/// <summary>
/// Processes a <see cref="StackNavigatorRequest"/> based on its <see cref="StackNavigatorRequestType"/>.
/// </summary>
/// <param name="stackNavigator">The stack navigator.</param>
/// <param name="ct">The cancellation token.</param>
/// <param name="request">The request to process.</param>
public static Task ProcessRequest(this IStackNavigator stackNavigator, CancellationToken ct, StackNavigatorRequest request)
{
switch (request.RequestType)
{
case StackNavigatorRequestType.NavigateForward:
return(stackNavigator.Navigate(ct, request));
case StackNavigatorRequestType.NavigateBack:
return(stackNavigator.NavigateBack(ct));
case StackNavigatorRequestType.Clear:
return(stackNavigator.Clear(ct));
case StackNavigatorRequestType.RemoveEntry:
return(stackNavigator.RemoveEntries(ct, request.EntryIndexesToRemove));
default:
throw new NotSupportedException($"The request type '{request.RequestType}' is not supported.");
}
}
/// <summary>
/// Tries to navigate back to the ViewModel matching <typeparamref name="TPageViewModel"/>.
/// </summary>
/// <remarks>
/// If no previous entry matches <typeparamref name="TPageViewModel"/>, nothing happens.
/// </remarks>
/// <typeparam name="TPageViewModel">The ViewModel type.</typeparam>
/// <param name="navigator">The stack navigator.</param>
/// <param name="ct">The cancellation token.</param>
/// <returns>True if the navigate back happened. False otherwise.</returns>
public static async Task <bool> TryNavigateBackTo <TPageViewModel>(this IStackNavigator navigator, CancellationToken ct)
{
var logger = typeof(StackNavigatorExtensions).Log();
// Retrieve the current stack and its size
var stack = navigator.State.Stack;
var count = stack.Count;
// Retrieve the instance of the target ViewModel
var targetEntry = stack.FirstOrDefault(entry => entry.ViewModel.GetType() == typeof(TPageViewModel));
if (targetEntry != null)
{
// Retrieve the index of the target viewModel
var startIndex = stack.ToList().IndexOf(targetEntry);
// Count how many items we should delete between the target viewModel and the current page viewmodel
var itemsToDelete = count - 1 - startIndex - 1;
if (itemsToDelete > 0)
{
var indexesToRemove = Enumerable.Range(startIndex + 1, itemsToDelete);
await navigator.RemoveEntries(ct, indexesToRemove);
}
// Navigate back to the target view model
await navigator.NavigateBack(ct);
return(true);
}
else
{
if (logger.IsEnabled(LogLevel.Warning))
{
logger.LogWarning($"Can't navigate back to '{typeof(TPageViewModel).Name}' because it's not in the navigation stack.");
}
return(false);
}
}
/// <inheritdoc/>
public Task <INavigableViewModel> NavigateBack(CancellationToken ct)
{
return(_inner.NavigateBack(ct));
}