Add plugin slash command support (#7941)

* add plugin slash command support

* remove unused string

* rebase

10 files changed, 224 insertions, 10 deletions

diff --git a/plugin/api.go b/plugin/api.go
index fee55eeff..437188f6e 100644
--- a/plugin/api.go
+++ b/plugin/api.go
@@ -16,6 +16,13 @@ type API interface {
 	// struct that the configuration JSON can be unmarshalled to.
 	LoadPluginConfiguration(dest interface{}) error
 
+	// RegisterCommand registers a custom slash command. When the command is triggered, your plugin
+	// can fulfill it via the ExecuteCommand hook.
+	RegisterCommand(command *model.Command) error
+
+	// UnregisterCommand unregisters a command previously registered via RegisterCommand.
+	UnregisterCommand(teamId, trigger string) error
+
 	// CreateUser creates a user.
 	CreateUser(user *model.User) (*model.User, *model.AppError)
 
diff --git a/plugin/hooks.go b/plugin/hooks.go
index 04d5c7c14..814609e8c 100644
--- a/plugin/hooks.go
+++ b/plugin/hooks.go
@@ -5,6 +5,8 @@ package plugin
 
 import (
 	"net/http"
+
+	"github.com/mattermost/mattermost-server/model"
 )
 
 // Methods from the Hooks interface can be used by a plugin to respond to events. Methods are likely
@@ -30,4 +32,8 @@ type Hooks interface {
 	// The Mattermost-User-Id header will be present if (and only if) the request is by an
 	// authenticated user.
 	ServeHTTP(http.ResponseWriter, *http.Request)
+
+	// ExecuteCommand executes a command that has been previously registered via the RegisterCommand
+	// API.
+	ExecuteCommand(args *model.CommandArgs) (*model.CommandResponse, *model.AppError)
 }
diff --git a/plugin/pluginenv/environment.go b/plugin/pluginenv/environment.go
index 26511c651..f53021f74 100644
--- a/plugin/pluginenv/environment.go
+++ b/plugin/pluginenv/environment.go
@@ -223,35 +223,59 @@ func (env *Environment) Shutdown() (errs []error) {
 	return
 }
 
-type EnvironmentHooks struct {
+type MultiPluginHooks struct {
 	env *Environment
 }
 
-func (env *Environment) Hooks() *EnvironmentHooks {
-	return &EnvironmentHooks{env}
+type SinglePluginHooks struct {
+	env      *Environment
+	pluginId string
 }
 
-// OnConfigurationChange invokes the OnConfigurationChange hook for all plugins. Any errors
-// encountered will be returned.
-func (h *EnvironmentHooks) OnConfigurationChange() (errs []error) {
+func (env *Environment) Hooks() *MultiPluginHooks {
+	return &MultiPluginHooks{
+		env: env,
+	}
+}
+
+func (env *Environment) HooksForPlugin(id string) *SinglePluginHooks {
+	return &SinglePluginHooks{
+		env:      env,
+		pluginId: id,
+	}
+}
+
+func (h *MultiPluginHooks) invoke(f func(plugin.Hooks) error) (errs []error) {
 	h.env.mutex.RLock()
 	defer h.env.mutex.RUnlock()
+
 	for _, activePlugin := range h.env.activePlugins {
 		if activePlugin.Supervisor == nil {
 			continue
 		}
-		if err := activePlugin.Supervisor.Hooks().OnConfigurationChange(); err != nil {
-			errs = append(errs, errors.Wrapf(err, "OnConfigurationChange error for %v", activePlugin.BundleInfo.Manifest.Id))
+		if err := f(activePlugin.Supervisor.Hooks()); err != nil {
+			errs = append(errs, errors.Wrapf(err, "hook error for %v", activePlugin.BundleInfo.Manifest.Id))
 		}
 	}
 	return
 }
 
+// OnConfigurationChange invokes the OnConfigurationChange hook for all plugins. Any errors
+// encountered will be returned.
+func (h *MultiPluginHooks) OnConfigurationChange() []error {
+	return h.invoke(func(hooks plugin.Hooks) error {
+		if err := hooks.OnConfigurationChange(); err != nil {
+			return errors.Wrapf(err, "error calling OnConfigurationChange hook")
+		}
+		return nil
+	})
+}
+
 // ServeHTTP invokes the ServeHTTP hook for the plugin identified by the request or responds with a
 // 404 not found.
 //
 // It expects the request's context to have a plugin_id set.
-func (h *EnvironmentHooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+func (h *MultiPluginHooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if id := r.Context().Value("plugin_id"); id != nil {
 		if idstr, ok := id.(string); ok {
 			h.env.mutex.RLock()
@@ -264,3 +288,25 @@ func (h *EnvironmentHooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 	http.NotFound(w, r)
 }
+
+func (h *SinglePluginHooks) invoke(f func(plugin.Hooks) error) error {
+	h.env.mutex.RLock()
+	defer h.env.mutex.RUnlock()
+
+	if activePlugin, ok := h.env.activePlugins[h.pluginId]; ok && activePlugin.Supervisor != nil {
+		if err := f(activePlugin.Supervisor.Hooks()); err != nil {
+			return errors.Wrapf(err, "hook error for plugin: %v", activePlugin.BundleInfo.Manifest.Id)
+		}
+		return nil
+	}
+	return fmt.Errorf("unable to invoke hook for plugin: %v", h.pluginId)
+}
+
+// ExecuteCommand invokes the ExecuteCommand hook for the plugin.
+func (h *SinglePluginHooks) ExecuteCommand(args *model.CommandArgs) (resp *model.CommandResponse, appErr *model.AppError, err error) {
+	err = h.invoke(func(hooks plugin.Hooks) error {
+		resp, appErr = hooks.ExecuteCommand(args)
+		return nil
+	})
+	return
+}
diff --git a/plugin/pluginenv/environment_test.go b/plugin/pluginenv/environment_test.go
index 988e5b08f..2a52b3830 100644
--- a/plugin/pluginenv/environment_test.go
+++ b/plugin/pluginenv/environment_test.go
@@ -355,3 +355,51 @@ func TestEnvironment_ConcurrentHookInvocations(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestEnvironment_HooksForPlugins(t *testing.T) {
+	dir := initTmpDir(t, map[string]string{
+		"foo/plugin.json": `{"id": "foo", "backend": {}}`,
+	})
+	defer os.RemoveAll(dir)
+
+	var provider MockProvider
+	defer provider.AssertExpectations(t)
+
+	env, err := New(
+		SearchPath(dir),
+		APIProvider(provider.API),
+		SupervisorProvider(provider.Supervisor),
+	)
+	require.NoError(t, err)
+	defer env.Shutdown()
+
+	var api struct{ plugin.API }
+	var supervisor MockSupervisor
+	defer supervisor.AssertExpectations(t)
+	var hooks plugintest.Hooks
+	defer hooks.AssertExpectations(t)
+
+	provider.On("API").Return(&api, nil)
+	provider.On("Supervisor").Return(&supervisor, nil)
+
+	supervisor.On("Start", &api).Return(nil)
+	supervisor.On("Stop").Return(nil)
+	supervisor.On("Hooks").Return(&hooks)
+
+	hooks.On("OnDeactivate").Return(nil)
+	hooks.On("ExecuteCommand", mock.AnythingOfType("*model.CommandArgs")).Return(&model.CommandResponse{
+		Text: "bar",
+	}, nil)
+
+	assert.NoError(t, env.ActivatePlugin("foo"))
+	assert.Equal(t, env.ActivePluginIds(), []string{"foo"})
+
+	resp, appErr, err := env.HooksForPlugin("foo").ExecuteCommand(&model.CommandArgs{
+		Command: "/foo",
+	})
+	assert.Equal(t, "bar", resp.Text)
+	assert.Nil(t, appErr)
+	assert.NoError(t, err)
+
+	assert.Empty(t, env.Shutdown())
+}
diff --git a/plugin/plugintest/api.go b/plugin/plugintest/api.go
index b00542032..75174a9a6 100644
--- a/plugin/plugintest/api.go
+++ b/plugin/plugintest/api.go
@@ -30,6 +30,22 @@ func (m *API) LoadPluginConfiguration(dest interface{}) error {
 	return ret.Error(0)
 }
 
+func (m *API) RegisterCommand(command *model.Command) error {
+	ret := m.Called(command)
+	if f, ok := ret.Get(0).(func(*model.Command) error); ok {
+		return f(command)
+	}
+	return ret.Error(0)
+}
+
+func (m *API) UnregisterCommand(teamId, trigger string) error {
+	ret := m.Called(teamId, trigger)
+	if f, ok := ret.Get(0).(func(string, string) error); ok {
+		return f(teamId, trigger)
+	}
+	return ret.Error(0)
+}
+
 func (m *API) CreateUser(user *model.User) (*model.User, *model.AppError) {
 	ret := m.Called(user)
 	if f, ok := ret.Get(0).(func(*model.User) (*model.User, *model.AppError)); ok {
diff --git a/plugin/plugintest/hooks.go b/plugin/plugintest/hooks.go
index 56d048d6a..9ea11a9fb 100644
--- a/plugin/plugintest/hooks.go
+++ b/plugin/plugintest/hooks.go
@@ -8,6 +8,7 @@ import (
 
 	"github.com/stretchr/testify/mock"
 
+	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/plugin"
 )
 
@@ -18,7 +19,11 @@ type Hooks struct {
 var _ plugin.Hooks = (*Hooks)(nil)
 
 func (m *Hooks) OnActivate(api plugin.API) error {
-	return m.Called(api).Error(0)
+	ret := m.Called(api)
+	if f, ok := ret.Get(0).(func(plugin.API) error); ok {
+		return f(api)
+	}
+	return ret.Error(0)
 }
 
 func (m *Hooks) OnDeactivate() error {
@@ -32,3 +37,13 @@ func (m *Hooks) OnConfigurationChange() error {
 func (m *Hooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	m.Called(w, r)
 }
+
+func (m *Hooks) ExecuteCommand(args *model.CommandArgs) (*model.CommandResponse, *model.AppError) {
+	ret := m.Called(args)
+	if f, ok := ret.Get(0).(func(*model.CommandArgs) (*model.CommandResponse, *model.AppError)); ok {
+		return f(args)
+	}
+	resp, _ := ret.Get(0).(*model.CommandResponse)
+	err, _ := ret.Get(1).(*model.AppError)
+	return resp, err
+}
diff --git a/plugin/rpcplugin/api.go b/plugin/rpcplugin/api.go
index 76c6e3039..5b5b11a62 100644
--- a/plugin/rpcplugin/api.go
+++ b/plugin/rpcplugin/api.go
@@ -32,6 +32,14 @@ func (api *LocalAPI) LoadPluginConfiguration(args struct{}, reply *[]byte) error
 	return nil
 }
 
+func (api *LocalAPI) RegisterCommand(args *model.Command, reply *APITeamReply) error {
+	return api.api.RegisterCommand(args)
+}
+
+func (api *LocalAPI) UnregisterCommand(args *APIUnregisterCommandArgs, reply *APITeamReply) error {
+	return api.api.UnregisterCommand(args.TeamId, args.Trigger)
+}
+
 type APIErrorReply struct {
 	Error *model.AppError
 }
@@ -344,6 +352,22 @@ func (api *RemoteAPI) LoadPluginConfiguration(dest interface{}) error {
 	return json.Unmarshal(config, dest)
 }
 
+func (api *RemoteAPI) RegisterCommand(command *model.Command) error {
+	return api.client.Call("LocalAPI.RegisterCommand", command, nil)
+}
+
+type APIUnregisterCommandArgs struct {
+	TeamId  string
+	Trigger string
+}
+
+func (api *RemoteAPI) UnregisterCommand(teamId, trigger string) error {
+	return api.client.Call("LocalAPI.UnregisterCommand", &APIUnregisterCommandArgs{
+		TeamId:  teamId,
+		Trigger: trigger,
+	}, nil)
+}
+
 func (api *RemoteAPI) CreateUser(user *model.User) (*model.User, *model.AppError) {
 	var reply APIUserReply
 	if err := api.client.Call("LocalAPI.CreateUser", user, &reply); err != nil {
diff --git a/plugin/rpcplugin/api_test.go b/plugin/rpcplugin/api_test.go
index f9e474d4a..145ec9005 100644
--- a/plugin/rpcplugin/api_test.go
+++ b/plugin/rpcplugin/api_test.go
@@ -2,6 +2,7 @@ package rpcplugin
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
 	"testing"
@@ -84,6 +85,16 @@ func TestAPI(t *testing.T) {
 		assert.Equal(t, "foo", config.Foo)
 		assert.Equal(t, "baz", config.Bar.Baz)
 
+		api.On("RegisterCommand", mock.AnythingOfType("*model.Command")).Return(fmt.Errorf("foo")).Once()
+		assert.Error(t, remote.RegisterCommand(&model.Command{}))
+		api.On("RegisterCommand", mock.AnythingOfType("*model.Command")).Return(nil).Once()
+		assert.NoError(t, remote.RegisterCommand(&model.Command{}))
+
+		api.On("UnregisterCommand", "team", "trigger").Return(fmt.Errorf("foo")).Once()
+		assert.Error(t, remote.UnregisterCommand("team", "trigger"))
+		api.On("UnregisterCommand", "team", "trigger").Return(nil).Once()
+		assert.NoError(t, remote.UnregisterCommand("team", "trigger"))
+
 		api.On("CreateChannel", mock.AnythingOfType("*model.Channel")).Return(func(c *model.Channel) (*model.Channel, *model.AppError) {
 			c.Id = "thechannelid"
 			return c, nil
diff --git a/plugin/rpcplugin/hooks.go b/plugin/rpcplugin/hooks.go
index 22f26e22e..7b44d0de7 100644
--- a/plugin/rpcplugin/hooks.go
+++ b/plugin/rpcplugin/hooks.go
@@ -11,6 +11,7 @@ import (
 	"net/rpc"
 	"reflect"
 
+	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/plugin"
 )
 
@@ -125,6 +126,20 @@ func (h *LocalHooks) ServeHTTP(args ServeHTTPArgs, reply *struct{}) error {
 	return nil
 }
 
+type HooksExecuteCommandReply struct {
+	Response *model.CommandResponse
+	Error    *model.AppError
+}
+
+func (h *LocalHooks) ExecuteCommand(args *model.CommandArgs, reply *HooksExecuteCommandReply) error {
+	if hook, ok := h.hooks.(interface {
+		ExecuteCommand(*model.CommandArgs) (*model.CommandResponse, *model.AppError)
+	}); ok {
+		reply.Response, reply.Error = hook.ExecuteCommand(args)
+	}
+	return nil
+}
+
 func ServeHooks(hooks interface{}, conn io.ReadWriteCloser, muxer *Muxer) {
 	server := rpc.NewServer()
 	server.Register(&LocalHooks{
@@ -141,6 +156,7 @@ const (
 	remoteOnDeactivate          = 1
 	remoteServeHTTP             = 2
 	remoteOnConfigurationChange = 3
+	remoteExecuteCommand        = 4
 	maxRemoteHookCount          = iota
 )
 
@@ -225,6 +241,17 @@ func (h *RemoteHooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func (h *RemoteHooks) ExecuteCommand(args *model.CommandArgs) (*model.CommandResponse, *model.AppError) {
+	if !h.implemented[remoteExecuteCommand] {
+		return nil, model.NewAppError("RemoteHooks.ExecuteCommand", "plugin.rpcplugin.invocation.error", nil, "err=ExecuteCommand hook not implemented", http.StatusInternalServerError)
+	}
+	var reply HooksExecuteCommandReply
+	if err := h.client.Call("LocalHooks.ExecuteCommand", args, &reply); err != nil {
+		return nil, model.NewAppError("RemoteHooks.ExecuteCommand", "plugin.rpcplugin.invocation.error", nil, "err="+err.Error(), http.StatusInternalServerError)
+	}
+	return reply.Response, reply.Error
+}
+
 func (h *RemoteHooks) Close() error {
 	if h.apiCloser != nil {
 		h.apiCloser.Close()
@@ -253,6 +280,8 @@ func ConnectHooks(conn io.ReadWriteCloser, muxer *Muxer) (*RemoteHooks, error) {
 			remote.implemented[remoteOnConfigurationChange] = true
 		case "ServeHTTP":
 			remote.implemented[remoteServeHTTP] = true
+		case "ExecuteCommand":
+			remote.implemented[remoteExecuteCommand] = true
 		}
 	}
 	return remote, nil
diff --git a/plugin/rpcplugin/hooks_test.go b/plugin/rpcplugin/hooks_test.go
index 37c529510..116038dae 100644
--- a/plugin/rpcplugin/hooks_test.go
+++ b/plugin/rpcplugin/hooks_test.go
@@ -13,6 +13,7 @@ import (
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
 
+	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/plugin"
 	"github.com/mattermost/mattermost-server/plugin/plugintest"
 )
@@ -79,6 +80,17 @@ func TestHooks(t *testing.T) {
 		body, err := ioutil.ReadAll(resp.Body)
 		assert.NoError(t, err)
 		assert.Equal(t, "bar", string(body))
+
+		hooks.On("ExecuteCommand", &model.CommandArgs{
+			Command: "/foo",
+		}).Return(&model.CommandResponse{
+			Text: "bar",
+		}, nil)
+		commandResponse, appErr := hooks.ExecuteCommand(&model.CommandArgs{
+			Command: "/foo",
+		})
+		assert.Equal(t, "bar", commandResponse.Text)
+		assert.Nil(t, appErr)
 	}))
 }