/// <summary>
/// Starts an asynchronous operation if one is not already in progress
/// </summary>
/// <param name="operation">The operation to start</param>
/// <exception cref="InvalidOperationException"> is returned if this method is called while
/// another asynchronous operation is still being processed.
/// </exception>
private void StartOperation(AuthenticationOperation operation)
{
Debug.Assert(operation != null, "The operation cannot be null.");
lock (this._syncLock)
{
if (this.IsBusy)
{
throw new InvalidOperationException(Resources.ApplicationServices_UserServiceIsBusy);
}
this.Operation = operation;
}
try
{
var task = operation.InvokeAsync(operation.CancellationToken);
// Continue on same SynchronizationContext
var scheduler = SynchronizationContext.Current != null?TaskScheduler.FromCurrentSynchronizationContext() : TaskScheduler.Default;
task.ContinueWith(StartOperationComplete, operation, CancellationToken.None, TaskContinuationOptions.HideScheduler, scheduler);
}
catch (Exception)
{
this.Operation = null;
throw;
}
this.RaisePropertyChanged(nameof(IsBusy));
this.RaisePropertyChanged(AuthenticationService.GetBusyPropertyName(operation));
}
/// <summary>
/// Marks an operation in error as handled.
/// </summary>
/// <param name="ao">The operation in error.</param>
private static void HandleOperationError(AuthenticationOperation ao)
{
if (ao.HasError)
{
ao.MarkErrorAsHandled();
}
}
/// <summary>
/// Returns the name of the "busy" property for the specified operation
/// </summary>
/// <param name="operation">The operation to get the property name for</param>
/// <returns>The name of the "busy" property for the operation</returns>
/// <seealso cref="IsLoggingIn"/>
/// <seealso cref="IsLoggingOut"/>
/// <seealso cref="IsLoadingUser"/>
/// <seealso cref="IsSavingUser"/>
private static string GetBusyPropertyName(AuthenticationOperation operation)
{
Debug.Assert(operation != null, "The operation cannot be null.");
Type operationType = operation.GetType();
if (typeof(LoginOperation) == operationType)
{
return("IsLoggingIn");
}
else if (typeof(LogoutOperation) == operationType)
{
return("IsLoggingOut");
}
else if (typeof(LoadUserOperation) == operationType)
{
return("IsLoadingUser");
}
else if (typeof(SaveUserOperation) == operationType)
{
return("IsSavingUser");
}
else
{
Debug.Assert(false, "operationType parameter is invalid.");
return(string.Empty);
}
}
/// <summary>
/// Starts an asynchronous operation if one is not already in progress
/// </summary>
/// <param name="operation">The operation to start</param>
/// <exception cref="InvalidOperationException"> is returned if this method is called while
/// another asynchronous operation is still being processed.
/// </exception>
private void StartOperation(AuthenticationOperation operation)
{
Debug.Assert(operation != null, "The operation cannot be null.");
lock (this._syncLock)
{
if (this.IsBusy)
{
throw new InvalidOperationException(Resources.ApplicationServices_UserServiceIsBusy);
}
this.Operation = operation;
}
try
{
operation.Start();
}
catch (Exception)
{
this.Operation = null;
throw;
}
this.RaisePropertyChanged("IsBusy");
this.RaisePropertyChanged(AuthenticationService.GetBusyPropertyName(this.Operation));
}
/// <summary>
/// Returns the name of the "busy" property for the specified operation
/// </summary>
/// <param name="operation">The operation to get the property name for</param>
/// <returns>The name of the "busy" property for the operation</returns>
/// <seealso cref="IsLoggingIn"/>
/// <seealso cref="IsLoggingOut"/>
/// <seealso cref="IsLoadingUser"/>
/// <seealso cref="IsSavingUser"/>
private static string GetBusyPropertyName(AuthenticationOperation operation)
{
Debug.Assert(operation != null, "The operation cannot be null.");
return(operation switch
{
LoginOperation _ => nameof(IsLoggingIn),
LogoutOperation _ => nameof(IsLoggingOut),
LoadUserOperation _ => nameof(IsLoadingUser),
SaveUserOperation _ => nameof(IsSavingUser),
_ => throw new NotImplementedException("unknown operation type"),
});
/// <summary>
/// This is run on the calling SynchronizationContext when an operation started
/// by <see cref="StartOperation"/> completes
/// </summary>
private void StartOperationComplete(Task <AuthenticationResult> res, object state)
{
var operation = (AuthenticationOperation)state;
AuthenticationResult endResult = null;
bool raiseUserChanged = false;
bool raiseLoggedIn = false;
bool raiseLoggedOut = false;
// Setting the operation to null indicates the service is no longer busy and
// can process another operation
this.Operation = null;
try
{
if (res.IsCanceled)
{
operation.SetCancelled();
return;
}
try
{
endResult = res.GetAwaiter().GetResult();
}
catch (Exception ex)
{
operation.SetError(ex);
if (ex.IsFatal())
{
throw;
}
return;
}
// If the operation completed successfully, update the user and
// determine which events should be raised
IPrincipal currentUser = this._user;
if (endResult?.User != null && currentUser != endResult.User)
{
raiseLoggedIn =
// anonymous -> authenticated
currentUser == null ||
(!currentUser.Identity.IsAuthenticated && endResult.User.Identity.IsAuthenticated)
// authenticated -> authenticated
|| (endResult.User.Identity.IsAuthenticated && currentUser.Identity.Name != endResult.User.Identity.Name);
raiseLoggedOut =
// authenticated -> anonymous
currentUser != null &&
currentUser.Identity.IsAuthenticated && !endResult.User.Identity.IsAuthenticated;
this._user = endResult.User;
raiseUserChanged = true;
}
operation.Complete(endResult);
}
finally
{
// Raise notification events as appropriate
if (raiseUserChanged)
{
this.RaisePropertyChanged(nameof(User));
}
this.RaisePropertyChanged(nameof(IsBusy));
this.RaisePropertyChanged(AuthenticationService.GetBusyPropertyName(operation));
if (raiseLoggedIn)
{
this.LoggedIn?.Invoke(this, new AuthenticationEventArgs(endResult.User));
}
if (raiseLoggedOut)
{
this.LoggedOut?.Invoke(this, new AuthenticationEventArgs(endResult.User));
}
}
}
/// <summary>
/// Wraps the specified action so the <see cref="AuthenticationService"/> can complete
/// processing of the operation before invoking the <paramref name="completeAction"/>.
/// </summary>
/// <typeparam name="T">The type of operation.</typeparam>
/// <param name="completeAction">The action to invoke once the service finishes
/// processing the operation. This parameter is optional.
/// </param>
/// <returns>An action that will complete processing of the operation before invoking
/// the wrapped action.
/// </returns>
private Action <T> WrapCompleteAction <T>(Action <T> completeAction) where T : AuthenticationOperation
{
return(new Action <T>(ao =>
{
bool raiseUserChanged = false;
bool raiseLoggedIn = false;
bool raiseLoggedOut = false;
// If the operation completed successfully, update the user and
// determine which events should be raised
if (!ao.IsCanceled && !ao.HasError && (ao.User != null))
{
if (this._user != ao.User)
{
raiseLoggedIn =
// anonymous -> authenticated
(this._user == null) ||
(!this._user.Identity.IsAuthenticated && ao.User.Identity.IsAuthenticated) ||
// authenticated -> authenticated
(ao.User.Identity.IsAuthenticated && (this._user.Identity.Name != ao.User.Identity.Name));
raiseLoggedOut =
// authenticated -> anonymous
(this._user != null) &&
(this._user.Identity.IsAuthenticated && !ao.User.Identity.IsAuthenticated);
this._user = ao.User;
raiseUserChanged = true;
}
}
// Setting the operation to null indicates the service is no longer busy and
// can process another operation
this.Operation = null;
// Invoke the wrapped action
if (completeAction != null)
{
try
{
completeAction.DynamicInvoke(ao);
}
catch (TargetInvocationException tie)
{
if (tie.InnerException != null)
{
throw tie.InnerException;
}
throw;
}
}
// Raise notification events as appropriate
if (raiseUserChanged)
{
this.RaisePropertyChanged("User");
}
this.RaisePropertyChanged("IsBusy");
this.RaisePropertyChanged(AuthenticationService.GetBusyPropertyName(ao));
if (raiseLoggedIn)
{
this.OnLoggedIn(new AuthenticationEventArgs(ao.User));
}
if (raiseLoggedOut)
{
this.OnLoggedOut(new AuthenticationEventArgs(ao.User));
}
}));
}
