/// <summary>
/// Initializes a new instance of the <see cref="ViewStackService"/> class.
/// </summary>
/// <param name="viewShell">The view shell (platform specific).</param>
/// <param name="pages">A list of pages to initialize the page stack with.</param>
public ViewStackService(IViewShell viewShell, IList <IPageViewModel> pages = null)
{
_viewShell = viewShell ?? throw new NullReferenceException("The viewShell can't be null.");
_currentPageStack = new BehaviorSubject <IImmutableList <IPageViewModel> >(ImmutableList <IPageViewModel> .Empty);
_modalPageStack = new BehaviorSubject <IImmutableList <IPageViewModel> >(ImmutableList <IPageViewModel> .Empty);
_nullPageStack = new BehaviorSubject <IImmutableList <IPageViewModel> >(null);
var immutablePages = pages != null?pages.ToImmutableList() : ImmutableList <IPageViewModel> .Empty;
_defaultNavigationStack = new BehaviorSubject <IImmutableList <IPageViewModel> >(immutablePages);
for (int i = 0; i < immutablePages.Count; ++i)
{
ViewShell.InsertPage(i, pages[i], null);
}
_modalPageStack
.Select(
x =>
{
if (x.Count > 0)
{
if (x[x.Count - 1] is INavigationPageViewModel navigationPage)
{
return(navigationPage.PageStack);
}
else
{
return(_nullPageStack);
}
}
else
{
return(_defaultNavigationStack);
}
})
.Subscribe(x => _currentPageStack = x);
_viewShell
.PagePopped
.Do(
_ =>
{
var removedPage = PopStackAndTick(_currentPageStack);
this.Log().Debug("Removed page '{0}' from stack.", removedPage.Title);
})
.Subscribe();
_viewShell
.ModalPopped
.Do(
_ =>
{
var removedPage = PopStackAndTick(_modalPageStack);
this.Log().Debug("Removed modal page '{0}' from stack.", removedPage.Title);
})
.Subscribe();
}
public ViewStackServiceTests()
{
_viewShell = Substitute.For <IViewShell>();
_page = Substitute.For <IPageViewModel>();
_pagePopped = new Subject <IPageViewModel>();
_modalPopped = new Subject <Unit>();
_viewShell.PagePopped.Returns(_pagePopped);
_viewShell.ModalPopped.Returns(_modalPopped);
_viewShell
.When(x => x.PopPage(Arg.Any <bool>()))
.Do(_ => _pagePopped.OnNext(_page));
_viewShell
.When(x => x.PopModal())
.Do(_ => _modalPopped.OnNext(Unit.Default));
}
