Change target branch for pull request (#6488)

* Adds functionality to change target branch of created pull requests

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Use const instead of var in JavaScript additions

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Check if branches are equal and if PR already exists before changing target branch

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Make sure to check all commits

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Print error messages for user as error flash message

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Disallow changing target branch of closed or merged pull requests

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Resolve conflicts after merge of upstream/master

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Change order of branch select fields

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Removes duplicate check

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Use ctx.Tr for translations

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Recompile JS

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Use correct translation namespace

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Remove redundant if condition

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Moves most change branch logic into pull service

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Completes comment

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Add Ref to ChangesPayload for logging changed target branches
instead of creating a new struct

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Revert changes to go.mod

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Directly use createComment method

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Return 404 if pull request is not found. Move written check up

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Remove variable declaration

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Return client errors on change pull request target errors

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Return error in commit.HasPreviousCommit

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Adds blank line

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Test patch before persisting new target branch

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Update patch before testing (not working)

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Removes patch calls when changeing pull request target

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Removes unneeded check for base name

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Moves ChangeTargetBranch completely to pull service. Update patch status.

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Set webhook mode after errors were validated

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Update PR in one transaction

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Move logic for check if head is equal with branch to pull model

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Adds missing comment and simplify return

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Adjust CreateComment method call

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

2 files changed, 88 insertions, 0 deletions

diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index 7d11ed3537..07292c1993 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -605,6 +605,19 @@ func commentTag(repo *models.Repository, poster *models.User, issue *models.Issu
 	return models.CommentTagNone, nil
 }
 
+func getBranchData(ctx *context.Context, issue *models.Issue) {
+	ctx.Data["BaseBranch"] = nil
+	ctx.Data["HeadBranch"] = nil
+	ctx.Data["HeadUserName"] = nil
+	ctx.Data["BaseName"] = ctx.Repo.Repository.OwnerName
+	if issue.IsPull {
+		pull := issue.PullRequest
+		ctx.Data["BaseBranch"] = pull.BaseBranch
+		ctx.Data["HeadBranch"] = pull.HeadBranch
+		ctx.Data["HeadUserName"] = pull.MustHeadUserName()
+	}
+}
+
 // ViewIssue render issue view page
 func ViewIssue(ctx *context.Context) {
 	if ctx.Params(":type") == "issues" {
@@ -885,6 +898,7 @@ func ViewIssue(ctx *context.Context) {
 		}
 	}
 
+	getBranchData(ctx, issue)
 	if issue.IsPull {
 		pull := issue.PullRequest
 		pull.Issue = issue
diff --git a/routers/repo/pull.go b/routers/repo/pull.go
index 559d9b267a..f8612d2b3b 100644
--- a/routers/repo/pull.go
+++ b/routers/repo/pull.go
@@ -11,6 +11,7 @@ import (
 	"crypto/subtle"
 	"fmt"
 	"html"
+	"net/http"
 	"path"
 	"strings"
 
@@ -467,6 +468,7 @@ func ViewPullCommits(ctx *context.Context) {
 	ctx.Data["Commits"] = commits
 	ctx.Data["CommitCount"] = commits.Len()
 
+	getBranchData(ctx, issue)
 	ctx.HTML(200, tplPullCommits)
 }
 
@@ -596,6 +598,7 @@ func ViewPullFiles(ctx *context.Context) {
 		ctx.ServerError("GetCurrentReview", err)
 		return
 	}
+	getBranchData(ctx, issue)
 	ctx.HTML(200, tplPullFiles)
 }
 
@@ -1010,3 +1013,74 @@ func DownloadPullDiffOrPatch(ctx *context.Context, patch bool) {
 		return
 	}
 }
+
+// UpdatePullRequestTarget change pull request's target branch
+func UpdatePullRequestTarget(ctx *context.Context) {
+	issue := GetActionIssue(ctx)
+	pr := issue.PullRequest
+	if ctx.Written() {
+		return
+	}
+	if !issue.IsPull {
+		ctx.Error(http.StatusNotFound)
+		return
+	}
+
+	if !ctx.IsSigned || (!issue.IsPoster(ctx.User.ID) && !ctx.Repo.CanWriteIssuesOrPulls(issue.IsPull)) {
+		ctx.Error(http.StatusForbidden)
+		return
+	}
+
+	targetBranch := ctx.QueryTrim("target_branch")
+	if len(targetBranch) == 0 {
+		ctx.Error(http.StatusNoContent)
+		return
+	}
+
+	if err := pull_service.ChangeTargetBranch(pr, ctx.User, targetBranch); err != nil {
+		if models.IsErrPullRequestAlreadyExists(err) {
+			err := err.(models.ErrPullRequestAlreadyExists)
+
+			RepoRelPath := ctx.Repo.Owner.Name + "/" + ctx.Repo.Repository.Name
+			errorMessage := ctx.Tr("repo.pulls.has_pull_request", ctx.Repo.RepoLink, RepoRelPath, err.IssueID)
+
+			ctx.Flash.Error(errorMessage)
+			ctx.JSON(http.StatusConflict, map[string]interface{}{
+				"error":      err.Error(),
+				"user_error": errorMessage,
+			})
+		} else if models.IsErrIssueIsClosed(err) {
+			errorMessage := ctx.Tr("repo.pulls.is_closed")
+
+			ctx.Flash.Error(errorMessage)
+			ctx.JSON(http.StatusConflict, map[string]interface{}{
+				"error":      err.Error(),
+				"user_error": errorMessage,
+			})
+		} else if models.IsErrPullRequestHasMerged(err) {
+			errorMessage := ctx.Tr("repo.pulls.has_merged")
+
+			ctx.Flash.Error(errorMessage)
+			ctx.JSON(http.StatusConflict, map[string]interface{}{
+				"error":      err.Error(),
+				"user_error": errorMessage,
+			})
+		} else if models.IsErrBranchesEqual(err) {
+			errorMessage := ctx.Tr("repo.pulls.nothing_to_compare")
+
+			ctx.Flash.Error(errorMessage)
+			ctx.JSON(http.StatusBadRequest, map[string]interface{}{
+				"error":      err.Error(),
+				"user_error": errorMessage,
+			})
+		} else {
+			ctx.ServerError("UpdatePullRequestTarget", err)
+		}
+		return
+	}
+	notification.NotifyPullRequestChangeTargetBranch(ctx.User, pr, targetBranch)
+
+	ctx.JSON(http.StatusOK, map[string]interface{}{
+		"base_branch": pr.BaseBranch,
+	})
+}