/**
 * Svelte action: show a custom tooltip after a 500ms hover delay.
 * Uses a positioned div instead of the native `title` attribute —
 * native tooltips only appear on mousemove, not on mouseenter, which
 * causes a "hover then wiggle" requirement that feels broken.
 *
 * If text is empty, does nothing.
 */

const TOOLTIP_CLASS = 'hu-tooltip';

// Shared tooltip element — one per page, repositioned as needed.
let tooltipEl: HTMLDivElement | null = null;

function getTooltipEl(): HTMLDivElement {
  if (!tooltipEl) {
    tooltipEl = document.createElement('div');
    tooltipEl.className = TOOLTIP_CLASS;
    document.body.appendChild(tooltipEl);
  }
  return tooltipEl;
}

export function tooltip(node: HTMLElement, text: string) {
  let timer: ReturnType<typeof setTimeout> | null = null;
  let currentText = text;

  function show(e: MouseEvent) {
    if (!currentText) return;
    const el = getTooltipEl();
    el.textContent = currentText;

    // Position near cursor, clamped to viewport
    const x = Math.min(e.clientX + 12, window.innerWidth - el.offsetWidth - 8);
    const y = e.clientY + 20;
    el.style.left = `${x}px`;
    el.style.top = `${y}px`;
    el.classList.add('hu-tooltip--visible');
  }

  function enter(e: MouseEvent) {
    if (!currentText) return;
    timer = setTimeout(() => show(e), 500);
  }

  function move(e: MouseEvent) {
    // Keep tooltip near cursor while hovering
    if (!tooltipEl?.classList.contains('hu-tooltip--visible')) return;
    const el = getTooltipEl();
    const x = Math.min(e.clientX + 12, window.innerWidth - el.offsetWidth - 8);
    const y = e.clientY + 20;
    el.style.left = `${x}px`;
    el.style.top = `${y}px`;
  }

  function leave() {
    if (timer !== null) {
      clearTimeout(timer);
      timer = null;
    }
    tooltipEl?.classList.remove('hu-tooltip--visible');
  }

  node.addEventListener('mouseenter', enter);
  node.addEventListener('mousemove', move);
  node.addEventListener('mouseleave', leave);

  return {
    update(newText: string) {
      currentText = newText;
      if (tooltipEl?.classList.contains('hu-tooltip--visible')) {
        tooltipEl.textContent = newText;
      }
    },
    destroy() {
      if (timer !== null) clearTimeout(timer);
      node.removeEventListener('mouseenter', enter);
      node.removeEventListener('mousemove', move);
      node.removeEventListener('mouseleave', leave);
      tooltipEl?.classList.remove('hu-tooltip--visible');
    }
  };
}