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{})
+}