MM-9674 Add plugin API for publishing custom WebSocket events (#8999)

* Add plugin API for publishing custom WebSocket events

* Add clearer payload comment

* Update comment

app/plugin_api.go

@@ -5,6 +5,7 @@ package app
 
 import (
 	"encoding/json"
+	"fmt"
 
 	"github.com/mattermost/mattermost-server/model"
 )
@@ -176,3 +177,11 @@ func (api *PluginAPI) KVGet(key string) ([]byte, *model.AppError) {
 func (api *PluginAPI) KVDelete(key string) *model.AppError {
 	return api.app.DeletePluginKey(api.id, key)
 }
+
+func (api *PluginAPI) PublishWebSocketEvent(event string, payload map[string]interface{}, broadcast *model.WebsocketBroadcast) {
+	api.app.Publish(&model.WebSocketEvent{
+		Event:     fmt.Sprintf("custom_%v_%v", api.id, event),
+		Data:      payload,
+		Broadcast: broadcast,
+	})
+}

plugin/api.go

@@ -113,6 +113,12 @@ type API interface {
 
 	// Delete will remove a key-value pair. Returns nil for non-existent keys.
 	KVDelete(key string) *model.AppError
+
+	// PublishWebSocketEvent sends an event to WebSocket connections.
+	// event is the type and will be prepended with "custom_<pluginid>_"
+	// payload is the data sent with the event. Interface values must be primitive Go types or mattermost-server/model types
+	// broadcast determines to which users to send the event
+	PublishWebSocketEvent(event string, payload map[string]interface{}, broadcast *model.WebsocketBroadcast)
 }
 
 var Handshake = plugin.HandshakeConfig{

plugin/client_rpc_generated.go

@@ -1101,3 +1101,30 @@ func (s *APIRPCServer) KVDelete(args *KVDeleteArgs, returns *KVDeleteReturns) er
 	}
 	return nil
 }
+
+type PublishWebSocketEventArgs struct {
+	A string
+	B map[string]interface{}
+	C *model.WebsocketBroadcast
+}
+
+type PublishWebSocketEventReturns struct {
+}
+
+func (g *APIRPCClient) PublishWebSocketEvent(event string, payload map[string]interface{}, broadcast *model.WebsocketBroadcast) {
+	_args := &PublishWebSocketEventArgs{event, payload, broadcast}
+	_returns := &PublishWebSocketEventReturns{}
+	if err := g.client.Call("Plugin.PublishWebSocketEvent", _args, _returns); err != nil {
+		g.log.Error("RPC call to PublishWebSocketEvent API failed.", mlog.Err(err))
+	}
+	return
+}
+
+func (s *APIRPCServer) PublishWebSocketEvent(args *PublishWebSocketEventArgs, returns *PublishWebSocketEventReturns) error {
+	if hook, ok := s.impl.(interface {
+		PublishWebSocketEvent(event string, payload map[string]interface{}, broadcast *model.WebsocketBroadcast)
+	}); ok {
+		hook.PublishWebSocketEvent(args.A, args.B, args.C)
+	}
+	return nil
+}

plugin/plugintest/api.go

@@ -1,4 +1,4 @@
-// Code generated by mockery v1.0.0. DO NOT EDIT.
+// Code generated by mockery v1.0.0
 
 // Regenerate this file using `make plugin-mocks`.
 
@@ -563,6 +563,11 @@ func (_m *API) LoadPluginConfiguration(dest interface{}) error {
 	return r0
 }
 
+// PublishWebSocketEvent provides a mock function with given fields: event, payload, broadcast
+func (_m *API) PublishWebSocketEvent(event string, payload map[string]interface{}, broadcast *model.WebsocketBroadcast) {
+	_m.Called(event, payload, broadcast)
+}
+
 // RegisterCommand provides a mock function with given fields: command
 func (_m *API) RegisterCommand(command *model.Command) error {
 	ret := _m.Called(command)

plugin/plugintest/hooks.go

@@ -1,4 +1,4 @@
-// Code generated by mockery v1.0.0. DO NOT EDIT.
+// Code generated by mockery v1.0.0
 
 // Regenerate this file using `make plugin-mocks`.