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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using Tango.Core;
using Tango.SharedUI.Controls;
namespace Tango.FSE.Common.Navigation
{
public abstract class ModularNavigationManager<T> : ExtendedObject, IModularNavigationNavigationManager<T>
{
private FrameworkElement _navigationControlParent;
private NavigationControl _navigationControl;
private Stack<T> _history;
private T _currentView;
public T CurrentView
{
get { return _currentView; }
protected set { _currentView = value; RaisePropertyChangedAuto(); }
}
public bool CanNavigateBack
{
get { return _history.Count > 0; }
}
public ModularNavigationManager(FrameworkElement navigationControlParent)
{
_history = new Stack<T>();
_navigationControlParent = navigationControlParent;
_navigationControlParent.RegisterForLoadedOrNow((_, __) =>
{
_navigationControl = _navigationControlParent.FindChildOffline<NavigationControl>();
});
}
public Task NavigateTo(T view, bool pushToHistory = true)
{
return NavigateToInternal<Object>(view, null, pushToHistory);
}
public Task NavigateTo<TPass>(T view, TPass objectToPass, bool pushToHistory = true)
{
return NavigateToInternal<TPass>(view, objectToPass, pushToHistory);
}
private Task NavigateToInternal<TPass>(T view, TPass objectToPass, bool pushToHistory)
{
LogManager.Log($"Navigating to {view}...");
TaskCompletionSource<object> completion = new TaskCompletionSource<object>();
var fromVM = _navigationControl.SelectedElement.DataContext as FSEViewModel;
var toVM = _navigationControl.GetElement(view.ToString()).DataContext as FSEViewModel;
if (fromVM != toVM)
{
fromVM.OnBeforeNavigatedFrom();
toVM.OnBeforeNavigatedTo();
if (toVM is INavigationObjectReceiver<TPass> && objectToPass != null)
{
(toVM as INavigationObjectReceiver<TPass>).OnNavigatedToWithObject(objectToPass);
}
_navigationControl.NavigateTo(view.ToString(), () =>
{
if (pushToHistory)
{
_history.Push(CurrentView);
DistinctHistory();
RaisePropertyChanged(nameof(CanNavigateBack));
}
CurrentView = view;
fromVM.OnNavigatedFrom();
toVM.OnNavigatedTo();
completion.SetResult(true);
});
}
else
{
completion.SetResult(true);
}
return completion.Task;
}
public async Task<bool> NavigateBack()
{
if (CanNavigateBack)
{
var toView = _history.Peek();
var fromVM = _navigationControl.GetElement(CurrentView.ToString()).DataContext as FSEViewModel;
if (fromVM is INavigationBlocker)
{
if (!await (fromVM as INavigationBlocker).OnNavigateBackRequest())
{
return false;
}
}
_history.Pop();
RaisePropertyChanged(nameof(CanNavigateBack));
await NavigateTo(toView, false);
return true;
}
else
{
return false;
}
}
private void DistinctHistory()
{
var list = _history.Distinct().ToList();
list.Reverse();
_history.Clear();
foreach (var item in list)
{
_history.Push(item);
}
RaisePropertyChanged(nameof(CanNavigateBack));
}
public async Task<FSEViewModel> GetCurrentViewModel()
{
if (_navigationControl == null)
{
await Task.Factory.StartNew(() =>
{
while (_navigationControl == null)
{
Thread.Sleep(10);
}
});
}
return _navigationControl.GetElement(CurrentView.ToString()).DataContext as FSEViewModel;
}
public async void RaiseOnBeforeNavigatedToFirst()
{
var currentVM = await GetCurrentViewModel();
if (currentVM != null && _navigationControl.Elements.Count > 0 && currentVM == _navigationControl.Elements.First().DataContext)
{
currentVM.OnBeforeNavigatedTo();
}
}
public async void RaiseOnNavigatedToFirst()
{
var currentVM = await GetCurrentViewModel();
if (currentVM != null && _navigationControl.Elements.Count > 0 && currentVM == _navigationControl.Elements.First().DataContext)
{
currentVM.OnNavigatedTo();
}
}
}
}
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