"use client";

import Link from "next/link";
import { useEffect, useId, useRef, useState, type KeyboardEvent } from "react";

export interface ActionsMenuItem {
  key: string;
  label: string;
  /** Entweder Link (Abo verwalten, Download) oder Aktion (Dialog oeffnen). */
  href?: string;
  download?: boolean;
  onSelect?: () => void;
}

/**
 * Kleines Aktionsmenue im Kopf der Detailseite (Muster "menu button" der
 * WAI-ARIA Authoring Practices): Pfeiltasten wandern, Escape schliesst und
 * gibt den Fokus an den Knopf zurueck, ein Klick daneben schliesst ebenfalls.
 */
export function ActionsMenu({ label, items }: { label: string; items: readonly ActionsMenuItem[] }) {
  const [open, setOpen] = useState(false);
  const buttonRef = useRef<HTMLButtonElement>(null);
  const menuRef = useRef<HTMLDivElement>(null);
  const menuId = useId();

  useEffect(() => {
    if (!open) return;
    menuRef.current?.querySelector<HTMLElement>("[role=menuitem]")?.focus();
    function onPointerDown(event: PointerEvent) {
      const target = event.target as Node;
      if (!menuRef.current?.contains(target) && !buttonRef.current?.contains(target)) setOpen(false);
    }
    document.addEventListener("pointerdown", onPointerDown);
    return () => document.removeEventListener("pointerdown", onPointerDown);
  }, [open]);

  function close(returnFocus: boolean) {
    setOpen(false);
    if (returnFocus) buttonRef.current?.focus();
  }

  function onMenuKeyDown(event: KeyboardEvent<HTMLDivElement>) {
    const entries = Array.from(menuRef.current?.querySelectorAll<HTMLElement>("[role=menuitem]") ?? []);
    const index = entries.indexOf(document.activeElement as HTMLElement);
    if (event.key === "Escape") {
      event.preventDefault();
      close(true);
    } else if (event.key === "ArrowDown" || event.key === "ArrowUp") {
      event.preventDefault();
      const step = event.key === "ArrowDown" ? 1 : -1;
      entries[(index + step + entries.length) % entries.length]?.focus();
    } else if (event.key === "Home" || event.key === "End") {
      event.preventDefault();
      (event.key === "Home" ? entries[0] : entries.at(-1))?.focus();
    } else if (event.key === "Tab") {
      setOpen(false);
    }
  }

  const itemClass =
    "flex w-full items-center px-4 py-3 text-left text-sm text-ink transition-colors hover:bg-honey/10 focus-visible:bg-honey/10 focus-visible:outline-none";

  return (
    <div className="relative">
      <button
        ref={buttonRef}
        type="button"
        aria-haspopup="menu"
        aria-expanded={open}
        aria-controls={open ? menuId : undefined}
        aria-label={label}
        onClick={() => setOpen((value) => !value)}
        onKeyDown={(event) => {
          if (event.key === "ArrowDown") {
            event.preventDefault();
            setOpen(true);
          }
        }}
        className="inline-flex h-11 w-11 touch-manipulation items-center justify-center border border-ink/20 text-heading transition-[border-color,background-color,transform] duration-200 hover:border-heading active:scale-[0.96] aria-expanded:border-heading aria-expanded:bg-forest aria-expanded:text-cream"
      >
        <svg viewBox="0 0 24 24" className="h-5 w-5" fill="currentColor" aria-hidden="true">
          <circle cx="5" cy="12" r="1.6" />
          <circle cx="12" cy="12" r="1.6" />
          <circle cx="19" cy="12" r="1.6" />
        </svg>
      </button>
      {open ? (
        <div
          ref={menuRef}
          id={menuId}
          role="menu"
          aria-label={label}
          onKeyDown={onMenuKeyDown}
          className="absolute right-0 top-full z-30 mt-2 min-w-[14rem] origin-top-right border border-ink/10 bg-background py-1.5 shadow-[0_24px_48px_-24px_rgba(36,53,43,0.45)] transition-[opacity,scale] duration-150 ease-[var(--ease-arrive)] starting:scale-[0.97] starting:opacity-0 motion-reduce:transition-none"
        >
          {items.map((item) =>
            item.href ? (
              item.download ? (
                <a key={item.key} role="menuitem" tabIndex={-1} href={item.href} download className={itemClass} onClick={() => close(false)}>
                  {item.label}
                </a>
              ) : (
                <Link key={item.key} role="menuitem" tabIndex={-1} href={item.href} className={itemClass} onClick={() => close(false)}>
                  {item.label}
                </Link>
              )
            ) : (
              <button
                key={item.key}
                type="button"
                role="menuitem"
                tabIndex={-1}
                className={itemClass}
                onClick={() => {
                  close(false);
                  item.onSelect?.();
                }}
              >
                {item.label}
              </button>
            )
          )}
        </div>
      ) : null}
    </div>
  );
}