/*
 * Copyright (c) 2014-2021 Thetya Team
 * Copyright (c) 2005-2011 Three Rings
 *
 * https://github.com/Thetya
 */

package com.github.thetya.tools;

import static com.github.thetya.tools.Log.log;

import com.threerings.presents.util.SecureUtil;
import java.io.FileWriter;
import java.io.IOException;
import java.security.KeyPair;

/**
 * A simple utility to generate RSA key pairs, using the {@link SecureUtil#genRSAKeyPair(int)}
 * method. The generated keys are outputted to a plaintext file or the standard output, if saving to
 * a file is impossible.
 */
public class RsaKeypairGenerator {

  /**
   * Used during the key pair generation, determines the key bits.
   */
  private static int keyBits = 2048;

  public static void main(final String... args) {
    if (args.length > 0) {
      try {
        keyBits = Integer.parseInt(args[0]);
      } catch (NumberFormatException e) {
        log.warning(
            "The passed argument is not an integer, falling back to the default key bits value.",
            "input",
            args[0]);
      }
    }

    log.info("Generating a new RSA key pair...", "keyBits", keyBits);

    // First generate the key pair itself.
    final KeyPair rsaKeyPair = SecureUtil.genRSAKeyPair(keyBits);

    // Now get the keys
    final String privateKey = SecureUtil.RSAKeyToString(rsaKeyPair.getPrivate());
    final String publicKey = SecureUtil.RSAKeyToString(rsaKeyPair.getPublic());

    try {
      final FileWriter writer = new FileWriter("keys.txt");
      writer.append("PUBLIC KEY\n");
      writer.append(publicKey);
      writer.append("\n\n");
      writer.append("PRIVATE KEY\n");
      writer.append(privateKey);

      writer.flush();
      writer.close();

      log.info("Done, see keys.txt.");
    } catch (IOException e) {
      log.warning(
          "Could not open a file writer, outputting the keys to the log instead.",
          "public",
          publicKey,
          "private",
          privateKey);
    }
  }
}