/**
 * Node regression tests for Web Serial readUntil buffer handling.
 * Run: node led-tool/static/web_serial_readuntil_test.mjs
 */

function bytesIndexOf(buf, suffix) {
  if (!suffix.length) return 0;
  if (buf.length < suffix.length) return -1;
  for (let i = 0; i <= buf.length - suffix.length; i += 1) {
    let ok = true;
    for (let j = 0; j < suffix.length; j += 1) {
      if (buf[i + j] !== suffix[j]) {
        ok = false;
        break;
      }
    }
    if (ok) return i;
  }
  return -1;
}

function readUntilConsume(rxBuf, suffixBytes) {
  const idx = bytesIndexOf(rxBuf, suffixBytes);
  if (idx < 0) return null;
  const end = idx + suffixBytes.length;
  const matched = rxBuf.slice(0, end);
  rxBuf.splice(0, end);
  return matched;
}

function enc(s) {
  return [...new TextEncoder().encode(s)];
}

function assert(cond, msg) {
  if (!cond) throw new Error(msg);
}

const RAW = 'raw REPL; CTRL-B to exit\r\n';
const SOFT = 'soft reboot\r\n';

// Old bug: one chunk with soft reboot + banner; suffix-at-end + clear-all loses banner.
{
  const rx = enc(`MPY: ${SOFT}${RAW}boot.py line\r\n`);
  const soft = enc(SOFT);
  const m1 = readUntilConsume(rx, soft);
  assert(m1 !== null, 'soft reboot should match');
  const banner = enc(RAW);
  const m2 = readUntilConsume(rx, banner);
  assert(m2 !== null, 'banner must remain in buffer after soft reboot match');
  assert(rx.length > 0, 'boot.py tail should remain after banner');
}

// Banner anywhere in buffer, not only at end.
{
  const rx = enc(`noise${RAW}>>> `);
  const banner = enc(RAW);
  const m = readUntilConsume(rx, banner);
  assert(m !== null, 'banner should match mid-buffer');
}

// MPY: soft reboot marker
{
  const rx = enc(`MPY: ${SOFT}`);
  const soft = enc('MPY: soft reboot\r\n');
  assert(readUntilConsume(rx, soft) !== null, 'MPY soft reboot marker');
}

console.log('web_serial_readuntil_test: ok');