@inject BrowserDatabase Database
@implements IAsyncDisposable

@ChildContent

@code {
    [Parameter]
    public RenderFragment? ChildContent { get; set; }

    [Parameter]
    public EventCallback OnReady { get; set; }

    [Parameter]
    public EventCallback OnTearDown { get; set; }

    protected override async Task OnInitializedAsync()
    {
        // Every page is prerendered on the server first, where there is no browser to open a database in.
        // The page renders its static content there; the database opens once it runs in the browser.
        if (RendererInfo.IsInteractive is false)
        {
            return;
        }

        Database.BeforeSessionReset += TearDownAsync;
        Database.AfterSessionReset += ReadyAsync;

        // Opening raises AfterSessionReset, which runs ReadyAsync once for every subscriber; only
        // an already-open database needs the explicit call.
        if (Database.Database.IsOpen)
        {
            await ReadyAsync();
        }
        else
        {
            await Database.EnsureSessionAsync();
        }
    }

    private async Task TearDownAsync()
    {
        if (OnTearDown.HasDelegate)
        {
            await OnTearDown.InvokeAsync();
        }
    }

    private async Task ReadyAsync()
    {
        if (OnReady.HasDelegate)
        {
            await OnReady.InvokeAsync();
        }
    }

    public async ValueTask DisposeAsync()
    {
        Database.BeforeSessionReset -= TearDownAsync;
        Database.AfterSessionReset -= ReadyAsync;
        await TearDownAsync();
    }
}