'use strict';
// Chafon H102 probe: scan baud rates, attempt GET_ALL_PARAM, attempt SET interface to CDC_COM

const { SerialPort } = require('serialport');
const PORT  = process.env.RFID_PORT || '/dev/cu.usbserial-5130';
const BAUDS = [115200, 9600, 38400, 57600, 19200];

function crc16(buf) {
  let crc = 0xFFFF;
  for (const b of buf) {
    crc ^= b;
    for (let i = 0; i < 8; i++)
      crc = (crc & 1) ? ((crc >> 1) ^ 0x8408) : (crc >> 1);
  }
  return crc;
}

function frame(cmd, data = Buffer.alloc(0)) {
  const hdr  = Buffer.from([0xCF, 0x00, cmd[0], cmd[1], data.length]);
  const body = Buffer.concat([hdr, data]);
  const chk  = crc16(body);
  const f    = Buffer.concat([body, Buffer.from([(chk >> 8) & 0xFF, chk & 0xFF])]);
  console.log(`  TX: ${f.toString('hex').replace(/../g,'$& ').trim().toUpperCase()}`);
  return f;
}

const CMD_INVENTORY  = [0x00, 0x01];
const CMD_GET_PARAM  = [0x00, 0x72];
const CMD_SET_PARAM  = [0x00, 0x71];

// AllParamBean minimal structure to set interface to CDC_COM (0x04)
// Based on SDK doc: mInterface byte is first param byte.
// We send a minimal known-safe config: keep everything default, just flip interface.
// Structure (from SDK AllParamBean): interface(1) baud(1) addr(1) power(1) ...
// We'll use GET_PARAM first to read existing values then patch interface byte.

function tryPort(baud) {
  return new Promise(resolve => {
    console.log(`\n── Testing ${baud} baud ──`);
    const port = new SerialPort({ path: PORT, baudRate: baud, autoOpen: false });
    port.open(err => {
      if (err) { console.log(`  open error: ${err.message}`); return resolve(null); }

      let buf = Buffer.alloc(0);
      let resolved = false;
      const done = (result) => {
        if (resolved) return;
        resolved = true;
        port.close(() => resolve(result));
      };

      port.on('data', chunk => {
        const hex = chunk.toString('hex').replace(/../g,'$& ').trim().toUpperCase();
        const asc = chunk.toString().replace(/[^\x20-\x7E]/g, '.');
        console.log(`  RX: ${hex}  "${asc}"`);
        buf = Buffer.concat([buf, chunk]);
      });

      // Send inventory first (simplest command)
      port.write(frame(CMD_INVENTORY));

      setTimeout(() => {
        if (buf.length > 0) {
          console.log(`  ✓ Got ${buf.length} bytes at ${baud} baud`);
          done({ baud, buf });
        } else {
          console.log(`  ✗ No response at ${baud} baud`);
          done(null);
        }
      }, 2000);
    });
  });
}

async function getAndPatchConfig(baud) {
  return new Promise(resolve => {
    console.log(`\n── GET_ALL_PARAM at ${baud} baud ──`);
    const port = new SerialPort({ path: PORT, baudRate: baud, autoOpen: false });
    port.open(err => {
      if (err) return resolve(false);

      let buf = Buffer.alloc(0);
      port.on('data', chunk => {
        buf = Buffer.concat([buf, chunk]);
        const hex = chunk.toString('hex').replace(/../g,'$& ').trim().toUpperCase();
        console.log(`  RX: ${hex}`);
      });

      port.write(frame(CMD_GET_PARAM));

      setTimeout(() => {
        if (buf.length < 7) {
          console.log('  No config response received');
          port.close(() => resolve(false));
          return;
        }

        // Response: CF ADDR CMD_H CMD_L LEN STATUS DATA... CRC_H CRC_L
        // DATA is the AllParamBean bytes — patch interface byte (index 0 of data = STATUS+0)
        // status = buf[5], param data starts at buf[6]
        const status = buf[5];
        console.log(`  GET_PARAM status: 0x${status.toString(16)}`);
        if (status !== 0x00) {
          port.close(() => resolve(false));
          return;
        }

        const paramData = buf.slice(6, buf.length - 2); // strip CRC
        console.log(`  Param bytes: ${paramData.toString('hex').replace(/../g,'$& ').trim().toUpperCase()}`);
        console.log(`  Current interface byte: 0x${paramData[0]?.toString(16)}`);

        // Patch interface byte to 0x04 (CDC_COM serial mode)
        paramData[0] = 0x04;
        console.log(`  Setting interface to 0x04 (CDC_COM)...`);
        port.write(frame(CMD_SET_PARAM, paramData));

        setTimeout(() => {
          const hex2 = buf.slice(paramData.length + 9).toString('hex').replace(/../g,'$& ').trim().toUpperCase();
          console.log(`  SET_PARAM response raw: ${hex2 || '(none yet)'}`);
          port.close(() => resolve(true));
        }, 2000);
      }, 2000);
    });
  });
}

async function main() {
  console.log(`Probing ${PORT}`);
  console.log('Place a tag on the reader if you have one handy.\n');

  let workingBaud = null;
  for (const baud of BAUDS) {
    const result = await tryPort(baud);
    if (result) { workingBaud = result.baud; break; }
  }

  if (!workingBaud) {
    console.log('\n━━━ No response at any baud rate ━━━');
    console.log('Device is likely in USB-HID keyboard wedge mode.');
    console.log('Serial port (CH340) is present but firmware is not routing data to it.');
    console.log('\nFix: use Chafon CfTech Android app over BLE to change Interface setting');
    console.log('     to "CDC_COM" (0x04) or "USB" (0x01), then reconnect USB.');
    console.log('\nSafer option: use one of the shop Android tablets (not your Pixel).');
    return;
  }

  console.log(`\n✓ Device communicating at ${workingBaud} baud`);
  await getAndPatchConfig(workingBaud);
  console.log('\nDone. If SET_PARAM succeeded, unplug and replug the H102 USB.');
  console.log(`Then restart the daemon with: RFID_BAUD=${workingBaud} node index.js`);
  console.log('(or update BAUD_RATE in index.js if it differs from 115200)');
}

main().catch(console.error);