Add labels to tasks (#45)

pkg/models/label_task_rights.go

@@ -0,0 +1,62 @@
+//  Vikunja is a todo-list application to facilitate your life.
+//  Copyright 2018 Vikunja and contributors. All rights reserved.
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"code.vikunja.io/api/pkg/log"
+	"code.vikunja.io/web"
+)
+
+// CanCreate checks if a user can add a label to a task
+func (lt *LabelTask) CanCreate(a web.Auth) bool {
+	label, err := getLabelByIDSimple(lt.LabelID)
+	if err != nil {
+		log.Log.Errorf("Error during CanCreate for LabelTask: %v", err)
+		return false
+	}
+
+	return label.hasAccessToLabel(a) && lt.canDoLabelTask(a)
+}
+
+// CanDelete checks if a user can delete a label from a task
+func (lt *LabelTask) CanDelete(a web.Auth) bool {
+	if !lt.canDoLabelTask(a) {
+		return false
+	}
+
+	// We don't care here if the label exists or not. The only relevant thing here is if the relation already exists,
+	// throw an error.
+	exists, err := x.Exist(&LabelTask{LabelID: lt.LabelID, TaskID: lt.TaskID})
+	if err != nil {
+		log.Log.Errorf("Error during CanDelete for LabelTask: %v", err)
+		return false
+	}
+	return exists
+}
+
+// Helper function to check if a user can write to a task
+// + is able to see the label
+// always the same check for either deleting or adding a label to a task
+func (lt *LabelTask) canDoLabelTask(a web.Auth) bool {
+	// A user can add a label to a task if he can write to the task
+	task, err := getTaskByIDSimple(lt.TaskID)
+	if err != nil {
+		log.Log.Error("Error occurred during canDoLabelTask for LabelTask: %v", err)
+		return false
+	}
+	return task.CanUpdate(a)
+}