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>

6 files changed, 66 insertions, 1 deletions

diff --git a/modules/git/commit.go b/modules/git/commit.go
index 0388d5e9be..dfb7adcd1a 100644
--- a/modules/git/commit.go
+++ b/modules/git/commit.go
@@ -306,6 +306,27 @@ func (c *Commit) CommitsBefore() (*list.List, error) {
 	return c.repo.getCommitsBefore(c.ID)
 }
 
+// HasPreviousCommit returns true if a given commitHash is contained in commit's parents
+func (c *Commit) HasPreviousCommit(commitHash SHA1) (bool, error) {
+	for i := 0; i < c.ParentCount(); i++ {
+		commit, err := c.Parent(i)
+		if err != nil {
+			return false, err
+		}
+		if commit.ID == commitHash {
+			return true, nil
+		}
+		commitInParentCommit, err := commit.HasPreviousCommit(commitHash)
+		if err != nil {
+			return false, err
+		}
+		if commitInParentCommit {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
 // CommitsBeforeLimit returns num commits before current revision
 func (c *Commit) CommitsBeforeLimit(num int) (*list.List, error) {
 	return c.repo.getCommitsBeforeLimit(c.ID, num)
diff --git a/modules/notification/base/notifier.go b/modules/notification/base/notifier.go
index 934ee80aa7..48846b3446 100644
--- a/modules/notification/base/notifier.go
+++ b/modules/notification/base/notifier.go
@@ -34,6 +34,7 @@ type Notifier interface {
 	NotifyMergePullRequest(*models.PullRequest, *models.User, *git.Repository)
 	NotifyPullRequestSynchronized(doer *models.User, pr *models.PullRequest)
 	NotifyPullRequestReview(*models.PullRequest, *models.Review, *models.Comment)
+	NotifyPullRequestChangeTargetBranch(doer *models.User, pr *models.PullRequest, oldBranch string)
 
 	NotifyCreateIssueComment(*models.User, *models.Repository,
 		*models.Issue, *models.Comment)
diff --git a/modules/notification/base/null.go b/modules/notification/base/null.go
index a04d0e8caa..bea4e55277 100644
--- a/modules/notification/base/null.go
+++ b/modules/notification/base/null.go
@@ -50,6 +50,10 @@ func (*NullNotifier) NotifyMergePullRequest(pr *models.PullRequest, doer *models
 func (*NullNotifier) NotifyPullRequestSynchronized(doer *models.User, pr *models.PullRequest) {
 }
 
+// NotifyPullRequestChangeTargetBranch places a place holder function
+func (*NullNotifier) NotifyPullRequestChangeTargetBranch(doer *models.User, pr *models.PullRequest, oldBranch string) {
+}
+
 // NotifyUpdateComment places a place holder function
 func (*NullNotifier) NotifyUpdateComment(doer *models.User, c *models.Comment, oldContent string) {
 }
diff --git a/modules/notification/notification.go b/modules/notification/notification.go
index ab671fa291..f567552df5 100644
--- a/modules/notification/notification.go
+++ b/modules/notification/notification.go
@@ -87,6 +87,13 @@ func NotifyPullRequestReview(pr *models.PullRequest, review *models.Review, comm
 	}
 }
 
+// NotifyPullRequestChangeTargetBranch notifies when a pull request's target branch was changed
+func NotifyPullRequestChangeTargetBranch(doer *models.User, pr *models.PullRequest, oldBranch string) {
+	for _, notifier := range notifiers {
+		notifier.NotifyPullRequestChangeTargetBranch(doer, pr, oldBranch)
+	}
+}
+
 // NotifyUpdateComment notifies update comment to notifiers
 func NotifyUpdateComment(doer *models.User, c *models.Comment, oldContent string) {
 	for _, notifier := range notifiers {
diff --git a/modules/notification/webhook/webhook.go b/modules/notification/webhook/webhook.go
index ee91a29f02..e0801445d8 100644
--- a/modules/notification/webhook/webhook.go
+++ b/modules/notification/webhook/webhook.go
@@ -559,6 +559,37 @@ func (*webhookNotifier) NotifyMergePullRequest(pr *models.PullRequest, doer *mod
 	}
 }
 
+func (m *webhookNotifier) NotifyPullRequestChangeTargetBranch(doer *models.User, pr *models.PullRequest, oldBranch string) {
+	issue := pr.Issue
+	if !issue.IsPull {
+		return
+	}
+	var err error
+
+	if err = issue.LoadPullRequest(); err != nil {
+		log.Error("LoadPullRequest failed: %v", err)
+		return
+	}
+	issue.PullRequest.Issue = issue
+	mode, _ := models.AccessLevel(issue.Poster, issue.Repo)
+	err = webhook_module.PrepareWebhooks(issue.Repo, models.HookEventPullRequest, &api.PullRequestPayload{
+		Action: api.HookIssueEdited,
+		Index:  issue.Index,
+		Changes: &api.ChangesPayload{
+			Ref: &api.ChangesFromPayload{
+				From: oldBranch,
+			},
+		},
+		PullRequest: issue.PullRequest.APIFormat(),
+		Repository:  issue.Repo.APIFormat(mode),
+		Sender:      doer.APIFormat(),
+	})
+
+	if err != nil {
+		log.Error("PrepareWebhooks [is_pull: %v]: %v", issue.IsPull, err)
+	}
+}
+
 func (m *webhookNotifier) NotifyPullRequestReview(pr *models.PullRequest, review *models.Review, comment *models.Comment) {
 	var reviewHookType models.HookEventType
 
diff --git a/modules/structs/hook.go b/modules/structs/hook.go
index e036442904..d62c900f42 100644
--- a/modules/structs/hook.go
+++ b/modules/structs/hook.go
@@ -398,10 +398,11 @@ type ChangesFromPayload struct {
 	From string `json:"from"`
 }
 
-// ChangesPayload FIXME
+// ChangesPayload represents the payload information of issue change
 type ChangesPayload struct {
 	Title *ChangesFromPayload `json:"title,omitempty"`
 	Body  *ChangesFromPayload `json:"body,omitempty"`
+	Ref   *ChangesFromPayload `json:"ref,omitempty"`
 }
 
 // __________      .__  .__    __________                                     __