Adding 'MessageHasBeenDeleted' hook to plugins (#22476)

* Adding 'MessageHasBeenDeleted' hook to plugins

* Remove debug logs

* Add unit test

* Bumping the required version

* Fix CI problems

* Increasing the minimum version

* go fmt

---------

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/plugin_hooks_test.go

@@ -429,6 +429,50 @@ func TestHookMessageHasBeenUpdated(t *testing.T) {
 	require.Nil(t, err)
 }
 
+func TestHookMessageHasBeenDeleted(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	var mockAPI plugintest.API
+	mockAPI.On("LoadPluginConfiguration", mock.Anything).Return(nil)
+	mockAPI.On("LogDebug", "message").Return(nil).Times(1)
+
+	tearDown, _, _ := SetAppEnvironmentWithPlugins(t,
+		[]string{
+			`
+		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) MessageHasBeenDeleted(c *plugin.Context, post *model.Post) {
+			p.API.LogDebug(post.Message)
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+	`}, th.App, func(*model.Manifest) plugin.API { return &mockAPI })
+	defer tearDown()
+
+	post := &model.Post{
+		UserId:    th.BasicUser.Id,
+		ChannelId: th.BasicChannel.Id,
+		Message:   "message",
+		CreateAt:  model.GetMillis() - 10000,
+	}
+	_, err := th.App.CreatePost(th.Context, post, th.BasicChannel, false, true)
+	require.Nil(t, err)
+	_, err = th.App.DeletePost(th.Context, post.Id, th.BasicUser.Id)
+	require.Nil(t, err)
+}
+
 func TestHookFileWillBeUploaded(t *testing.T) {
 	t.Run("rejected", func(t *testing.T) {
 		th := Setup(t).InitBasic()

server/channels/app/post.go

@@ -1339,6 +1339,15 @@ func (a *App) DeletePost(c request.CTX, postID, deleteByID string) (*model.Post,
 		a.deleteFlaggedPosts(post.Id)
 	})
 
+	pluginPost := post.ForPlugin()
+	pluginContext := pluginContext(c)
+	a.Srv().Go(func() {
+		a.ch.RunMultiHook(func(hooks plugin.Hooks) bool {
+			hooks.MessageHasBeenDeleted(pluginContext, pluginPost)
+			return true
+		}, plugin.MessageHasBeenDeletedID)
+	})
+
 	a.Srv().Go(func() {
 		if err = a.RemoveNotifications(c, post, channel); err != nil {
 			a.Log().Error("DeletePost failed to delete notification", mlog.Err(err))

server/public/plugin/client_rpc_generated.go

@@ -290,6 +290,40 @@ func (s *hooksRPCServer) MessageHasBeenUpdated(args *Z_MessageHasBeenUpdatedArgs
 	return nil
 }
 
+func init() {
+	hookNameToId["MessageHasBeenDeleted"] = MessageHasBeenDeletedID
+}
+
+type Z_MessageHasBeenDeletedArgs struct {
+	A *Context
+	B *model.Post
+}
+
+type Z_MessageHasBeenDeletedReturns struct {
+}
+
+func (g *hooksRPCClient) MessageHasBeenDeleted(c *Context, post *model.Post) {
+	_args := &Z_MessageHasBeenDeletedArgs{c, post}
+	_returns := &Z_MessageHasBeenDeletedReturns{}
+	if g.implemented[MessageHasBeenDeletedID] {
+		if err := g.client.Call("Plugin.MessageHasBeenDeleted", _args, _returns); err != nil {
+			g.log.Error("RPC call MessageHasBeenDeleted to plugin failed.", mlog.Err(err))
+		}
+	}
+
+}
+
+func (s *hooksRPCServer) MessageHasBeenDeleted(args *Z_MessageHasBeenDeletedArgs, returns *Z_MessageHasBeenDeletedReturns) error {
+	if hook, ok := s.impl.(interface {
+		MessageHasBeenDeleted(c *Context, post *model.Post)
+	}); ok {
+		hook.MessageHasBeenDeleted(args.A, args.B)
+	} else {
+		return encodableError(fmt.Errorf("Hook MessageHasBeenDeleted called but not implemented."))
+	}
+	return nil
+}
+
 func init() {
 	hookNameToId["ChannelHasBeenCreated"] = ChannelHasBeenCreatedID
 }

server/public/plugin/hooks.go

@@ -52,6 +52,7 @@ const (
 	ConfigurationWillBeSavedID                = 34
 	NotificationWillBePushedID                = 35
 	UserHasBeenDeactivatedID                  = 36
+	MessageHasBeenDeletedID                   = 37
 	TotalHooksID                              = iota
 )
 
@@ -169,6 +170,13 @@ type Hooks interface {
 	// Minimum server version: 5.2
 	MessageHasBeenUpdated(c *Context, newPost, oldPost *model.Post)
 
+	// MessageHasBeenDeleted is invoked after the message has been deleted from the database.
+	// Note that this method will be called for posts deleted by plugins, including the plugin that
+	// deleted the post.
+	//
+	// Minimum server version: 9.1
+	MessageHasBeenDeleted(c *Context, post *model.Post)
+
 	// ChannelHasBeenCreated is invoked after the channel has been committed to the database.
 	//
 	// Minimum server version: 5.2

server/public/plugin/hooks_timer_layer_generated.go

@@ -113,6 +113,12 @@ func (hooks *hooksTimerLayer) MessageHasBeenUpdated(c *Context, newPost, oldPost
 	hooks.recordTime(startTime, "MessageHasBeenUpdated", true)
 }
 
+func (hooks *hooksTimerLayer) MessageHasBeenDeleted(c *Context, post *model.Post) {
+	startTime := timePkg.Now()
+	hooks.hooksImpl.MessageHasBeenDeleted(c, post)
+	hooks.recordTime(startTime, "MessageHasBeenDeleted", true)
+}
+
 func (hooks *hooksTimerLayer) ChannelHasBeenCreated(c *Context, channel *model.Channel) {
 	startTime := timePkg.Now()
 	hooks.hooksImpl.ChannelHasBeenCreated(c, channel)

server/public/plugin/plugintest/hooks.go

@@ -131,6 +131,11 @@ func (_m *Hooks) Implemented() ([]string, error) {
 	return r0, r1
 }
 
+// MessageHasBeenDeleted provides a mock function with given fields: c, post
+func (_m *Hooks) MessageHasBeenDeleted(c *plugin.Context, post *model.Post) {
+	_m.Called(c, post)
+}
+
 // MessageHasBeenPosted provides a mock function with given fields: c, post
 func (_m *Hooks) MessageHasBeenPosted(c *plugin.Context, post *model.Post) {
 	_m.Called(c, post)

server/public/plugin/product_hooks_generated.go

@@ -50,6 +50,10 @@ type MessageHasBeenUpdatedIFace interface {
 	MessageHasBeenUpdated(c *Context, newPost, oldPost *model.Post)
 }
 
+type MessageHasBeenDeletedIFace interface {
+	MessageHasBeenDeleted(c *Context, post *model.Post)
+}
+
 type ChannelHasBeenCreatedIFace interface {
 	ChannelHasBeenCreated(c *Context, channel *model.Channel)
 }
@@ -220,6 +224,15 @@ func NewAdapter(productHooks any) (*HooksAdapter, error) {
 		return nil, errors.New("hook has MessageHasBeenUpdated method but does not implement plugin.MessageHasBeenUpdated interface")
 	}
 
+	// Assessing the type of the productHooks if it individually implements MessageHasBeenDeleted interface.
+	tt = reflect.TypeOf((*MessageHasBeenDeletedIFace)(nil)).Elem()
+
+	if ft.Implements(tt) {
+		a.implemented[MessageHasBeenDeletedID] = struct{}{}
+	} else if _, ok := ft.MethodByName("MessageHasBeenDeleted"); ok {
+		return nil, errors.New("hook has MessageHasBeenDeleted method but does not implement plugin.MessageHasBeenDeleted interface")
+	}
+
 	// Assessing the type of the productHooks if it individually implements ChannelHasBeenCreated interface.
 	tt = reflect.TypeOf((*ChannelHasBeenCreatedIFace)(nil)).Elem()
 
@@ -475,6 +488,15 @@ func (a *HooksAdapter) MessageHasBeenUpdated(c *Context, newPost, oldPost *model
 
 }
 
+func (a *HooksAdapter) MessageHasBeenDeleted(c *Context, post *model.Post) {
+	if _, ok := a.implemented[MessageHasBeenDeletedID]; !ok {
+		panic("product hooks must implement MessageHasBeenDeleted")
+	}
+
+	a.productHooks.(MessageHasBeenDeletedIFace).MessageHasBeenDeleted(c, post)
+
+}
+
 func (a *HooksAdapter) ChannelHasBeenCreated(c *Context, channel *model.Channel) {
 	if _, ok := a.implemented[ChannelHasBeenCreatedID]; !ok {
 		panic("product hooks must implement ChannelHasBeenCreated")