Iceshrimp.NET/Iceshrimp.Frontend/Pages/SingleNote.razor

@page "/notes/{NoteId}"
@using Iceshrimp.Frontend.Components
@using Iceshrimp.Frontend.Components.Note
@using Iceshrimp.Frontend.Core.Services
@using Iceshrimp.Frontend.Core.Services.StateServicePatterns
@using Iceshrimp.Shared.Schemas.Web
@inject ApiService        ApiService
@inject IJSRuntime        Js
@inject MessageService    MessageService
@inject StateService      State
@inject NavigationManager Navigation
@implements IDisposable

@if (_init)
{
    <div @ref="Scroller" class="scroller">
        <div class="wrapper">
            <div class="container">
                @if (Ascendants != null)
                {
                    <div class="ascendants">
                        @foreach (var note in Ascendants)
                        {
                            <AscendedNote Note="note"/>
                        }
                    </div>
                }
                <div @ref="RootNoteRef" class="root-note">
                    <Note NoteResponse="RootNote"></Note>
                </div>
                @if (Descendants != null)
                {
                    <div class="descendants">
                        @foreach (var element in Descendants)
                        {
                            <RecursiveNote Note="element" Depth="0" MaxDepth="_depth"/>
                        }
                    </div>
                }
            </div>
        </div>
    </div>
}
else
{
    <div>Loading</div>
}
@if (_error)
{
    <div>This note does not exist!</div>
}

@code {
    [Parameter] public string?                     NoteId      { get; set; }
    public             NoteResponse?               RootNote    { get; set; }
    private            IList<NoteResponse>?        Descendants { get; set; }
    private            IList<NoteResponse>?        Ascendants  { get; set; }
    private            IJSInProcessObjectReference Module      { get; set; } = null!;
    private            ElementReference            RootNoteRef { get; set; }
    private            bool                        _init;
    private            bool                        _error;
    private            int                         _depth = 20;
    private            ElementReference            Scroller { get; set; }
    private            IDisposable?                _locationChangingHandlerDisposable;

    protected override async Task OnParametersSetAsync()
    {
        _init = false;
        if (NoteId == null)
        {
            _error = true;
            return;
        }

        RootNote = await ApiService.Notes.GetNote(NoteId);
        if (RootNote == null)
        {
            _error = true;
            return;
        }

        Descendants = await ApiService.Notes.GetNoteDescendants(NoteId, _depth);
        Ascendants  = await ApiService.Notes.GetNoteAscendants(NoteId, default);
        _init       = true;

        StateHasChanged();
    }

    protected override void OnInitialized()
    {
        if (NoteId != null) MessageService.Register(NoteId, OnNoteChanged);
        _locationChangingHandlerDisposable = Navigation.RegisterLocationChangingHandler(LocationChangeHandler);
    }

    private void OnNoteChanged(object? _, NoteResponse note)
    {
        var __ = Refresh();
    }

    private async Task Refresh()
    {
        if (NoteId == null) throw new InvalidOperationException("RefreshNote called under impossible circumstances");
        Descendants = await ApiService.Notes.GetNoteDescendants(NoteId, default);
        Ascendants  = await ApiService.Notes.GetNoteAscendants(NoteId, default);
        StateHasChanged();
    }

    private ValueTask LocationChangeHandler(LocationChangingContext arg)
    {
        SaveState();
        return ValueTask.CompletedTask;
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            Module = (IJSInProcessObjectReference)await Js.InvokeAsync<IJSObjectReference>("import", "/Pages/SingleNote.razor.js");
        }

        if (_init)
        {
            var state = State.SingleNote.GetState(NoteId!);
            if (state != null)
            {
                Module.InvokeVoid("SetScrollTop", Scroller, state.ScrollTop);
            }
            else
            {
                Module.InvokeVoid("ScrollIntoView", RootNoteRef);
            }
        }
    }

    private void SaveState()
    {
        if (NoteId == null) return;
        var scrollTop = Module.Invoke<float>("GetScrollTop", Scroller);
        var state     = new SingleNoteState { ScrollTop = scrollTop };
        State.SingleNote.SetState(NoteId, state);
    }

    public void Dispose()
    {
        if (NoteId != null) MessageService.Unregister(NoteId, OnNoteChanged);
        SaveState();
        _locationChangingHandlerDisposable?.Dispose();
    }
}