/* 独立主站字节测试：启动示例自己的Windows Net后端，仅连接127.0.0.1随机端口。
 * Node内置模块即可运行，不安装包、不复用待测ASDU编码器，不更改系统时钟。
 */
'use strict';
const assert = require('node:assert/strict');
const net = require('node:net');
const { spawn, spawnSync } = require('node:child_process');
const { once } = require('node:events');
const { setTimeout: delay } = require('node:timers/promises');
const executable = process.argv[2];
if (!executable) throw new Error('Usage: node slave_example_loopback_test.cjs <example.exe>');

class Master {
  constructor(socket) {
    this.socket = socket;
    this.buffer = Buffer.alloc(0);
    this.frames = [];
    this.waiters = [];
    this.ns = this.nr = 0;
    socket.on('data', data => {
      this.buffer = Buffer.concat([this.buffer, data]);
      try {
        while (this.buffer.length >= 2) {
          assert.equal(this.buffer[0], 0x68);
          assert(this.buffer[1] >= 4 && this.buffer[1] <= 253);
          const length = this.buffer[1] + 2;
          if (this.buffer.length < length) break;
          const frame = this.buffer.subarray(0, length);
          this.buffer = this.buffer.subarray(length);
          const waiter = this.waiters.shift();
          if (waiter) { clearTimeout(waiter.timer); waiter.resolve(frame); }
          else this.frames.push(frame);
        }
      } catch (error) { this.fail(error); socket.destroy(); }
    });
    socket.on('error', error => this.fail(error));
    socket.on('close', () => this.fail(new Error('Connection closed')));
  }
  fail(error) {
    this.error = error;
    for (const waiter of this.waiters.splice(0)) {
      clearTimeout(waiter.timer);
      waiter.reject(error);
    }
  }
  next() {
    if (this.frames.length) return Promise.resolve(this.frames.shift());
    if (this.error) return Promise.reject(this.error);
    return new Promise((resolve, reject) => {
      const waiter = { resolve, reject };
      waiter.timer = setTimeout(() => {
        this.waiters.splice(this.waiters.indexOf(waiter), 1);
        reject(new Error('Timed out waiting for an APDU'));
      }, 1500);
      this.waiters.push(waiter);
    });
  }
  async control(code, expected) {
    this.socket.write(Buffer.from([0x68, 4, code, 0, 0, 0]));
    for (let i = 0; i < 8; i++) {
      const frame = await this.next();
      if (frame[2] === 1) continue; // 主站I帧的S确认允许穿插。
      assert.deepEqual([...frame], [0x68, 4, expected, 0, 0, 0]);
      return;
    }
    throw new Error('Missing U-frame confirmation');
  }
  frame(payload) {
    const frame = Buffer.alloc(payload.length + 6);
    frame[0] = 0x68;
    frame[1] = payload.length + 4;
    frame.writeUInt16LE(this.ns++ << 1, 2);
    frame.writeUInt16LE(this.nr << 1, 4);
    Buffer.from(payload).copy(frame, 6);
    return frame;
  }
  async send(payload, fragmented = false) {
    const frame = this.frame(payload);
    if (fragmented) {
      this.socket.write(frame.subarray(0, 3));
      await delay(10);
      this.socket.write(frame.subarray(3));
    } else this.socket.write(frame);
  }
  async readASDU() {
    for (let i = 0; i < 8; i++) {
      const frame = await this.next();
      if (frame[2] === 1) continue;
      assert.equal(frame[2] & 1, 0);
      assert.equal(frame.readUInt16LE(2) >> 1, this.nr++);
      assert.equal(frame.readUInt16LE(4) >> 1, this.ns);
      const ack = Buffer.from([0x68, 4, 1, 0, 0, 0]);
      ack.writeUInt16LE(this.nr << 1, 4);
      this.socket.write(ack); // k=1，每帧ACK后服务才可继续发下一帧。
      return frame.subarray(6);
    }
    throw new Error('Missing I frame');
  }
  async close() {
    const closed = once(this.socket, 'close');
    this.socket.end();
    await closed;
  }
}

const signals = [0, 1, 0, 1, 1, 0, 1, 0];
const measures = [2300, 2310, 2290, 5000, -125, 0, 1234, 42];
const request = (oa, qoi = 20, ca = 7) => [100, 1, 0x86, oa, ca & 0xff, ca >> 8, 0, 0, 0, qoi];
async function totalCall(master, oa, fragmented = false, qoi = 20, ca = 7) {
  await master.send(request(oa, qoi, ca), fragmented);
  await readTotalCall(master, oa, qoi);
}

async function readTotalCall(master, oa, qoi = 20, busyRequests = []) {
  const original = request(oa, qoi);
  const count = qoi === 20 ? 6 : 4;
  const busyReplies = busyRequests.map(payload => {
    const expected = [...payload]; expected[2] = 0xc7;
    if (expected[4] === 0xff && expected[5] === 0xff) { expected[4] = 7; expected[5] = 0; }
    return Buffer.from(expected);
  });
  for (let f = 0; f < count || busyReplies.length;) {
    const asdu = await master.readASDU();
    if ((asdu[2] & 0x40) !== 0) {
      const index = busyReplies.findIndex(expected => expected.equals(asdu));
      assert(index >= 0, `Unexpected negative reply: ${asdu.toString('hex')}`);
      busyReplies.splice(index, 1);
      continue;
    }
    assert(f < count, 'Unexpected response after ACT_TERM');
    if (f === 0 || f === count - 1) {
      const expected = [...original];
      expected[2] = f === 0 ? 0x87 : 0x8a;
      assert.deepEqual([...asdu], expected);
    } else {
      const digital = qoi === 20 ? f < 3 : qoi === 21;
      const width = digital ? 4 : 6;
      const first = (qoi === 20 && !digital ? f - 3 : f - 1) * 4;
      assert.equal(asdu.length, 6 + width * 4);
      assert.deepEqual([...asdu.subarray(0, 6)], [digital ? 1 : 11, 4, 0x80 | qoi, oa, 7, 0]);
      for (let p = 0; p < 4; p++) {
        const offset = 6 + p * width;
        assert.equal(asdu.readUIntLE(offset, 3), (digital ? 1001 : 2001) + first + p);
        if (digital) assert.equal(asdu[offset + 3], signals[first + p]);
        else {
          assert.equal(asdu.readInt16LE(offset + 3), measures[first + p]);
          assert.equal(asdu[offset + 5], 0);
        }
      }
    }
    f++;
  }
}

async function main() {
  const help = spawnSync(executable, ['--help'], { windowsHide: true, encoding: 'utf8' });
  assert.ifError(help.error);
  assert.equal(help.status, 0, help.stderr);
  assert(help.stdout.includes('--run-ms'));
  const invalid = spawnSync(executable, ['--ca', '0'], { windowsHide: true, encoding: 'utf8' });
  assert.ifError(invalid.error);
  assert.equal(invalid.status, 1);
  const child = spawn(executable, ['--port', '0', '--ca', '7', '--window', '1', '--run-ms', '4000'],
    { windowsHide: true, stdio: ['ignore', 'pipe', 'pipe'] });
  let output = '', errors = '';
  const sockets = [];
  child.stdout.on('data', data => { output += data.toString(); });
  child.stderr.on('data', data => { errors += data.toString(); });
  const exit = once(child, 'exit');
  const deadline = setTimeout(() => { child.kill(); }, 9000);
  try {
    const port = await new Promise((resolve, reject) => {
      const timer = setTimeout(() => reject(new Error(`No listening port: ${output} ${errors}`)), 2000);
      child.once('error', error => { clearTimeout(timer); reject(error); });
      child.stdout.on('data', () => {
        const match = output.match(/LISTEN 127\.0\.0\.1:(\d+) CA=7/);
        if (match) { clearTimeout(timer); resolve(Number(match[1])); }
      });
    });
    async function connect() {
      const socket = net.connect({ host: '127.0.0.1', port });
      sockets.push(socket);
      const master = new Master(socket);
      await once(socket, 'connect');
      await master.control(7, 0x0b);
      return master;
    }
    const master = await connect();
    await totalCall(master, 0x5a, true);
    await totalCall(master, 0x5b, false, 21);
    await totalCall(master, 0x5c, false, 22);
    // 广播请求的确认、数据和终止均按实际本站CA=7核对。
    await totalCall(master, 0x5d, true, 20, 65535);
    await totalCall(master, 0x5e, false, 21, 65535);
    await totalCall(master, 0x5f, false, 22, 65535);
    // 连续提交不同QOI：只执行第一个，后两个否定；结束后由主站重发才执行。
    const burst = [[0x31, 22, 65535], [0x32, 20, 65535], [0x33, 21, 7]];
    master.socket.write(Buffer.concat(burst.map(([oa, qoi, ca]) => master.frame(request(oa, qoi, ca)))));
    await readTotalCall(master, 0x31, 22, burst.slice(1).map(([oa, qoi, ca]) => request(oa, qoi, ca)));
    for (const [oa, qoi] of burst.slice(1)) await totalCall(master, oa, false, qoi);
    for (const [index, value, cot] of [[4, 8, 46], [9, 37, 7], [9, 36, 7], [0, 200, 44]]) {
      const invalidRequest = request(0x55);
      invalidRequest[index] = value;
      if (index === 9) { invalidRequest[4] = invalidRequest[5] = 0xff; }
      await master.send(invalidRequest);
      const expected = [...invalidRequest];
      expected[2] = 0xc0 | cot;
      if (index === 9) { expected[4] = 7; expected[5] = 0; }
      assert.deepEqual([...(await master.readASDU())], expected);
    }
    // 同一接收批次的激活/撤销在驱动业务前按FIFO处理；随后重复撤销应否定确认。
    const activation = request(0x4a, 21, 65535);
    const deactivation = request(0x4a, 21); deactivation[2] = 0x88;
    master.socket.write(Buffer.concat([master.frame(activation), master.frame(deactivation)]));
    const deactCon = [...deactivation]; deactCon[2] = 0x89;
    assert.deepEqual([...(await master.readASDU())], deactCon);
    deactivation[4] = deactivation[5] = 0xff;
    await master.send(deactivation);
    deactCon[2] = 0xc9;
    assert.deepEqual([...(await master.readASDU())], deactCon);
    await master.control(0x13, 0x23);
    await master.control(7, 0x0b);
    await totalCall(master, 0x6b);
    await master.close();
    const next = await connect();
    await totalCall(next, 0x7c);
    await next.close();
    const [code] = await exit;
    assert.equal(code, 0, `${output}\n${errors}`);
    assert.match(output, /STOP submitted=62 gi_submitted=11 /);
    assert.match(output, /deactivated=1 timeouts=0/);
    assert.match(output, /negative_submitted=\d+ dropped_requests=0/);
    assert.equal(errors, '');
    console.log('Slave example loopback: passed (real TCP, station/groups and broadcast CA, busy rejection and retry, broadcast/directed deactivation, fragmented input, k=1 ACK, errors, STOP/START, reconnect, cleanup)');
  } finally {
    clearTimeout(deadline);
    for (const socket of sockets) socket.destroy();
    if (child.exitCode === null) child.kill();
  }
}

main().catch(error => { console.error(error); process.exitCode = 1; });