@inherits DComponentBase

@* daisyUI Accordion: https://daisyui.com/components/accordion/ . Instead of daisyUI's radio group, the open item is an
   index in C# (@bind-Active, -1 = none). Each DAccordionItem registers itself through the cascading value and renders a
   DCollapse that is open only while its index is Active. The cascading value isn't fixed, so every item re-renders
   whenever the accordion does. *@
<div @attributes="AdditionalAttributes" class="@CssClass">
	<CascadingValue Value="this">
		@ChildContent
	</CascadingValue>
</div>

@code {
	[Parameter] public RenderFragment ChildContent { get; set; }
	/// <summary>Index of the open item, in registration order; -1 when all are closed.</summary>
	[Parameter] public int Active { get; set; } = -1;
	[Parameter] public EventCallback<int> ActiveChanged { get; set; }
	[Parameter] public DCollapseIcon Icon { get; set; }
	/// <summary>Join the items into one block (join join-vertical, join-item).</summary>
	[Parameter] public bool Joined { get; set; }

	readonly List<DAccordionItem> items = new();

	string CssClass => Cx(Joined ? "join join-vertical rounded-box neo-raised" : "flex flex-col gap-2", Class);

	internal int IndexOf(DAccordionItem item) => items.IndexOf(item);

	internal void Add(DAccordionItem item)
	{
		items.Add(item);
		StateHasChanged();
	}

	internal void Remove(DAccordionItem item)
	{
		items.Remove(item);
		StateHasChanged();
	}

	internal async Task Select(int index)
	{
		Active = index;
		await ActiveChanged.InvokeAsync(index);
		StateHasChanged();
	}
}