Repository transfer has to be confirmed, if user can not create repo for new owner (#14792)

* make repo as "pending transfer" if on transfer start doer has no right to create repo in new destination

* if new pending transfer ocured, create UI & Mail notifications

32 files changed, 898 insertions, 167 deletions

diff --git a/integrations/api_repo_test.go b/integrations/api_repo_test.go
index b6d41fe1e0..3404e050cf 100644
--- a/integrations/api_repo_test.go
+++ b/integrations/api_repo_test.go
@@ -444,12 +444,22 @@ func TestAPIRepoTransfer(t *testing.T) {
 		teams          *[]int64
 		expectedStatus int
 	}{
-		{ctxUserID: 1, newOwner: "user2", teams: nil, expectedStatus: http.StatusAccepted},
-		{ctxUserID: 2, newOwner: "user1", teams: nil, expectedStatus: http.StatusAccepted},
-		{ctxUserID: 2, newOwner: "user6", teams: nil, expectedStatus: http.StatusForbidden},
-		{ctxUserID: 1, newOwner: "user2", teams: &[]int64{2}, expectedStatus: http.StatusUnprocessableEntity},
+		// Disclaimer for test story: "user1" is an admin, "user2" is normal user and part of in owner team of org "user3"
+
+		// Transfer to a user with teams in another org should fail
 		{ctxUserID: 1, newOwner: "user3", teams: &[]int64{5}, expectedStatus: http.StatusForbidden},
+		// Transfer to a user with non-existent team IDs should fail
+		{ctxUserID: 1, newOwner: "user2", teams: &[]int64{2}, expectedStatus: http.StatusUnprocessableEntity},
+		// Transfer should go through
 		{ctxUserID: 1, newOwner: "user3", teams: &[]int64{2}, expectedStatus: http.StatusAccepted},
+		// Let user transfer it back to himself
+		{ctxUserID: 2, newOwner: "user2", expectedStatus: http.StatusAccepted},
+		// And revert transfer
+		{ctxUserID: 2, newOwner: "user3", teams: &[]int64{2}, expectedStatus: http.StatusAccepted},
+		// Cannot start transfer to an existing repo
+		{ctxUserID: 2, newOwner: "user3", teams: nil, expectedStatus: http.StatusUnprocessableEntity},
+		// Start transfer, repo is now in pending transfer mode
+		{ctxUserID: 2, newOwner: "user6", teams: nil, expectedStatus: http.StatusCreated},
 	}
 
 	defer prepareTestEnv(t)()
diff --git a/models/error.go b/models/error.go
index fc161ed806..84b7ebbfa3 100644
--- a/models/error.go
+++ b/models/error.go
@@ -757,6 +757,40 @@ func (err ErrRepoNotExist) Error() string {
 		err.ID, err.UID, err.OwnerName, err.Name)
 }
 
+// ErrNoPendingRepoTransfer is an error type for repositories without a pending
+// transfer request
+type ErrNoPendingRepoTransfer struct {
+	RepoID int64
+}
+
+func (e ErrNoPendingRepoTransfer) Error() string {
+	return fmt.Sprintf("repository doesn't have a pending transfer [repo_id: %d]", e.RepoID)
+}
+
+// IsErrNoPendingTransfer is an error type when a repository has no pending
+// transfers
+func IsErrNoPendingTransfer(err error) bool {
+	_, ok := err.(ErrNoPendingRepoTransfer)
+	return ok
+}
+
+// ErrRepoTransferInProgress represents the state of a repository that has an
+// ongoing transfer
+type ErrRepoTransferInProgress struct {
+	Uname string
+	Name  string
+}
+
+// IsErrRepoTransferInProgress checks if an error is a ErrRepoTransferInProgress.
+func IsErrRepoTransferInProgress(err error) bool {
+	_, ok := err.(ErrRepoTransferInProgress)
+	return ok
+}
+
+func (err ErrRepoTransferInProgress) Error() string {
+	return fmt.Sprintf("repository is already being transferred [uname: %s, name: %s]", err.Uname, err.Name)
+}
+
 // ErrRepoAlreadyExist represents a "RepoAlreadyExist" kind of error.
 type ErrRepoAlreadyExist struct {
 	Uname string
diff --git a/models/fixtures/repo_transfer.yml b/models/fixtures/repo_transfer.yml
new file mode 100644
index 0000000000..b841b5e983
--- /dev/null
+++ b/models/fixtures/repo_transfer.yml
@@ -0,0 +1,7 @@
+-
+  id: 1
+  doer_id: 3
+  recipient_id: 1
+  repo_id: 3
+  created_unix: 1553610671
+  updated_unix: 1553610671
diff --git a/models/issue.go b/models/issue.go
index b903e82ad7..c0bafb54e4 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -563,7 +563,7 @@ func (issue *Issue) ReadBy(userID int64) error {
 		return err
 	}
 
-	return setNotificationStatusReadIfUnread(x, userID, issue.ID)
+	return setIssueNotificationStatusReadIfUnread(x, userID, issue.ID)
 }
 
 func updateIssueCols(e Engine, issue *Issue, cols ...string) error {
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index 4fc737e1bf..27c159ee4a 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -294,6 +294,8 @@ var migrations = []Migration{
 	NewMigration("Add sessions table for go-chi/session", addSessionTable),
 	// v173 -> v174
 	NewMigration("Add time_id column to Comment", addTimeIDCommentColumn),
+	// v174 -> v175
+	NewMigration("create repo transfer table", addRepoTransfer),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v174.go b/models/migrations/v174.go
new file mode 100644
index 0000000000..ce337df2b3
--- /dev/null
+++ b/models/migrations/v174.go
@@ -0,0 +1,23 @@
+// 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 (
+	"xorm.io/xorm"
+)
+
+func addRepoTransfer(x *xorm.Engine) error {
+	type RepoTransfer struct {
+		ID          int64 `xorm:"pk autoincr"`
+		DoerID      int64
+		RecipientID int64
+		RepoID      int64
+		TeamIDs     []int64
+		CreatedUnix int64 `xorm:"INDEX NOT NULL created"`
+		UpdatedUnix int64 `xorm:"INDEX NOT NULL updated"`
+	}
+
+	return x.Sync(new(RepoTransfer))
+}
diff --git a/models/models.go b/models/models.go
index de50793fe7..ca4d1c4ad1 100644
--- a/models/models.go
+++ b/models/models.go
@@ -133,6 +133,7 @@ func init() {
 		new(ProjectBoard),
 		new(ProjectIssue),
 		new(Session),
+		new(RepoTransfer),
 	)
 
 	gonicNames := []string{"SSL", "UID"}
diff --git a/models/notification.go b/models/notification.go
index 32f3079bf4..a9178b97de 100644
--- a/models/notification.go
+++ b/models/notification.go
@@ -39,6 +39,8 @@ const (
 	NotificationSourcePullRequest
 	// NotificationSourceCommit is a notification of a commit
 	NotificationSourceCommit
+	// NotificationSourceRepository is a notification for a repository
+	NotificationSourceRepository
 )
 
 // Notification represents a notification
@@ -119,6 +121,46 @@ func GetNotifications(opts FindNotificationOptions) (NotificationList, error) {
 	return getNotifications(x, opts)
 }
 
+// CreateRepoTransferNotification creates  notification for the user a repository was transferred to
+func CreateRepoTransferNotification(doer, newOwner *User, repo *Repository) error {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+	var notify []*Notification
+
+	if newOwner.IsOrganization() {
+		users, err := getUsersWhoCanCreateOrgRepo(sess, newOwner.ID)
+		if err != nil || len(users) == 0 {
+			return err
+		}
+		for i := range users {
+			notify = append(notify, &Notification{
+				UserID:    users[i].ID,
+				RepoID:    repo.ID,
+				Status:    NotificationStatusUnread,
+				UpdatedBy: doer.ID,
+				Source:    NotificationSourceRepository,
+			})
+		}
+	} else {
+		notify = []*Notification{{
+			UserID:    newOwner.ID,
+			RepoID:    repo.ID,
+			Status:    NotificationStatusUnread,
+			UpdatedBy: doer.ID,
+			Source:    NotificationSourceRepository,
+		}}
+	}
+
+	if _, err := sess.InsertMulti(notify); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}
+
 // CreateOrUpdateIssueNotifications creates an issue notification
 // for each watcher, or updates it if already exists
 // receiverID > 0 just send to reciver, else send to all watcher
@@ -363,7 +405,7 @@ func (n *Notification) loadRepo(e Engine) (err error) {
 }
 
 func (n *Notification) loadIssue(e Engine) (err error) {
-	if n.Issue == nil {
+	if n.Issue == nil && n.IssueID != 0 {
 		n.Issue, err = getIssueByID(e, n.IssueID)
 		if err != nil {
 			return fmt.Errorf("getIssueByID [%d]: %v", n.IssueID, err)
@@ -374,7 +416,7 @@ func (n *Notification) loadIssue(e Engine) (err error) {
 }
 
 func (n *Notification) loadComment(e Engine) (err error) {
-	if n.Comment == nil && n.CommentID > 0 {
+	if n.Comment == nil && n.CommentID != 0 {
 		n.Comment, err = getCommentByID(e, n.CommentID)
 		if err != nil {
 			return fmt.Errorf("GetCommentByID [%d] for issue ID [%d]: %v", n.CommentID, n.IssueID, err)
@@ -405,10 +447,18 @@ func (n *Notification) GetIssue() (*Issue, error) {
 
 // HTMLURL formats a URL-string to the notification
 func (n *Notification) HTMLURL() string {
-	if n.Comment != nil {
-		return n.Comment.HTMLURL()
+	switch n.Source {
+	case NotificationSourceIssue, NotificationSourcePullRequest:
+		if n.Comment != nil {
+			return n.Comment.HTMLURL()
+		}
+		return n.Issue.HTMLURL()
+	case NotificationSourceCommit:
+		return n.Repository.HTMLURL() + "/commit/" + n.CommitID
+	case NotificationSourceRepository:
+		return n.Repository.HTMLURL()
 	}
-	return n.Issue.HTMLURL()
+	return ""
 }
 
 // APIURL formats a URL-string to the notification
@@ -562,8 +612,10 @@ func (nl NotificationList) LoadIssues() ([]int, error) {
 		if notification.Issue == nil {
 			notification.Issue = issues[notification.IssueID]
 			if notification.Issue == nil {
-				log.Error("Notification[%d]: IssueID: %d Not Found", notification.ID, notification.IssueID)
-				failures = append(failures, i)
+				if notification.IssueID != 0 {
+					log.Error("Notification[%d]: IssueID: %d Not Found", notification.ID, notification.IssueID)
+					failures = append(failures, i)
+				}
 				continue
 			}
 			notification.Issue.Repo = notification.Repository
@@ -683,7 +735,7 @@ func GetUIDsAndNotificationCounts(since, until timeutil.TimeStamp) ([]UserIDCoun
 	return res, x.SQL(sql, since, until, NotificationStatusUnread).Find(&res)
 }
 
-func setNotificationStatusReadIfUnread(e Engine, userID, issueID int64) error {
+func setIssueNotificationStatusReadIfUnread(e Engine, userID, issueID int64) error {
 	notification, err := getIssueNotification(e, userID, issueID)
 	// ignore if not exists
 	if err != nil {
@@ -700,6 +752,16 @@ func setNotificationStatusReadIfUnread(e Engine, userID, issueID int64) error {
 	return err
 }
 
+func setRepoNotificationStatusReadIfUnread(e Engine, userID, repoID int64) error {
+	_, err := e.Where(builder.Eq{
+		"user_id": userID,
+		"status":  NotificationStatusUnread,
+		"source":  NotificationSourceRepository,
+		"repo_id": repoID,
+	}).Cols("status").Update(&Notification{Status: NotificationStatusRead})
+	return err
+}
+
 // SetNotificationStatus change the notification status
 func SetNotificationStatus(notificationID int64, user *User, status NotificationStatus) error {
 	notification, err := getNotificationByID(x, notificationID)
diff --git a/models/org.go b/models/org.go
index ee867eec88..437d57d056 100644
--- a/models/org.go
+++ b/models/org.go
@@ -391,6 +391,20 @@ func CanCreateOrgRepo(orgID, uid int64) (bool, error) {
 		Exist(new(Team))
 }
 
+// GetUsersWhoCanCreateOrgRepo returns users which are able to create repo in organization
+func GetUsersWhoCanCreateOrgRepo(orgID int64) ([]*User, error) {
+	return getUsersWhoCanCreateOrgRepo(x, orgID)
+}
+
+func getUsersWhoCanCreateOrgRepo(e Engine, orgID int64) ([]*User, error) {
+	users := make([]*User, 0, 10)
+	return users, x.
+		Join("INNER", "`team_user`", "`team_user`.uid=`user`.id").
+		Join("INNER", "`team`", "`team`.id=`team_user`.team_id").
+		Where(builder.Eq{"team.can_create_org_repo": true}.Or(builder.Eq{"team.authorize": AccessModeOwner})).
+		And("team_user.org_id = ?", orgID).Asc("`user`.name").Find(&users)
+}
+
 func getOrgsByUserID(sess *xorm.Session, userID int64, showAll bool) ([]*User, error) {
 	orgs := make([]*User, 0, 10)
 	if !showAll {
diff --git a/models/org_test.go b/models/org_test.go
index 79f8b060e7..45268f0f23 100644
--- a/models/org_test.go
+++ b/models/org_test.go
@@ -635,3 +635,21 @@ func TestHasOrgVisibleTypePrivate(t *testing.T) {
 	assert.Equal(t, test2, false) // user not a part of org
 	assert.Equal(t, test3, false) // logged out user
 }
+
+func TestGetUsersWhoCanCreateOrgRepo(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	users, err := GetUsersWhoCanCreateOrgRepo(3)
+	assert.NoError(t, err)
+	assert.Len(t, users, 2)
+	var ids []int64
+	for i := range users {
+		ids = append(ids, users[i].ID)
+	}
+	assert.ElementsMatch(t, ids, []int64{2, 28})
+
+	users, err = GetUsersWhoCanCreateOrgRepo(7)
+	assert.NoError(t, err)
+	assert.Len(t, users, 1)
+	assert.EqualValues(t, 5, users[0].ID)
+}
diff --git a/models/repo.go b/models/repo.go
index 6cb6f38a48..2c71fc3e1e 100644
--- a/models/repo.go
+++ b/models/repo.go
@@ -139,8 +139,9 @@ type RepositoryStatus int
 
 // all kinds of RepositoryStatus
 const (
-	RepositoryReady         RepositoryStatus = iota // a normal repository
-	RepositoryBeingMigrated                         // repository is migrating
+	RepositoryReady           RepositoryStatus = iota // a normal repository
+	RepositoryBeingMigrated                           // repository is migrating
+	RepositoryPendingTransfer                         // repository pending in ownership transfer state
 )
 
 // TrustModelType defines the types of trust model for this repository
@@ -872,6 +873,11 @@ func (repo *Repository) DescriptionHTML() template.HTML {
 	return template.HTML(markup.Sanitize(string(desc)))
 }
 
+// ReadBy sets repo to be visited by given user.
+func (repo *Repository) ReadBy(userID int64) error {
+	return setRepoNotificationStatusReadIfUnread(x, userID, repo.ID)
+}
+
 func isRepositoryExist(e Engine, u *User, repoName string) (bool, error) {
 	has, err := e.Get(&Repository{
 		OwnerID:   u.ID,
@@ -1189,140 +1195,6 @@ func IncrementRepoForkNum(ctx DBContext, repoID int64) error {
 	return err
 }
 
-// TransferOwnership transfers all corresponding setting from old user to new one.
-func TransferOwnership(doer *User, newOwnerName string, repo *Repository) error {
-	newOwner, err := GetUserByName(newOwnerName)
-	if err != nil {
-		return fmt.Errorf("get new owner '%s': %v", newOwnerName, err)
-	}
-
-	// Check if new owner has repository with same name.
-	has, err := IsRepositoryExist(newOwner, repo.Name)
-	if err != nil {
-		return fmt.Errorf("IsRepositoryExist: %v", err)
-	} else if has {
-		return ErrRepoAlreadyExist{newOwnerName, repo.Name}
-	}
-
-	sess := x.NewSession()
-	defer sess.Close()
-	if err = sess.Begin(); err != nil {
-		return fmt.Errorf("sess.Begin: %v", err)
-	}
-
-	oldOwner := repo.Owner
-
-	// Note: we have to set value here to make sure recalculate accesses is based on
-	// new owner.
-	repo.OwnerID = newOwner.ID
-	repo.Owner = newOwner
-	repo.OwnerName = newOwner.Name
-
-	// Update repository.
-	if _, err := sess.ID(repo.ID).Update(repo); err != nil {
-		return fmt.Errorf("update owner: %v", err)
-	}
-
-	// Remove redundant collaborators.
-	collaborators, err := repo.getCollaborators(sess, ListOptions{})
-	if err != nil {
-		return fmt.Errorf("getCollaborators: %v", err)
-	}
-
-	// Dummy object.
-	collaboration := &Collaboration{RepoID: repo.ID}
-	for _, c := range collaborators {
-		if c.ID != newOwner.ID {
-			isMember, err := isOrganizationMember(sess, newOwner.ID, c.ID)
-			if err != nil {
-				return fmt.Errorf("IsOrgMember: %v", err)
-			} else if !isMember {
-				continue
-			}
-		}
-		collaboration.UserID = c.ID
-		if _, err = sess.Delete(collaboration); err != nil {
-			return fmt.Errorf("remove collaborator '%d': %v", c.ID, err)
-		}
-	}
-
-	// Remove old team-repository relations.
-	if oldOwner.IsOrganization() {
-		if err = oldOwner.removeOrgRepo(sess, repo.ID); err != nil {
-			return fmt.Errorf("removeOrgRepo: %v", err)
-		}
-	}
-
-	if newOwner.IsOrganization() {
-		if err := newOwner.getTeams(sess); err != nil {
-			return fmt.Errorf("GetTeams: %v", err)
-		}
-		for _, t := range newOwner.Teams {
-			if t.IncludesAllRepositories {
-				if err := t.addRepository(sess, repo); err != nil {
-					return fmt.Errorf("addRepository: %v", err)
-				}
-			}
-		}
-	} else if err = repo.recalculateAccesses(sess); err != nil {
-		// Organization called this in addRepository method.
-		return fmt.Errorf("recalculateAccesses: %v", err)
-	}
-
-	// Update repository count.
-	if _, err = sess.Exec("UPDATE `user` SET num_repos=num_repos+1 WHERE id=?", newOwner.ID); err != nil {
-		return fmt.Errorf("increase new owner repository count: %v", err)
-	} else if _, err = sess.Exec("UPDATE `user` SET num_repos=num_repos-1 WHERE id=?", oldOwner.ID); err != nil {
-		return fmt.Errorf("decrease old owner repository count: %v", err)
-	}
-
-	if err = watchRepo(sess, doer.ID, repo.ID, true); err != nil {
-		return fmt.Errorf("watchRepo: %v", err)
-	}
-
-	// Remove watch for organization.
-	if oldOwner.IsOrganization() {
-		if err = watchRepo(sess, oldOwner.ID, repo.ID, false); err != nil {
-			return fmt.Errorf("watchRepo [false]: %v", err)
-		}
-	}
-
-	// Rename remote repository to new path and delete local copy.
-	dir := UserPath(newOwner.Name)
-
-	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
-		return fmt.Errorf("Failed to create dir %s: %v", dir, err)
-	}
-
-	if err = os.Rename(RepoPath(oldOwner.Name, repo.Name), RepoPath(newOwner.Name, repo.Name)); err != nil {
-		return fmt.Errorf("rename repository directory: %v", err)
-	}
-
-	// Rename remote wiki repository to new path and delete local copy.
-	wikiPath := WikiPath(oldOwner.Name, repo.Name)
-	isExist, err := util.IsExist(wikiPath)
-	if err != nil {
-		log.Error("Unable to check if %s exists. Error: %v", wikiPath, err)
-		return err
-	}
-	if isExist {
-		if err = os.Rename(wikiPath, WikiPath(newOwner.Name, repo.Name)); err != nil {
-			return fmt.Errorf("rename repository wiki: %v", err)
-		}
-	}
-
-	// If there was previously a redirect at this location, remove it.
-	if err = deleteRepoRedirect(sess, newOwner.ID, repo.Name); err != nil {
-		return fmt.Errorf("delete repo redirect: %v", err)
-	}
-
-	if err := newRepoRedirect(sess, oldOwner.ID, repo.ID, repo.Name, repo.Name); err != nil {
-		return fmt.Errorf("newRepoRedirect: %v", err)
-	}
-
-	return sess.Commit()
-}
-
 // ChangeRepositoryName changes all corresponding setting from old repository name to new one.
 func ChangeRepositoryName(doer *User, repo *Repository, newRepoName string) (err error) {
 	oldRepoName := repo.Name
diff --git a/models/repo_transfer.go b/models/repo_transfer.go
new file mode 100644
index 0000000000..cf1e16b9c3
--- /dev/null
+++ b/models/repo_transfer.go
@@ -0,0 +1,335 @@
+// 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 models
+
+import (
+	"fmt"
+	"os"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
+)
+
+// RepoTransfer is used to manage repository transfers
+type RepoTransfer struct {
+	ID          int64 `xorm:"pk autoincr"`
+	DoerID      int64
+	Doer        *User `xorm:"-"`
+	RecipientID int64
+	Recipient   *User `xorm:"-"`
+	RepoID      int64
+	TeamIDs     []int64
+	Teams       []*Team `xorm:"-"`
+
+	CreatedUnix timeutil.TimeStamp `xorm:"INDEX NOT NULL created"`
+	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX NOT NULL updated"`
+}
+
+// LoadAttributes fetches the transfer recipient from the database
+func (r *RepoTransfer) LoadAttributes() error {
+	if r.Recipient == nil {
+		u, err := GetUserByID(r.RecipientID)
+		if err != nil {
+			return err
+		}
+
+		r.Recipient = u
+	}
+
+	if r.Recipient.IsOrganization() && len(r.TeamIDs) != len(r.Teams) {
+
+		for _, v := range r.TeamIDs {
+			team, err := GetTeamByID(v)
+			if err != nil {
+				return err
+			}
+
+			if team.OrgID != r.Recipient.ID {
+				return fmt.Errorf("team %d belongs not to org %d", v, r.Recipient.ID)
+			}
+
+			r.Teams = append(r.Teams, team)
+		}
+	}
+
+	if r.Doer == nil {
+		u, err := GetUserByID(r.DoerID)
+		if err != nil {
+			return err
+		}
+
+		r.Doer = u
+	}
+
+	return nil
+}
+
+// CanUserAcceptTransfer checks if the user has the rights to accept/decline a repo transfer.
+// For user, it checks if it's himself
+// For organizations, it checks if the user is able to create repos
+func (r *RepoTransfer) CanUserAcceptTransfer(u *User) bool {
+	if err := r.LoadAttributes(); err != nil {
+		log.Error("LoadAttributes: %v", err)
+		return false
+	}
+
+	if !r.Recipient.IsOrganization() {
+		return r.RecipientID == u.ID
+	}
+
+	allowed, err := CanCreateOrgRepo(r.RecipientID, u.ID)
+	if err != nil {
+		log.Error("CanCreateOrgRepo: %v", err)
+		return false
+	}
+
+	return allowed
+}
+
+// GetPendingRepositoryTransfer fetches the most recent and ongoing transfer
+// process for the repository
+func GetPendingRepositoryTransfer(repo *Repository) (*RepoTransfer, error) {
+	var transfer = new(RepoTransfer)
+
+	has, err := x.Where("repo_id = ? ", repo.ID).Get(transfer)
+	if err != nil {
+		return nil, err
+	}
+
+	if !has {
+		return nil, ErrNoPendingRepoTransfer{RepoID: repo.ID}
+	}
+
+	return transfer, nil
+}
+
+func deleteRepositoryTransfer(e Engine, repoID int64) error {
+	_, err := e.Where("repo_id = ?", repoID).Delete(&RepoTransfer{})
+	return err
+}
+
+// CancelRepositoryTransfer marks the repository as ready and remove pending transfer entry,
+// thus cancel the transfer process.
+func CancelRepositoryTransfer(repo *Repository) error {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	repo.Status = RepositoryReady
+	if err := updateRepositoryCols(sess, repo, "status"); err != nil {
+		return err
+	}
+
+	if err := deleteRepositoryTransfer(sess, repo.ID); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}
+
+// TestRepositoryReadyForTransfer make sure repo is ready to transfer
+func TestRepositoryReadyForTransfer(status RepositoryStatus) error {
+	switch status {
+	case RepositoryBeingMigrated:
+		return fmt.Errorf("repo is not ready, currently migrating")
+	case RepositoryPendingTransfer:
+		return ErrRepoTransferInProgress{}
+	}
+	return nil
+}
+
+// CreatePendingRepositoryTransfer transfer a repo from one owner to a new one.
+// it marks the repository transfer as "pending"
+func CreatePendingRepositoryTransfer(doer, newOwner *User, repoID int64, teams []*Team) error {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	repo, err := getRepositoryByID(sess, repoID)
+	if err != nil {
+		return err
+	}
+
+	// Make sure repo is ready to transfer
+	if err := TestRepositoryReadyForTransfer(repo.Status); err != nil {
+		return err
+	}
+
+	repo.Status = RepositoryPendingTransfer
+	if err := updateRepositoryCols(sess, repo, "status"); err != nil {
+		return err
+	}
+
+	// Check if new owner has repository with same name.
+	if has, err := isRepositoryExist(sess, newOwner, repo.Name); err != nil {
+		return fmt.Errorf("IsRepositoryExist: %v", err)
+	} else if has {
+		return ErrRepoAlreadyExist{newOwner.LowerName, repo.Name}
+	}
+
+	transfer := &RepoTransfer{
+		RepoID:      repo.ID,
+		RecipientID: newOwner.ID,
+		CreatedUnix: timeutil.TimeStampNow(),
+		UpdatedUnix: timeutil.TimeStampNow(),
+		DoerID:      doer.ID,
+		TeamIDs:     make([]int64, 0, len(teams)),
+	}
+
+	for k := range teams {
+		transfer.TeamIDs = append(transfer.TeamIDs, teams[k].ID)
+	}
+
+	if _, err := sess.Insert(transfer); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}
+
+// TransferOwnership transfers all corresponding repository items from old user to new one.
+func TransferOwnership(doer *User, newOwnerName string, repo *Repository) error {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return fmt.Errorf("sess.Begin: %v", err)
+	}
+
+	newOwner, err := getUserByName(sess, newOwnerName)
+	if err != nil {
+		return fmt.Errorf("get new owner '%s': %v", newOwnerName, err)
+	}
+
+	// Check if new owner has repository with same name.
+	if has, err := isRepositoryExist(sess, newOwner, repo.Name); err != nil {
+		return fmt.Errorf("IsRepositoryExist: %v", err)
+	} else if has {
+		return ErrRepoAlreadyExist{newOwnerName, repo.Name}
+	}
+
+	oldOwner := repo.Owner
+
+	// Note: we have to set value here to make sure recalculate accesses is based on
+	// new owner.
+	repo.OwnerID = newOwner.ID
+	repo.Owner = newOwner
+	repo.OwnerName = newOwner.Name
+
+	// Update repository.
+	if _, err := sess.ID(repo.ID).Update(repo); err != nil {
+		return fmt.Errorf("update owner: %v", err)
+	}
+
+	// Remove redundant collaborators.
+	collaborators, err := repo.getCollaborators(sess, ListOptions{})
+	if err != nil {
+		return fmt.Errorf("getCollaborators: %v", err)
+	}
+
+	// Dummy object.
+	collaboration := &Collaboration{RepoID: repo.ID}
+	for _, c := range collaborators {
+		if c.ID != newOwner.ID {
+			isMember, err := isOrganizationMember(sess, newOwner.ID, c.ID)
+			if err != nil {
+				return fmt.Errorf("IsOrgMember: %v", err)
+			} else if !isMember {
+				continue
+			}
+		}
+		collaboration.UserID = c.ID
+		if _, err := sess.Delete(collaboration); err != nil {
+			return fmt.Errorf("remove collaborator '%d': %v", c.ID, err)
+		}
+	}
+
+	// Remove old team-repository relations.
+	if oldOwner.IsOrganization() {
+		if err := oldOwner.removeOrgRepo(sess, repo.ID); err != nil {
+			return fmt.Errorf("removeOrgRepo: %v", err)
+		}
+	}
+
+	if newOwner.IsOrganization() {
+		if err := newOwner.getTeams(sess); err != nil {
+			return fmt.Errorf("GetTeams: %v", err)
+		}
+		for _, t := range newOwner.Teams {
+			if t.IncludesAllRepositories {
+				if err := t.addRepository(sess, repo); err != nil {
+					return fmt.Errorf("addRepository: %v", err)
+				}
+			}
+		}
+	} else if err := repo.recalculateAccesses(sess); err != nil {
+		// Organization called this in addRepository method.
+		return fmt.Errorf("recalculateAccesses: %v", err)
+	}
+
+	// Update repository count.
+	if _, err := sess.Exec("UPDATE `user` SET num_repos=num_repos+1 WHERE id=?", newOwner.ID); err != nil {
+		return fmt.Errorf("increase new owner repository count: %v", err)
+	} else if _, err := sess.Exec("UPDATE `user` SET num_repos=num_repos-1 WHERE id=?", oldOwner.ID); err != nil {
+		return fmt.Errorf("decrease old owner repository count: %v", err)
+	}
+
+	if err := watchRepo(sess, doer.ID, repo.ID, true); err != nil {
+		return fmt.Errorf("watchRepo: %v", err)
+	}
+
+	// Remove watch for organization.
+	if oldOwner.IsOrganization() {
+		if err := watchRepo(sess, oldOwner.ID, repo.ID, false); err != nil {
+			return fmt.Errorf("watchRepo [false]: %v", err)
+		}
+	}
+
+	// Rename remote repository to new path and delete local copy.
+	dir := UserPath(newOwner.Name)
+
+	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
+		return fmt.Errorf("Failed to create dir %s: %v", dir, err)
+	}
+
+	if err := os.Rename(RepoPath(oldOwner.Name, repo.Name), RepoPath(newOwner.Name, repo.Name)); err != nil {
+		return fmt.Errorf("rename repository directory: %v", err)
+	}
+
+	// Rename remote wiki repository to new path and delete local copy.
+	wikiPath := WikiPath(oldOwner.Name, repo.Name)
+
+	if isExist, err := util.IsExist(wikiPath); err != nil {
+		log.Error("Unable to check if %s exists. Error: %v", wikiPath, err)
+		return err
+	} else if isExist {
+		if err := os.Rename(wikiPath, WikiPath(newOwner.Name, repo.Name)); err != nil {
+			return fmt.Errorf("rename repository wiki: %v", err)
+		}
+	}
+
+	if err := deleteRepositoryTransfer(sess, repo.ID); err != nil {
+		return fmt.Errorf("deleteRepositoryTransfer: %v", err)
+	}
+	repo.Status = RepositoryReady
+	if err := updateRepositoryCols(sess, repo, "status"); err != nil {
+		return err
+	}
+
+	// If there was previously a redirect at this location, remove it.
+	if err := deleteRepoRedirect(sess, newOwner.ID, repo.Name); err != nil {
+		return fmt.Errorf("delete repo redirect: %v", err)
+	}
+
+	if err := newRepoRedirect(sess, oldOwner.ID, repo.ID, repo.Name, repo.Name); err != nil {
+		return fmt.Errorf("newRepoRedirect: %v", err)
+	}
+
+	return sess.Commit()
+}
diff --git a/models/repo_transfer_test.go b/models/repo_transfer_test.go
new file mode 100644
index 0000000000..55aedac95d
--- /dev/null
+++ b/models/repo_transfer_test.go
@@ -0,0 +1,54 @@
+// 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 models
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRepositoryTransfer(t *testing.T) {
+
+	assert.NoError(t, PrepareTestDatabase())
+
+	doer := AssertExistsAndLoadBean(t, &User{ID: 3}).(*User)
+	repo := AssertExistsAndLoadBean(t, &Repository{ID: 3}).(*Repository)
+
+	transfer, err := GetPendingRepositoryTransfer(repo)
+	assert.NoError(t, err)
+	assert.NotNil(t, transfer)
+
+	// Cancel transfer
+	assert.NoError(t, CancelRepositoryTransfer(repo))
+
+	transfer, err = GetPendingRepositoryTransfer(repo)
+	assert.Error(t, err)
+	assert.Nil(t, transfer)
+	assert.True(t, IsErrNoPendingTransfer(err))
+
+	user2 := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+
+	assert.NoError(t, CreatePendingRepositoryTransfer(doer, user2, repo.ID, nil))
+
+	transfer, err = GetPendingRepositoryTransfer(repo)
+	assert.Nil(t, err)
+	assert.NoError(t, transfer.LoadAttributes())
+	assert.Equal(t, "user2", transfer.Recipient.Name)
+
+	user6 := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+
+	// Only transfer can be started at any given time
+	err = CreatePendingRepositoryTransfer(doer, user6, repo.ID, nil)
+	assert.Error(t, err)
+	assert.True(t, IsErrRepoTransferInProgress(err))
+
+	// Unknown user
+	err = CreatePendingRepositoryTransfer(doer, &User{ID: 1000, LowerName: "user1000"}, repo.ID, nil)
+	assert.Error(t, err)
+
+	// Cancel transfer
+	assert.NoError(t, CancelRepositoryTransfer(repo))
+}
diff --git a/modules/context/repo.go b/modules/context/repo.go
index bf149b8158..ba3cfe9bf2 100644
--- a/modules/context/repo.go
+++ b/modules/context/repo.go
@@ -600,6 +600,24 @@ func RepoAssignment() func(http.Handler) http.Handler {
 			ctx.Data["CanCompareOrPull"] = canCompare
 			ctx.Data["PullRequestCtx"] = ctx.Repo.PullRequest
 
+			if ctx.Repo.Repository.Status == models.RepositoryPendingTransfer {
+				repoTransfer, err := models.GetPendingRepositoryTransfer(ctx.Repo.Repository)
+				if err != nil {
+					ctx.ServerError("GetPendingRepositoryTransfer", err)
+					return
+				}
+
+				if err := repoTransfer.LoadAttributes(); err != nil {
+					ctx.ServerError("LoadRecipient", err)
+					return
+				}
+
+				ctx.Data["RepoTransfer"] = repoTransfer
+				if ctx.User != nil {
+					ctx.Data["CanUserAcceptTransfer"] = repoTransfer.CanUserAcceptTransfer(ctx.User)
+				}
+			}
+
 			if ctx.Query("go-get") == "1" {
 				ctx.Data["GoGetImport"] = ComposeGoGetImport(owner.Name, repo.Name)
 				prefix := setting.AppURL + path.Join(owner.Name, repo.Name, "src", "branch", ctx.Repo.BranchName)
diff --git a/modules/convert/notification.go b/modules/convert/notification.go
index fff891b15d..49abe01253 100644
--- a/modules/convert/notification.go
+++ b/modules/convert/notification.go
@@ -52,8 +52,14 @@ func ToNotificationThread(n *models.Notification) *api.NotificationThread {
 		result.Subject = &api.NotificationSubject{
 			Type:  "Commit",
 			Title: n.CommitID,
+			URL:   n.Repository.HTMLURL() + "/commit/" + n.CommitID,
+		}
+	case models.NotificationSourceRepository:
+		result.Subject = &api.NotificationSubject{
+			Type:  "Repository",
+			Title: n.Repository.FullName(),
+			URL:   n.Repository.Link(),
 		}
-		//unused until now
 	}
 
 	return result
diff --git a/modules/notification/base/notifier.go b/modules/notification/base/notifier.go
index 5bb833d275..8f8aa659b4 100644
--- a/modules/notification/base/notifier.go
+++ b/modules/notification/base/notifier.go
@@ -57,4 +57,6 @@ type Notifier interface {
 	NotifySyncPushCommits(pusher *models.User, repo *models.Repository, opts *repository.PushUpdateOptions, commits *repository.PushCommits)
 	NotifySyncCreateRef(doer *models.User, repo *models.Repository, refType, refFullName string)
 	NotifySyncDeleteRef(doer *models.User, repo *models.Repository, refType, refFullName string)
+
+	NotifyRepoPendingTransfer(doer, newOwner *models.User, repo *models.Repository)
 }
diff --git a/modules/notification/base/null.go b/modules/notification/base/null.go
index 2386f925ce..e61b37a943 100644
--- a/modules/notification/base/null.go
+++ b/modules/notification/base/null.go
@@ -166,3 +166,7 @@ func (*NullNotifier) NotifySyncCreateRef(doer *models.User, repo *models.Reposit
 // NotifySyncDeleteRef places a place holder function
 func (*NullNotifier) NotifySyncDeleteRef(doer *models.User, repo *models.Repository, refType, refFullName string) {
 }
+
+// NotifyRepoPendingTransfer places a place holder function
+func (*NullNotifier) NotifyRepoPendingTransfer(doer, newOwner *models.User, repo *models.Repository) {
+}
diff --git a/modules/notification/mail/mail.go b/modules/notification/mail/mail.go
index f984ea7661..f7192f5a52 100644
--- a/modules/notification/mail/mail.go
+++ b/modules/notification/mail/mail.go
@@ -170,3 +170,9 @@ func (m *mailNotifier) NotifyNewRelease(rel *models.Release) {
 
 	mailer.MailNewRelease(rel)
 }
+
+func (m *mailNotifier) NotifyRepoPendingTransfer(doer, newOwner *models.User, repo *models.Repository) {
+	if err := mailer.SendRepoTransferNotifyMail(doer, newOwner, repo); err != nil {
+		log.Error("NotifyRepoPendingTransfer: %v", err)
+	}
+}
diff --git a/modules/notification/notification.go b/modules/notification/notification.go
index d22d157bec..b574f3ccda 100644
--- a/modules/notification/notification.go
+++ b/modules/notification/notification.go
@@ -290,3 +290,10 @@ func NotifySyncDeleteRef(pusher *models.User, repo *models.Repository, refType,
 		notifier.NotifySyncDeleteRef(pusher, repo, refType, refFullName)
 	}
 }
+
+// NotifyRepoPendingTransfer notifies creation of pending transfer to notifiers
+func NotifyRepoPendingTransfer(doer, newOwner *models.User, repo *models.Repository) {
+	for _, notifier := range notifiers {
+		notifier.NotifyRepoPendingTransfer(doer, newOwner, repo)
+	}
+}
diff --git a/modules/notification/ui/ui.go b/modules/notification/ui/ui.go
index 25ea4d91c6..b1374f5608 100644
--- a/modules/notification/ui/ui.go
+++ b/modules/notification/ui/ui.go
@@ -201,3 +201,9 @@ func (ns *notificationService) NotifyPullReviewRequest(doer *models.User, issue
 		_ = ns.issueQueue.Push(opts)
 	}
 }
+
+func (ns *notificationService) NotifyRepoPendingTransfer(doer, newOwner *models.User, repo *models.Repository) {
+	if err := models.CreateRepoTransferNotification(doer, newOwner, repo); err != nil {
+		log.Error("NotifyRepoPendingTransfer: %v", err)
+	}
+}
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index 99f07b9050..4c4cc694be 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -735,6 +735,13 @@ delete_preexisting = Delete pre-existing files
 delete_preexisting_content = Delete files in %s
 delete_preexisting_success = Deleted unadopted files in %s
 
+transfer.accept = Accept Transfer
+transfer.accept_desc =  Transfer to "%s"
+transfer.reject = Reject Transfer
+transfer.reject_desc =  Cancel transfer to "%s"
+transfer.no_permission_to_accept = You do not have permission to Accept
+transfer.no_permission_to_reject = You do not have permission to Reject
+
 desc.private = Private
 desc.public = Public
 desc.private_template = Private template
@@ -1554,10 +1561,20 @@ settings.convert_fork_notices_1 = This operation will convert the fork into a re
 settings.convert_fork_confirm = Convert Repository
 settings.convert_fork_succeed = The fork has been converted into a regular repository.
 settings.transfer = Transfer Ownership
+settings.transfer.rejected = Repository transfer was rejected.
+settings.transfer.success = Repository transfer was successful.
+settings.transfer_abort = Cancel transfer
+settings.transfer_abort_invalid = You cannot cancel a non existent repository transfer.
+settings.transfer_abort_success = The repository transfer to %s was successfully cancelled.
 settings.transfer_desc = Transfer this repository to a user or to an organization for which you have administrator rights.
+settings.transfer_form_title = Enter the repository name as confirmation:
+settings.transfer_in_progress = There is currently an ongoing transfer. Please cancel it if you will like to transfer this repository to another user.
 settings.transfer_notices_1 = - You will lose access to the repository if you transfer it to an individual user.
 settings.transfer_notices_2 = - You will keep access to the repository if you transfer it to an organization that you (co-)own.
-settings.transfer_form_title = Enter the repository name as confirmation:
+settings.transfer_owner = New Owner
+settings.transfer_perform = Perform Transfer
+settings.transfer_started = This repository has been marked for transfer and awaits confirmation from "%s"
+settings.transfer_succeed = The repository has been transferred.
 settings.signing_settings = Signing Verification Settings
 settings.trust_model = Signature Trust Model
 settings.trust_model.default = Default Trust Model
@@ -1583,9 +1600,6 @@ settings.delete_notices_2 = - This operation will permanently delete the <strong
 settings.delete_notices_fork_1 = - Forks of this repository will become independent after deletion.
 settings.deletion_success = The repository has been deleted.
 settings.update_settings_success = The repository settings have been updated.
-settings.transfer_owner = New Owner
-settings.make_transfer = Perform Transfer
-settings.transfer_succeed = The repository has been transferred.
 settings.confirm_delete = Delete Repository
 settings.add_collaborator = Add Collaborator
 settings.add_collaborator_success = The collaborator has been added.
diff --git a/routers/api/v1/repo/transfer.go b/routers/api/v1/repo/transfer.go
index 656ace032e..2e052aa4ff 100644
--- a/routers/api/v1/repo/transfer.go
+++ b/routers/api/v1/repo/transfer.go
@@ -96,17 +96,27 @@ func Transfer(ctx *context.APIContext) {
 		}
 	}
 
-	if err = repo_service.TransferOwnership(ctx.User, newOwner, ctx.Repo.Repository, teams); err != nil {
+	if err := repo_service.StartRepositoryTransfer(ctx.User, newOwner, ctx.Repo.Repository, teams); err != nil {
+		if models.IsErrRepoTransferInProgress(err) {
+			ctx.Error(http.StatusConflict, "CreatePendingRepositoryTransfer", err)
+			return
+		}
+
+		if models.IsErrRepoAlreadyExist(err) {
+			ctx.Error(http.StatusUnprocessableEntity, "CreatePendingRepositoryTransfer", err)
+			return
+		}
+
 		ctx.InternalServerError(err)
 		return
 	}
 
-	newRepo, err := models.GetRepositoryByName(newOwner.ID, ctx.Repo.Repository.Name)
-	if err != nil {
-		ctx.InternalServerError(err)
+	if ctx.Repo.Repository.Status == models.RepositoryPendingTransfer {
+		log.Trace("Repository transfer initiated: %s -> %s", ctx.Repo.Repository.FullName(), newOwner.Name)
+		ctx.JSON(http.StatusCreated, convert.ToRepo(ctx.Repo.Repository, models.AccessModeAdmin))
 		return
 	}
 
 	log.Trace("Repository transferred: %s -> %s", ctx.Repo.Repository.FullName(), newOwner.Name)
-	ctx.JSON(http.StatusAccepted, convert.ToRepo(newRepo, models.AccessModeAdmin))
+	ctx.JSON(http.StatusAccepted, convert.ToRepo(ctx.Repo.Repository, models.AccessModeAdmin))
 }
diff --git a/routers/repo/repo.go b/routers/repo/repo.go
index a8cfb9ad7c..6fa566e7d6 100644
--- a/routers/repo/repo.go
+++ b/routers/repo/repo.go
@@ -6,6 +6,7 @@
 package repo
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -274,6 +275,10 @@ func Action(ctx *context.Context) {
 		err = models.StarRepo(ctx.User.ID, ctx.Repo.Repository.ID, true)
 	case "unstar":
 		err = models.StarRepo(ctx.User.ID, ctx.Repo.Repository.ID, false)
+	case "accept_transfer":
+		err = acceptOrRejectRepoTransfer(ctx, true)
+	case "reject_transfer":
+		err = acceptOrRejectRepoTransfer(ctx, false)
 	case "desc": // FIXME: this is not used
 		if !ctx.Repo.IsOwner() {
 			ctx.Error(404)
@@ -293,6 +298,36 @@ func Action(ctx *context.Context) {
 	ctx.RedirectToFirst(ctx.Query("redirect_to"), ctx.Repo.RepoLink)
 }
 
+func acceptOrRejectRepoTransfer(ctx *context.Context, accept bool) error {
+	repoTransfer, err := models.GetPendingRepositoryTransfer(ctx.Repo.Repository)
+	if err != nil {
+		return err
+	}
+
+	if err := repoTransfer.LoadAttributes(); err != nil {
+		return err
+	}
+
+	if !repoTransfer.CanUserAcceptTransfer(ctx.User) {
+		return errors.New("user does not have enough permissions")
+	}
+
+	if accept {
+		if err := repo_service.TransferOwnership(repoTransfer.Doer, repoTransfer.Recipient, ctx.Repo.Repository, repoTransfer.Teams); err != nil {
+			return err
+		}
+		ctx.Flash.Success(ctx.Tr("repo.settings.transfer.success"))
+	} else {
+		if err := models.CancelRepositoryTransfer(ctx.Repo.Repository); err != nil {
+			return err
+		}
+		ctx.Flash.Success(ctx.Tr("repo.settings.transfer.rejected"))
+	}
+
+	ctx.Redirect(ctx.Repo.Repository.HTMLURL())
+	return nil
+}
+
 // RedirectDownload return a file based on the following infos:
 func RedirectDownload(ctx *context.Context) {
 	var (
diff --git a/routers/repo/setting.go b/routers/repo/setting.go
index 3e22e8804e..b35828d7b1 100644
--- a/routers/repo/setting.go
+++ b/routers/repo/setting.go
@@ -477,18 +477,54 @@ func SettingsPost(ctx *context.Context) {
 			ctx.Repo.GitRepo.Close()
 			ctx.Repo.GitRepo = nil
 		}
-		if err = repo_service.TransferOwnership(ctx.User, newOwner, repo, nil); err != nil {
+
+		if err := repo_service.StartRepositoryTransfer(ctx.User, newOwner, repo, nil); err != nil {
 			if models.IsErrRepoAlreadyExist(err) {
 				ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_has_same_repo"), tplSettingsOptions, nil)
+			} else if models.IsErrRepoTransferInProgress(err) {
+				ctx.RenderWithErr(ctx.Tr("repo.settings.transfer_in_progress"), tplSettingsOptions, nil)
 			} else {
 				ctx.ServerError("TransferOwnership", err)
 			}
+
+			return
+		}
+
+		log.Trace("Repository transfer process was started: %s/%s -> %s", ctx.Repo.Owner.Name, repo.Name, newOwner)
+		ctx.Flash.Success(ctx.Tr("repo.settings.transfer_started", newOwner.DisplayName()))
+		ctx.Redirect(setting.AppSubURL + "/" + ctx.Repo.Owner.Name + "/" + repo.Name + "/settings")
+
+	case "cancel_transfer":
+		if !ctx.Repo.IsOwner() {
+			ctx.Error(404)
+			return
+		}
+
+		repoTransfer, err := models.GetPendingRepositoryTransfer(ctx.Repo.Repository)
+		if err != nil {
+			if models.IsErrNoPendingTransfer(err) {
+				ctx.Flash.Error("repo.settings.transfer_abort_invalid")
+				ctx.Redirect(setting.AppSubURL + "/" + ctx.User.Name + "/" + repo.Name + "/settings")
+			} else {
+				ctx.ServerError("GetPendingRepositoryTransfer", err)
+			}
+
+			return
+		}
+
+		if err := repoTransfer.LoadAttributes(); err != nil {
+			ctx.ServerError("LoadRecipient", err)
+			return
+		}
+
+		if err := models.CancelRepositoryTransfer(ctx.Repo.Repository); err != nil {
+			ctx.ServerError("CancelRepositoryTransfer", err)
 			return
 		}
 
-		log.Trace("Repository transferred: %s/%s -> %s", ctx.Repo.Owner.Name, repo.Name, newOwner)
-		ctx.Flash.Success(ctx.Tr("repo.settings.transfer_succeed"))
-		ctx.Redirect(setting.AppSubURL + "/" + newOwner.Name + "/" + repo.Name)
+		log.Trace("Repository transfer process was cancelled: %s/%s ", ctx.Repo.Owner.Name, repo.Name)
+		ctx.Flash.Success(ctx.Tr("repo.settings.transfer_abort_success", repoTransfer.Recipient.Name))
+		ctx.Redirect(setting.AppSubURL + "/" + ctx.Repo.Owner.Name + "/" + repo.Name + "/settings")
 
 	case "delete":
 		if !ctx.Repo.IsOwner() {
diff --git a/routers/repo/view.go b/routers/repo/view.go
index a5e3cbe3e4..39f16d183c 100644
--- a/routers/repo/view.go
+++ b/routers/repo/view.go
@@ -586,6 +586,14 @@ func Home(ctx *context.Context) {
 			return
 		}
 
+		if ctx.IsSigned {
+			// Set repo notification-status read if unread
+			if err := ctx.Repo.Repository.ReadBy(ctx.User.ID); err != nil {
+				ctx.ServerError("ReadBy", err)
+				return
+			}
+		}
+
 		var firstUnit *models.Unit
 		for _, repoUnit := range ctx.Repo.Units {
 			if repoUnit.Type == models.UnitTypeCode {
diff --git a/services/mailer/mail.go b/services/mailer/mail.go
index e87d34ab29..7d6214c742 100644
--- a/services/mailer/mail.go
+++ b/services/mailer/mail.go
@@ -34,6 +34,8 @@ const (
 
 	mailNotifyCollaborator base.TplName = "notify/collaborator"
 
+	mailRepoTransferNotify base.TplName = "notify/repo_transfer"
+
 	// There's no actual limit for subject in RFC 5322
 	mailMaxSubjectRunes = 256
 )
diff --git a/services/mailer/mail_repo.go b/services/mailer/mail_repo.go
new file mode 100644
index 0000000000..b9d24f4334
--- /dev/null
+++ b/services/mailer/mail_repo.go
@@ -0,0 +1,57 @@
+// 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 mailer
+
+import (
+	"bytes"
+	"fmt"
+
+	"code.gitea.io/gitea/models"
+)
+
+// SendRepoTransferNotifyMail triggers a notification e-mail when a pending repository transfer was created
+func SendRepoTransferNotifyMail(doer, newOwner *models.User, repo *models.Repository) error {
+	var (
+		emails      []string
+		destination string
+		content     bytes.Buffer
+	)
+
+	if newOwner.IsOrganization() {
+		users, err := models.GetUsersWhoCanCreateOrgRepo(newOwner.ID)
+		if err != nil {
+			return err
+		}
+
+		for i := range users {
+			emails = append(emails, users[i].Email)
+		}
+		destination = newOwner.DisplayName()
+	} else {
+		emails = []string{newOwner.Email}
+		destination = "you"
+	}
+
+	subject := fmt.Sprintf("%s would like to transfer \"%s\" to %s", doer.DisplayName(), repo.FullName(), destination)
+	data := map[string]interface{}{
+		"Doer":    doer,
+		"User":    repo.Owner,
+		"Repo":    repo.FullName(),
+		"Link":    repo.HTMLURL(),
+		"Subject": subject,
+
+		"Destination": destination,
+	}
+
+	if err := bodyTemplates.ExecuteTemplate(&content, string(mailRepoTransferNotify), data); err != nil {
+		return err
+	}
+
+	msg := NewMessage(emails, subject, content.String())
+	msg.Info = fmt.Sprintf("UID: %d, repository pending transfer notification", newOwner.ID)
+
+	SendAsync(msg)
+	return nil
+}
diff --git a/services/repository/transfer.go b/services/repository/transfer.go
index e2416cf8de..ec769190bd 100644
--- a/services/repository/transfer.go
+++ b/services/repository/transfer.go
@@ -70,3 +70,38 @@ func ChangeRepositoryName(doer *models.User, repo *models.Repository, newRepoNam
 
 	return nil
 }
+
+// StartRepositoryTransfer transfer a repo from one owner to a new one.
+// it make repository into pending transfer state, if doer can not create repo for new owner.
+func StartRepositoryTransfer(doer, newOwner *models.User, repo *models.Repository, teams []*models.Team) error {
+	if err := models.TestRepositoryReadyForTransfer(repo.Status); err != nil {
+		return err
+	}
+
+	// Admin is always allowed to transfer || user transfer repo back to his account
+	if doer.IsAdmin || doer.ID == newOwner.ID {
+		return TransferOwnership(doer, newOwner, repo, teams)
+	}
+
+	// If new owner is an org and user can create repos he can transfer directly too
+	if newOwner.IsOrganization() {
+		allowed, err := models.CanCreateOrgRepo(newOwner.ID, doer.ID)
+		if err != nil {
+			return err
+		}
+		if allowed {
+			return TransferOwnership(doer, newOwner, repo, teams)
+		}
+	}
+
+	// Make repo as pending for transfer
+	repo.Status = models.RepositoryPendingTransfer
+	if err := models.CreatePendingRepositoryTransfer(doer, newOwner, repo.ID, teams); err != nil {
+		return err
+	}
+
+	// notify users who are able to accept / reject transfer
+	notification.NotifyRepoPendingTransfer(doer, newOwner, repo)
+
+	return nil
+}
diff --git a/templates/mail/notify/repo_transfer.tmpl b/templates/mail/notify/repo_transfer.tmpl
new file mode 100644
index 0000000000..68ceded116
--- /dev/null
+++ b/templates/mail/notify/repo_transfer.tmpl
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+	<title>{{.Subject}}</title>
+</head>
+
+<body>
+	<p>{{.Subject}}.
+		To accept or reject it visit <a href="{{.Link}}">{{.Repo}}</a> or just ignore it.
+	<p>
+		---
+		<br>
+		<a href="{{.Link}}">View it on Gitea</a>.
+	</p>
+</body>
+</html>
diff --git a/templates/repo/header.tmpl b/templates/repo/header.tmpl
index 31bcd5c48a..2f593567d5 100644
--- a/templates/repo/header.tmpl
+++ b/templates/repo/header.tmpl
@@ -42,6 +42,24 @@
 			</div>
 			{{if not .IsBeingCreated}}
 				<div class="repo-buttons">
+					{{if $.RepoTransfer}}
+						<form method="post" action="{{$.RepoLink}}/action/accept_transfer?redirect_to={{$.RepoLink}}">
+							{{$.CsrfTokenHtml}}
+							<div class="ui poping up" data-content="{{if $.CanUserAcceptTransfer}}{{$.i18n.Tr "repo.transfer.accept_desc" $.RepoTransfer.Recipient.DisplayName}}{{else}}{{$.i18n.Tr "repo.transfer.no_permission_to_accept"}}{{end}}" data-position="bottom center" data-variation="tiny">
+								<button type="submit" class="ui button {{if $.CanUserAcceptTransfer}}green {{end}} ok inverted small"{{if not $.CanUserAcceptTransfer}} disabled{{end}}>
+									{{$.i18n.Tr "repo.transfer.accept"}}
+								</button>
+							</div>
+						</form>
+						<form method="post" action="{{$.RepoLink}}/action/reject_transfer?redirect_to={{$.RepoLink}}">
+							{{$.CsrfTokenHtml}}
+							<div class="ui poping up" data-content="{{if $.CanUserAcceptTransfer}}{{$.i18n.Tr "repo.transfer.reject_desc" $.RepoTransfer.Recipient.DisplayName}}{{else}}{{$.i18n.Tr "repo.transfer.no_permission_to_reject"}}{{end}}" data-position="bottom center" data-variation="tiny">
+								<button type="submit" class="ui button {{if $.CanUserAcceptTransfer}}red {{end}}ok inverted small"{{if not $.CanUserAcceptTransfer}} disabled{{end}}>
+									{{$.i18n.Tr "repo.transfer.reject"}}
+								</button>
+							</div>
+						</form>
+					{{end}}
 					<form method="post" action="{{$.RepoLink}}/action/{{if $.IsWatchingRepo}}un{{end}}watch?redirect_to={{$.Link}}">
 						{{$.CsrfTokenHtml}}
 						<div class="ui labeled button{{if not $.IsSigned}} poping up{{end}}" tabindex="0"{{if not $.IsSigned}} data-content="{{$.i18n.Tr "repo.watch_guest_user" }}" data-position="top center" data-variation="tiny"{{end}}>
diff --git a/templates/repo/settings/options.tmpl b/templates/repo/settings/options.tmpl
index e85451ac39..b69f90f9c5 100644
--- a/templates/repo/settings/options.tmpl
+++ b/templates/repo/settings/options.tmpl
@@ -444,11 +444,23 @@
 			{{end}}
 			<div class="item">
 				<div class="ui right">
-					<button class="ui basic red show-modal button" data-modal="#transfer-repo-modal">{{.i18n.Tr "repo.settings.transfer"}}</button>
+					{{if .RepoTransfer}}
+						<form class="ui form" action="{{.Link}}" method="post">
+							{{.CsrfTokenHtml}}
+							<input type="hidden" name="action" value="cancel_transfer">
+							<button class="ui red button">{{.i18n.Tr "repo.settings.transfer_abort"}}</button>
+						</form>
+					{{ else }}
+						<button class="ui basic red show-modal button" data-modal="#transfer-repo-modal">{{.i18n.Tr "repo.settings.transfer"}}</button>
+					{{ end }}
 				</div>
 				<div>
 					<h5>{{.i18n.Tr "repo.settings.transfer"}}</h5>
-					<p>{{.i18n.Tr "repo.settings.transfer_desc"}}</p>
+					{{if .RepoTransfer}}
+						<p>{{.i18n.Tr "repo.settings.transfer_started" .RepoTransfer.Recipient.DisplayName}}</p>
+					{{else}}
+						<p>{{.i18n.Tr "repo.settings.transfer_desc"}}</p>
+					{{end}}
 				</div>
 			</div>
 
@@ -599,7 +611,7 @@
 
 				<div class="text right actions">
 					<div class="ui cancel button">{{.i18n.Tr "settings.cancel"}}</div>
-					<button class="ui red button">{{.i18n.Tr "repo.settings.make_transfer"}}</button>
+					<button class="ui red button">{{.i18n.Tr "repo.settings.transfer_perform"}}</button>
 				</div>
 			</form>
 		</div>
diff --git a/templates/user/notification/notification_div.tmpl b/templates/user/notification/notification_div.tmpl
index 2f25e73387..2158dcb000 100644
--- a/templates/user/notification/notification_div.tmpl
+++ b/templates/user/notification/notification_div.tmpl
@@ -39,6 +39,8 @@
                                 <td class="collapsing" data-href="{{.HTMLURL}}">
                                     {{if eq .Status 3}}
                                         <span class="blue">{{svg "octicon-pin"}}</span>
+                                    {{else if not $issue}}
+                                        <span class="gray">{{svg "octicon-repo"}}</span>
                                     {{else if $issue.IsPull}}
                                         {{if $issue.IsClosed}}
                                             {{if $issue.GetPullRequest.HasMerged}}
@@ -59,7 +61,11 @@
                                 </td>
                                 <td class="eleven wide" data-href="{{.HTMLURL}}">
                                     <a class="item" href="{{.HTMLURL}}">
-                                        #{{$issue.Index}} - {{$issue.Title}}
+                                        {{if $issue}}
+                                            #{{$issue.Index}} - {{$issue.Title}}
+                                        {{else}}
+                                            {{$repo.FullName}}
+                                        {{end}}
                                     </a>
                                 </td>
                                 <td data-href="{{AppSubUrl}}/{{$repoOwner.Name}}/{{$repo.Name}}">