// Copyright (c) 2019 .NET Foundation and Contributors. All rights reserved.

// Licensed to the .NET Foundation under one or more agreements.

// The .NET Foundation licenses this file to you under the MIT license.

// See the LICENSE file in the project root for full license information.

using System;

using ReactiveUI;

using Xamarin.Forms;

namespace ReactiveUI.XamForms

{

/// <summary>

/// This is an <see cref="ContentPage"/> that is also an <see cref="IViewFor{T}"/>.

/// </summary>

/// <typeparam name="TViewModel">The type of the view model.</typeparam>

/// <seealso cref="Xamarin.Forms.ContentPage" />

/// <seealso cref="ReactiveUI.IViewFor{TViewModel}" />

public class ReactiveContentPage<TViewModel> : ContentPage, IViewFor<TViewModel>

where TViewModel : class

{

/// <summary>

/// The view model bindable property.

/// </summary>

public static readonly BindableProperty ViewModelProperty = BindableProperty.Create(

nameof(ViewModel),

typeof(TViewModel),

typeof(ReactiveContentPage<TViewModel>),

default(TViewModel),

BindingMode.OneWay,

propertyChanged: OnViewModelChanged);

/// <summary>

/// Gets or sets the ViewModel to display.

/// </summary>

public TViewModel ViewModel

{

get => (TViewModel)GetValue(ViewModelProperty);

set => SetValue(ViewModelProperty, value);

}

/// <inheritdoc/>

object IViewFor.ViewModel

{

get => ViewModel;

set => ViewModel = (TViewModel)value;

}

/// <inheritdoc/>

protected override void OnBindingContextChanged()

{

base.OnBindingContextChanged();

ViewModel = BindingContext as TViewModel;

}

private static void OnViewModelChanged(BindableObject bindableObject, object oldValue, object newValue)

{

bindableObject.BindingContext = newValue;

}

}

}