@implements IAsyncDisposable
@inject IJSRuntime JS

<dialog @ref="element" class="dialog-content app-modal" aria-labelledby="@titleId">
    <ToastHost InDialog="true" />
    <h2 id="@titleId" class="visually-hidden">@Title</h2>
    <div inert="@discardPrompt">@ChildContent</div>
    @if (discardPrompt)
    {
        <section role="alertdialog" aria-label="Ungespeicherte Eingaben">
            <h3>Ungespeicherte Eingaben</h3>
            <p>Die Änderungen wurden noch nicht gespeichert. Möchtest du weiter bearbeiten oder die Eingaben verwerfen?</p>
            <div class="dialog-actions">
                <button type="button" class="btn btn-primary" data-discard-continue @onclick="ContinueEditing">Weiter bearbeiten</button>
                <button type="button" class="btn btn-outline-danger" @onclick="Discard">Eingaben verwerfen</button>
            </div>
        </section>
    }
</dialog>

@code {
    [Parameter] public string Title { get; set; } = "Dialog";
    [Parameter] public RenderFragment? ChildContent { get; set; }
    [Parameter] public EventCallback OnCancel { get; set; }
    [Parameter] public bool Dirty { get; set; }
    [Parameter] public bool Busy { get; set; }
    private readonly string titleId = "dialog-" + Guid.NewGuid().ToString("N");
    private ElementReference element;
    private DotNetObjectReference<ModalDialog>? reference;
    private bool discardPrompt;
    private bool focusPrompt;
    private bool disposed;

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            reference = DotNetObjectReference.Create(this);
            await JS.InvokeVoidAsync("duempelkasDialog.open", element, reference);
        }
        if (focusPrompt)
        {
            focusPrompt = false;
            await JS.InvokeVoidAsync("duempelkasDialog.focus", element, discardPrompt ? "[data-discard-continue]" : "[data-initial-focus],input,select,textarea,button");
        }
    }

    [JSInvokable]
    public async Task RequestCloseAsync()
    {
        if (Busy || disposed) return;
        if (Dirty && !discardPrompt)
        {
            discardPrompt = true;
            focusPrompt = true;
            await InvokeAsync(StateHasChanged);
        }
        else if (discardPrompt)
        {
            await ContinueEditing();
            await InvokeAsync(StateHasChanged);
        }
        else await OnCancel.InvokeAsync();
    }

    private Task ContinueEditing()
    {
        discardPrompt = false;
        focusPrompt = true;
        return Task.CompletedTask;
    }
    private Task Discard() => OnCancel.InvokeAsync();
    public async ValueTask DisposeAsync()
    {
        disposed = true;
        try { await JS.InvokeVoidAsync("duempelkasDialog.close", element); }
        catch (Exception ex) when (ex is JSException or JSDisconnectedException or ObjectDisposedException or TaskCanceledException) { }
        reference?.Dispose();
    }
}