Add GetFileLink method to plugin API (#9665)

* add GetFileLink method to plugin API

* Update plugin/api.go

* add translations for new plugin API errors

app/plugin_api.go

@@ -369,6 +369,23 @@ func (api *PluginAPI) GetFileInfo(fileId string) (*model.FileInfo, *model.AppErr
 	return api.app.GetFileInfo(fileId)
 }
 
+func (api *PluginAPI) GetFileLink(fileId string) (string, *model.AppError) {
+	if !api.app.Config().FileSettings.EnablePublicLink {
+		return "", model.NewAppError("GetFileLink", "plugin_api.get_file_link.disabled.app_error", nil, "", http.StatusNotImplemented)
+	}
+
+	info, err := api.app.GetFileInfo(fileId)
+	if err != nil {
+		return "", err
+	}
+
+	if len(info.PostId) == 0 {
+		return "", model.NewAppError("GetFileLink", "plugin_api.get_file_link.no_post.app_error", nil, "file_id="+info.Id, http.StatusBadRequest)
+	}
+
+	return api.app.GeneratePublicLink(api.app.GetSiteURL(), info), nil
+}
+
 func (api *PluginAPI) ReadFile(path string) ([]byte, *model.AppError) {
 	return api.app.ReadFile(path)
 }

i18n/en.json

@@ -4842,6 +4842,14 @@
     "id": "oauth.gitlab.tos.error",
     "translation": "GitLab's Terms of Service have updated. Please go to gitlab.com to accept them and then try logging into Mattermost again."
   },
+  {
+    "id": "plugin_api.get_file_link.disabled.app_error",
+    "translation": "Public links have been disabled"
+  },
+  {
+    "id": "plugin_api.get_file_link.no_post.app_error",
+    "translation": "Unable to get public link for file. File must be attached to a post that can be read."
+  },
   {
     "id": "plugin.api.update_user_status.bad_status",
     "translation": "Unable to set the user status. Unknown user status."

plugin/api.go

@@ -256,6 +256,11 @@ type API interface {
 	// Minimum server version: 5.3
 	GetFileInfo(fileId string) (*model.FileInfo, *model.AppError)
 
+	// GetFileLink gets the public link to a file by fileId.
+	//
+	// Minimum server version: 5.6
+	GetFileLink(fileId string) (string, *model.AppError)
+
 	// ReadFileAtPath reads the file from the backend for a specific path
 	//
 	// Minimum server version: 5.3

plugin/client_rpc_generated.go

@@ -2399,6 +2399,35 @@ func (s *apiRPCServer) GetFileInfo(args *Z_GetFileInfoArgs, returns *Z_GetFileIn
 	return nil
 }
 
+type Z_GetFileLinkArgs struct {
+	A string
+}
+
+type Z_GetFileLinkReturns struct {
+	A string
+	B *model.AppError
+}
+
+func (g *apiRPCClient) GetFileLink(fileId string) (string, *model.AppError) {
+	_args := &Z_GetFileLinkArgs{fileId}
+	_returns := &Z_GetFileLinkReturns{}
+	if err := g.client.Call("Plugin.GetFileLink", _args, _returns); err != nil {
+		log.Printf("RPC call to GetFileLink API failed: %s", err.Error())
+	}
+	return _returns.A, _returns.B
+}
+
+func (s *apiRPCServer) GetFileLink(args *Z_GetFileLinkArgs, returns *Z_GetFileLinkReturns) error {
+	if hook, ok := s.impl.(interface {
+		GetFileLink(fileId string) (string, *model.AppError)
+	}); ok {
+		returns.A, returns.B = hook.GetFileLink(args.A)
+	} else {
+		return encodableError(fmt.Errorf("API GetFileLink called but not implemented."))
+	}
+	return nil
+}
+
 type Z_ReadFileArgs struct {
 	A string
 }

plugin/plugintest/api.go

@@ -574,6 +574,29 @@ func (_m *API) GetFileInfo(fileId string) (*model.FileInfo, *model.AppError) {
 	return r0, r1
 }
 
+// GetFileLink provides a mock function with given fields: fileId
+func (_m *API) GetFileLink(fileId string) (string, *model.AppError) {
+	ret := _m.Called(fileId)
+
+	var r0 string
+	if rf, ok := ret.Get(0).(func(string) string); ok {
+		r0 = rf(fileId)
+	} else {
+		r0 = ret.Get(0).(string)
+	}
+
+	var r1 *model.AppError
+	if rf, ok := ret.Get(1).(func(string) *model.AppError); ok {
+		r1 = rf(fileId)
+	} else {
+		if ret.Get(1) != nil {
+			r1 = ret.Get(1).(*model.AppError)
+		}
+	}
+
+	return r0, r1
+}
+
 // GetGroupChannel provides a mock function with given fields: userIds
 func (_m *API) GetGroupChannel(userIds []string) (*model.Channel, *model.AppError) {
 	ret := _m.Called(userIds)