import { sleep } from '@/infrastructure/Threading/AsyncSleep';
import type { IUrlStatus } from './IUrlStatus';

const DefaultBaseRetryIntervalInMs = 5 /* sec */ * 1000;

export async function retryWithExponentialBackOff(
  action: () => Promise<IUrlStatus>,
  baseRetryIntervalInMs: number = DefaultBaseRetryIntervalInMs,
  currentRetry = 1,
): Promise<IUrlStatus> {
  const maxTries = 3;
  const status = await action();
  if (shouldRetry(status)) {
    if (currentRetry <= maxTries) {
      const exponentialBackOffInMs = getRetryTimeoutInMs(currentRetry, baseRetryIntervalInMs);
      console.log(`Retrying (${currentRetry}) in ${exponentialBackOffInMs / 1000} seconds`, status);
      await sleep(exponentialBackOffInMs);
      return retryWithExponentialBackOff(action, baseRetryIntervalInMs, currentRetry + 1);
    }
  }
  return status;
}

function shouldRetry(status: IUrlStatus) {
  if (status.error) {
    return true;
  }
  if (status.code === undefined) {
    return true;
  }
  return isTransientError(status.code)
    || status.code === 429; // Too Many Requests
}

function isTransientError(statusCode: number) {
  return statusCode >= 500 && statusCode <= 599;
}

function getRetryTimeoutInMs(
  currentRetry: number,
  baseRetryIntervalInMs: number = DefaultBaseRetryIntervalInMs,
) {
  const retryRandomFactor = 0.5; // Retry intervals are between 50% and 150%
  // of the exponentially increasing base amount
  const minRandom = 1 - retryRandomFactor;
  const maxRandom = 1 + retryRandomFactor;
  const randomization = (Math.random() * (maxRandom - minRandom)) + maxRandom;
  const exponential = 2 ** (currentRetry - 1);
  return Math.ceil(exponential * baseRetryIntervalInMs * randomization);
}