Stylet/Samples/Stylet.Samples.NavigationController/NavigationController.cs

using Stylet.Samples.NavigationController.Pages;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Stylet.Samples.NavigationController
{
    public interface INavigationController
    {
        void NavigateToPage1();
        void NavigateToPage2(string initiator);
    }

    public interface INavigationControllerDelegate
    {
        void NavigateTo(IScreen screen);
    }

    public class NavigationController : INavigationController
    {
        private readonly Func<Page1ViewModel> page1ViewModelFactory;
        private readonly Func<Page2ViewModel> page2ViewModelFactory;

        public INavigationControllerDelegate Delegate { get; set; }

        public NavigationController(Func<Page1ViewModel> page1ViewModelFactory, Func<Page2ViewModel> page2ViewModelFactory)
        {
            this.page1ViewModelFactory = page1ViewModelFactory ?? throw new ArgumentNullException(nameof(page1ViewModelFactory));
            this.page2ViewModelFactory = page2ViewModelFactory ?? throw new ArgumentNullException(nameof(page2ViewModelFactory));
        }

        public void NavigateToPage1()
        {
            this.Delegate?.NavigateTo(this.page1ViewModelFactory());
        }

        public void NavigateToPage2(string initiator)
        {
            var vm = this.page2ViewModelFactory();
            vm.Initiator = initiator;
            this.Delegate?.NavigateTo(vm);
        }
    }
}