let bleDevice, gattServer;
let epdService, epdCharacteristic;
let startTime, msgIndex, appVersion;
let canvas, ctx, textDecoder;

const EpdCmd = {
  SET_PINS:  0x00,
  INIT:      0x01,
  CLEAR:     0x02,
  SEND_CMD:  0x03,
  SEND_DATA: 0x04,
  REFRESH:   0x05,
  SLEEP:     0x06,

  SET_TIME:  0x20,

  WRITE_IMG: 0x30, // v1.6

  SET_CONFIG: 0x90,
  SYS_RESET:  0x91,
  SYS_SLEEP:  0x92,
  CFG_ERASE:  0x99,
};

function hex2bytes(hex) {
  for (var bytes = [], c = 0; c < hex.length; c += 2)
    bytes.push(parseInt(hex.substr(c, 2), 16));
  return new Uint8Array(bytes);
}

function bytes2hex(data) {
  return new Uint8Array(data).reduce(
    function (memo, i) {
      return memo + ("0" + i.toString(16)).slice(-2);
    }, "");
}

function intToHex(intIn) {
  let stringOut = ("0000" + intIn.toString(16)).substr(-4)
  return stringOut.substring(2, 4) + stringOut.substring(0, 2);
}

function resetVariables() {
  gattServer = null;
  epdService = null;
  epdCharacteristic = null;
  msgIndex = 0;
  document.getElementById("log").value = '';
}

async function write(cmd, data, withResponse=true) {
  if (!epdCharacteristic) {
    addLog("服务不可用，请检查蓝牙连接");
    return false;
  }
  let payload = [cmd];
  if (data) {
    if (typeof data == 'string') data = hex2bytes(data);
    if (data instanceof Uint8Array) data = Array.from(data);
    payload.push(...data)
  }
  addLog(bytes2hex(payload), '⇑');
  try {
    if (withResponse)
      await epdCharacteristic.writeValueWithResponse(Uint8Array.from(payload));
    else
      await epdCharacteristic.writeValueWithoutResponse(Uint8Array.from(payload));
  } catch (e) {
    console.error(e);
    if (e.message) addLog("write: " + e.message);
    return false;
  }
  return true;
}

async function epdWrite(cmd, data) {
  const chunkSize = document.getElementById('mtusize').value - 1;
  const interleavedCount = document.getElementById('interleavedcount').value;
  const count = Math.round(data.length / chunkSize);
  let chunkIdx = 0;
  let noReplyCount = interleavedCount;

  if (typeof data == 'string') data = hex2bytes(data);

  await write(EpdCmd.SEND_CMD, [cmd]);
  for (let i = 0; i < data.length; i += chunkSize) {
    let currentTime = (new Date().getTime() - startTime) / 1000.0;
    setStatus(`命令：0x${cmd.toString(16)}, 数据块: ${chunkIdx+1}/${count+1}, 总用时: ${currentTime}s`);
    if (noReplyCount > 0) {
      await write(EpdCmd.SEND_DATA, data.slice(i, i + chunkSize), false);
      noReplyCount--;
    } else {
      await write(EpdCmd.SEND_DATA, data.slice(i, i + chunkSize), true);
      noReplyCount = interleavedCount;
    }
    chunkIdx++;
  }
}

async function epdWriteImage(step = 'bw') {
  const data = canvas2bytes(canvas, step);
  const chunkSize = document.getElementById('mtusize').value - 2;
  const interleavedCount = document.getElementById('interleavedcount').value;
  const count = Math.round(data.length / chunkSize);
  let chunkIdx = 0;
  let noReplyCount = interleavedCount;

  for (let i = 0; i < data.length; i += chunkSize) {
    let currentTime = (new Date().getTime() - startTime) / 1000.0;
    setStatus(`${step == 'bw' ? '黑白' : '颜色'}块: ${chunkIdx+1}/${count+1}, 总用时: ${currentTime}s`);
    const payload = [
      (step == 'bw' ? 0x0F : 0x00) | ( i == 0 ? 0x00 : 0xF0),
      ...data.slice(i, i + chunkSize),
    ];
    if (noReplyCount > 0) {
      await write(EpdCmd.WRITE_IMG, payload, false);
      noReplyCount--;
    } else {
      await write(EpdCmd.WRITE_IMG, payload, true);
      noReplyCount = interleavedCount;
    }
    chunkIdx++;
  }
}

async function setDriver() {
  await write(EpdCmd.SET_PINS, document.getElementById("epdpins").value);
  await write(EpdCmd.INIT, document.getElementById("epddriver").value);
}

async function syncTime(mode) {
  const timestamp = new Date().getTime() / 1000;
  const data = new Uint8Array([
    (timestamp >> 24) & 0xFF,
    (timestamp >> 16) & 0xFF,
    (timestamp >> 8) & 0xFF,
    timestamp & 0xFF,
    -(new Date().getTimezoneOffset() / 60),
    mode
  ]);
  if(await write(EpdCmd.SET_TIME, data)) {
    addLog("时间已同步！");
    addLog("屏幕刷新完成前请不要操作。");
  }
}

async function clearScreen() {
  if(confirm('确认清除屏幕内容?')) {
    await write(EpdCmd.CLEAR);
    addLog("清屏指令已发送！");
    addLog("屏幕刷新完成前请不要操作。");
  }
}

async function sendcmd() {
  const cmdTXT = document.getElementById('cmdTXT').value;
  if (cmdTXT == '') return;
  const bytes = hex2bytes(cmdTXT);
  await write(bytes[0], bytes.length > 1 ? bytes.slice(1) : null);
}

async function sendimg() {
  const status = document.getElementById("status");
  const driver = document.getElementById("epddriver").value;
  const mode = document.getElementById('dithering').value;

  startTime = new Date().getTime();
  status.parentElement.style.display = "block";

  updateButtonStatus(true);
  if (appVersion < 0x16) {
    if (mode.startsWith('bwry')) {
      addLog("当前固件版本不支持四色屏幕。");
      return;
    } if (mode.startsWith('bwr')) {
      await epdWrite(driver === "02" ? 0x24 : 0x10, canvas2bytes(canvas, 'bw'));
      await epdWrite(driver === "02" ? 0x26 : 0x13, canvas2bytes(canvas, 'red', driver === '02'));
    } else {
      await epdWrite(driver === "04" ? 0x24 : 0x13, canvas2bytes(canvas, 'bw'));
    }
  } else {
    if (mode.startsWith('bwry')) {
      await epdWriteImage('bwry');
    } else {
      await epdWriteImage('bw');
      if (mode.startsWith('bwr')) await epdWriteImage('red');
    }
  }

  await write(EpdCmd.REFRESH);
  updateButtonStatus();

  const sendTime = (new Date().getTime() - startTime) / 1000.0;
  addLog(`发送完成！耗时: ${sendTime}s`);
  setStatus(`发送完成！耗时: ${sendTime}s`);
  addLog("屏幕刷新完成前请不要操作。");
  setTimeout(() => {
    status.parentElement.style.display = "none";
  }, 5000);
}

function updateButtonStatus(forceDisabled = false) {
  const connected = gattServer != null && gattServer.connected;
  const status = forceDisabled ? 'disabled' : (connected ? null : 'disabled');
  document.getElementById("reconnectbutton").disabled = (gattServer == null || gattServer.connected) ? 'disabled' : null;
  document.getElementById("sendcmdbutton").disabled = status;
  document.getElementById("calendarmodebutton").disabled = status;
  document.getElementById("clockmodebutton").disabled = status;
  document.getElementById("clearscreenbutton").disabled = status;
  document.getElementById("sendimgbutton").disabled = status;
  document.getElementById("setDriverbutton").disabled = status;
}

function disconnect() {
  updateButtonStatus();
  resetVariables();
  addLog('已断开连接.');
  document.getElementById("connectbutton").innerHTML = '连接';
}

async function preConnect() {
  if (gattServer != null && gattServer.connected) {
    if (bleDevice != null && bleDevice.gatt.connected) {
      bleDevice.gatt.disconnect();
    }
  }
  else {
    resetVariables();
    try {
      bleDevice = await navigator.bluetooth.requestDevice({
        optionalServices: ['62750001-d828-918d-fb46-b6c11c675aec'],
        acceptAllDevices: true
      });
    } catch (e) {
      console.error(e);
      if (e.message) addLog("requestDevice: " + e.message);
      addLog("请检查蓝牙是否已开启，且使用的浏览器支持蓝牙！建议使用以下浏览器：");
      addLog("• 电脑: Chrome/Edge");
      addLog("• Android: Chrome/Edge");
      addLog("• iOS: Bluefy 浏览器");
      return;
    }

    await bleDevice.addEventListener('gattserverdisconnected', disconnect);
    setTimeout(async function () { await connect(); }, 300);
  }
}

async function reConnect() {
  if (bleDevice != null && bleDevice.gatt.connected)
    bleDevice.gatt.disconnect();
  resetVariables();
  addLog("正在重连");
  setTimeout(async function () { await connect(); }, 300);
}

function handleNotify(value, idx) {
  const data = new Uint8Array(value.buffer, value.byteOffset, value.byteLength);
  if (idx == 0) {
    addLog(`收到配置：${bytes2hex(data)}`);
    const epdpins = document.getElementById("epdpins");
    const epddriver = document.getElementById("epddriver");
    epdpins.value = bytes2hex(data.slice(0, 7));
    if (data.length > 10) epdpins.value += bytes2hex(data.slice(10, 11));
    epddriver.value = bytes2hex(data.slice(7, 8));
    filterDitheringOptions();
  } else {
    if (textDecoder == null) textDecoder = new TextDecoder();
    addLog(textDecoder.decode(data), '⇓');
  }
}

async function connect() {
  if (bleDevice == null || epdCharacteristic != null) return;

  try {
    addLog("正在连接: " + bleDevice.name);
    gattServer = await bleDevice.gatt.connect();
    addLog('  找到 GATT Server');
    epdService = await gattServer.getPrimaryService('62750001-d828-918d-fb46-b6c11c675aec');
    addLog('  找到 EPD Service');
    epdCharacteristic = await epdService.getCharacteristic('62750002-d828-918d-fb46-b6c11c675aec');
    addLog('  找到 Characteristic');
  } catch (e) {
    console.error(e);
    if (e.message) addLog("connect: " + e.message);
    disconnect();
    return;
  }

  try {
    const versionCharacteristic = await epdService.getCharacteristic('62750003-d828-918d-fb46-b6c11c675aec');
    const versionData = await versionCharacteristic.readValue();
    appVersion = versionData.getUint8(0);
    addLog(`固件版本: 0x${appVersion.toString(16)}`);
  } catch (e) {
    console.error(e);
    appVersion = 0x15;
  }

  try {
    await epdCharacteristic.startNotifications();
    epdCharacteristic.addEventListener('characteristicvaluechanged', (event) => {
      handleNotify(event.target.value, msgIndex++);
    });
  } catch (e) {
    console.error(e);
    if (e.message) addLog("startNotifications: " + e.message);
  }

  await write(EpdCmd.INIT);

  document.getElementById("connectbutton").innerHTML = '断开';
  updateButtonStatus();
}

function setStatus(statusText) {
  document.getElementById("status").innerHTML = statusText;
}

function addLog(logTXT, action = '') {
  const log = document.getElementById("log");
  const now = new Date();
  const time = String(now.getHours()).padStart(2, '0') + ":" +
         String(now.getMinutes()).padStart(2, '0') + ":" +
         String(now.getSeconds()).padStart(2, '0') + " ";

  const logEntry = document.createElement('div');
  const timeSpan = document.createElement('span');
  timeSpan.className = 'time';
  timeSpan.textContent = time;
  logEntry.appendChild(timeSpan);
  
  if (action !== '') {
    const actionSpan = document.createElement('span');
    actionSpan.className = 'action';
    actionSpan.innerHTML = action;
    logEntry.appendChild(actionSpan);
  }
  logEntry.appendChild(document.createTextNode(logTXT));

  log.appendChild(logEntry);
  log.scrollTop = log.scrollHeight;
  
  while (log.childNodes.length > 20) {
    log.removeChild(log.firstChild);
  }
}

function clearLog() {
  document.getElementById("log").innerHTML = '';
}

function onDitheringChange() {
  const mode = document.getElementById('dithering').value;
  const thresholdInput = document.getElementById('threshold');
  thresholdInput.disabled = (mode === '' || mode.startsWith('bwr'));
  updateImage(false);
}

function updateImage(clear = false) {
  const image_file = document.getElementById('image_file');
  if (image_file.files.length == 0) return;

  if (clear) clearCanvas();

  const file = image_file.files[0];
  let image = new Image();;
  image.src = URL.createObjectURL(file);
  image.onload = function(event) {
    URL.revokeObjectURL(this.src);
    ctx.drawImage(image, 0, 0, image.width, image.height, 0, 0, canvas.width, canvas.height);
    convertDithering()
  }
}

function clearCanvas() {
  if (confirm('清除画布已有内容?')) {
    ctx.fillStyle = 'white';
    ctx.fillRect(0, 0, canvas.width, canvas.height);
    textElements = []; // Clear stored text positions
    lineSegments = []; // Clear stored line segments
    return true;
  }
  return false;
}

function convertDithering() {
  const mode = document.getElementById('dithering').value;
  if (mode === '') return;

  if (mode.startsWith('bwr')) {
    ditheringByPalette(canvas, mode);
  } else {
    const threshold = document.getElementById('threshold').value;
    dithering(ctx, canvas.width, canvas.height, parseInt(threshold), mode);
  }

  // Redraw text and lines
  redrawTextElements();
  redrawLineSegments();
}

function filterDitheringOptions() {
  const driver = document.getElementById('epddriver').value;
  const dithering = document.getElementById('dithering');
  let currentOptionStillValid = false;
  let lastValidOptionValue = null;

  for (let optgroup of dithering.getElementsByTagName('optgroup')) {
    const drivers = optgroup.getAttribute('data-driver').split('|');
    const show = drivers.includes(driver);
    for (option of optgroup.getElementsByTagName('option')) {
      if (show) {
        option.removeAttribute('disabled');
        if (option.value == dithering.value) currentOptionStillValid = true;
        lastValidOptionValue = option.value;
      } else {
        option.setAttribute('disabled', 'disabled');
      }
    }
  }
  if (!currentOptionStillValid) dithering.value = lastValidOptionValue;
}

function checkDebugMode() {
  const link = document.getElementById('debug-toggle');
  const urlParams = new URLSearchParams(window.location.search);
  const debugMode = urlParams.get('debug');
  
  if (debugMode === 'true') {
      document.body.classList.add('debug-mode');
      link.innerHTML = '正常模式';
      link.setAttribute('href', window.location.pathname);
      addLog("注意：开发模式功能已开启！不懂请不要随意修改，否则后果自负！");
  } else {
      document.body.classList.remove('debug-mode');
      link.innerHTML = '开发模式';
      link.setAttribute('href', window.location.pathname + '?debug=true');
  }
}

document.body.onload = () => {
  textDecoder = null;
  canvas = document.getElementById('canvas');
  ctx = canvas.getContext("2d");

  ctx.fillStyle = 'white';
  ctx.fillRect(0, 0, canvas.width, canvas.height);

  initPaintTools();
  updateButtonStatus();
  checkDebugMode();
}