Add dismiss review feature (#12674)

* Add dismiss review feature

refs:
    https://github.blog/2016-10-12-dismissing-reviews-on-pull-requests/
    https://developer.github.com/v3/pulls/reviews/#dismiss-a-review-for-a-pull-request

* change modal ui and error message

* Add unDismissReview api

Signed-off-by: a1012112796 <1012112796@qq.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>

36 files changed, 593 insertions, 39 deletions

diff --git a/integrations/api_pull_review_test.go b/integrations/api_pull_review_test.go
index 261a3a8bfa..8be194602f 100644
--- a/integrations/api_pull_review_test.go
+++ b/integrations/api_pull_review_test.go
@@ -111,6 +111,22 @@ func TestAPIPullReview(t *testing.T) {
 	assert.EqualValues(t, "APPROVED", review.State)
 	assert.EqualValues(t, 3, review.CodeCommentsCount)
 
+	// test dismiss review
+	req = NewRequestWithJSON(t, http.MethodPost, fmt.Sprintf("/api/v1/repos/%s/%s/pulls/%d/reviews/%d/dismissals?token=%s", repo.OwnerName, repo.Name, pullIssue.Index, review.ID, token), &api.DismissPullReviewOptions{
+		Message: "test",
+	})
+	resp = session.MakeRequest(t, req, http.StatusOK)
+	DecodeJSON(t, resp, &review)
+	assert.EqualValues(t, 6, review.ID)
+	assert.EqualValues(t, true, review.Dismissed)
+
+	// test dismiss review
+	req = NewRequest(t, http.MethodPost, fmt.Sprintf("/api/v1/repos/%s/%s/pulls/%d/reviews/%d/undismissals?token=%s", repo.OwnerName, repo.Name, pullIssue.Index, review.ID, token))
+	resp = session.MakeRequest(t, req, http.StatusOK)
+	DecodeJSON(t, resp, &review)
+	assert.EqualValues(t, 6, review.ID)
+	assert.EqualValues(t, false, review.Dismissed)
+
 	// test DeletePullReview
 	req = NewRequestWithJSON(t, http.MethodPost, fmt.Sprintf("/api/v1/repos/%s/%s/pulls/%d/reviews?token=%s", repo.OwnerName, repo.Name, pullIssue.Index, token), &api.CreatePullReviewOptions{
 		Body:  "just a comment",
diff --git a/models/action.go b/models/action.go
index 2fdab7f4e9..e8a1336566 100644
--- a/models/action.go
+++ b/models/action.go
@@ -26,30 +26,31 @@ type ActionType int
 
 // Possible action types.
 const (
-	ActionCreateRepo         ActionType = iota + 1 // 1
-	ActionRenameRepo                               // 2
-	ActionStarRepo                                 // 3
-	ActionWatchRepo                                // 4
-	ActionCommitRepo                               // 5
-	ActionCreateIssue                              // 6
-	ActionCreatePullRequest                        // 7
-	ActionTransferRepo                             // 8
-	ActionPushTag                                  // 9
-	ActionCommentIssue                             // 10
-	ActionMergePullRequest                         // 11
-	ActionCloseIssue                               // 12
-	ActionReopenIssue                              // 13
-	ActionClosePullRequest                         // 14
-	ActionReopenPullRequest                        // 15
-	ActionDeleteTag                                // 16
-	ActionDeleteBranch                             // 17
-	ActionMirrorSyncPush                           // 18
-	ActionMirrorSyncCreate                         // 19
-	ActionMirrorSyncDelete                         // 20
-	ActionApprovePullRequest                       // 21
-	ActionRejectPullRequest                        // 22
-	ActionCommentPull                              // 23
-	ActionPublishRelease                           // 24
+	ActionCreateRepo          ActionType = iota + 1 // 1
+	ActionRenameRepo                                // 2
+	ActionStarRepo                                  // 3
+	ActionWatchRepo                                 // 4
+	ActionCommitRepo                                // 5
+	ActionCreateIssue                               // 6
+	ActionCreatePullRequest                         // 7
+	ActionTransferRepo                              // 8
+	ActionPushTag                                   // 9
+	ActionCommentIssue                              // 10
+	ActionMergePullRequest                          // 11
+	ActionCloseIssue                                // 12
+	ActionReopenIssue                               // 13
+	ActionClosePullRequest                          // 14
+	ActionReopenPullRequest                         // 15
+	ActionDeleteTag                                 // 16
+	ActionDeleteBranch                              // 17
+	ActionMirrorSyncPush                            // 18
+	ActionMirrorSyncCreate                          // 19
+	ActionMirrorSyncDelete                          // 20
+	ActionApprovePullRequest                        // 21
+	ActionRejectPullRequest                         // 22
+	ActionCommentPull                               // 23
+	ActionPublishRelease                            // 24
+	ActionPullReviewDismissed                       // 25
 )
 
 // Action represents user operation type and other information to
@@ -259,7 +260,7 @@ func (a *Action) GetCreate() time.Time {
 // GetIssueInfos returns a list of issues associated with
 // the action.
 func (a *Action) GetIssueInfos() []string {
-	return strings.SplitN(a.Content, "|", 2)
+	return strings.SplitN(a.Content, "|", 3)
 }
 
 // GetIssueTitle returns the title of first issue associated
diff --git a/models/branches.go b/models/branches.go
index 80df8c433e..440c093095 100644
--- a/models/branches.go
+++ b/models/branches.go
@@ -157,7 +157,8 @@ func (protectBranch *ProtectedBranch) HasEnoughApprovals(pr *PullRequest) bool {
 func (protectBranch *ProtectedBranch) GetGrantedApprovalsCount(pr *PullRequest) int64 {
 	sess := x.Where("issue_id = ?", pr.IssueID).
 		And("type = ?", ReviewTypeApprove).
-		And("official = ?", true)
+		And("official = ?", true).
+		And("dismissed = ?", false)
 	if protectBranch.DismissStaleApprovals {
 		sess = sess.And("stale = ?", false)
 	}
@@ -178,6 +179,7 @@ func (protectBranch *ProtectedBranch) MergeBlockedByRejectedReview(pr *PullReque
 	rejectExist, err := x.Where("issue_id = ?", pr.IssueID).
 		And("type = ?", ReviewTypeReject).
 		And("official = ?", true).
+		And("dismissed = ?", false).
 		Exist(new(Review))
 	if err != nil {
 		log.Error("MergeBlockedByRejectedReview: %v", err)
diff --git a/models/fixtures/review.yml b/models/fixtures/review.yml
index c7c16fb109..d44d0cde98 100644
--- a/models/fixtures/review.yml
+++ b/models/fixtures/review.yml
@@ -104,4 +104,4 @@
   issue_id: 12
   official: true
   updated_unix: 1603196749
-  created_unix: 1603196749
\ No newline at end of file
+  created_unix: 1603196749
diff --git a/models/issue_comment.go b/models/issue_comment.go
index ea179d49d9..b15b5169ff 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -99,6 +99,8 @@ const (
 	CommentTypeProject
 	// 31 Project board changed
 	CommentTypeProjectBoard
+	// Dismiss Review
+	CommentTypeDismissReview
 )
 
 // CommentTag defines comment tag type
diff --git a/models/issue_list.go b/models/issue_list.go
index 628058eb35..5789ad84ae 100644
--- a/models/issue_list.go
+++ b/models/issue_list.go
@@ -530,7 +530,7 @@ func (issues IssueList) getApprovalCounts(e Engine) (map[int64][]*ReviewCount, e
 	}
 	sess := e.In("issue_id", ids)
 	err := sess.Select("issue_id, type, count(id) as `count`").
-		Where("official = ?", true).
+		Where("official = ? AND dismissed = ?", true, false).
 		GroupBy("issue_id, type").
 		OrderBy("issue_id").
 		Table("review").
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index c926ee6ccf..16e2f177ad 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -286,6 +286,8 @@ var migrations = []Migration{
 	NewMigration("Recreate user table to fix default values", recreateUserTableToFixDefaultValues),
 	// v169 -> v170
 	NewMigration("Update DeleteBranch comments to set the old_ref to the commit_sha", commentTypeDeleteBranchUseOldRef),
+	// v170 -> v171
+	NewMigration("Add Dismissed to Review table", addDismissedReviewColumn),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v170.go b/models/migrations/v170.go
new file mode 100644
index 0000000000..853a23d290
--- /dev/null
+++ b/models/migrations/v170.go
@@ -0,0 +1,22 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"fmt"
+
+	"xorm.io/xorm"
+)
+
+func addDismissedReviewColumn(x *xorm.Engine) error {
+	type Review struct {
+		Dismissed bool `xorm:"NOT NULL DEFAULT false"`
+	}
+
+	if err := x.Sync2(new(Review)); err != nil {
+		return fmt.Errorf("Sync2: %v", err)
+	}
+	return nil
+}
diff --git a/models/pull.go b/models/pull.go
index 9b6f0830d7..0d4691aac9 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -234,7 +234,7 @@ func (pr *PullRequest) GetApprovalCounts() ([]*ReviewCount, error) {
 func (pr *PullRequest) getApprovalCounts(e Engine) ([]*ReviewCount, error) {
 	rCounts := make([]*ReviewCount, 0, 6)
 	sess := e.Where("issue_id = ?", pr.IssueID)
-	return rCounts, sess.Select("issue_id, type, count(id) as `count`").Where("official = ?", true).GroupBy("issue_id, type").Table("review").Find(&rCounts)
+	return rCounts, sess.Select("issue_id, type, count(id) as `count`").Where("official = ? AND dismissed = ?", true, false).GroupBy("issue_id, type").Table("review").Find(&rCounts)
 }
 
 // GetApprovers returns the approvers of the pull request
diff --git a/models/review.go b/models/review.go
index aeb5f21ea9..7775fcdf53 100644
--- a/models/review.go
+++ b/models/review.go
@@ -63,9 +63,10 @@ type Review struct {
 	IssueID          int64  `xorm:"index"`
 	Content          string `xorm:"TEXT"`
 	// Official is a review made by an assigned approver (counts towards approval)
-	Official bool   `xorm:"NOT NULL DEFAULT false"`
-	CommitID string `xorm:"VARCHAR(40)"`
-	Stale    bool   `xorm:"NOT NULL DEFAULT false"`
+	Official  bool   `xorm:"NOT NULL DEFAULT false"`
+	CommitID  string `xorm:"VARCHAR(40)"`
+	Stale     bool   `xorm:"NOT NULL DEFAULT false"`
+	Dismissed bool   `xorm:"NOT NULL DEFAULT false"`
 
 	CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
 	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
@@ -466,8 +467,8 @@ func GetReviewersByIssueID(issueID int64) ([]*Review, error) {
 	}
 
 	// Get latest review of each reviwer, sorted in order they were made
-	if err := sess.SQL("SELECT * FROM review WHERE id IN (SELECT max(id) as id FROM review WHERE issue_id = ? AND reviewer_team_id = 0 AND type in (?, ?, ?) AND original_author_id = 0 GROUP BY issue_id, reviewer_id) ORDER BY review.updated_unix ASC",
-		issueID, ReviewTypeApprove, ReviewTypeReject, ReviewTypeRequest).
+	if err := sess.SQL("SELECT * FROM review WHERE id IN (SELECT max(id) as id FROM review WHERE issue_id = ? AND reviewer_team_id = 0 AND type in (?, ?, ?) AND dismissed = ? AND original_author_id = 0 GROUP BY issue_id, reviewer_id) ORDER BY review.updated_unix ASC",
+		issueID, ReviewTypeApprove, ReviewTypeReject, ReviewTypeRequest, false).
 		Find(&reviews); err != nil {
 		return nil, err
 	}
@@ -558,6 +559,19 @@ func MarkReviewsAsNotStale(issueID int64, commitID string) (err error) {
 	return
 }
 
+// DismissReview change the dismiss status of a review
+func DismissReview(review *Review, isDismiss bool) (err error) {
+	if review.Dismissed == isDismiss || (review.Type != ReviewTypeApprove && review.Type != ReviewTypeReject) {
+		return nil
+	}
+
+	review.Dismissed = isDismiss
+
+	_, err = x.Cols("dismissed").Update(review)
+
+	return
+}
+
 // InsertReviews inserts review and review comments
 func InsertReviews(reviews []*Review) error {
 	sess := x.NewSession()
diff --git a/models/review_test.go b/models/review_test.go
index 702e216824..7315650488 100644
--- a/models/review_test.go
+++ b/models/review_test.go
@@ -142,3 +142,13 @@ func TestGetReviewersByIssueID(t *testing.T) {
 		}
 	}
 }
+
+func TestDismissReview(t *testing.T) {
+	review1 := AssertExistsAndLoadBean(t, &Review{ID: 9}).(*Review)
+	review2 := AssertExistsAndLoadBean(t, &Review{ID: 11}).(*Review)
+	assert.NoError(t, DismissReview(review1, true))
+	assert.NoError(t, DismissReview(review2, true))
+	assert.NoError(t, DismissReview(review2, true))
+	assert.NoError(t, DismissReview(review2, false))
+	assert.NoError(t, DismissReview(review2, false))
+}
diff --git a/modules/convert/pull_review.go b/modules/convert/pull_review.go
index 0ef1fec39c..d1d6e767d4 100644
--- a/modules/convert/pull_review.go
+++ b/modules/convert/pull_review.go
@@ -34,6 +34,7 @@ func ToPullReview(r *models.Review, doer *models.User) (*api.PullReview, error)
 		CommitID:          r.CommitID,
 		Stale:             r.Stale,
 		Official:          r.Official,
+		Dismissed:         r.Dismissed,
 		CodeCommentsCount: r.GetCodeCommentsCount(),
 		Submitted:         r.CreatedUnix.AsTime(),
 		HTMLURL:           r.HTMLURL(),
diff --git a/modules/forms/repo_form.go b/modules/forms/repo_form.go
index f177b21f05..48af3450f3 100644
--- a/modules/forms/repo_form.go
+++ b/modules/forms/repo_form.go
@@ -622,6 +622,12 @@ func (f SubmitReviewForm) HasEmptyContent() bool {
 		len(strings.TrimSpace(f.Content)) == 0
 }
 
+// DismissReviewForm for dismissing stale review by repo admin
+type DismissReviewForm struct {
+	ReviewID int64 `binding:"Required"`
+	Message  string
+}
+
 // __________       .__
 // \______   \ ____ |  |   ____ _____    ______ ____
 //  |       _// __ \|  | _/ __ \\__  \  /  ___// __ \
diff --git a/modules/notification/action/action.go b/modules/notification/action/action.go
index 360906f076..836cb51b3e 100644
--- a/modules/notification/action/action.go
+++ b/modules/notification/action/action.go
@@ -275,6 +275,26 @@ func (*actionNotifier) NotifyMergePullRequest(pr *models.PullRequest, doer *mode
 	}
 }
 
+func (*actionNotifier) NotifyPullRevieweDismiss(doer *models.User, review *models.Review, comment *models.Comment) {
+	reviewerName := review.Reviewer.Name
+	if len(review.OriginalAuthor) > 0 {
+		reviewerName = review.OriginalAuthor
+	}
+	if err := models.NotifyWatchers(&models.Action{
+		ActUserID: doer.ID,
+		ActUser:   doer,
+		OpType:    models.ActionPullReviewDismissed,
+		Content:   fmt.Sprintf("%d|%s|%s", review.Issue.Index, reviewerName, comment.Content),
+		RepoID:    review.Issue.Repo.ID,
+		Repo:      review.Issue.Repo,
+		IsPrivate: review.Issue.Repo.IsPrivate,
+		CommentID: comment.ID,
+		Comment:   comment,
+	}); err != nil {
+		log.Error("NotifyWatchers [%d]: %v", review.Issue.ID, err)
+	}
+}
+
 func (a *actionNotifier) NotifyPushCommits(pusher *models.User, repo *models.Repository, opts *repository.PushUpdateOptions, commits *repository.PushCommits) {
 	data, err := json.Marshal(commits)
 	if err != nil {
diff --git a/modules/notification/base/notifier.go b/modules/notification/base/notifier.go
index b01026dfc5..5bb833d275 100644
--- a/modules/notification/base/notifier.go
+++ b/modules/notification/base/notifier.go
@@ -39,6 +39,7 @@ type Notifier interface {
 	NotifyPullRequestCodeComment(pr *models.PullRequest, comment *models.Comment, mentions []*models.User)
 	NotifyPullRequestChangeTargetBranch(doer *models.User, pr *models.PullRequest, oldBranch string)
 	NotifyPullRequestPushCommits(doer *models.User, pr *models.PullRequest, comment *models.Comment)
+	NotifyPullRevieweDismiss(doer *models.User, review *models.Review, comment *models.Comment)
 
 	NotifyCreateIssueComment(doer *models.User, repo *models.Repository,
 		issue *models.Issue, comment *models.Comment, mentions []*models.User)
diff --git a/modules/notification/base/null.go b/modules/notification/base/null.go
index d80ba859f3..2386f925ce 100644
--- a/modules/notification/base/null.go
+++ b/modules/notification/base/null.go
@@ -62,6 +62,10 @@ func (*NullNotifier) NotifyPullRequestChangeTargetBranch(doer *models.User, pr *
 func (*NullNotifier) NotifyPullRequestPushCommits(doer *models.User, pr *models.PullRequest, comment *models.Comment) {
 }
 
+// NotifyPullRevieweDismiss notifies when a review was dismissed by repo admin
+func (*NullNotifier) NotifyPullRevieweDismiss(doer *models.User, review *models.Review, comment *models.Comment) {
+}
+
 // NotifyUpdateComment places a place holder function
 func (*NullNotifier) NotifyUpdateComment(doer *models.User, c *models.Comment, oldContent string) {
 }
diff --git a/modules/notification/mail/mail.go b/modules/notification/mail/mail.go
index ee8a0c436c..f984ea7661 100644
--- a/modules/notification/mail/mail.go
+++ b/modules/notification/mail/mail.go
@@ -152,6 +152,12 @@ func (m *mailNotifier) NotifyPullRequestPushCommits(doer *models.User, pr *model
 	m.NotifyCreateIssueComment(doer, comment.Issue.Repo, comment.Issue, comment, nil)
 }
 
+func (m *mailNotifier) NotifyPullRevieweDismiss(doer *models.User, review *models.Review, comment *models.Comment) {
+	if err := mailer.MailParticipantsComment(comment, models.ActionPullReviewDismissed, review.Issue, []*models.User{}); err != nil {
+		log.Error("MailParticipantsComment: %v", err)
+	}
+}
+
 func (m *mailNotifier) NotifyNewRelease(rel *models.Release) {
 	if err := rel.LoadAttributes(); err != nil {
 		log.Error("NotifyNewRelease: %v", err)
diff --git a/modules/notification/notification.go b/modules/notification/notification.go
index 7ced57ce2d..d22d157bec 100644
--- a/modules/notification/notification.go
+++ b/modules/notification/notification.go
@@ -108,6 +108,13 @@ func NotifyPullRequestPushCommits(doer *models.User, pr *models.PullRequest, com
 	}
 }
 
+// NotifyPullRevieweDismiss notifies when a review was dismissed by repo admin
+func NotifyPullRevieweDismiss(doer *models.User, review *models.Review, comment *models.Comment) {
+	for _, notifier := range notifiers {
+		notifier.NotifyPullRevieweDismiss(doer, review, comment)
+	}
+}
+
 // 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/ui/ui.go b/modules/notification/ui/ui.go
index 8e510e9cd4..25ea4d91c6 100644
--- a/modules/notification/ui/ui.go
+++ b/modules/notification/ui/ui.go
@@ -161,6 +161,15 @@ func (ns *notificationService) NotifyPullRequestPushCommits(doer *models.User, p
 	_ = ns.issueQueue.Push(opts)
 }
 
+func (ns *notificationService) NotifyPullRevieweDismiss(doer *models.User, review *models.Review, comment *models.Comment) {
+	var opts = issueNotificationOpts{
+		IssueID:              review.IssueID,
+		NotificationAuthorID: doer.ID,
+		CommentID:            comment.ID,
+	}
+	_ = ns.issueQueue.Push(opts)
+}
+
 func (ns *notificationService) NotifyIssueChangeAssignee(doer *models.User, issue *models.Issue, assignee *models.User, removed bool, comment *models.Comment) {
 	if !removed {
 		var opts = issueNotificationOpts{
diff --git a/modules/structs/pull_review.go b/modules/structs/pull_review.go
index 07fa968d28..261d00fde8 100644
--- a/modules/structs/pull_review.go
+++ b/modules/structs/pull_review.go
@@ -36,6 +36,7 @@ type PullReview struct {
 	CommitID          string          `json:"commit_id"`
 	Stale             bool            `json:"stale"`
 	Official          bool            `json:"official"`
+	Dismissed         bool            `json:"dismissed"`
 	CodeCommentsCount int             `json:"comments_count"`
 	// swagger:strfmt date-time
 	Submitted time.Time `json:"submitted_at"`
@@ -92,6 +93,11 @@ type SubmitPullReviewOptions struct {
 	Body  string          `json:"body"`
 }
 
+// DismissPullReviewOptions are options to dismiss a pull review
+type DismissPullReviewOptions struct {
+	Message string `json:"message"`
+}
+
 // PullReviewRequestOptions are options to add or remove pull review requests
 type PullReviewRequestOptions struct {
 	Reviewers     []string `json:"reviewers"`
diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index 987a6ad983..b8e4f5d505 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -798,6 +798,8 @@ func ActionIcon(opType models.ActionType) string {
 		return "diff"
 	case models.ActionPublishRelease:
 		return "tag"
+	case models.ActionPullReviewDismissed:
+		return "x"
 	default:
 		return "question"
 	}
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index a4b677e43b..767696cfb9 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -76,6 +76,7 @@ pull_requests = Pull Requests
 issues = Issues
 milestones = Milestones
 
+ok = OK
 cancel = Cancel
 save = Save
 add = Add
@@ -1104,6 +1105,8 @@ issues.re_request_review=Re-request review
 issues.is_stale = There have been changes to this PR since this review
 issues.remove_request_review=Remove review request
 issues.remove_request_review_block=Can't remove review request
+issues.dismiss_review = Dismiss Review
+issues.dismiss_review_warning = Are you sure you want to dismiss this review?
 issues.sign_in_require_desc = <a href="%s">Sign in</a> to join this conversation.
 issues.edit = Edit
 issues.cancel = Cancel
@@ -1216,6 +1219,8 @@ issues.review.self.approval = You cannot approve your own pull request.
 issues.review.self.rejection = You cannot request changes on your own pull request.
 issues.review.approve = "approved these changes %s"
 issues.review.comment = "reviewed %s"
+issues.review.dismissed = "dismissed %s’s review %s"
+issues.review.dismissed_label = Dismissed
 issues.review.left_comment = left a comment
 issues.review.content.empty = You need to leave a comment indicating the requested change(s).
 issues.review.reject = "requested changes %s"
@@ -2519,6 +2524,8 @@ mirror_sync_delete = synced and deleted reference <code>%[2]s</code> at <a href=
 approve_pull_request = `approved <a href="%s/pulls/%s">%s#%[2]s</a>`
 reject_pull_request = `suggested changes for <a href="%s/pulls/%s">%s#%[2]s</a>`
 publish_release  = `released <a href="%s/releases/tag/%s"> "%[4]s" </a> at <a href="%[1]s">%[3]s</a>`
+review_dismissed = `dismissed review from <b>%[4]s</b> for <a href="%[1]s/pulls/%[2]s">%[3]s#%[2]s</a>`
+review_dismissed_reason = Reason:
 create_branch = created branch <a href="%[1]s/src/branch/%[2]s">%[3]s</a> in <a href="%[1]s">%[4]s</a>
 
 [tool]
diff --git a/routers/api/v1/api.go b/routers/api/v1/api.go
index 9c21107a28..85c4e4d5bf 100644
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@@ -891,6 +891,8 @@ func Routes() *web.Route {
 									Post(reqToken(), bind(api.SubmitPullReviewOptions{}), repo.SubmitPullReview)
 								m.Combo("/comments").
 									Get(repo.GetPullReviewComments)
+								m.Post("/dismissals", reqToken(), bind(api.DismissPullReviewOptions{}), repo.DismissPullReview)
+								m.Post("/undismissals", reqToken(), repo.UnDismissPullReview)
 							})
 						})
 						m.Combo("/requested_reviewers").
diff --git a/routers/api/v1/repo/pull_review.go b/routers/api/v1/repo/pull_review.go
index d39db4c660..63179aa990 100644
--- a/routers/api/v1/repo/pull_review.go
+++ b/routers/api/v1/repo/pull_review.go
@@ -757,3 +757,129 @@ func apiReviewRequest(ctx *context.APIContext, opts api.PullReviewRequestOptions
 		return
 	}
 }
+
+// DismissPullReview dismiss a review for a pull request
+func DismissPullReview(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/pulls/{index}/reviews/{id}/dismissals repository repoDismissPullReview
+	// ---
+	// summary: Dismiss a review for a pull request
+	// 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: index
+	//   in: path
+	//   description: index of the pull request
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// - name: id
+	//   in: path
+	//   description: id of the review
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// - name: body
+	//   in: body
+	//   required: true
+	//   schema:
+	//     "$ref": "#/definitions/DismissPullReviewOptions"
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/PullReview"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+	opts := web.GetForm(ctx).(*api.DismissPullReviewOptions)
+	dismissReview(ctx, opts.Message, true)
+}
+
+// UnDismissPullReview cancel to dismiss a review for a pull request
+func UnDismissPullReview(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/pulls/{index}/reviews/{id}/undismissals repository repoUnDismissPullReview
+	// ---
+	// summary: Cancel to dismiss a review for a pull request
+	// 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: index
+	//   in: path
+	//   description: index of the pull request
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// - name: id
+	//   in: path
+	//   description: id of the review
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/PullReview"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+	dismissReview(ctx, "", false)
+}
+
+func dismissReview(ctx *context.APIContext, msg string, isDismiss bool) {
+	if !ctx.Repo.IsAdmin() {
+		ctx.Error(http.StatusForbidden, "", "Must be repo admin")
+		return
+	}
+	review, pr, isWrong := prepareSingleReview(ctx)
+	if isWrong {
+		return
+	}
+
+	if review.Type != models.ReviewTypeApprove && review.Type != models.ReviewTypeReject {
+		ctx.Error(http.StatusForbidden, "", "not need to dismiss this review because it's type is not Approve or change request")
+		return
+	}
+
+	if pr.Issue.IsClosed {
+		ctx.Error(http.StatusForbidden, "", "not need to dismiss this review because this pr is closed")
+		return
+	}
+
+	_, err := pull_service.DismissReview(review.ID, msg, ctx.User, isDismiss)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "pull_service.DismissReview", err)
+		return
+	}
+
+	if review, err = models.GetReviewByID(review.ID); err != nil {
+		ctx.Error(http.StatusInternalServerError, "GetReviewByID", err)
+		return
+	}
+
+	// convert response
+	apiReview, err := convert.ToPullReview(review, ctx.User)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "convertToPullReview", err)
+		return
+	}
+	ctx.JSON(http.StatusOK, apiReview)
+}
diff --git a/routers/api/v1/swagger/options.go b/routers/api/v1/swagger/options.go
index 8919a969ec..a2dc2193a8 100644
--- a/routers/api/v1/swagger/options.go
+++ b/routers/api/v1/swagger/options.go
@@ -151,6 +151,9 @@ type swaggerParameterBodies struct {
 	SubmitPullReviewOptions api.SubmitPullReviewOptions
 
 	// in:body
+	DismissPullReviewOptions api.DismissPullReviewOptions
+
+	// in:body
 	MigrateRepoOptions api.MigrateRepoOptions
 
 	// in:body
diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index 71c8f1efbb..fa1ee99771 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -1364,7 +1364,7 @@ func ViewIssue(ctx *context.Context) {
 					return
 				}
 			}
-		} else if comment.Type == models.CommentTypeCode || comment.Type == models.CommentTypeReview {
+		} else if comment.Type == models.CommentTypeCode || comment.Type == models.CommentTypeReview || comment.Type == models.CommentTypeDismissReview {
 			comment.RenderedContent = string(markdown.Render([]byte(comment.Content), ctx.Repo.RepoLink,
 				ctx.Repo.Repository.ComposeMetas()))
 			if err = comment.LoadReview(); err != nil && !models.IsErrReviewNotExist(err) {
diff --git a/routers/repo/pull_review.go b/routers/repo/pull_review.go
index df49b6cfe1..89e87ccc44 100644
--- a/routers/repo/pull_review.go
+++ b/routers/repo/pull_review.go
@@ -223,3 +223,15 @@ func SubmitReview(ctx *context.Context) {
 
 	ctx.Redirect(fmt.Sprintf("%s/pulls/%d#%s", ctx.Repo.RepoLink, issue.Index, comm.HashTag()))
 }
+
+// DismissReview dismissing stale review by repo admin
+func DismissReview(ctx *context.Context) {
+	form := web.GetForm(ctx).(*auth.DismissReviewForm)
+	comm, err := pull_service.DismissReview(form.ReviewID, form.Message, ctx.User, true)
+	if err != nil {
+		ctx.ServerError("pull_service.DismissReview", err)
+		return
+	}
+
+	ctx.Redirect(fmt.Sprintf("%s/pulls/%d#%s", ctx.Repo.RepoLink, comm.Issue.Index, comm.HashTag()))
+}
diff --git a/routers/routes/web.go b/routers/routes/web.go
index 9e3e690fb9..2f28e567f9 100644
--- a/routers/routes/web.go
+++ b/routers/routes/web.go
@@ -734,6 +734,7 @@ func RegisterRoutes(m *web.Route) {
 			m.Post("/projects", reqRepoIssuesOrPullsWriter, repo.UpdateIssueProject)
 			m.Post("/assignee", reqRepoIssuesOrPullsWriter, repo.UpdateIssueAssignee)
 			m.Post("/request_review", reqRepoIssuesOrPullsReader, repo.UpdatePullReviewRequest)
+			m.Post("/dismiss_review", reqRepoAdmin, bindIgnErr(auth.DismissReviewForm{}), repo.DismissReview)
 			m.Post("/status", reqRepoIssuesOrPullsWriter, repo.UpdateIssueStatus)
 			m.Post("/resolve_conversation", reqRepoIssuesOrPullsReader, repo.UpdateResolveConversation)
 			m.Post("/attachments", repo.UploadIssueAttachment)
diff --git a/services/mailer/mail.go b/services/mailer/mail.go
index b4217c0466..e87d34ab29 100644
--- a/services/mailer/mail.go
+++ b/services/mailer/mail.go
@@ -304,6 +304,8 @@ func actionToTemplate(issue *models.Issue, actionType models.ActionType,
 		name = "reopen"
 	case models.ActionMergePullRequest:
 		name = "merge"
+	case models.ActionPullReviewDismissed:
+		name = "review_dismissed"
 	default:
 		switch commentType {
 		case models.CommentTypeReview:
diff --git a/services/pull/review.go b/services/pull/review.go
index 8994a9e78a..4e77e11daa 100644
--- a/services/pull/review.go
+++ b/services/pull/review.go
@@ -253,3 +253,54 @@ func SubmitReview(doer *models.User, gitRepo *git.Repository, issue *models.Issu
 
 	return review, comm, nil
 }
+
+// DismissReview dismissing stale review by repo admin
+func DismissReview(reviewID int64, message string, doer *models.User, isDismiss bool) (comment *models.Comment, err error) {
+	review, err := models.GetReviewByID(reviewID)
+	if err != nil {
+		return
+	}
+
+	if review.Type != models.ReviewTypeApprove && review.Type != models.ReviewTypeReject {
+		return nil, fmt.Errorf("not need to dismiss this review because it's type is not Approve or change request")
+	}
+
+	if err = models.DismissReview(review, isDismiss); err != nil {
+		return
+	}
+
+	if !isDismiss {
+		return nil, nil
+	}
+
+	// load data for notify
+	if err = review.LoadAttributes(); err != nil {
+		return
+	}
+	if err = review.Issue.LoadPullRequest(); err != nil {
+		return
+	}
+	if err = review.Issue.LoadAttributes(); err != nil {
+		return
+	}
+
+	comment, err = models.CreateComment(&models.CreateCommentOptions{
+		Doer:     doer,
+		Content:  message,
+		Type:     models.CommentTypeDismissReview,
+		ReviewID: review.ID,
+		Issue:    review.Issue,
+		Repo:     review.Issue.Repo,
+	})
+	if err != nil {
+		return
+	}
+
+	comment.Review = review
+	comment.Poster = doer
+	comment.Issue = review.Issue
+
+	notification.NotifyPullRevieweDismiss(doer, review, comment)
+
+	return
+}
diff --git a/templates/mail/issue/default.tmpl b/templates/mail/issue/default.tmpl
index e062dca7f1..b7d576bef4 100644
--- a/templates/mail/issue/default.tmpl
+++ b/templates/mail/issue/default.tmpl
@@ -49,6 +49,8 @@
 			<b>@{{.Doer.Name}}</b> requested changes on this pull request.
 		{{else if eq .ActionName "review"}}
 			<b>@{{.Doer.Name}}</b> commented on this pull request.
+		{{else if eq .ActionName "review_dismissed"}}
+			<b>@{{.Doer.Name}}</b> dismissed last review from {{.Comment.Review.Reviewer.Name}} for this pull request.
 		{{end}}
 
 		{{- if eq .Body ""}}
diff --git a/templates/repo/issue/view_content/comments.tmpl b/templates/repo/issue/view_content/comments.tmpl
index 63fe73857c..b971c6b1ae 100644
--- a/templates/repo/issue/view_content/comments.tmpl
+++ b/templates/repo/issue/view_content/comments.tmpl
@@ -8,7 +8,8 @@
 	 18 = REMOVED_DEADLINE, 19 = ADD_DEPENDENCY, 20 = REMOVE_DEPENDENCY, 21 = CODE,
 	 22 = REVIEW, 23 = ISSUE_LOCKED, 24 = ISSUE_UNLOCKED, 25 = TARGET_BRANCH_CHANGED,
 	 26 = DELETE_TIME_MANUAL, 27 = REVIEW_REQUEST, 28 = MERGE_PULL_REQUEST,
-	 29 = PULL_PUSH_EVENT, 30 = PROJECT_CHANGED, 31 = PROJECT_BOARD_CHANGED -->
+	 29 = PULL_PUSH_EVENT, 30 = PROJECT_CHANGED, 31 = PROJECT_BOARD_CHANGED 
+	 32 = DISMISSED_REVIEW -->
 	{{if eq .Type 0}}
 		<div class="timeline-item comment" id="{{.HashTag}}">
 		{{if .OriginalAuthor }}
@@ -415,6 +416,9 @@
 					{{else}}
 						{{$.i18n.Tr "repo.issues.review.comment" $createdStr | Safe}}
 					{{end}}
+					{{if .Review.Dismissed}}
+						<div class="ui small label">{{$.i18n.Tr "repo.issues.review.dismissed_label"}}</div>
+					{{end}}
 				</span>
 			</div>
 			{{if .Content}}
@@ -698,5 +702,44 @@
 			</span>
 		</div>
 		{{end}}
+	{{else if eq .Type 32}}
+		<div class="timeline-item-group">
+			<div class="timeline-item event" id="{{.HashTag}}">
+				<a class="timeline-avatar"{{if gt .Poster.ID 0}} href="{{.Poster.HomeLink}}"{{end}}>
+					<img src="{{.Poster.RelAvatarLink}}">
+				</a>
+				<span class="badge grey">{{svg "octicon-x" 16}}</span>
+				<span class="text grey">
+					<a class="author"{{if gt .Poster.ID 0}} href="{{.Poster.HomeLink}}"{{end}}>{{.Poster.GetDisplayName}}</a>
+					{{$reviewerName := ""}}
+					{{if eq .Review.OriginalAuthor ""}}
+						{{$reviewerName = .Review.Reviewer.Name}}
+					{{else}}
+						{{$reviewerName = .Review.OriginalAuthor}}
+					{{end}}
+					{{$.i18n.Tr "repo.issues.review.dismissed" $reviewerName $createdStr | Safe}}
+				</span>
+			</div>
+			{{if .Content}}
+				<div class="timeline-item comment">
+					<div class="content">
+						<div class="ui top attached header arrow-top">
+							<span class="text grey">
+								{{$.i18n.Tr "action.review_dismissed_reason"}}
+							</span>
+						</div>
+						<div class="ui attached segment">
+							<div class="render-content markdown">
+								{{if .RenderedContent}}
+									{{.RenderedContent|Str2html}}
+								{{else}}
+									<span class="no-content">{{$.i18n.Tr "repo.issues.no_content"}}</span>
+								{{end}}
+							</div>
+						</div>
+					</div>
+				</div>
+			{{end}}
+		</div>
 	{{end}}
 {{end}}
diff --git a/templates/repo/issue/view_content/pull.tmpl b/templates/repo/issue/view_content/pull.tmpl
index 34eaa83eb2..9e883c0a93 100644
--- a/templates/repo/issue/view_content/pull.tmpl
+++ b/templates/repo/issue/view_content/pull.tmpl
@@ -34,9 +34,36 @@
 						</div>
 						<div class="review-item-right">
 							{{if .Review.Stale}}
-							<span class="ui poping up type-icon text grey" data-content="{{$.i18n.Tr "repo.issues.is_stale"}}">
-								<i class="octicon icon fa-hourglass-end"></i>
-							</span>
+								<span class="ui poping up type-icon text grey" data-content="{{$.i18n.Tr "repo.issues.is_stale"}}">
+									<i class="octicon icon fa-hourglass-end"></i>
+								</span>
+							{{end}}
+							{{if (and $.Permission.IsAdmin (or (eq .Review.Type 1) (eq .Review.Type 3)) (not $.Issue.IsClosed))}}
+								<a href="#" class="ui grey poping up icon dismiss-review-btn" data-review-id="dismiss-review-{{.Review.ID}}" data-content="{{$.i18n.Tr "repo.issues.dismiss_review"}}">
+									{{svg "octicon-x" 16}}
+								</a>
+								<div class="ui small modal" id="dismiss-review-modal">
+									<div class="header">
+										{{$.i18n.Tr "repo.issues.dismiss_review"}}
+									</div>
+									<div class="content">
+										<div class="ui warning message text left">
+											{{$.i18n.Tr "repo.issues.dismiss_review_warning"}}
+										</div>
+										<form class="ui form dismiss-review-form" id="dismiss-review-{{.Review.ID}}" action="{{$.RepoLink}}/issues/dismiss_review" method="post">
+											{{$.CsrfTokenHtml}}
+											<input type="hidden" name="review_id" value="{{.Review.ID}}">
+											<div class="field">
+												<label for="message">{{$.i18n.Tr "action.review_dismissed_reason"}}</label>
+												<input id="message" name="message">
+											</div>
+											<div class="text right actions">
+												<div class="ui cancel button">{{$.i18n.Tr "settings.cancel"}}</div>
+												<button class="ui red button" type="submit">{{$.i18n.Tr "ok"}}</button>
+											</div>
+										</form>
+									</div>
+								</div>
 							{{end}}
 							<span class="type-icon text {{if eq .Review.Type 1}}green
 								{{- else if eq .Review.Type 2}}grey
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 28aa617799..94493749af 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -7761,6 +7761,124 @@
         }
       }
     },
+    "/repos/{owner}/{repo}/pulls/{index}/reviews/{id}/dismissals": {
+      "post": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "repository"
+        ],
+        "summary": "Dismiss a review for a pull request",
+        "operationId": "repoDismissPullReview",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "index of the pull request",
+            "name": "index",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "id of the review",
+            "name": "id",
+            "in": "path",
+            "required": true
+          },
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/DismissPullReviewOptions"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/PullReview"
+          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
+          "422": {
+            "$ref": "#/responses/validationError"
+          }
+        }
+      }
+    },
+    "/repos/{owner}/{repo}/pulls/{index}/reviews/{id}/undismissals": {
+      "post": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "repository"
+        ],
+        "summary": "Cancel to dismiss a review for a pull request",
+        "operationId": "repoUnDismissPullReview",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "index of the pull request",
+            "name": "index",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "id of the review",
+            "name": "id",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/PullReview"
+          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
+          "422": {
+            "$ref": "#/responses/validationError"
+          }
+        }
+      }
+    },
     "/repos/{owner}/{repo}/pulls/{index}/update": {
       "post": {
         "produces": [
@@ -13036,6 +13154,17 @@
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"
     },
+    "DismissPullReviewOptions": {
+      "description": "DismissPullReviewOptions are options to dismiss a pull review",
+      "type": "object",
+      "properties": {
+        "message": {
+          "type": "string",
+          "x-go-name": "Message"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
     "EditAttachmentOptions": {
       "description": "EditAttachmentOptions options for editing attachments",
       "type": "object",
@@ -15199,6 +15328,10 @@
           "type": "string",
           "x-go-name": "CommitID"
         },
+        "dismissed": {
+          "type": "boolean",
+          "x-go-name": "Dismissed"
+        },
         "html_url": {
           "type": "string",
           "x-go-name": "HTMLURL"
diff --git a/templates/user/dashboard/feeds.tmpl b/templates/user/dashboard/feeds.tmpl
index 744e028bc2..d25920a24e 100644
--- a/templates/user/dashboard/feeds.tmpl
+++ b/templates/user/dashboard/feeds.tmpl
@@ -78,6 +78,10 @@
 							{{ $branchLink := .GetBranch | EscapePound | Escape}}
 							{{ $linkText := .Content | RenderEmoji }}
 							{{$.i18n.Tr "action.publish_release" .GetRepoLink $branchLink .ShortRepoPath $linkText | Str2html}}
+						{{else if eq .GetOpType 25}}
+							{{ $index := index .GetIssueInfos 0}}
+							{{ $reviewer := index .GetIssueInfos 1}}
+							{{$.i18n.Tr "action.review_dismissed" .GetRepoLink $index .ShortRepoPath $reviewer | Str2html}}
 						{{end}}
 					</p>
 					{{if or (eq .GetOpType 5) (eq .GetOpType 18)}}
@@ -111,6 +115,9 @@
 						<p class="text light grey">{{index .GetIssueInfos 1}}</p>
 					{{else if or (eq .GetOpType 12) (eq .GetOpType 13) (eq .GetOpType 14) (eq .GetOpType 15)}}
 						<span class="text truncate issue title">{{.GetIssueTitle | RenderEmoji}}</span>
+					{{else if eq .GetOpType 25}}
+					<p class="text light grey">{{$.i18n.Tr "action.review_dismissed_reason"}}</p>
+						<p class="text light grey">{{index .GetIssueInfos 2 | RenderEmoji}}</p>
 					{{end}}
 					<p class="text italic light grey">{{TimeSince .GetCreate $.i18n.Lang}}</p>
 				</div>
diff --git a/web_src/js/index.js b/web_src/js/index.js
index f5f4841410..0d60c21cca 100644
--- a/web_src/js/index.js
+++ b/web_src/js/index.js
@@ -677,6 +677,13 @@ function initIssueComments() {
     return false;
   });
 
+  $('.dismiss-review-btn').on('click', function (e) {
+    e.preventDefault();
+    const $this = $(this);
+    const $dismissReviewModal = $this.next();
+    $dismissReviewModal.modal('show');
+  });
+
   $(document).on('click', (event) => {
     const urlTarget = $(':target');
     if (urlTarget.length === 0) return;