Nexus.Reader/src/NexusReader.UI.Shared/Pages/Home.razor

@page "/reader"
@page "/reader/{BookId:guid}"
@layout ReaderLayout
@attribute [Authorize]
@using NexusReader.UI.Shared.Services
@implements IAsyncDisposable
@inject IQuizStateService QuizState
@inject IFocusModeService FocusMode
@inject IJSRuntime JS
@inject NavigationManager NavManager
@inject IReaderNavigationService NavService
@inject IIdentityService IdentityService
<PageTitle>Nexus E-Reader</PageTitle>

<div class="home-reader-container">
    <ReaderCanvas @ref="readerCanvas" />
</div>


@code {
    [Parameter] public Guid? BookId { get; set; }

    private ReaderCanvas? readerCanvas;
    private string? _activeQuizBlockId;
    
    private IJSObjectReference? _interopModule;
    private IJSObjectReference? _keydownHandler;
    private DotNetObjectReference<Home>? _dotNetRef;

    protected override void OnInitialized()
    {
        QuizState.OnQuizRequested += HandleQuizRequestedAsync;
        FocusMode.OnFocusModeChanged += HandleUpdate;
    }

    protected override async Task OnParametersSetAsync()
    {
        var uri = NavManager.ToAbsoluteUri(NavManager.Uri);
        int chapterIndex = 0;
        if (Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(uri.Query).TryGetValue("chapter", out var chapterValue))
        {
            int.TryParse(chapterValue, out chapterIndex);
        }

        if (BookId.HasValue && BookId.Value != Guid.Empty)
        {
            if (NavService.CurrentEbookId != BookId.Value || NavService.CurrentChapterIndex != chapterIndex)
            {
                NavService.SetBook(BookId.Value, chapterIndex);
            }
        }
        else if (NavService.CurrentEbookId == Guid.Empty)
        {
            // If no BookId in URL and no book currently selected, try to load last read book
            var profileResult = await IdentityService.GetProfileAsync();
            if (profileResult.IsSuccess && profileResult.Value.LastReadBook != null)
            {
                NavService.SetBook(profileResult.Value.LastReadBook.Id, chapterIndex > 0 ? chapterIndex : profileResult.Value.LastReadBook.LastChapterIndex);
            }
        }
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            await FocusMode.InitializeAsync();
            try {
                _interopModule = await JS.InvokeAsync<IJSObjectReference>("import", "./_content/NexusReader.UI.Shared/js/focusInterop.js");
                _dotNetRef = DotNetObjectReference.Create(this);
                _keydownHandler = await _interopModule.InvokeAsync<IJSObjectReference>("attachKeyboardListener", _dotNetRef);
            } catch { } /* ignored dynamically */
            StateHasChanged();
        }
    }

    [JSInvokable]
    public async Task OnFocusKeypressed()
    {
        await FocusMode.ToggleAsync();
        StateHasChanged();
    }

    private async Task HandleNodeSelected(string nodeId)
    {
        if (readerCanvas != null)
        {
            await readerCanvas.ScrollToNodeAsync(nodeId);
        }
    }

    private async Task HandleQuizRequestedAsync(string blockId)
    {
        _activeQuizBlockId = blockId;
        await InvokeAsync(StateHasChanged);
    }

    private Task HandleUpdate() => InvokeAsync(StateHasChanged);

    public async ValueTask DisposeAsync()
    {
        QuizState.OnQuizRequested -= HandleQuizRequestedAsync;
        FocusMode.OnFocusModeChanged -= HandleUpdate;
        
        if (_interopModule != null && _keydownHandler != null)
        {
            try {
                await _interopModule.InvokeVoidAsync("detachKeyboardListener", _keydownHandler);
                await _interopModule.DisposeAsync();
                await _keydownHandler.DisposeAsync();
            } catch { } // Circuit disconnected catch explicitly
        }
        
        _dotNetRef?.Dispose();
    }
}