/*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package io.netty5.handler.ssl;
  
  import io.netty5.buffer.api.Buffer;
  import io.netty5.buffer.api.BufferAllocator;
  import io.netty5.buffer.api.BufferHolder;
  import io.netty5.buffer.api.SensitiveBufferAllocator;
  import io.netty5.util.CharsetUtil;
  
  import javax.security.auth.Destroyable;
  import java.security.PrivateKey;
  
  import static io.netty5.buffer.api.DefaultBufferAllocators.offHeapAllocator;
  
  /**
   * This is a special purpose implementation of a {@link PrivateKey} which allows the
   * user to pass PEM/PKCS#8 encoded key material straight into {@link OpenSslContext}
   * without having to parse and re-encode bytes in Java land.
   * <p>
   * All methods other than what's implemented in {@link PemEncoded} and {@link Destroyable}
   * throw {@link UnsupportedOperationException}s.
   *
   * @see PemEncoded
   * @see OpenSslContext
   * @see #valueOf(byte[])
   * @see #valueOf(Buffer)
   */
  public final class PemPrivateKey extends BufferHolder<PemPrivateKey> implements PrivateKey, PemEncoded {
      private static final long serialVersionUID = 7978017465645018936L;
  
      private static final byte[] BEGIN_PRIVATE_KEY = "-----BEGIN PRIVATE KEY-----\n".getBytes(CharsetUtil.US_ASCII);
      private static final byte[] END_PRIVATE_KEY = "\n-----END PRIVATE KEY-----\n".getBytes(CharsetUtil.US_ASCII);
  
      private static final String PKCS8_FORMAT = "PKCS#8";
  
      /**
       * Creates a {@link PemEncoded} value from the {@link PrivateKey}.
       */
      static PemEncoded toPEM(PrivateKey key) {
          // We can take a shortcut if the private key happens to be already
          // PEM/PKCS#8 encoded. This is the ideal case and reason why all
          // this exists. It allows the user to pass pre-encoded bytes straight
          // into OpenSSL without having to do any of the extra work.
          if (key instanceof PemEncoded) {
              return ((PemEncoded) key).copy();
          }
  
          byte[] bytes = key.getEncoded();
          if (bytes == null) {
              throw new IllegalArgumentException(key.getClass().getName() + " does not support encoding");
          }
  
          return toPEM(bytes);
      }
  
      static PemEncoded toPEM(byte[] bytes) {
          BufferAllocator allocator = SensitiveBufferAllocator.sensitiveOffHeapAllocator();
          try (Buffer encoded = allocator.copyOf(bytes);
               Buffer base64 = SslUtils.toBase64(allocator, encoded)) {
              int size = BEGIN_PRIVATE_KEY.length + base64.readableBytes() + END_PRIVATE_KEY.length;
  
              boolean success = false;
              final Buffer pem = allocator.allocate(size);
              try {
                  pem.writeBytes(BEGIN_PRIVATE_KEY);
                  pem.writeBytes(base64);
                  pem.writeBytes(END_PRIVATE_KEY);
  
                  PemValue value = new PemValue(pem);
                  success = true;
                  return value;
              } finally {
                  // Make sure we never leak that PEM Buffer if there's an Exception.
                  if (!success) {
                      pem.close();
                  }
              }
          }
      }
  
      /**
       * Creates a {@link PemPrivateKey} from raw {@code byte[]}.
       *
       * ATTENTION: It's assumed that the given argument is a PEM/PKCS#8 encoded value.
       * No input validation is performed to validate it.
      */
     public static PemPrivateKey valueOf(byte[] key) {
         return valueOf(offHeapAllocator().copyOf(key));
     }
 
     /**
      * Creates a {@link PemPrivateKey} from raw {@link Buffer}.
      *
      * ATTENTION: It's assumed that the given argument is a PEM/PKCS#8 encoded value.
      * No input validation is performed to validate it.
      */
     public static PemPrivateKey valueOf(Buffer key) {
         return new PemPrivateKey(key);
     }
 
     private PemPrivateKey(Buffer content) {
         super(content.makeReadOnly());
     }
 
     @Override
     public Buffer content() {
         if (!isAccessible()) {
             throw new IllegalStateException("PemPrivateKey is closed.");
         }
 
         return getBuffer();
     }
 
     @Override
     public PemPrivateKey copy() {
         Buffer buffer = getBuffer();
         return new PemPrivateKey(buffer.copy(true));
     }
 
     @Override
     protected PemPrivateKey receive(Buffer buf) {
         return new PemPrivateKey(buf);
     }
 
     @Override
     public byte[] getEncoded() {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public String getAlgorithm() {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public String getFormat() {
         return PKCS8_FORMAT;
     }
 
     @Override
     public void destroy() {
         close();
     }
 
     @Override
     public boolean isDestroyed() {
         return !isAccessible();
     }
 }