LeaderboardViewModel.cs

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using System.Threading.Tasks;
using PhotoSharingApp.Universal.Commands;
using PhotoSharingApp.Universal.Facades;
using PhotoSharingApp.Universal.Models;
using PhotoSharingApp.Universal.Services;
using PhotoSharingApp.Universal.Views;
using Windows.ApplicationModel.Resources;

namespace PhotoSharingApp.Universal.ViewModels
{
    /// <summary>
    /// ViewModel for Leaderboards view.
    /// </summary>
    public class LeaderboardViewModel : ViewModelBase
    {
        private readonly IDialogService _dialogService;

        private bool _isBusy;

        private Leaderboard _leaderboard;

        private ResourceLoader _resourceLoader;

        /// <summary>
        /// The navigation facade
        /// </summary>
        private readonly INavigationFacade _navigationFacade;

        /// <summary>
        /// The photo service
        /// </summary>
        private readonly IPhotoService _photoService;

        /// <summary>
        /// Initializes a new instance of the <see cref="LeaderboardViewModel" /> class.
        /// </summary>
        /// <param name="navigationFacade">The navigation facade.</param>
        /// <param name="photoService">The photo service.</param>
        /// <param name="dialogService">The dialog service.</param>
        public LeaderboardViewModel(INavigationFacade navigationFacade, IPhotoService photoService,
            IDialogService dialogService)
        {
            _navigationFacade = navigationFacade;
            _photoService = photoService;
            _dialogService = dialogService;
            _resourceLoader = ResourceLoader.GetForCurrentView();

            PhotoSelectedCommand = new RelayCommand<Photo>(OnPhotoSelected);
            CategorySelectedCommand = new RelayCommand<Category>(OnCategorySelected);
            UserSelectedCommand = new RelayCommand<User>(OnUserSelected);
        }

        public string PageHeaderText
        {
            get
            {
                return _resourceLoader.GetString("LeaderboardsPage_PageHeader");
            }
        }

        public string FirstHubHeaderText
        {
            get
            {
                return _resourceLoader.GetString("LeaderboardsPage_FirstHubHeaderText");
            }
        }

        public string SecondHubHeaderText
        {
            get
            {
                return _resourceLoader.GetString("LeaderboardsPage_SecondHubHeaderText");
            }
        }

        public string ThirdHubHeaderText
        {
            get
            {
                return _resourceLoader.GetString("LeaderboardsPage_ThirdHubHeaderText");
            }
        }

        public string FourthHubHeaderText
        {
            get
            {
                return _resourceLoader.GetString("LeaderboardsPage_FourthHubHeaderText");
            }
        }

        /// <summary>
        /// Gets photo selected command.
        /// </summary>
        public RelayCommand<Category> CategorySelectedCommand { get; private set; }

        /// <summary>
        /// Gets or sets a value indicating whether this instance is busy.
        /// </summary>
        /// <value>
        /// <c>true</c> if this instance is busy; otherwise, <c>false</c>.
        /// </value>
        public bool IsBusy
        {
            get { return _isBusy; }
            set
            {
                if (value != _isBusy)
                {
                    _isBusy = value;
                    NotifyPropertyChanged(nameof(IsBusy));
                }
            }
        }

        /// <summary>
        /// The leaderboard data
        /// </summary>
        public Leaderboard Leaderboard
        {
            get { return _leaderboard; }
            private set
            {
                if (value != _leaderboard)
                {
                    _leaderboard = value;
                    NotifyPropertyChanged(nameof(Leaderboard));
                }
            }
        }

        /// <summary>
        /// Gets photo selected command.
        /// </summary>
        public RelayCommand<Photo> PhotoSelectedCommand { get; private set; }

        /// <summary>
        /// Gets the user selected command.
        /// </summary>
        public RelayCommand<User> UserSelectedCommand { get; private set; }

        /// <summary>
        /// Loads the state.
        /// </summary>
        public override async Task LoadState()
        {
            await base.LoadState();
            IsBusy = true;

            try
            {
                Leaderboard = await _photoService.GetLeaderboardData(5, 5, 5, 5);
            }
            catch (ServiceException)
            {
                await _dialogService.ShowNotification("GenericError_Message", "GenericError_Title");
            }
            finally
            {
                IsBusy = false;
            }
        }

        /// <summary>
        /// Action to take when a photo has been selected
        /// </summary>
        /// <param name="category">The category.</param>
        private void OnCategorySelected(Category category)
        {
            _navigationFacade.NavigateToPhotoStream(category);
        }

        /// <summary>
        /// Action to take when a photo has been selected
        /// </summary>
        /// <param name="photo">The photo.</param>
        private void OnPhotoSelected(Photo photo)
        {
            _navigationFacade.NavigateToPhotoDetailsView(photo);
        }

        /// <summary>
        /// Action to take when a user has been selected.
        /// </summary>
        /// <param name="user">The user.</param>
        private void OnUserSelected(User user)
        {
            _navigationFacade.NavigateToProfileView(user);
        }
    }
}