import assert from 'node:assert/strict';
import test from 'node:test';
import { installPageLangReport, LANG_REPORT_RETRIES } from '../src/pageLang.ts';

/** A page whose <html lang> never changes, with timers we step by hand. */
function fakePage(lang: string, parsed = true) {
  const timers: Array<() => void> = [];
  const listeners = new Map<string, () => void>();
  const root = { getAttribute: (name: string) => (name === 'lang' ? lang : null) };
  const document = {
    documentElement: parsed ? root : null,
    addEventListener: (type: string, fn: () => void) => { listeners.set(type, fn); },
    removeEventListener: (type: string) => { listeners.delete(type); },
  };
  const win = {
    document,
    MutationObserver: class { observe() {} disconnect() {} },
    setTimeout: (fn: () => void) => { timers.push(fn); return timers.length; },
    clearTimeout: () => {},
  } as unknown as Window & typeof globalThis;
  const parse = () => { document.documentElement = root; listeners.get('DOMContentLoaded')?.(); };
  return { win, timers, parse, listeners };
}
const settle = () => new Promise(resolve => setImmediate(resolve));

test('a language report lost at document start (no IPC bridge yet) is sent again', async () => {
  const { win, timers } = fakePage('en-GB');
  const sent: unknown[] = [];
  let bridge = false;
  installPageLangReport(win, async (command, args) => {
    if (!bridge) throw new Error('IPC bridge not ready');
    sent.push([command, args]);
  });
  await settle();
  assert.equal(sent.length, 0);
  assert.equal(timers.length, 1, 'a retry is scheduled');
  bridge = true;
  timers.shift()!();
  await settle();
  assert.deepEqual(sent, [['tab_report', { report: { lang: 'en-GB' } }]]);
  assert.equal(timers.length, 0, 'nothing more once it went through');
});

test('retries are bounded and stop after dispose', async () => {
  const { win, timers } = fakePage('tr');
  let calls = 0;
  const handle = installPageLangReport(win, async () => { calls += 1; throw new Error('down'); });
  for (let i = 0; i < LANG_REPORT_RETRIES + 5; i += 1) { await settle(); timers.shift()?.(); }
  await settle();
  assert.equal(calls, LANG_REPORT_RETRIES + 1);
  assert.equal(timers.length, 0);

  const second = fakePage('ja');
  let later = 0;
  const h2 = installPageLangReport(second.win, async () => { later += 1; throw new Error('down'); });
  await settle();
  h2.dispose();
  second.timers.shift()?.();
  await settle();
  assert.equal(later, 1, 'no report after dispose');
  handle.dispose();
});

test('installed at document start before <html> exists, it reports once the parser made it', async () => {
  const page = fakePage('en-GB', false);
  const sent: unknown[] = [];
  const handle = installPageLangReport(page.win, async (command, args) => { sent.push([command, args]); });
  await settle();
  assert.equal(sent.length, 0);
  page.parse();
  await settle();
  assert.deepEqual(sent, [['tab_report', { report: { lang: 'en-GB' } }]]);
  handle.dispose();
  assert.equal(page.listeners.size, 0);
});