(() => {
  'use strict';
  const $ = (id) => document.getElementById(id);
  const sleep = (ms) => new Promise((resolve) => window.setTimeout(resolve, ms));
  const pad3 = (n) => String(n).padStart(3, '0');
  const hostClock = () => new Date().toLocaleTimeString('zh-TW', { hour12: false });

  $('topic').value = `dosmqtt/demo/${Math.random().toString(36).slice(2, 9)}`;
  $('clock').textContent = hostClock();
  window.setInterval(() => { $('clock').textContent = hostClock(); }, 1000);

  const B_INTERVAL_MS = 5000;
  const machines = {};              // 'A' | 'B' -> { vm, ready, ip }
  let bTimer;
  let running = false;
  let runs = 0;
  const seen = new Set();           // de-duplicate lines read from the DOS screens
  const sentAt = new Map();         // B payload -> host time first seen
  const matched = new Set();
  const counts = { rx: 0, echo: 0, sent: 0 };
  let toastTimer;

  // ---------- helpers ----------

  function setNet(text, on) {
    $('netText').textContent = text;
    $('liveDot').classList.toggle('on', !!on);
  }

  function toast(text) {
    $('toast').textContent = text;
    $('toast').classList.add('show');
    window.clearTimeout(toastTimer);
    toastTimer = window.setTimeout(() => $('toast').classList.remove('show'), 1800);
  }

  function logRow(src, text, cls = '') {
    const log = $('log');
    const empty = log.querySelector('.log-empty');
    if (empty) empty.remove();
    const row = document.createElement('div');
    row.className = `log-row ${cls}`;
    const t = document.createElement('span'); t.className = 't'; t.textContent = hostClock();
    const s = document.createElement('span'); s.className = 'src'; s.textContent = src;
    const m = document.createElement('span'); m.className = 'msg'; m.textContent = text;
    row.append(t, s, m);
    log.append(row);
    while (log.children.length > 200) log.firstElementChild.remove();
    log.scrollTop = log.scrollHeight;
  }

  async function gunzipBase64(b64) {
    const bin = Uint8Array.from(atob(b64), (c) => c.charCodeAt(0));
    const stream = new Blob([bin]).stream().pipeThrough(new DecompressionStream('gzip'));
    return new Response(stream).arrayBuffer();
  }

  const screenLines = (vm) => vm.screen_adapter.get_text_screen().map((l) => l.replace(/\s+$/, ''));
  const screenText = (vm) => screenLines(vm).join('\n');
  const lastLine = (vm) => {
    const lines = screenLines(vm).filter((l) => l.trim() !== '');
    return lines.length ? lines[lines.length - 1] : '';
  };
  const atPrompt = (vm) => /^[A-Z]:\\>$/.test(lastLine(vm).trim());

  // Type into the real DOS keyboard buffer (slowly enough that FreeCOM keeps up).
  async function typeLine(name, text) {
    await machines[name].vm.keyboard_send_text(`${text}\n`, 25);
    await sleep(250);
  }

  // ---------- booting the two DOS machines ----------

  async function boot() {
    const assets = window.DOSMQTT_ASSETS;
    if (!window.V86 || !assets || !window.MqttBridge) {
      setNet('LOAD ERROR', false);
      $('note').textContent = 'v86 或資產載入失敗，請重新整理頁面。';
      return;
    }
    if (typeof DecompressionStream !== 'function') {
      setNet('UNSUPPORTED', false);
      $('note').textContent = '這個瀏覽器不支援 DecompressionStream，請改用較新的 Chrome / Edge / Safari / Firefox。';
      return;
    }
    window.MqttBridge.install();
    window.MqttBridge.onEvent = (machine, text) => logRow('BRIDGE', `${machine}: ${text}`, 'bridge');

    const [wasmBytes, bios, vga, img] = await Promise.all(
      ['wasm', 'bios', 'vga', 'img'].map((k) => gunzipBase64(assets[k])));
    const wasmModule = await WebAssembly.compile(wasmBytes);

    for (const name of ['A', 'B']) {
      const vm = new window.V86({
        wasm_fn: async (imports) => (await WebAssembly.instantiate(wasmModule, imports)).exports,
        memory_size: 16 * 1024 * 1024,
        vga_memory_size: 2 * 1024 * 1024,
        screen_container: $(`screen${name}`),
        bios: { buffer: bios.slice(0) },
        vga_bios: { buffer: vga.slice(0) },
        fda: { buffer: img.slice(0) },
        net_device: { type: 'ne2k', relay_url: window.MqttBridge.relayUrl(name), dns_method: 'doh' },
        autostart: true,
        disable_speaker: true,
      });
      machines[name] = { vm, ready: false, ip: '' };
      vm.keyboard_set_status(false);
      vm.add_listener('screen-set-size', () => window.setTimeout(() => fitScreen(name), 50));
      $(`screen${name}`).addEventListener('mousedown', () => focusMachine(name));
      $(`screen${name}`).addEventListener('touchstart', () => focusMachine(name), { passive: true });
    }
    watchBoot();
  }

  // In text mode v86 renders an 80x25 DOM text layer at a fixed font size; in graphics
  // modes it draws a canvas. Scale whichever one is visible to the width of its card.
  function fitScreen(name) {
    const box = $(`screen${name}`);
    const text = box.firstElementChild;
    const canvas = box.querySelector('canvas');
    if (!box.clientWidth) return;
    const useCanvas = canvas && getComputedStyle(canvas).display !== 'none' && canvas.width > 0;
    const layer = useCanvas ? canvas : text;
    const naturalW = useCanvas ? canvas.width : text.offsetWidth;
    const naturalH = useCanvas ? canvas.height : text.offsetHeight;
    if (!naturalW || !naturalH) return;
    const k = box.clientWidth / naturalW;
    layer.style.transformOrigin = '0 0';
    layer.style.transform = `scale(${k})`;
    box.style.height = `${Math.round(naturalH * k)}px`;
  }
  window.addEventListener('resize', () => { fitScreen('A'); fitScreen('B'); });

  function focusMachine(name) {
    for (const key of Object.keys(machines)) {
      machines[key].vm.keyboard_set_status(key === name);
      $(`screen${key}`).classList.toggle('focus', key === name);
    }
  }

  function watchBoot() {
    const timer = window.setInterval(() => {
      for (const name of ['A', 'B']) {
        const m = machines[name];
        if (m.ready) continue;
        const text = screenText(m.vm);
        const ip = /IPADDR\s+([\d.]+)/.exec(text);
        if (ip) m.ip = ip[1];
        if (/TCP\/IP is up/.test(text)) {
          m.ready = true;
          $(`${name.toLowerCase()}State`).textContent = 'NET UP';
          $(`${name.toLowerCase()}State`).classList.add('on');
          $(`${name.toLowerCase()}Ip`).textContent = `IP ${m.ip || '192.168.86.x'}`;
        }
      }
      if (machines.A.ready && machines.B.ready) {
        window.clearInterval(timer);
        setNet('DOS NET UP', true);
        $('bootTag').textContent = '2 × FREEDOS READY';
        $('startButton').disabled = false;
        $('startButton').innerHTML = '<span class="button-icon">▶</span>開始（啟動 A，B 每 5 秒執行）';
        $('note').textContent = '兩台 DOS 都已取得 DHCP 位址。按「開始」會在 DOS 內設定環境變數、啟動 A.EXE，之後每 5 秒執行 B.EXE。';
      }
    }, 500);
  }

  // ---------- running the demo ----------

  async function runB() {
    const b = machines.B;
    if (!running) return;
    if (!atPrompt(b.vm)) { logRow('B', '上一次 B.EXE 尚未結束，略過這一次', 'err'); return; }
    runs += 1;
    $('runCount').textContent = pad3(runs);
    await typeLine('B', 'B');
  }

  async function start() {
    const url = $('broker').value.trim();
    const topic = $('topic').value.trim();
    let host;
    try { host = new URL(url).hostname; } catch { host = ''; }
    if (!/^wss:\/\//i.test(url) || !host || !topic || /[+#\s%&|<>^"]/.test(topic)) {
      toast('請輸入有效的 wss:// broker 與不含空白、+、# 的 topic');
      return;
    }
    $('startButton').disabled = true;
    $('startButton').innerHTML = '<span class="button-icon">◌</span>啟動中…';
    window.MqttBridge.brokerUrl = url;
    running = true;
    logRow('SYS', `broker ${url}  topic ${topic}`);

    for (const name of ['A', 'B']) {
      await typeLine(name, `SET MQTT_HOST=${host}`);
      await typeLine(name, 'SET MQTT_PORT=1883');
      await typeLine(name, `SET MQTT_TOPIC=${topic}`);
      await typeLine(name, 'CLS');
    }
    await typeLine('A', 'A');
    $('aState').textContent = 'A.EXE';

    // Wait until A reports that it subscribed, then start B on its 5 second schedule.
    const deadline = Date.now() + 45000;
    while (Date.now() < deadline && !/subscribed to/.test(screenText(machines.A.vm))) await sleep(400);
    if (!/subscribed to/.test(screenText(machines.A.vm))) {
      logRow('A', 'A.EXE 沒有在 45 秒內完成訂閱（broker 無回應？）', 'err');
      toast('A 無法訂閱，請檢查 broker');
    }
    $('bState').textContent = 'B EVERY 5s';
    $('bState').classList.add('on');
    await runB();
    bTimer = window.setInterval(runB, B_INTERVAL_MS);
    $('startButton').disabled = false;
    $('startButton').innerHTML = '<span class="button-icon">■</span>停止並重新開機';
    $('note').textContent = '運作中：B.EXE 每 5 秒由網頁在機器 B 的 DOS 提示字元執行一次。';
  }

  function stop() {
    running = false;
    window.clearInterval(bTimer);
    bTimer = undefined;
    for (const name of ['A', 'B']) {
      const m = machines[name];
      m.ready = false;
      $(`${name.toLowerCase()}State`).textContent = 'REBOOT';
      $(`${name.toLowerCase()}State`).classList.remove('on');
      m.vm.restart();
    }
    setNet('REBOOTING', false);
    $('startButton').disabled = true;
    $('startButton').innerHTML = '<span class="button-icon">◌</span>重新開機中…';
    watchBoot();
  }

  // ---------- reading results from the DOS screens ----------

  function scan() {
    if (!machines.A || !machines.A.vm) return;
    for (const line of screenLines(machines.A.vm)) {
      const rx = /^\[(\d\d:\d\d:\d\d)\] A rx: (.+)$/.exec(line.trim());
      const echo = /^\[(\d\d:\d\d:\d\d)\] A echo: (.+)$/.exec(line.trim());
      if (rx && !seen.has(line)) {
        seen.add(line); counts.rx += 1; $('rxCount').textContent = pad3(counts.rx);
        logRow('A', `收到 ${rx[2]}`);
      }
      if (echo && !seen.has(line)) {
        seen.add(line); counts.echo += 1; $('echoCount').textContent = pad3(counts.echo);
        const t0 = sentAt.get(echo[2]);
        const ms = t0 ? ` （距 B 送出 ${((Date.now() - t0) / 1000).toFixed(1)} 秒）` : '';
        if (t0) matched.add(echo[2]);
        logRow('A', `echo ${echo[2]}${ms}`, 'ok');
        $('matchTag').textContent = `${matched.size} / ${counts.sent} MATCHED`;
      }
    }
    if (machines.B && machines.B.vm) {
      for (const line of screenLines(machines.B.vm)) {
        const sent = /^\[(\d\d:\d\d:\d\d)\] B sent: (.+)$/.exec(line.trim());
        if (sent && !seen.has(`B${line}`)) {
          seen.add(`B${line}`); counts.sent += 1; $('sentCount').textContent = pad3(counts.sent);
          sentAt.set(sent[2], Date.now());
          logRow('B', `送出 ${sent[2]}`, 'b');
          $('matchTag').textContent = `${matched.size} / ${counts.sent} MATCHED`;
        }
      }
    }
  }
  window.setInterval(() => { scan(); fitScreen('A'); fitScreen('B'); }, 400);

  $('startButton').addEventListener('click', () => { if (running) stop(); else start(); });
  $('copyButton').addEventListener('click', async () => {
    const topic = $('topic').value.trim();
    try { await navigator.clipboard.writeText(topic); toast('Topic 已複製到剪貼簿'); }
    catch { $('topic').select(); document.execCommand('copy'); toast(`Topic: ${topic}`); }
  });

  boot().catch((error) => {
    setNet('BOOT ERROR', false);
    $('note').textContent = `啟動失敗：${error && error.message ? error.message : error}`;
    console.error(error);
  });
})();