// Copyright 2017 Google Inc.
//
// Licensed 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
//
//      http://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 com.google.crypto.tink.streamingaead;

import com.google.crypto.tink.PrimitiveSet;
import com.google.crypto.tink.StreamingAead;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.SeekableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.security.GeneralSecurityException;

A helper for creating StreamingAead-primitives from keysets. /**
 * A helper for creating {@link StreamingAead}-primitives from keysets.
 */
final class StreamingAeadHelper implements StreamingAead {
  PrimitiveSet<StreamingAead> primitives;

  
Creates a helper that uses the provided primitives for encryption
and decryption of data provided via channels.
For encryption it uses the primitive corresponding to the primary key.
For decryption it uses an enabled primitive that matches the given ciphertext.
/**
   * Creates a helper that uses the provided primitives for encryption
   * and decryption of data provided via channels.
   * For encryption it uses the primitive corresponding to the primary key.
   * For decryption it uses an enabled primitive that matches the given ciphertext.
   */
  public StreamingAeadHelper(PrimitiveSet<StreamingAead> primitives)
      throws GeneralSecurityException {
    if (primitives.getPrimary() == null) {
      throw new GeneralSecurityException("Missing primary primitive.");
    }
    this.primitives = primitives;
  }

  @Override
  public WritableByteChannel newEncryptingChannel(
      WritableByteChannel ciphertextDestination, byte[] associatedData)
      throws GeneralSecurityException, IOException {
    return primitives.getPrimary().getPrimitive()
        .newEncryptingChannel(ciphertextDestination, associatedData);
  }

  @Override
  public ReadableByteChannel newDecryptingChannel(
      ReadableByteChannel ciphertextChannel, byte[] associatedData)
      throws GeneralSecurityException, IOException {
    return new ReadableByteChannelDecrypter(primitives, ciphertextChannel, associatedData);
  }

  @Override
  public SeekableByteChannel newSeekableDecryptingChannel(
      SeekableByteChannel ciphertextChannel, byte[] associatedData)
      throws GeneralSecurityException, IOException {
    return new SeekableByteChannelDecrypter(primitives, ciphertextChannel, associatedData);
  }

  @Override
  public InputStream newDecryptingStream(
      InputStream ciphertextStream,
      byte[] associatedData)
      throws GeneralSecurityException, IOException {
    return new InputStreamDecrypter(primitives, ciphertextStream, associatedData);
  }

  @Override
  public OutputStream newEncryptingStream(
      OutputStream ciphertext, byte[] associatedData)
      throws GeneralSecurityException, IOException {
    return primitives.getPrimary().getPrimitive()
        .newEncryptingStream(ciphertext, associatedData);
  }
}