MM-53924 - Implement NotificationWillBePushed plugin hook (#24263)

* add NotificationWillBePushed hook

* mocks

* use a struct for hook parameters; simplify number of parameters sent across RPC

* missing wg.Wait

* change to a bool return value

server/channels/app/notification_push.go

@@ -14,6 +14,8 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/mattermost/mattermost/server/public/plugin"
+
 	"github.com/mattermost/mattermost/server/public/model"
 	"github.com/mattermost/mattermost/server/public/shared/i18n"
 	"github.com/mattermost/mattermost/server/public/shared/mlog"
@@ -138,6 +140,24 @@ func (a *App) sendPushNotificationToAllSessions(msg *model.PushNotification, use
 }
 
 func (a *App) sendPushNotification(notification *PostNotification, user *model.User, explicitMention, channelWideMention bool, replyToThreadType string) {
+	cancelled := false
+	a.ch.RunMultiHook(func(hooks plugin.Hooks) bool {
+		cancelled = hooks.NotificationWillBePushed(&model.PluginPushNotification{
+			Post:    notification.Post.ForPlugin(),
+			Channel: notification.Channel,
+			UserID:  user.Id,
+		})
+		if cancelled {
+			mlog.Info("Notification cancelled by plugin")
+			return false
+		}
+		return true
+	}, plugin.NotificationWillBePushedID)
+
+	if cancelled {
+		return
+	}
+
 	cfg := a.Config()
 	channel := notification.Channel
 	post := notification.Post

server/channels/app/notification_push_test.go

@@ -1468,7 +1468,6 @@ func TestPushNotificationRace(t *testing.T) {
 	require.NoError(t, err)
 	s.products["channels"] = ch
 
-	app := New(ServerConnector(s.Channels()))
 	require.NotPanics(t, func() {
 		s.createPushNotificationsHub(th.Context)
 
@@ -1476,9 +1475,9 @@ func TestPushNotificationRace(t *testing.T) {
 
 		// Now we start sending messages after the PN hub is shut down.
 		// We test all 3 notification types.
-		app.clearPushNotification("currentSessionId", "userId", "channelId", "")
+		th.App.clearPushNotification("currentSessionId", "userId", "channelId", "")
 
-		app.UpdateMobileAppBadge("userId")
+		th.App.UpdateMobileAppBadge("userId")
 
 		notification := &PostNotification{
 			Post:    &model.Post{},
@@ -1488,7 +1487,7 @@ func TestPushNotificationRace(t *testing.T) {
 			},
 			Sender: &model.User{},
 		}
-		app.sendPushNotification(notification, &model.User{}, true, false, model.CommentsNotifyAny)
+		th.App.sendPushNotification(notification, &model.User{}, true, false, model.CommentsNotifyAny)
 	})
 }
 

server/channels/app/plugin_hooks_test.go

@@ -6,11 +6,14 @@ package app
 import (
 	"bytes"
 	"context"
+	_ "embed"
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"sync"
 	"testing"
 	"time"
 
@@ -1331,3 +1334,118 @@ func TestHookOnCloudLimitsUpdated(t *testing.T) {
 
 	require.True(t, hookCalled)
 }
+
+//go:embed test_templates/hook_notification_will_be_pushed.tmpl
+var hookNotificationWillBePushedTmpl string
+
+func TestHookNotificationWillBePushed(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping TestHookNotificationWillBePushed test in short mode")
+	}
+
+	tests := []struct {
+		name                  string
+		testCode              string
+		expectedNotifications int
+	}{
+		{
+			name:                  "successfully pushed",
+			testCode:              `return false`,
+			expectedNotifications: 6,
+		},
+		{
+			name:                  "push notification rejected",
+			testCode:              `return true`,
+			expectedNotifications: 0,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			th := Setup(t).InitBasic()
+			defer th.TearDown()
+
+			templatedPlugin := fmt.Sprintf(hookNotificationWillBePushedTmpl, tt.testCode)
+			tearDown, _, _ := SetAppEnvironmentWithPlugins(t, []string{templatedPlugin}, th.App, th.NewPluginAPI)
+			defer tearDown()
+
+			// Create 3 users, each having 2 sessions.
+			type userSession struct {
+				user    *model.User
+				session *model.Session
+			}
+			var userSessions []userSession
+			for i := 0; i < 3; i++ {
+				u := th.CreateUser()
+				sess, err := th.App.CreateSession(&model.Session{
+					UserId:    u.Id,
+					DeviceId:  "deviceID" + u.Id,
+					ExpiresAt: model.GetMillis() + 100000,
+				})
+				require.Nil(t, err)
+				// We don't need to track the 2nd session.
+				_, err = th.App.CreateSession(&model.Session{
+					UserId:    u.Id,
+					DeviceId:  "deviceID" + u.Id,
+					ExpiresAt: model.GetMillis() + 100000,
+				})
+				require.Nil(t, err)
+				_, err = th.App.AddTeamMember(th.Context, th.BasicTeam.Id, u.Id)
+				require.Nil(t, err)
+				th.AddUserToChannel(u, th.BasicChannel)
+				userSessions = append(userSessions, userSession{
+					user:    u,
+					session: sess,
+				})
+			}
+
+			handler := &testPushNotificationHandler{
+				t:        t,
+				behavior: "simple",
+			}
+			pushServer := httptest.NewServer(
+				http.HandlerFunc(handler.handleReq),
+			)
+			defer pushServer.Close()
+
+			th.App.UpdateConfig(func(cfg *model.Config) {
+				*cfg.EmailSettings.PushNotificationContents = model.GenericNotification
+				*cfg.EmailSettings.PushNotificationServer = pushServer.URL
+			})
+
+			var wg sync.WaitGroup
+			for _, data := range userSessions {
+				wg.Add(1)
+				go func(user model.User) {
+					defer wg.Done()
+					notification := &PostNotification{
+						Post:    th.CreatePost(th.BasicChannel),
+						Channel: th.BasicChannel,
+						ProfileMap: map[string]*model.User{
+							user.Id: &user,
+						},
+						Sender: &user,
+					}
+					th.App.sendPushNotification(notification, &user, true, false, model.CommentsNotifyAny)
+				}(*data.user)
+			}
+			wg.Wait()
+
+			// Hack to let the worker goroutines complete.
+			time.Sleep(1 * time.Second)
+			// Server side verification.
+			assert.Equal(t, tt.expectedNotifications, handler.numReqs())
+			var numMessages int
+			for _, n := range handler.notifications() {
+				switch n.Type {
+				case model.PushTypeMessage:
+					numMessages++
+					assert.Equal(t, th.BasicChannel.Id, n.ChannelId)
+					assert.Contains(t, n.Message, "mentioned you")
+				default:
+					assert.Fail(t, "should not receive any other push notification types")
+				}
+			}
+			assert.Equal(t, tt.expectedNotifications, numMessages)
+		})
+	}
+}

server/channels/app/test_templates/hook_notification_will_be_pushed.tmpl

@@ -0,0 +1,18 @@
+package main
+
+import (
+    "github.com/mattermost/mattermost/server/public/plugin"
+    "github.com/mattermost/mattermost/server/public/model"
+)
+
+type MyPlugin struct {
+    plugin.MattermostPlugin
+}
+
+func (p *MyPlugin) NotificationWillBePushed(notification *model.PluginPushNotification) (cancel bool) {
+    %s
+}
+
+func main() {
+    plugin.ClientMain(&MyPlugin{})
+}

server/public/model/plugin_push_notification.go

@@ -0,0 +1,12 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+// PluginPushNotification is sent to the plugin when a push notification is going to be sent (via the
+// NotificationWillBePushed hook).
+type PluginPushNotification struct {
+	Post    *Post
+	Channel *Channel
+	UserID  string
+}

server/public/plugin/client_rpc_generated.go

@@ -843,6 +843,40 @@ func (s *hooksRPCServer) ConfigurationWillBeSaved(args *Z_ConfigurationWillBeSav
 	return nil
 }
 
+func init() {
+	hookNameToId["NotificationWillBePushed"] = NotificationWillBePushedID
+}
+
+type Z_NotificationWillBePushedArgs struct {
+	A *model.PluginPushNotification
+}
+
+type Z_NotificationWillBePushedReturns struct {
+	A bool
+}
+
+func (g *hooksRPCClient) NotificationWillBePushed(pushNotification *model.PluginPushNotification) (cancel bool) {
+	_args := &Z_NotificationWillBePushedArgs{pushNotification}
+	_returns := &Z_NotificationWillBePushedReturns{}
+	if g.implemented[NotificationWillBePushedID] {
+		if err := g.client.Call("Plugin.NotificationWillBePushed", _args, _returns); err != nil {
+			g.log.Error("RPC call NotificationWillBePushed to plugin failed.", mlog.Err(err))
+		}
+	}
+	return _returns.A
+}
+
+func (s *hooksRPCServer) NotificationWillBePushed(args *Z_NotificationWillBePushedArgs, returns *Z_NotificationWillBePushedReturns) error {
+	if hook, ok := s.impl.(interface {
+		NotificationWillBePushed(pushNotification *model.PluginPushNotification) (cancel bool)
+	}); ok {
+		returns.A = hook.NotificationWillBePushed(args.A)
+	} else {
+		return encodableError(fmt.Errorf("Hook NotificationWillBePushed called but not implemented."))
+	}
+	return nil
+}
+
 type Z_RegisterCommandArgs struct {
 	A *model.Command
 }

server/public/plugin/hooks.go

@@ -50,6 +50,7 @@ const (
 	deprecatedGetCollectionMetadataByIdsID    = 32
 	deprecatedGetTopicMetadataByIdsID         = 33
 	ConfigurationWillBeSavedID                = 34
+	NotificationWillBePushedID                = 35
 	TotalHooksID                              = iota
 )
 
@@ -284,4 +285,12 @@ type Hooks interface {
 	// config object can be returned to be stored in place of the provided one.
 	// Minimum server version: 8.0
 	ConfigurationWillBeSaved(newCfg *model.Config) (*model.Config, error)
+
+	// NotificationWillBePushed is invoked before a push notification is sent to the push
+	// notification server. The intention is to allow plugins to cancel a push notification.
+	//
+	// To cancel a push notification, return true.
+	//
+	// Minimum server version: 9.0
+	NotificationWillBePushed(pushNotification *model.PluginPushNotification) (cancel bool)
 }

server/public/plugin/hooks_timer_layer_generated.go

@@ -218,3 +218,10 @@ func (hooks *hooksTimerLayer) ConfigurationWillBeSaved(newCfg *model.Config) (*m
 	hooks.recordTime(startTime, "ConfigurationWillBeSaved", _returnsB == nil)
 	return _returnsA, _returnsB
 }
+
+func (hooks *hooksTimerLayer) NotificationWillBePushed(pushNotification *model.PluginPushNotification) (cancel bool) {
+	startTime := timePkg.Now()
+	_returnsA := hooks.hooksImpl.NotificationWillBePushed(pushNotification)
+	hooks.recordTime(startTime, "NotificationWillBePushed", true)
+	return _returnsA
+}

server/public/plugin/plugintest/hooks.go

@@ -193,6 +193,20 @@ func (_m *Hooks) MessageWillBeUpdated(c *plugin.Context, newPost *model.Post, ol
 	return r0, r1
 }
 
+// NotificationWillBePushed provides a mock function with given fields: pushNotification
+func (_m *Hooks) NotificationWillBePushed(pushNotification *model.PluginPushNotification) bool {
+	ret := _m.Called(pushNotification)
+
+	var r0 bool
+	if rf, ok := ret.Get(0).(func(*model.PluginPushNotification) bool); ok {
+		r0 = rf(pushNotification)
+	} else {
+		r0 = ret.Get(0).(bool)
+	}
+
+	return r0
+}
+
 // OnActivate provides a mock function with given fields:
 func (_m *Hooks) OnActivate() error {
 	ret := _m.Called()

server/public/plugin/product_hooks_generated.go

@@ -118,6 +118,10 @@ type ConfigurationWillBeSavedIFace interface {
 	ConfigurationWillBeSaved(newCfg *model.Config) (*model.Config, error)
 }
 
+type NotificationWillBePushedIFace interface {
+	NotificationWillBePushed(pushNotification *model.PluginPushNotification) (cancel bool)
+}
+
 type HooksAdapter struct {
 	implemented  map[int]struct{}
 	productHooks any
@@ -365,6 +369,15 @@ func NewAdapter(productHooks any) (*HooksAdapter, error) {
 		return nil, errors.New("hook has ConfigurationWillBeSaved method but does not implement plugin.ConfigurationWillBeSaved interface")
 	}
 
+	// Assessing the type of the productHooks if it individually implements NotificationWillBePushed interface.
+	tt = reflect.TypeOf((*NotificationWillBePushedIFace)(nil)).Elem()
+
+	if ft.Implements(tt) {
+		a.implemented[NotificationWillBePushedID] = struct{}{}
+	} else if _, ok := ft.MethodByName("NotificationWillBePushed"); ok {
+		return nil, errors.New("hook has NotificationWillBePushed method but does not implement plugin.NotificationWillBePushed interface")
+	}
+
 	return a, nil
 }
 
@@ -601,3 +614,12 @@ func (a *HooksAdapter) ConfigurationWillBeSaved(newCfg *model.Config) (*model.Co
 	return a.productHooks.(ConfigurationWillBeSavedIFace).ConfigurationWillBeSaved(newCfg)
 
 }
+
+func (a *HooksAdapter) NotificationWillBePushed(pushNotification *model.PluginPushNotification) (cancel bool) {
+	if _, ok := a.implemented[NotificationWillBePushedID]; !ok {
+		panic("product hooks must implement NotificationWillBePushed")
+	}
+
+	return a.productHooks.(NotificationWillBePushedIFace).NotificationWillBePushed(pushNotification)
+
+}