import { spawn } from 'node:child_process';

let input = '';
let held = null;
let keepAlive = null;
let descendant = null;
const counts = Object.create(null);

function response(command, data = {}) {
  return JSON.stringify({
    type: 'response',
    id: command.id,
    command: command.type,
    success: true,
    data,
  });
}

function writeRecord(record) {
  process.stdout.write(`${typeof record === 'string' ? record : JSON.stringify(record)}\n`);
}

function handle(command) {
  counts[command.type] = (counts[command.type] ?? 0) + 1;
  if (command.type === 'echo') {
    writeRecord(response(command, { value: command.value }));
    return;
  }
  if (command.type === 'emit_event') {
    writeRecord({ type: 'agent_start', marker: command.marker });
    writeRecord(response(command, { emitted: true }));
    return;
  }
  if (command.type === 'hold') {
    held = command;
    return;
  }
  if (command.type === 'release') {
    writeRecord(response(command, { order: 'first' }));
    if (held) {
      writeRecord(response(held, { order: 'second' }));
      held = null;
    }
    return;
  }
  if (command.type === 'partial') {
    const record = `${response(command, { partial: true })}\n`;
    process.stdout.write(record.slice(0, 7));
    setTimeout(() => process.stdout.write(record.slice(7, 19)), 5);
    setTimeout(() => process.stdout.write(record.slice(19)), 10);
    return;
  }
  if (command.type === 'malformed') {
    process.stdout.write('not-json\n');
    return;
  }
  if (command.type === 'blank') {
    process.stdout.write('\n');
    return;
  }
  if (command.type === 'invalid_utf8') {
    process.stdout.write(Buffer.from([0xff, 0x0a]));
    return;
  }
  if (command.type === 'trailing_partial') {
    process.stdout.write(response(command, { partial: true }));
    setTimeout(() => process.exit(0), 5);
    return;
  }
  if (command.type === 'large') {
    writeRecord(response(command, { value: 'x'.repeat(command.bytes ?? 4096) }));
    return;
  }
  if (command.type === 'get_state' && command.fakeRetry) {
    if (counts.get_state > 1) writeRecord(response(command, { attempts: counts.get_state }));
    return;
  }
  if (command.type === 'no_response' || command.type === 'prompt') return;
  if (command.type === 'stats') {
    writeRecord(response(command, { counts }));
    return;
  }
  if (command.type === 'stderr_secret') {
    const secret = process.env.FAKE_PI_SECRET ?? 'missing-secret';
    process.stderr.write(`${'diagnostic '.repeat(50)}\n`);
    process.stderr.write(`Authorization: Bearer ${secret}\n`);
    process.stderr.write(`token=${secret}\n`);
    writeRecord(response(command, { wrote: true }));
    return;
  }
  if (command.type === 'spawn_descendant') {
    descendant = spawn(process.execPath, ['-e', 'setInterval(() => {}, 1000)'], {
      stdio: 'ignore',
      windowsHide: true,
    });
    keepAlive = setInterval(() => {}, 1000);
    writeRecord(response(command, { pid: descendant.pid }));
    return;
  }
  if (command.type === 'crash') {
    process.exit(7);
  }
  if (command.type === 'crash_with_stderr') {
    const secret = process.env.FAKE_PI_SECRET ?? 'missing-secret';
    process.stderr.write(`Authorization: Bearer ${secret}\n`);
    process.stderr.write(`token=${secret}\n`);
    process.stderr.write(`cwd=${process.cwd()}\n`);
    process.stderr.write('worker-exit-marker\n', () => process.exit(9));
    return;
  }
  writeRecord({
    type: 'response',
    id: command.id,
    command: command.type,
    success: false,
    error: 'unsupported fake command',
  });
}

process.stdin.setEncoding('utf8');
process.stdin.on('data', (chunk) => {
  input += chunk;
  while (true) {
    const newline = input.indexOf('\n');
    if (newline === -1) break;
    const line = input.slice(0, newline).replace(/\r$/, '');
    input = input.slice(newline + 1);
    if (line) handle(JSON.parse(line));
  }
});
process.stdin.on('end', () => {
  if (!keepAlive) process.exit(0);
});
process.on('exit', () => {
  if (keepAlive) clearInterval(keepAlive);
});