namespace Htmx.ApiDemo.Templates.Components;

/// <summary>
/// shadcn-style Accordion. Items collapse/expand client-side via components.js.
/// Pass a list of (Title, Content) tuples; set openIndex to expand one by default (-1 = all closed).
/// </summary>
public sealed class Accordion : AccordionBase
{
    private const string ChevronSvg =
        """<svg class="accordion-chevron h-4 w-4 shrink-0 transition-transform duration-200" """ +
        """xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" """ +
        """stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="m6 9 6 6 6-6"/></svg>""";

    private readonly byte[] _idData;
    private readonly byte[] _itemsData;

    public Accordion(string id, IEnumerable<(string Title, string Content)> items, int openIndex = -1)
    {
        _idData = id.ToUtf8Bytes();

        var list = items.ToList();
        var sb   = new System.Text.StringBuilder();

        for (int i = 0; i < list.Count; i++)
        {
            var (title, content) = list[i];
            var expanded = i == openIndex;
            var height   = expanded ? "auto" : "0";
            var opacity  = expanded ? "1" : "0";

            sb.Append($"""
                <div class="accordion-item border-b border-border">
                  <h3 class="flex">
                    <button type="button"
                            class="accordion-trigger flex flex-1 items-center justify-between py-4 font-medium
                                   transition-all hover:underline text-left"
                            aria-expanded="{(expanded ? "true" : "false")}">
                      {title}
                      {ChevronSvg}
                    </button>
                  </h3>
                  <div class="accordion-panel overflow-hidden text-sm transition-all duration-200"
                       style="height:{height};opacity:{opacity}">
                    <div class="pb-4 pt-0">{content}</div>
                  </div>
                </div>
                """);
        }

        _itemsData = sb.ToString().ToUtf8Bytes();
    }

    protected override void RenderId(HtmxRenderContext ctx)    => ctx.Writer.WriteUtf8(_idData);
    protected override void RenderItems(HtmxRenderContext ctx) => ctx.Writer.WriteUtf8(_itemsData);
}