default merge commit message
+	message := fmt.Sprintf("Merge branch '%s' into %s", issue.PullRequest.BaseBranch, issue.PullRequest.HeadBranch)
+
+	if err = pull_service.Update(issue.PullRequest, ctx.User, message); err != nil {
+		sanitize := func(x string) string {
+			runes := []rune(x)
+
+			if len(runes) > 512 {
+				x = "..." + string(runes[len(runes)-512:])
+			}
+
+			return strings.Replace(html.EscapeString(x), "\n", "<br>", -1)
+		}
+		if models.IsErrMergeConflicts(err) {
+			conflictError := err.(models.ErrMergeConflicts)
+			ctx.Flash.Error(ctx.Tr("repo.pulls.merge_conflict", sanitize(conflictError.StdErr), sanitize(conflictError.StdOut)))
+			ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+			return
+		}
+		ctx.Flash.Error(err.Error())
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+	}
+
+	time.Sleep(1 * time.Second)
+
+	ctx.Flash.Success(ctx.Tr("repo.pulls.update_branch_success"))
+	ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+}
+
 // MergePullRequest response for merging pull request
 func MergePullRequest(ctx *context.Context, form auth.MergePullRequestForm) {
 	issue := checkPullInfo(ctx)

routers/routes/routes.go

@@ -855,6 +855,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 			m.Get(".patch", repo.DownloadPullPatch)
 			m.Get("/commits", context.RepoRef(), repo.ViewPullCommits)
 			m.Post("/merge", context.RepoMustNotBeArchived(), reqRepoPullsWriter, bindIgnErr(auth.MergePullRequestForm{}), repo.MergePullRequest)
+			m.Post("/update", repo.UpdatePullRequest)
 			m.Post("/cleanup", context.RepoMustNotBeArchived(), context.RepoRef(), repo.CleanUpPullRequest)
 			m.Group("/files", func() {
 				m.Get("", context.RepoRef(), repo.SetEditorconfigIfExists, repo.SetDiffViewStyle, repo.SetWhitespaceBehavior, repo.ViewPullFiles)