import { browser } from 'k6/experimental/browser';
import encoding from 'k6/encoding';
import { open } from 'k6/experimental/fs';

export const options = {
  scenarios: {
    ui: {
      executor: 'shared-iterations',
      iterations: 1,
      vus: 1,
      options: {
        browser: {
          type: 'chromium'
        },
      },
    },
  },
}

let file;
(async function () {
  file = await open('/abs/path/to/file.txt');
})();

export default async function () {
  const page = browser.newPage();

  await page.goto(url)

  const buffer = await readAll(file);

  page.setInputFiles('input[id="upload"]', { name: 'file.txt', mimetype: 'text/plain', buffer: encoding.b64encode(buffer) })
  
  const submitButton = page.locator('input[type="submit"]')
  await Promise.all([page.waitForNavigation(), submitButton.click()])

  page.close();
}

async function readAll(file) {
  const fileInfo = await file.stat();
  const buffer = new Uint8Array(fileInfo.size);

  const bytesRead = await file.read(buffer);
  if (bytesRead !== fileInfo.size) {
    throw new Error(
      'unexpected number of bytes read; expected ' +
      fileInfo.size +
      ' but got ' +
      bytesRead +
      ' bytes'
    );
  }

  return buffer;
}