Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/platform/services/remotecluster/invitation.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package remotecluster
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+)
+
+// AcceptInvitation is called when accepting an invitation to connect with a remote cluster.
+func (rcs *Service) AcceptInvitation(invite *model.RemoteClusterInvite, name string, displayName, creatorId string, teamId string, siteURL string) (*model.RemoteCluster, error) {
+	rc := &model.RemoteCluster{
+		RemoteId:     invite.RemoteId,
+		RemoteTeamId: invite.RemoteTeamId,
+		Name:         name,
+		DisplayName:  displayName,
+		Token:        model.NewId(),
+		RemoteToken:  invite.Token,
+		SiteURL:      invite.SiteURL,
+		CreatorId:    creatorId,
+	}
+
+	rcSaved, err := rcs.server.GetStore().RemoteCluster().Save(rc)
+	if err != nil {
+		return nil, err
+	}
+
+	// confirm the invitation with the originating site
+	frame, err := makeConfirmFrame(rcSaved, teamId, siteURL)
+	if err != nil {
+		return nil, err
+	}
+
+	url := fmt.Sprintf("%s/%s", rcSaved.SiteURL, ConfirmInviteURL)
+
+	resp, err := rcs.sendFrameToRemote(PingTimeout, rc, frame, url)
+	if err != nil {
+		rcs.server.GetStore().RemoteCluster().Delete(rcSaved.RemoteId)
+		return nil, err
+	}
+
+	var response Response
+	err = json.Unmarshal(resp, &response)
+	if err != nil {
+		rcs.server.GetStore().RemoteCluster().Delete(rcSaved.RemoteId)
+		return nil, fmt.Errorf("invalid response from remote server: %w", err)
+	}
+
+	if !response.IsSuccess() {
+		rcs.server.GetStore().RemoteCluster().Delete(rcSaved.RemoteId)
+		return nil, errors.New(response.Err)
+	}
+
+	// issue the first ping right away. The goroutine will exit when ping completes or PingTimeout exceeded.
+	go rcs.pingRemote(rcSaved)
+
+	return rcSaved, nil
+}
+
+func makeConfirmFrame(rc *model.RemoteCluster, teamId string, siteURL string) (*model.RemoteClusterFrame, error) {
+	confirm := model.RemoteClusterInvite{
+		RemoteId:     rc.RemoteId,
+		RemoteTeamId: teamId,
+		SiteURL:      siteURL,
+		Token:        rc.Token,
+	}
+	confirmRaw, err := json.Marshal(confirm)
+	if err != nil {
+		return nil, err
+	}
+
+	msg := model.NewRemoteClusterMsg(InvitationTopic, confirmRaw)
+
+	frame := &model.RemoteClusterFrame{
+		RemoteId: rc.RemoteId,
+		Msg:      msg,
+	}
+	return frame, nil
+}