feat: [CODE-1277]: Add support for PR target branch change (#3579)

* Merge remote-tracking branch 'origin/main' into dd/change-target-branch
* Merge remote-tracking branch 'origin/main' into dd/change-target-branch
* Add openapi spec for opChangeTargetBranch
* Fix updateMergeData args
* Refactor ChangeTargetBranch to use verifyBranchExistence and git.GetRefPath
* Merge remote-tracking branch 'origin/main' into dd/change-target-branch
* Refactor instumentation and event payload
* Change instrumentation and event payload
* Add target-branch-changed event
* Get new merge base and clear merge related fields
* Merge remote-tracking branch 'origin/main' into dd/change-target-branch
* Merge remote-tracking branch 'origin/main' into dd/change-target-branch
* Add merge check to target branch change
* Merge remote-tracking branch 'origin/main' into dd/change-target-branch
* Add new PullReqActivityType and EventType for audit track
* Add support for PR target branch change

app/api/controller/pullreq/branch_change_target.go

@@ -0,0 +1,148 @@
+// Copyright 2023 Harness, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pullreq
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/harness/gitness/app/api/usererror"
+	"github.com/harness/gitness/app/auth"
+	pullreqevents "github.com/harness/gitness/app/events/pullreq"
+	"github.com/harness/gitness/app/services/instrument"
+	"github.com/harness/gitness/errors"
+	"github.com/harness/gitness/git"
+	gitenum "github.com/harness/gitness/git/enum"
+	"github.com/harness/gitness/types"
+	"github.com/harness/gitness/types/enum"
+
+	"github.com/rs/zerolog/log"
+)
+
+type ChangeTargetBranchInput struct {
+	BranchName string `json:"branch_name"`
+}
+
+func (c *Controller) ChangeTargetBranch(ctx context.Context,
+	session *auth.Session,
+	repoRef string,
+	pullreqNum int64,
+	in *ChangeTargetBranchInput,
+) (*types.PullReq, error) {
+	repo, err := c.getRepoCheckAccess(ctx, session, repoRef, enum.PermissionRepoPush)
+	if err != nil {
+		return nil, fmt.Errorf("failed to acquire access to repo: %w", err)
+	}
+
+	pr, err := c.pullreqStore.FindByNumber(ctx, repo.ID, pullreqNum)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get pull request by number: %w", err)
+	}
+
+	if _, err = c.verifyBranchExistence(ctx, repo, in.BranchName); err != nil {
+		return nil,
+			fmt.Errorf("failed to verify branch existence: %w", err)
+	}
+
+	if pr.TargetBranch == in.BranchName {
+		return pr, nil
+	}
+	if pr.SourceBranch == in.BranchName {
+		return nil,
+			errors.InvalidArgument("source branch %q is same as new target branch", pr.SourceBranch)
+	}
+
+	ref1, err := git.GetRefPath(pr.SourceBranch, gitenum.RefTypeBranch)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get ref path: %w", err)
+	}
+	ref2, err := git.GetRefPath(in.BranchName, gitenum.RefTypeBranch)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get ref path: %w", err)
+	}
+	mergeBase, err := c.git.MergeBase(ctx, git.MergeBaseParams{
+		ReadParams: git.ReadParams{RepoUID: repo.GitUID},
+		Ref1:       ref1,
+		Ref2:       ref2,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to find merge base: %w", err)
+	}
+
+	if mergeBase.MergeBaseSHA.String() == pr.SourceSHA {
+		return nil,
+			usererror.BadRequest("The source branch doesn't contain any new commits")
+	}
+
+	oldTargetBranch := pr.TargetBranch
+	oldMergeBaseSHA := pr.MergeBaseSHA
+
+	_, err = c.pullreqStore.UpdateOptLock(ctx, pr, func(pr *types.PullReq) error {
+		// clear merge and stats related fields
+		pr.MergeSHA = nil
+		pr.MergeTargetSHA = nil
+		pr.Stats.DiffStats = types.DiffStats{}
+
+		pr.MergeBaseSHA = mergeBase.MergeBaseSHA.String()
+		pr.TargetBranch = in.BranchName
+
+		pr.MarkAsMergeUnchecked()
+
+		pr.ActivitySeq++
+
+		return nil
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to update PR target branch in db with error: %w", err)
+	}
+
+	_, err = c.activityStore.CreateWithPayload(
+		ctx, pr, session.Principal.ID,
+		&types.PullRequestActivityPayloadBranchChangeTarget{
+			Old: oldTargetBranch,
+			New: in.BranchName,
+		},
+		nil,
+	)
+	if err != nil {
+		log.Ctx(ctx).Err(err).Msgf("failed to write pull request activity for successful branch restore")
+	}
+
+	err = c.instrumentation.Track(ctx, instrument.Event{
+		Type:      instrument.EventTypeChangeTargetBranch,
+		Principal: session.Principal.ToPrincipalInfo(),
+		Path:      repo.Path,
+		Properties: map[instrument.Property]any{
+			instrument.PropertyRepositoryID:   repo.ID,
+			instrument.PropertyRepositoryName: repo.Identifier,
+			instrument.PropertyTargetBranch:   in.BranchName,
+			instrument.PropertyPullRequestID:  pr.Number,
+		},
+	})
+	if err != nil {
+		log.Ctx(ctx).Warn().Msgf("failed to insert instrumentation record for create branch operation: %s", err)
+	}
+
+	c.eventReporter.TargetBranchChanged(ctx, &pullreqevents.TargetBranchChangedPayload{
+		Base:            eventBase(pr, &session.Principal),
+		SourceSHA:       pr.SourceSHA,
+		OldTargetBranch: oldTargetBranch,
+		NewTargetBranch: in.BranchName,
+		OldMergeBaseSHA: oldMergeBaseSHA,
+		NewMergeBaseSHA: mergeBase.MergeBaseSHA.String(),
+	})
+
+	return pr, nil
+}

app/api/handler/pullreq/branch_change_target.go

@@ -0,0 +1,60 @@
+// Copyright 2023 Harness, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pullreq
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/harness/gitness/app/api/controller/pullreq"
+	"github.com/harness/gitness/app/api/render"
+	"github.com/harness/gitness/app/api/request"
+)
+
+func HandleChangeTargetBranch(pullreqCtrl *pullreq.Controller) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+		session, _ := request.AuthSessionFrom(ctx)
+
+		repoRef, err := request.GetRepoRefFromPath(r)
+		if err != nil {
+			render.TranslatedUserError(ctx, w, err)
+			return
+		}
+
+		pullreqNumber, err := request.GetPullReqNumberFromPath(r)
+		if err != nil {
+			render.TranslatedUserError(ctx, w, err)
+			return
+		}
+
+		in := new(pullreq.ChangeTargetBranchInput)
+		err = json.NewDecoder(r.Body).Decode(in)
+		if err != nil {
+			render.BadRequestf(ctx, w, "Invalid request body: %s.", err)
+			return
+		}
+
+		out, err := pullreqCtrl.ChangeTargetBranch(
+			ctx, session, repoRef, pullreqNumber, in,
+		)
+		if err != nil {
+			render.TranslatedUserError(ctx, w, err)
+			return
+		}
+
+		render.JSON(w, http.StatusOK, out)
+	}
+}

app/api/openapi/pullreq.go

@@ -757,6 +757,21 @@ func pullReqOperations(reflector *openapi3.Reflector) {
 	_ = reflector.SetJSONResponse(&opDeleteBranch, new(types.RulesViolations), http.StatusUnprocessableEntity)
 	_ = reflector.Spec.AddOperation(http.MethodDelete, "/repos/{repo_ref}/pullreq/{pullreq_number}/branch", opDeleteBranch)
 
+	opChangeTargetBranch := openapi3.Operation{}
+	opChangeTargetBranch.WithTags("pullreq")
+	opChangeTargetBranch.WithMapOfAnything(map[string]interface{}{"operationId": "changeTargetBranch"})
+	_ = reflector.SetRequest(&opChangeTargetBranch, struct {
+		pullReqRequest
+		pullreq.ChangeTargetBranchInput
+	}{}, http.MethodPost)
+	_ = reflector.SetJSONResponse(&opChangeTargetBranch, new(types.PullReq), http.StatusOK)
+	_ = reflector.SetJSONResponse(&opChangeTargetBranch, new(usererror.Error), http.StatusBadRequest)
+	_ = reflector.SetJSONResponse(&opChangeTargetBranch, new(usererror.Error), http.StatusInternalServerError)
+	_ = reflector.SetJSONResponse(&opChangeTargetBranch, new(usererror.Error), http.StatusUnauthorized)
+	_ = reflector.SetJSONResponse(&opChangeTargetBranch, new(usererror.Error), http.StatusForbidden)
+	_ = reflector.Spec.AddOperation(http.MethodPut,
+		"/repos/{repo_ref}/pullreq/{pullreq_number}/branch", opChangeTargetBranch)
+
 	fileViewAdd := openapi3.Operation{}
 	fileViewAdd.WithTags("pullreq")
 	fileViewAdd.WithMapOfAnything(map[string]interface{}{"operationId": "fileViewAddPullReq"})

app/events/pullreq/events_branch.go

@@ -47,7 +47,46 @@ func (r *Reporter) BranchUpdated(ctx context.Context, payload *BranchUpdatedPayl
 	log.Ctx(ctx).Debug().Msgf("reported pull request branch updated event with id '%s'", eventID)
 }
 
-func (r *Reader) RegisterBranchUpdated(fn events.HandlerFunc[*BranchUpdatedPayload],
+func (r *Reader) RegisterBranchUpdated(
+	fn events.HandlerFunc[*BranchUpdatedPayload],
 	opts ...events.HandlerOption) error {
 	return events.ReaderRegisterEvent(r.innerReader, BranchUpdatedEvent, fn, opts...)
 }
+
+const TargetBranchChangedEvent events.EventType = "target-branch-changed"
+
+type TargetBranchChangedPayload struct {
+	Base
+	SourceSHA       string `json:"source_sha"`
+	OldTargetBranch string `json:"old_target_branch"`
+	NewTargetBranch string `json:"new_target_branch"`
+	OldMergeBaseSHA string `json:"old_merge_base_sha"`
+	NewMergeBaseSHA string `json:"new_merge_base_sha"`
+}
+
+func (r *Reporter) TargetBranchChanged(
+	ctx context.Context,
+	payload *TargetBranchChangedPayload,
+) {
+	if payload == nil {
+		return
+	}
+
+	eventID, err := events.ReporterSendEvent(
+		r.innerReporter, ctx, TargetBranchChangedEvent, payload,
+	)
+	if err != nil {
+		log.Ctx(ctx).Err(err).Msgf("failed to send pull request target branch changed event")
+		return
+	}
+
+	log.Ctx(ctx).Debug().Msgf(
+		"reported pull request target branch changed event with id '%s'", eventID,
+	)
+}
+
+func (r *Reader) RegisterTargetBranchChanged(
+	fn events.HandlerFunc[*TargetBranchChangedPayload],
+	opts ...events.HandlerOption) error {
+	return events.ReaderRegisterEvent(r.innerReader, TargetBranchChangedEvent, fn, opts...)
+}

app/router/api.go

@@ -694,6 +694,7 @@ func SetupPullReq(r chi.Router, pullreqCtrl *pullreq.Controller) {
 			r.Route("/branch", func(r chi.Router) {
 				r.Post("/", handlerpullreq.HandleRestoreBranch(pullreqCtrl))
 				r.Delete("/", handlerpullreq.HandleDeleteBranch(pullreqCtrl))
+				r.Put("/", handlerpullreq.HandleChangeTargetBranch(pullreqCtrl))
 			})
 
 			r.Route("/file-views", func(r chi.Router) {

app/services/instrument/instrument.go

@@ -42,6 +42,7 @@ const (
 	PropertyIsDefaultBranch           Property = "is_default_branch"
 	PropertyDecision                  Property = "decision"
 	PropertyRepositories              Property = "repositories"
+	PropertyTargetBranch              Property = "target_branch"
 
 	PropertySpaceID   Property = "space_id"
 	PropertySpaceName Property = "space_name"
@@ -55,6 +56,7 @@ const (
 	EventTypeCommitCount         EventType = "Commit count"
 	EventTypeCreateCommit        EventType = "Create commit"
 	EventTypeCreateBranch        EventType = "Create branch"
+	EventTypeChangeTargetBranch  EventType = "Change target branch"
 	EventTypeCreateTag           EventType = "Create tag"
 	EventTypeCreatePullRequest   EventType = "Create pull request"
 	EventTypeMergePullRequest    EventType = "Merge pull request"

app/services/pullreq/handlers_mergeable.go

@@ -65,6 +65,20 @@ func (s *Service) mergeCheckOnBranchUpdate(ctx context.Context,
 	)
 }
 
+// mergeCheckOnTargetBranchChange handles pull request target branch changed events.
+func (s *Service) mergeCheckOnTargetBranchChange(
+	ctx context.Context,
+	event *events.Event[*pullreqevents.TargetBranchChangedPayload],
+) error {
+	return s.updateMergeData(
+		ctx,
+		event.Payload.TargetRepoID,
+		event.Payload.Number,
+		sha.None.String(),
+		event.Payload.SourceSHA,
+	)
+}
+
 // mergeCheckOnReopen handles pull request StateChanged events.
 // It updates the PR head git ref to point to the source branch commit SHA.
 func (s *Service) mergeCheckOnReopen(ctx context.Context,

app/services/pullreq/service.go

@@ -195,6 +195,7 @@ func New(ctx context.Context,
 			_ = r.RegisterCreated(service.mergeCheckOnCreated)
 			_ = r.RegisterBranchUpdated(service.mergeCheckOnBranchUpdate)
 			_ = r.RegisterReopened(service.mergeCheckOnReopen)
+			_ = r.RegisterTargetBranchChanged(service.mergeCheckOnTargetBranchChange)
 
 			return nil
 		})

app/store/database/pullreq.go

@@ -302,6 +302,7 @@ func (s *PullReqStore) Update(ctx context.Context, pr *types.PullReq) error {
 		,pullreq_description = :pullreq_description
 		,pullreq_activity_seq = :pullreq_activity_seq
 		,pullreq_source_sha = :pullreq_source_sha
+		,pullreq_target_branch = :pullreq_target_branch
 		,pullreq_merged_by = :pullreq_merged_by
 		,pullreq_merged = :pullreq_merged
 		,pullreq_merge_method = :pullreq_merge_method

types/enum/pullreq.go

@@ -88,6 +88,7 @@ const (
 	PullReqActivityTypeBranchUpdate       PullReqActivityType = "branch-update"
 	PullReqActivityTypeBranchDelete       PullReqActivityType = "branch-delete"
 	PullReqActivityTypeBranchRestore      PullReqActivityType = "branch-restore"
+	PullReqActivityTypeTargetBranchChange PullReqActivityType = "target-branch-change"
 	PullReqActivityTypeMerge              PullReqActivityType = "merge"
 	PullReqActivityTypeLabelModify        PullReqActivityType = "label-modify"
 )
@@ -103,6 +104,7 @@ var pullReqActivityTypes = sortEnum([]PullReqActivityType{
 	PullReqActivityTypeBranchUpdate,
 	PullReqActivityTypeBranchDelete,
 	PullReqActivityTypeBranchRestore,
+	PullReqActivityTypeTargetBranchChange,
 	PullReqActivityTypeMerge,
 	PullReqActivityTypeLabelModify,
 })

types/pullreq_activity_payload.go

@@ -179,6 +179,15 @@ func (a *PullRequestActivityPayloadBranchRestore) ActivityType() enum.PullReqAct
 	return enum.PullReqActivityTypeBranchRestore
 }
 
+type PullRequestActivityPayloadBranchChangeTarget struct {
+	Old string `json:"old"`
+	New string `json:"new"`
+}
+
+func (a *PullRequestActivityPayloadBranchChangeTarget) ActivityType() enum.PullReqActivityType {
+	return enum.PullReqActivityTypeTargetBranchChange
+}
+
 type PullRequestActivityLabelBase struct {
 	Label         string           `json:"label"`
 	LabelColor    enum.LabelColor  `json:"label_color"`
@@ -188,6 +197,7 @@ type PullRequestActivityLabelBase struct {
 	OldValue      *string          `json:"old_value,omitempty"`
 	OldValueColor *enum.LabelColor `json:"old_value_color,omitempty"`
 }
+
 type PullRequestActivityLabel struct {
 	PullRequestActivityLabelBase
 	Type enum.PullReqLabelActivityType `json:"type"`