[MM-47542] Extend Plugin API (#21446)

* Extend Plugin API

* Use Error, NoError in tests

* Address suggestions

* Simplify code

* Add new line

* Add featureflag and GetCollectionMetadataByIds hook

* Add enter at the end of file

* make build-templates

* Fix test

* Fix GetCollectionMetadataByIds ret type

* Add GetTopicMetadataByIds hook

* Add log

* Extract i18n

* Add experimental notice on hooks

* Update model/feature_flags.go

* Swap user to userId

* Change userId to userID

Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>

app/channels.go

@@ -77,6 +77,12 @@ type Channels struct {
 
 	postReminderMut  sync.Mutex
 	postReminderTask *model.ScheduledTask
+
+	// collectionTypes maps collection types array to the registering plugin
+	collectionTypes map[string][]string
+	// topicTypes maps topic types array to collection types
+	topicTypes                 map[string][]string
+	collectionAndTopicTypesMut sync.Mutex
 }
 
 func init() {
@@ -94,9 +100,11 @@ func init() {
 
 func NewChannels(s *Server, services map[ServiceKey]any) (*Channels, error) {
 	ch := &Channels{
-		srv:           s,
-		imageProxy:    imageproxy.MakeImageProxy(s.platform, s.httpService, s.Log()),
-		uploadLockMap: map[string]bool{},
+		srv:             s,
+		imageProxy:      imageproxy.MakeImageProxy(s.platform, s.httpService, s.Log()),
+		uploadLockMap:   map[string]bool{},
+		collectionTypes: map[string][]string{},
+		topicTypes:      map[string][]string{},
 	}
 
 	// To get another service:

app/collection.go

@@ -0,0 +1,45 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"net/http"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/utils"
+)
+
+func (a *App) registerCollectionAndTopic(pluginID, collectionType, topicType string) error {
+	// we have a race condition due to multiple plugins calling this method
+	a.ch.collectionAndTopicTypesMut.Lock()
+	defer a.ch.collectionAndTopicTypesMut.Unlock()
+
+	// check if collectionType was already registered by other plugin
+	for existingPluginID, existingCollectionTypes := range a.ch.collectionTypes {
+		if existingPluginID != pluginID && utils.StringInSlice(collectionType, existingCollectionTypes) {
+			return model.NewAppError("registerCollectionAndTopic", "app.collection.add_collection.exists.app_error", nil, "", http.StatusBadRequest)
+		}
+	}
+
+	// check if topicType was already registered to other collection
+	for existingCollectionType, existingTopicTypes := range a.ch.topicTypes {
+		if existingCollectionType != collectionType && utils.StringInSlice(topicType, existingTopicTypes) {
+			return model.NewAppError("registerCollectionAndTopic", "app.collection.add_topic.exists.app_error", nil, "", http.StatusBadRequest)
+		}
+	}
+
+	a.ch.collectionTypes[pluginID] = appendIfUnique(a.ch.collectionTypes[pluginID], collectionType)
+	a.ch.topicTypes[collectionType] = appendIfUnique(a.ch.topicTypes[collectionType], topicType)
+
+	a.ch.srv.Log().Info("registered collection and topic type", mlog.String("plugin_id", pluginID), mlog.String("collection_type", collectionType), mlog.String("topic_type", topicType))
+	return nil
+}
+
+func appendIfUnique(slice []string, a string) []string {
+	if utils.StringInSlice(a, slice) {
+		return slice
+	}
+	return append(slice, a)
+}

app/plugin.go

@@ -486,6 +486,11 @@ func (a *App) DisablePlugin(id string) *model.AppError {
 }
 
 func (ch *Channels) disablePlugin(id string) *model.AppError {
+	for _, collectionType := range ch.collectionTypes[id] {
+		delete(ch.topicTypes, collectionType)
+	}
+	delete(ch.collectionTypes, id)
+
 	pluginsEnvironment := ch.GetPluginsEnvironment()
 	if pluginsEnvironment == nil {
 		return model.NewAppError("DisablePlugin", "app.plugin.disabled.app_error", nil, "", http.StatusNotImplemented)

app/plugin_api.go

@@ -1231,3 +1231,9 @@ func (api *PluginAPI) GetCloudLimits() (*model.ProductLimits, error) {
 	limits, err := api.app.Cloud().GetCloudLimits("")
 	return limits, err
 }
+
+// RegisterCollectionAndTopic informs the server that this plugin handles
+// the given collection and topic types.
+func (api *PluginAPI) RegisterCollectionAndTopic(collectionType, topicType string) error {
+	return api.app.registerCollectionAndTopic(api.id, collectionType, topicType)
+}

app/plugin_api_test.go

@@ -2017,3 +2017,86 @@ func TestPluginAPIIsEnterpriseReady(t *testing.T) {
 
 	assert.Equal(t, true, api.IsEnterpriseReady())
 }
+
+func TestRegisterCollectionAndTopic(t *testing.T) {
+	os.Setenv("MM_FEATUREFLAGS_THREADSEVERYWHERE", "true")
+	defer os.Unsetenv("MM_FEATUREFLAGS_THREADSEVERYWHERE")
+	th := Setup(t)
+	defer th.TearDown()
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		cfg.FeatureFlags.ThreadsEverywhere = true
+	})
+	api := th.SetupPluginAPI()
+
+	err := api.RegisterCollectionAndTopic("collection1", "topic1")
+	assert.NoError(t, err)
+	err = api.RegisterCollectionAndTopic("collection1", "topic1")
+	assert.NoError(t, err)
+	err = api.RegisterCollectionAndTopic("collection1", "topic2")
+	assert.NoError(t, err)
+	err = api.RegisterCollectionAndTopic("collection2", "topic3")
+	assert.NoError(t, err)
+	err = api.RegisterCollectionAndTopic("collection2", "topic1")
+	assert.Error(t, err)
+
+	pluginCode := `
+    package main
+
+    import (
+	  "github.com/pkg/errors"
+      "github.com/mattermost/mattermost-server/v6/plugin"
+    )
+
+    type MyPlugin struct {
+      plugin.MattermostPlugin
+    }
+
+	func (p *MyPlugin) OnActivate() error {
+		if err := p.API.RegisterCollectionAndTopic("collectionTypeToBeRepeated", "some topic"); err != nil {
+			return errors.Wrap(err, "cannot register collection")
+		}
+		if err := p.API.RegisterCollectionAndTopic("some collection", "topicToBeRepeated"); err != nil {
+			return errors.Wrap(err, "cannot register collection")
+		}
+		return nil
+	}
+
+    func main() {
+      plugin.ClientMain(&MyPlugin{})
+    }
+  `
+	pluginDir, err := os.MkdirTemp("", "")
+	require.NoError(t, err)
+	webappPluginDir, err := os.MkdirTemp("", "")
+	require.NoError(t, err)
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.PluginSettings.Directory = pluginDir
+		*cfg.PluginSettings.ClientDirectory = webappPluginDir
+	})
+
+	newPluginAPI := func(manifest *model.Manifest) plugin.API {
+		return th.App.NewPluginAPI(th.Context, manifest)
+	}
+
+	env, err := plugin.NewEnvironment(newPluginAPI, NewDriverImpl(th.App.Srv()), pluginDir, webappPluginDir, th.App.Log(), nil)
+	require.NoError(t, err)
+
+	th.App.ch.SetPluginsEnvironment(env)
+
+	pluginID := "testplugin"
+	pluginManifest := `{"id": "testplugin", "server": {"executable": "backend.exe"}}`
+	backend := filepath.Join(pluginDir, pluginID, "backend.exe")
+	utils.CompileGo(t, pluginCode, backend)
+
+	os.WriteFile(filepath.Join(pluginDir, pluginID, "plugin.json"), []byte(pluginManifest), 0600)
+	manifest, activated, reterr := env.Activate(pluginID)
+	require.NoError(t, reterr)
+	require.NotNil(t, manifest)
+	require.True(t, activated)
+
+	err = api.RegisterCollectionAndTopic("collectionTypeToBeRepeated", "some other topic")
+	assert.Error(t, err)
+	err = api.RegisterCollectionAndTopic("some other collection", "topicToBeRepeated")
+	assert.Error(t, err)
+}