A Pluggable Architecture for Building Silverlight Applications with MVVM

using System;
using System.Windows;
using System.Windows.Controls;
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Messaging;
using IssueVision.Common;
using MVVMPlugin;

namespace IssueVision.Client
{
    public partial class MainPage : UserControl
    {
        #region "Private Data"
        private bool _noErrorMessage = true;
        private PluginCatalogService _catalogService = PluginCatalogService.Instance;
        #endregion "Private Data"

        #region "Constructor"
        public MainPage()
        {
            InitializeComponent();

            // register for ChangeScreenMessage
            AppMessages.ChangeScreenMessage.Register(this, OnChangeScreenMessage);
            // register for ChangeScreenNoAnimationMessage
            AppMessages.ChangeScreenNoAnimationMessage.Register(this, OnChangeScreenNoAnimationMessage);
            // register for RaiseErrorMessage
            AppMessages.RaiseErrorMessage.Register(this, OnRaiseErrorMessage);
            // register for PleaseConfirmMessage
            AppMessages.PleaseConfirmMessage.Register(this, OnPleaseConfirmMessage);
            // register for StatusUpdateMessage
            AppMessages.StatusUpdateMessage.Register(this, OnStatusUpdateMessage);

            if (!ViewModelBase.IsInDesignModeStatic)
            {
                // set DataContext
                DataContext = _catalogService.FindPlugin(
                    ViewModelTypes.MainPageViewModel, PluginType.ViewModel);
            }
        }
        #endregion "Constructor"

        #region "ChangeScreenMessage"

        private void OnChangeScreenMessage(string changeScreen)
        {
            object currentScreen;
            // call Cleanup() on the current screen before switching
            var cleanUp = mainPageContent.Content as ICleanup;
            if (cleanUp != null)
                cleanUp.Cleanup();

            // reset noErrorMessage
            _noErrorMessage = true;

            switch (changeScreen)
            {
                case ViewTypes.HomeView:
                    currentScreen = new Home();
                    break;
                case ViewTypes.NewIssueView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.NewIssueView, PluginType.View);
                    break;
                case ViewTypes.AllIssuesView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.AllIssuesView, PluginType.View);
                    break;
                case ViewTypes.MyIssuesView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.MyIssuesView, PluginType.View);
                    break;
                case ViewTypes.BugReportView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.BugReportView, PluginType.View);
                    break;
                case ViewTypes.MyProfileView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.MyProfileView, PluginType.View);
                    break;
                case ViewTypes.UserMaintenanceView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.UserMaintenanceView, PluginType.View);
                    break;
                case ViewTypes.AuditIssueView:
                    currentScreen = _catalogService.FindPlugin(
                        ViewTypes.AuditIssueView, PluginType.View);
                    break;
                default:
                    throw new NotImplementedException();
            }
            // change main page content with animation
            currentScreen = mainPageContent.ChangeMainPageContent(currentScreen, true);
            // call ReleasePlugin on replaced screen
            _catalogService.ReleasePlugin(currentScreen);
        }

        #endregion "ChangeScreenMessage"

        #region "ChangeScreenNoAnimationMessage"

        private void OnChangeScreenNoAnimationMessage(string changeScreen)
        {
            object currentScreen;
            // call Cleanup() on the current screen before switching
            var cleanUp = mainPageContent.Content as ICleanup;
            if (cleanUp != null)
                cleanUp.Cleanup();

            // reset noErrorMessage
            _noErrorMessage = true;

            switch (changeScreen)
            {
                case ViewTypes.HomeView:
                    currentScreen = new Home();
                    break;
                case ViewTypes.MyProfileView:
                    currentScreen = _catalogService.FindPlugin(ViewTypes.MyProfileView);
                    break;
                default:
                    throw new NotImplementedException();
            }
            // change main page content without animation
            currentScreen = mainPageContent.ChangeMainPageContent(currentScreen, false);
            // call ReleasePlugin on replaced screen
            _catalogService.ReleasePlugin(currentScreen);
        }

        #endregion "ChangeScreenNoAnimationMessage"

        #region "RaiseErrorMessage"

        private void OnRaiseErrorMessage(Exception ex)
        {
            if (_noErrorMessage && ex != null)
            {
                ErrorWindow.CreateNew(ex);
                // logout after display the error message
                hyperlinkButton_Logout.Command.Execute(true);
                _noErrorMessage = false;
            }
        }

        #endregion "RaiseErrorMessage"

        #region "PleaseConfirmMessage"

        private static void OnPleaseConfirmMessage(DialogMessage dialogMessage)
        {
            if (dialogMessage != null)
            {
                MessageBoxResult result = MessageBox.Show(dialogMessage.Content,
                    dialogMessage.Caption, dialogMessage.Button);

                dialogMessage.ProcessCallback(result);
            }
        }

        #endregion "PleaseConfirmMessage"

        #region "StatusUpdateMessage"

        private static void OnStatusUpdateMessage(DialogMessage dialogMessage)
        {
            if (dialogMessage != null)
            {
                MessageBoxResult result = MessageBox.Show(dialogMessage.Content,
                    dialogMessage.Caption, dialogMessage.Button);

                dialogMessage.ProcessCallback(result);
            }
        }

        #endregion "StatusUpdateMessage"
    }
}