import { test } from "node:test";
import assert from "node:assert/strict";
import { focusInto, restoreFocus, triggerOf } from "../src/ui/popover/focus.ts";

// Stand-ins for DOM elements: only the members the helpers call.
function el({ contains = () => false, first = null, matches = false } = {}) {
  const calls = { focus: 0 };
  return {
    calls,
    focus() {
      calls.focus += 1;
    },
    contains,
    matches: () => matches,
    querySelector: () => first,
  };
}

test("focusInto: focuses the first control in the box", () => {
  const control = el();
  const box = el({ first: control });
  focusInto(box, null);
  assert.equal(control.calls.focus, 1);
  assert.equal(box.calls.focus, 0);
});

test("focusInto: focuses the box when it has no control", () => {
  const box = el();
  focusInto(box, null);
  assert.equal(box.calls.focus, 1);
});

test("focusInto: keeps focus a control inside the box took itself", () => {
  const inner = el();
  const control = el();
  const box = el({ first: control, contains: (n) => n === inner });
  focusInto(box, inner);
  assert.equal(control.calls.focus, 0);
  assert.equal(box.calls.focus, 0);
});

test("focusInto: a missing box does nothing", () => {
  focusInto(null, null);
});

test("restoreFocus: focus on body goes back to the trigger", () => {
  const body = el();
  const trigger = el();
  restoreFocus(trigger, body, body);
  assert.equal(trigger.calls.focus, 1);
});

test("restoreFocus: no focused element goes back to the trigger", () => {
  const trigger = el();
  restoreFocus(trigger, null, el());
  assert.equal(trigger.calls.focus, 1);
});

test("restoreFocus: another focused control keeps focus", () => {
  const trigger = el();
  restoreFocus(trigger, el(), el());
  assert.equal(trigger.calls.focus, 0);
});

test("restoreFocus: a missing trigger does nothing", () => {
  const body = el();
  restoreFocus(null, body, body);
});

test("triggerOf: the anchor itself when Tab reaches it", () => {
  const anchor = el({ matches: true, first: el() });
  assert.equal(triggerOf(anchor), anchor);
});

test("triggerOf: the first control inside a wrapper", () => {
  const inner = el();
  const anchor = el({ first: inner });
  assert.equal(triggerOf(anchor), inner);
});

test("triggerOf: a missing anchor has no trigger", () => {
  assert.equal(triggerOf(null), null);
});