//Display all courses
        // GET: /Admin/ManageCourses/DisplayCourses
        public ActionResult DisplayCourses(string statusFilter, string themeFilter, string lectorFilter, string courseNameFilter, int?page, string statusMessage)
        {
            logManager.AddEventLog("ManageCoursesController(Admin area) => DisplayCourses ActionResult called(GET)", "ActionResult");
            ViewBag.StatusMessage       = statusMessage;
            ViewBag.CurrentStatusFilter = statusFilter;
            ViewBag.CurrentThemeFilter  = themeFilter;
            ViewBag.CurrentLectorFilter = lectorFilter;
            ViewBag.CourseNameFilter    = courseNameFilter;
            ViewBag.Themes = new SelectList(coursesManager.GetAllThemes(themeFilter));
            ViewBag.Status = new SelectList(new List <string> {
                "All", "Unknown", "Upcoming", "Active", "Ended"
            });
            int pageSize    = 10;
            int pageNumber  = (page ?? 1);
            var coursesList = coursesManager.GetCoursesForAdmin();

            if (Request.HttpMethod == "POST")
            {
                coursesList = coursesManager.GetSortedCourses(null, statusFilter, themeFilter, lectorFilter, courseNameFilter, coursesList);
                var coursesPost = CourseViewModel.GetCoursesList(coursesList, 1);
                ViewBag.CurrentStatusFilter = statusFilter;
                ViewBag.CurrentThemeFilter  = themeFilter;
                ViewBag.CurrentLectorFilter = lectorFilter;
                ViewBag.CourseNameFilter    = courseNameFilter;
                ViewBag.Lectors             = new SelectList(usersManager.GetAllLectorsString(
                                                                 coursesPost.Select(c => c.Lector).ToList(), lectorFilter), lectorFilter);
                return(View(coursesPost.ToPagedList(pageNumber, pageSize)));
            }

            coursesList = coursesManager.GetSortedCourses(null, statusFilter, themeFilter, lectorFilter, courseNameFilter, coursesList);
            var courses = CourseViewModel.GetCoursesList(coursesList, 1);

            ViewBag.Lectors = new SelectList(usersManager.GetAllLectorsString(
                                                 courses.Select(c => c.Lector).ToList(), lectorFilter), lectorFilter);

            return(View(courses.ToPagedList(pageNumber, pageSize)));
        }