ModernWpfPlayground/Dialogs/DialogService.cs

using System;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;
using ModernWpf.Controls;
using Prism.Common;
using Prism.Ioc;
using Prism.Services.Dialogs;

namespace Dialogs
{
    /// <summary>
    /// Implements <see cref="IDialogService"/> to show modal and non-modal dialogs.
    /// </summary>
    /// <remarks>
    /// The dialog's ViewModel must implement IDialogAware.
    /// </remarks>
    public class DialogService : IDialogService
    {
        private readonly IContainerExtension _containerExtension;

        /// <summary>
        /// Initializes a new instance of the <see cref="DialogService"/> class.
        /// </summary>
        /// <param name="containerExtension"></param>
        public DialogService(IContainerExtension containerExtension)
        {
            _containerExtension = containerExtension;
        }

        /// <summary>
        /// Shows a non-modal dialog.
        /// </summary>
        /// <param name="name">The name of the dialog to show.</param>
        /// <param name="parameters">The parameters to pass to the dialog.</param>
        /// <param name="callback">The action to perform when the dialog is closed.</param>
        public void Show(string name, IDialogParameters parameters, Action<IDialogResult> callback)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// Shows a non-modal dialog.
        /// </summary>
        /// <param name="name">The name of the dialog to show.</param>
        /// <param name="parameters">The parameters to pass to the dialog.</param>
        /// <param name="callback">The action to perform when the dialog is closed.</param>
        /// <param name="windowName">The name of the hosting window registered with the IContainerRegistry.</param>
        public void Show(string name, IDialogParameters parameters, Action<IDialogResult> callback, string windowName)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// Shows a modal dialog.
        /// </summary>
        /// <param name="name">The name of the dialog to show.</param>
        /// <param name="parameters">The parameters to pass to the dialog.</param>
        /// <param name="callback">The action to perform when the dialog is closed.</param>
        public void ShowDialog(string name, IDialogParameters parameters, Action<IDialogResult> callback)
        {
            ShowDialogInternal(name, parameters, callback, null);
        }

        /// <summary>
        /// Shows a modal dialog.
        /// </summary>
        /// <param name="name">The name of the dialog to show.</param>
        /// <param name="parameters">The parameters to pass to the dialog.</param>
        /// <param name="callback">The action to perform when the dialog is closed.</param>
        /// <param name="windowName">The name of the hosting window registered with the IContainerRegistry.</param>
        public void ShowDialog(string name, IDialogParameters parameters, Action<IDialogResult> callback,
            string windowName)
        {
            ShowDialogInternal(name, parameters, callback, windowName);
        }

        void ShowDialogInternal(string name, IDialogParameters parameters, Action<IDialogResult> callback,
            string windowName)
        {
            var content = _containerExtension.Resolve<object>(name);
            if (!(content is ContentDialog contentDialog))
                throw new NullReferenceException("A dialog's content must be a content dialog");

            if (!(contentDialog.DataContext is IDialogAware viewModel))
                throw new NullReferenceException("A dialog's ViewModel must implement the IDialogAware interface");

            MvvmHelpers.ViewAndViewModelAction<IDialogAware>(viewModel, d => d.OnDialogOpened(parameters));
            Action<IDialogResult> closeHandler = default;

            closeHandler += e =>
            {
                viewModel.RequestClose -= closeHandler;
                callback?.Invoke(e);
            };
            viewModel.RequestClose += closeHandler;

            if (contentDialog.Owner == null)
                contentDialog.Owner = Application.Current?.Windows.OfType<Window>().FirstOrDefault(x => x.IsActive);
            contentDialog.ShowAsync().Await();
        }
    }
}