How to use different behaviours in the same ViewModel? - wpf

Question

I have the view designed for the long running tasks. It has a header and a progress bar.
So the model has the text for a header and a counter for a progress bar and a TotalAmountOfWork field. The model also has
public delegate void TaskCompleted(string resultDescription);
public event TaskCompletedCopyingCompletedEvent;
public event Action UpdateViewState;
When counters change the model invokes UpdateViewState.
ViewModel is subscribed for the events and updates in it's turn the view.
Ok. I have two classes intended to copy files from a hard disk to a flash drive and one class intended for diagnostic information retrieving and this information should be copied to a flash drive finally too.
I want to use them in the same ViewModel, but I can't figure out how to avoid code repeating. I can't figure out how to make it relying on the proper object oriented design.
Those three classes could implement an interface like this:
interface ILongRunningTask {
void DoWork();
}
And then I can implement ViewModel taking ILongRunningTask as an argument.
But look at the name of the name of the interface. It looks too generalized. It seems that something wrong with such an abstraction.
Ok. It seems to me that ViewModel should take a delegate in order to invoke a long running task. But in this case how the ViewModel will interact with the model updating it's properties?
//update
Now, model looks like:
public class FilesCopyingModel : IFilesCopier {
protected int filesCountToCopy;
public int FilesCountToCopy {
get { return filesCountToCopy; }
set {
filesCountToCopy = value;
InvokeUpdateViewState();
}
}
protected int currentProgressValue;
public int CurrentProgressValue {
get { return currentProgressValue; }
set {
currentProgressValue = value;
InvokeUpdateViewState();
}
}
public delegate void CopyingCompleted(string resultDescription);
public event CopyingCompleted CopyingCompletedEvent;
public event Action UpdateViewState;
private readonly IFilesCopier filesCopier;
protected FilesCopyingModel() {
}
public FilesCopyingModel(IFilesCopier filesCopier) {
if (filesCopier == null)
throw new ArgumentNullException("filesCopier");
this.filesCopier = filesCopier;
}
protected static string GetCurrentDateTime() {
return DateTime.Now.ToString("dd.MM.yyyy hh.mm.ss");
}
protected void InvokeCopyCompletedEvent(string resultDescription) {
if (CopyingCompletedEvent != null)
CopyingCompletedEvent(resultDescription);
}
protected void InvokeUpdateViewState() {
if (UpdateViewState != null)
UpdateViewState();
}
protected DriveInfo GetFirstReadyRemovableDrive() {
return
DriveInfo.GetDrives()
.FirstOrDefault(driveInfo => driveInfo.DriveType == DriveType.Removable && driveInfo.IsReady);
}
public void Copy() {
filesCopier.Copy();
}
}
public interface IFilesCopier {
void Copy();
}
public class KFilesCopier : FilesCopyingModel, IFilesCopier {
private string destinationKFilesDirPath;
public new void Copy() {
//some code
}
private static string ComposeDestinationKFilesDirPath(DriveInfo drive) {
//some code
}
}
public class LogsDirCopier : FilesCopyingModel, IFilesCopier {
public readonly string LogsDirPath;
public LogsDirCopier() {
//some code
}
public new void Copy() {
//some code
}
private void InternalCopyLogsDir(string destinationPath) {
//some code
}
private static void CloseStorer(ZipStorer zipStorer) {
//some code
}
private static string ComposeDestinationArchiveFilePath(string destinationPath) {
//some code
}
private void DetermineLogFilesCount() {
//some code
}
ViewModel interact with infrastructure above like this:
public class FilesCopyingViewModel: Screen {
private readonly FilesCopyingModel model;
private readonly IWindowManager windowManager;
public int CurrentProgress {
get { return model.CurrentProgressValue; }
}
public int FilesCountToCopy {
get { return model.FilesCountToCopy; }
}
[ImportingConstructor]
public LongRunningViewModel(IFilesCopier copier) {
model = copier as FilesCopyingModel;
model.CopyingCompletedEvent += CopyingCompletedHandler;
model.UpdateViewState += UpdateViewStateHandler;
windowManager = new WindowManager();
}
private void UpdateViewStateHandler() {
NotifyOfPropertyChange(() => CurrentProgress);
NotifyOfPropertyChange(() => FilesCountToCopy);
}
private void CopyingCompletedHandler(string resultDescription) {
//some code
}
private void RemoveDriveSafely() {
//some code
}
private void PromptEjection(string result) {
//some code
}
private void PromptSuccessEjection() {
//some code
}
private void PromptEjectFlashError() {
//some code
}
protected override void OnActivate() {
try {
var copier = (IFilesCopier) model;
Task.Factory.StartNew(copier.Copy);
}
catch (Exception ex) {
//error handling
}
}
}
These two classes use "Copy" as the name of the method. Now I want to add one more class with very similar behavior, but it seems that it's method should be named like "CollectDiagnosticInfo". Or maybe I can add a class DiagnosticInfoCopier:IFilesCopier and then just do the same. I really don't know, but the sixth sense suggests that there is a smell of some kind.