'use strict';

/**
 * SIM 卡短信读取器
 * - 扫描 /dev/serial/by-path 中以 :1.3-port0 结尾的 Quectel AT 串口
 * - 每 15 秒读取一次，过滤 5 分钟内的短信
 * - 去重后追加写入 ~/sms-messages.txt
 */

const fs      = require('fs');
const path    = require('path');
const os      = require('os');
const crypto  = require('crypto');
const { execSync } = require('child_process');

const BY_PATH_DIR     = '/dev/serial/by-path';
const TARGET_SUFFIX   = ':1.3-port0';
const OUT_FILE        = path.join(os.homedir(), 'sms-messages.txt');
const STATE_FILE      = path.join(os.homedir(), '.sms-seen.json');
const BAUD            = 9600;
const POLL_MS         = 15_000;
const WINDOW_MINUTES  = 5;
const SEEN_LIMIT      = 2000;

// ── 工具 ─────────────────────────────────────────────────────────────────────

const sleep = ms => new Promise(r => setTimeout(r, ms));

// ── 串口操作 ──────────────────────────────────────────────────────────────────

function setupPort(dev) {
  execSync(
    `stty -F "${dev}" ${BAUD} cs8 -cstopb -parenb cread clocal -crtscts raw ` +
    `-echo -echoe -echok -echonl min 0 time 5`,
    { stdio: 'ignore' }
  );
}

/** 读取串口原始数据，直到 OK/ERROR 或超时 */
async function readRaw(fd, timeoutMs = 2000, stopOnOk = true) {
  const buf      = Buffer.alloc(4096);
  const deadline = Date.now() + timeoutMs;
  let   text     = '';

  while (Date.now() < deadline) {
    let n = 0;
    try {
      n = fs.readSync(fd, buf, 0, buf.length, null);
    } catch (e) {
      if (e.code !== 'EAGAIN' && e.code !== 'EWOULDBLOCK') throw e;
    }

    if (n > 0) {
      text += buf.slice(0, n).toString('utf8');
      if (stopOnOk && (/\nOK|\rOK|ERROR/.test(text))) {
        // 排尽剩余缓冲
        await sleep(120);
        try {
          while (true) {
            const n2 = fs.readSync(fd, buf, 0, buf.length, null);
            if (n2 <= 0) break;
            text += buf.slice(0, n2).toString('utf8');
          }
        } catch (_) {}
        break;
      }
    } else {
      await sleep(50);
    }
  }
  return text;
}

/** 发送 AT 命令，返回清理后的响应行数组 */
async function atCmd(fd, command, waitMs = 2000) {
  // 清空输入缓冲
  try { while (fs.readSync(fd, Buffer.alloc(256), 0, 256, null) > 0) {} } catch (_) {}
  fs.writeSync(fd, Buffer.from(command + '\r'));
  const raw = await readRaw(fd, waitMs, true);
  return cleanLines(raw);
}

function cleanLines(raw) {
  return raw
    .replace(/\r/g, '\n')
    .split('\n')
    .map(l => l.trim())
    .filter(l => {
      if (!l) return false;
      if (l === 'OK' || l === 'ERROR') return false;
      if (l.startsWith('AT')) return false;
      const printable = [...l].filter(c => c >= ' ').length;
      return printable / Math.max(1, l.length) >= 0.85;
    });
}

// ── 端口发现 ──────────────────────────────────────────────────────────────────

function discoverPorts() {
  if (!fs.existsSync(BY_PATH_DIR)) return [];
  return fs.readdirSync(BY_PATH_DIR)
    .filter(n => n.endsWith(TARGET_SUFFIX))
    .sort()
    .map(n => {
      const link = path.join(BY_PATH_DIR, n);
      try {
        const real = fs.realpathSync(link);
        return fs.existsSync(real) ? { link, real } : null;
      } catch (_) { return null; }
    })
    .filter(Boolean);
}

// ── SMS 解析 ──────────────────────────────────────────────────────────────────

/** 尝试将纯 UCS2 hex 解码为中文 */
function maybeDecodeUcs2(text) {
  const s = (text || '').replace(/\s+/g, '');
  if (!s || s.length % 4 !== 0) return '';
  if (/^\d+$/.test(s)) return '';           // 纯数字不解码（验证码原文）
  if (!/^[0-9A-Fa-f]+$/.test(s)) return '';
  try {
    const decoded = Buffer.from(s, 'hex').toString('utf16le');
    // utf16le 是 little-endian，Quectel 发的是 big-endian，需交换字节
    const beDecoded = Buffer.from(s, 'hex').swap16().toString('utf16le');
    const printable = c => c >= ' ';
    const score = s => [...s].filter(printable).length / Math.max(1, s.length);
    const best = score(beDecoded) >= score(decoded) ? beDecoded : decoded;
    return score(best) >= 0.85 ? best.trim() : '';
  } catch (_) { return ''; }
}

/** 从文本提取 4-8 位验证码 */
function extractOtp(text) {
  const m = (text || '').match(/(?<!\d)(\d{4,8})(?!\d)/);
  return m ? m[1] : '';
}

/** 解析 +CMGL 响应行为消息对象数组 */
function parseSms(lines) {
  const messages = [];
  let current = null;
  for (const line of lines) {
    if (line.startsWith('+CMGL:') || line.startsWith('+CMGR:')) {
      const parts = line.split(',').map(p => p.trim().replace(/^"|"$/g, ''));
      const sender = line.startsWith('+CMGL:')
        ? (parts[2] || 'UNKNOWN')
        : (parts[1] || 'UNKNOWN');
      // 时间戳在 +CMGL: idx,stat,sender,,"yy/MM/dd,HH:mm:ss+tz"
      const tsRaw = parts[4] || '';
      current = { sender, tsRaw, timestamp: parseTimestamp(tsRaw), content: '', decoded: '' };
      messages.push(current);
    } else if (current && !line.startsWith('+')) {
      const raw = (current.content + ' ' + line).trim();
      current.content = raw;
      current.decoded = maybeDecodeUcs2(raw);
      current = null;
    }
  }
  return messages;
}

/** 解析 Quectel 时间戳 "26/04/30,12:34:56+32"（+tz 单位 1/4 小时） */
function parseTimestamp(raw) {
  if (!raw) return new Date();
  const m = raw.match(/(\d{2})\/(\d{2})\/(\d{2}),(\d{2}):(\d{2}):(\d{2})([+-]\d+)?/);
  if (!m) return new Date();
  const [, yy, mo, dd, hh, mm, ss, tz] = m;
  const tzMin = tz ? parseInt(tz) * 15 : 0;
  const iso = `20${yy}-${mo}-${dd}T${hh}:${mm}:${ss}${tzOffsetStr(tzMin)}`;
  const d = new Date(iso);
  return isNaN(d) ? new Date() : d;
}

function tzOffsetStr(totalMin) {
  const sign = totalMin >= 0 ? '+' : '-';
  const abs  = Math.abs(totalMin);
  const h    = String(Math.floor(abs / 60)).padStart(2, '0');
  const m    = String(abs % 60).padStart(2, '0');
  return `${sign}${h}:${m}`;
}

/** 过滤 N 分钟内的短信 */
function recentOnly(messages, minutes = WINDOW_MINUTES) {
  const cutoff = Date.now() - minutes * 60 * 1000;
  return messages.filter(m => m.timestamp >= cutoff);
}

// ── 去重 ──────────────────────────────────────────────────────────────────────

function fingerprint(imsi, msg) {
  const key = [
    imsi || 'UNKNOWN',
    msg.sender || 'UNKNOWN',
    msg.decoded || msg.content || '',
    msg.timestamp.toISOString(),
  ].join('|');
  return crypto.createHash('sha1').update(key).digest('hex');
}

function loadSeen() {
  try {
    const data = JSON.parse(fs.readFileSync(STATE_FILE, 'utf8'));
    return Array.isArray(data) ? data : [];
  } catch (_) { return []; }
}

function saveSeen(seen) {
  fs.writeFileSync(STATE_FILE, JSON.stringify(seen.slice(-SEEN_LIMIT), null, 2), 'utf8');
}

function filterNew(results, seen) {
  const seenSet = new Set(seen);
  const newSeen = [...seen];
  const filtered = [];
  for (const item of results) {
    const msgs = [];
    for (const msg of item.messages) {
      const fp = fingerprint(item.imsi, msg);
      if (seenSet.has(fp)) continue;
      seenSet.add(fp);
      newSeen.push(fp);
      msgs.push(msg);
    }
    filtered.push({ ...item, messages: msgs });
  }
  return { filtered, newSeen: newSeen.slice(-SEEN_LIMIT) };
}

// ── 读取一个端口 ──────────────────────────────────────────────────────────────

async function readPort({ link, real }) {
  let fd;
  try {
    setupPort(real);
    fd = fs.openSync(real, fs.constants.O_RDWR | fs.constants.O_NOCTTY | fs.constants.O_NONBLOCK);

    // 排空缓冲
    await readRaw(fd, 400, false);

    // 获取 IMSI
    const cimiLines = await atCmd(fd, 'AT+CIMI');
    const imsiMatch = cimiLines.join('\n').match(/\b(\d{15})\b/);
    const imsi = imsiMatch ? imsiMatch[1] : 'UNKNOWN';

    // 切换文本模式
    await atCmd(fd, 'AT+CMGF=1');

    // 读取所有短信
    const smsLines = await atCmd(fd, 'AT+CMGL="ALL"', 4000);
    const messages = recentOnly(parseSms(smsLines));

    return { link, device: real, imsi, messages };
  } catch (e) {
    return { link, device: real, imsi: 'UNKNOWN', messages: [], error: e.message };
  } finally {
    if (fd !== undefined) try { fs.closeSync(fd); } catch (_) {}
  }
}

// ── 输出渲染 ──────────────────────────────────────────────────────────────────

function render(results) {
  const now = new Date().toLocaleString('zh-CN', { hour12: false,
    year: 'numeric', month: '2-digit', day: '2-digit',
    hour: '2-digit', minute: '2-digit', second: '2-digit',
    timeZoneName: 'short' });
  const lines = [`=== ${now} ===`];
  let anySms = false;

  for (const item of results) {
    const errStr = item.error ? `  ERROR: ${item.error}` : '';
    lines.push(`Port: ${item.device}  IMSI: ${item.imsi}  Messages: ${item.messages.length}${errStr}`);
    for (const msg of item.messages) {
      anySms = true;
      lines.push(`Time:    ${msg.timestamp.toLocaleString('zh-CN', { hour12: false })}`);
      lines.push(`IMSI:    ${item.imsi}`);
      lines.push(`From:    ${msg.sender}`);
      lines.push(`Content: ${msg.decoded || msg.content}`);
      const otp = extractOtp(msg.decoded || msg.content);
      if (otp) lines.push(`Code:    ${otp}`);
      lines.push('');
    }
  }
  if (!anySms) lines.push(`No new SMS in last ${WINDOW_MINUTES} minutes.`);
  return lines.join('\n').trimEnd() + '\n';
}

// ── 主循环 ────────────────────────────────────────────────────────────────────

async function poll() {
  const ports   = discoverPorts();
  const results = await Promise.all(ports.map(readPort));

  for (const item of results) {
    for (const msg of item.messages) {
      msg.otp = extractOtp(msg.decoded || msg.content);
    }
  }

  const seen = loadSeen();
  const { filtered, newSeen } = filterNew(results, seen);
  const text = render(filtered);

  fs.appendFileSync(OUT_FILE, text, 'utf8');
  saveSeen(newSeen);
  process.stdout.write(text);
}

async function main() {
  console.log(`SIM SMS reader started. Poll every ${POLL_MS / 1000}s → ${OUT_FILE}`);
  while (true) {
    try {
      await poll();
    } catch (e) {
      console.error('poll error:', e.message);
    }
    await sleep(POLL_MS);
  }
}

main();