'use strict';

const assert = require('node:assert/strict');
const net = require('node:net');
const path = require('node:path');

const ROOT = path.resolve(__dirname, '..');

function listenEphemeral() {
  return new Promise((resolve, reject) => {
    const server = net.createServer();
    server.once('error', reject);
    server.listen(0, '127.0.0.1', () => resolve(server));
  });
}

async function main() {
  const previousFlowPort = process.env.QIWEI_FLOW_PORT;
  const blocker = await listenEphemeral();
  try {
    const occupiedPort = blocker.address().port;
    process.env.QIWEI_FLOW_PORT = String(occupiedPort);
    const { canListen, defaultFlowPort, selectFlowPort } = require(path.join(ROOT, 'bin', 'qiwei-training.js'));
    const selectedPort = await selectFlowPort(4320);

    assert.equal(defaultFlowPort(4320), 4310);
    assert.notEqual(selectedPort, occupiedPort);
    assert.equal(await canListen(selectedPort), true);

    process.stdout.write(`${JSON.stringify({
      status: 'ok',
      checks: 3,
      coverage: [
        'default_dashboard_flow_port_pair',
        'occupied_flow_port_selects_next_available_port',
        'selected_flow_port_is_listenable',
      ],
    }, null, 2)}\n`);
  } finally {
    await new Promise(resolve => blocker.close(resolve));
    if (previousFlowPort === undefined) delete process.env.QIWEI_FLOW_PORT;
    else process.env.QIWEI_FLOW_PORT = previousFlowPort;
  }
}

main().catch(error => {
  process.stderr.write(`${error.stack || error.message}\n`);
  process.exitCode = 1;
});