ase the current version by 1 and use ".0a1" to point to the first Nightly.
    // We do not support forward compatibility at all.
    maxVersion: localMajorVersion + 1 + ".0a1",
  };
}

/**
 * Tells if the remote device is using a supported version of Firefox.
 *
 * @param {DevToolsClient} devToolsClient
 *        DevToolsClient instance connected to the target remote Firefox.
 * @return Object with the following attributes:
 *   * String status, one of COMPATIBILITY_STATUS
 *            COMPATIBLE if the runtime is compatible,
 *            TOO_RECENT if the runtime uses a too recent version,
 *            TOO_OLD if the runtime uses a too old version.
 *   * String minVersion
 *            The minimum supported version.
 *   * String runtimeVersion
 *            The remote runtime version.
 *   * String localID
 *            Build ID of local runtime. A date with like this: YYYYMMDD.
 *   * String deviceID
 *            Build ID of remote runtime. A date with like this: YYYYMMDD.
 */
async function checkVersionCompatibility(devToolsClient) {
  const localDescription = {
    appbuildid: Services.appinfo.appBuildID,
    platformversion: AppConstants.MOZ_APP_VERSION,
  };

  try {
    const deviceFront = await devToolsClient.mainRoot.getFront("device");
    const description = await deviceFront.getDescription();
    return _compareVersionCompatibility(localDescription, description);
  } catch (e) {
    // If we failed to retrieve the device description, assume we are trying to connect to
    // a really old version of Firefox.
    const localVersion = localDescription.platformversion;
    const { minVersion } = computeMinMaxVersion(localVersion);
    return {
      minVersion,
      runtimeVersion: "<55",
      status: COMPATIBILITY_STATUS.TOO_OLD,
    };
  }
}
exports.checkVersionCompatibility = checkVersionCompatibility;

function _compareVersionCompatibility(localDescription, deviceDescription) {
  const runtimeID = deviceDescription.appbuildid.substr(0, 8);
  const localID = localDescription.appbuildid.substr(0, 8);

  const runtimeDate = getDateFromBuildID(runtimeID);
  const localDate = getDateFromBuildID(localID);

  const runtimeVersion = deviceDescription.platformversion;
  const localVersion = localDescription.platformversion;

  const { minVersion, maxVersion } = computeMinMaxVersion(localVersion);
  const isTooOld = Services.vc.compare(runtimeVersion, minVersion) < 0;
  const isTooRecent = Services.vc.compare(runtimeVersion, maxVersion) >= 0;

  const runtimeMajorVersion = getMajorVersion(runtimeVersion);
  const localMajorVersion = getMajorVersion(localVersion);
  const isSameMajorVersion = runtimeMajorVersion === localMajorVersion;

  let status;
  if (isTooOld) {
    if (runtimeMajorVersion === 68 && deviceDescription.os === "Android") {
      status = COMPATIBILITY_STATUS.TOO_OLD_FENNEC;
    } else {
      status = COMPATIBILITY_STATUS.TOO_OLD;
    }
  } else if (isTooRecent) {
    status = COMPATIBILITY_STATUS.TOO_RECENT;
  } else if (isSameMajorVersion && runtimeDate - localDate > 7 * MS_PER_DAY) {
    // If both local and remote runtimes have the same major version, compare build dates.
    // This check is useful for Gecko developers as we might introduce breaking changes
    // within a Nightly cycle.
    // Still allow devices to be newer by up to a week. This accommodates those with local
    // device builds, since their devices will almost always be newer than the client.
    status = COMPATIBILITY_STATUS.TOO_RECENT;
  } else {
    status = COMPATIBILITY_STATUS.COMPATIBLE;
  }

  return {
    localID,
    localVersion,
    minVersion,
    runtimeID,
    runtimeVersion,
    status,
  };
}
// Exported for tests.
exports._compareVersionCompatibility = _compareVersionCompatibility;
PK