/*
 * SonarQube
 * Copyright (C) 2009-2025 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.auth.saml;

import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Base64;
import org.sonar.api.server.ServerSide;

@ServerSide
class SamlPrivateKeyConverter {

  PrivateKey toPrivateKey(String privateKeyString) {
    String cleanedPrivateKeyString = sanitizePrivateKeyString(privateKeyString);

    byte[] decoded = Base64.getDecoder().decode(cleanedPrivateKeyString);
    PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decoded);
    try {
      KeyFactory keyFactory = KeyFactory.getInstance("RSA");
      return keyFactory.generatePrivate(keySpec);
    } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
      throw new IllegalArgumentException("Error while loading PKCS8 private key, please check the format", e);
    }
  }

  private static String sanitizePrivateKeyString(String privateKeyString) {
    return privateKeyString
      .replace("-----BEGIN PRIVATE KEY-----", "")
      .replace("-----END PRIVATE KEY-----", "")
      .replaceAll("\\s+", "");
  }
}