import { exec, execSync } from "child_process";
import { createHash } from "crypto";

type MixedOrNative = "mixed" | "native" | "";

const win32RegBinPath: Record<MixedOrNative, string> = {
  native: "%windir%\\System32",
  mixed: "%windir%\\sysnative\\cmd.exe /c %windir%\\System32",
  "": ""
};

const guid: Partial<Record<NodeJS.Platform, string>> = {
  darwin: "ioreg -rd1 -c IOPlatformExpertDevice",
  win32:
    `${
      win32RegBinPath[isWindowsProcessMixedOrNativeArchitecture()]
    }\\REG.exe ` +
    "QUERY HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Cryptography " +
    "/v MachineGuid",
  linux:
    "( cat /var/lib/dbus/machine-id /etc/machine-id 2> /dev/null || hostname ) | head -n 1 || :",
  freebsd: "kenv -q smbios.system.uuid || sysctl -n kern.hostuuid"
};

function isWindowsProcessMixedOrNativeArchitecture(): MixedOrNative | "" {
  // detect if the node binary is the same arch as the Windows OS.
  // or if this is 32 bit node on 64 bit windows.
  if (process.platform !== "win32") {
    return "";
  }
  if (
    process.arch === "ia32" &&
    process.env.hasOwnProperty("PROCESSOR_ARCHITEW6432")
  ) {
    return "mixed";
  }
  return "native";
}

function hash(guid: string): string {
  return createHash("sha256")
    .update(guid)
    .digest("hex");
}

function expose(result: string): string {
  switch (process.platform) {
    case "darwin":
      return result
        .split("IOPlatformUUID")[1]
        .split("\n")[0]
        .replace(/\=|\s+|\"/gi, "")
        .toLowerCase();
    case "win32":
      return result
        .toString()
        .split("REG_SZ")[1]
        .replace(/\r+|\n+|\s+/gi, "")
        .toLowerCase();
    case "linux":
      return result
        .toString()
        .replace(/\r+|\n+|\s+/gi, "")
        .toLowerCase();
    case "freebsd":
      return result
        .toString()
        .replace(/\r+|\n+|\s+/gi, "")
        .toLowerCase();
    default:
      throw new Error(`Unsupported platform: ${process.platform}`);
  }
}

export function machineIdSync(original: boolean): string {
  const id: string = expose(execSync(guid[process.platform]!).toString());
  return original ? id : hash(id);
}

export function machineId(original: boolean): Promise<string> {
  return new Promise((resolve, reject) => {
    const g = guid[process.platform];
    if (!g) {
      return reject(new Error(`Error while obtaining machine id`));
    }
    return exec(g, {}, (err, stdout) => {
      if (err) {
        return reject(
          new Error(`Error while obtaining machine id: ${err.stack}`)
        );
      }
      const id: string = expose(stdout.toString());
      return resolve(original ? id : hash(id));
    });
  });
}