@inherits DComponentBase
@inject NavigationManager NavigationManager

@* daisyUI Carousel: https://daisyui.com/components/carousel/ . A scroll-snap strip of DCarouselItem children; the
   user scrolls or swipes it. Give each item w-full for one slide at a time. ShowNavigation (previous/next on every
   slide) and ShowIndicators (numbered buttons under the strip) are links to the slides' ids, as in daisyUI's examples:
   they keep the current path, so Blazor treats them as same-page fragments and scrolls the slide into view. *@
<CascadingValue Value="this" IsFixed="true">
	@if (ShowIndicators)
	{
		<div class="flex flex-col gap-2">
			@Strip
			<div class="flex w-full justify-center gap-2">
				@for (var i = 0; i < items.Count; i++)
				{
					<a href="@Link(i)" class="btn btn-xs" aria-label="@($"{SlideText} {i + 1}")">@(i + 1)</a>
				}
			</div>
		</div>
	}
	else
	{
		@Strip
	}
</CascadingValue>

@code {
	[Parameter] public RenderFragment ChildContent { get; set; }
	[Parameter] public DCarouselSnap Snap { get; set; }
	[Parameter] public DDirection Direction { get; set; }
	/// <summary>Previous/next buttons on every slide.</summary>
	[Parameter] public bool ShowNavigation { get; set; }
	/// <summary>A row of numbered buttons under the strip, one per slide.</summary>
	[Parameter] public bool ShowIndicators { get; set; }
	[Parameter] public string PreviousText { get; set; } = "Previous slide";
	[Parameter] public string NextText { get; set; } = "Next slide";
	[Parameter] public string SlideText { get; set; } = "Slide";

	readonly List<DCarouselItem> items = new();
	readonly string uid = "d" + Guid.NewGuid().ToString("N")[..8];

	RenderFragment Strip => @<div @attributes="AdditionalAttributes" class="@CssClass">@ChildContent</div>;

	string CssClass => Cx("carousel", SnapClass, Direction == DDirection.Vertical ? "carousel-vertical" : null, Class);

	string SnapClass => Snap switch
	{
		DCarouselSnap.Center => "carousel-center",
		DCarouselSnap.End => "carousel-end",
		_ => null
	};

	internal int Count => items.Count;

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

	internal string SlideId(int index) => $"{uid}-{index + 1}";

	/// <summary>The current page plus the slide's fragment; the index wraps around.</summary>
	internal string Link(int index)
	{
		var path = NavigationManager.ToBaseRelativePath(NavigationManager.Uri);
		var hash = path.IndexOf('#');
		if (hash >= 0)
			path = path[..hash];
		return $"{path}#{SlideId((index % items.Count + items.Count) % items.Count)}";
	}

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

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