determineMFE.js

const determineMFE = (event, logger, mfe, user) => {
  const defaultVersion = mfe.versions.find((v) => v.deployment.default);
  try {
    if (mfe.versions.length === 1) return mfe.versions[0];

    const versionString = mfe.versions.reduce(
      (res, cur) => `${res}-${cur.metadata.version}`,
      ""
    );
    const mfeHash = hashCode(mfe.mfeName + versionString);
    const userHash = hashCode(user);
    const mod = Math.abs((mfeHash + userHash) % 100);
    let iterator = 0;
    let deploymentVersion;

    for (let version of mfe.versions) {
      iterator += version.deployment.traffic;
      if (iterator >= mod) {
        deploymentVersion = version;
        break;
      }
    }

    if (deploymentVersion) return deploymentVersion;

    return defaultVersion;
  } catch (e) {
    logger.error({
      audit: {
        user,
        ipAddress: event.requestContext?.identity?.sourceIp ?? "Unknown",
        method: "GetProjectFrontends",
        projectId: mfe.projectId,
        microFrontendId: mfe.microFrontendId,
        statusCode: 200,
      },
    });
    logger.error(e);
    return defaultVersion;
  }
};

export const hashCode = (str) => {
  let hash = 0,
    i,
    chr;
  if (str.length === 0) return hash;
  for (i = 0; i < str.length; i++) {
    chr = str.charCodeAt(i);
    hash = (hash << 5) - hash + chr;
    hash |= 0;
  }
  return hash;
};

export default determineMFE;