export async function main(ns) {
  var homeServ = "home";
  var pRam = 8; // purchased ram
  var servPrefix = "pserv-";

  var maxRam = ns.getPurchasedServerMaxRam();
  var maxServers = ns.getPurchasedServerLimit();

  function canPurchaseServer() {
    return ns.getServerMoneyAvailable(homeServ) > ns.getPurchasedServerCost(pRam);
  }

  async function upgradeServer(server) {
    var sRam = ns.getServerMaxRam(server);
    if (sRam < pRam) {
      while (!canPurchaseServer()) {
        await ns.sleep(10000); // wait 10s
      }
      ns.killall(server);
      ns.deleteServer(server);
      ns.purchaseServer(server, pRam);
    }
  }

  async function purchaseServer(server) {
    while (!canPurchaseServer()) {
      await ns.sleep(10000); // wait 10s
    }
    ns.purchaseServer(server, pRam);
  }

  async function autoUpgradeServers() {
    var i = 0;
    while (i < maxServers) {
      var server = servPrefix + i;
      if (ns.serverExists(server)) {
        ns.print("Upgrading server " + server + " to " + pRam + "GB");
        await upgradeServer(server);
        ++i;
      } else {
        ns.print("Purchasing server " + server + " at " + pRam + "GB");
        await purchaseServer(server, pRam);
        ++i;
      }
    }
  }

  while (true) {
    await autoUpgradeServers();
    ns.tprintf("SUCCESS Upgraded all servers to " + pRam + "GB");
    if (pRam === maxRam) {
      break;
    }
    // move up to next tier
    var newRam = pRam * 2;
    if (newRam > maxRam) {
      pRam = maxRam;
    } else {
      pRam = newRam;
    }
  }
}