/**
 * Copyright 2009 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 org.waveprotocol.wave.examples.fedone.waveserver;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import com.google.inject.name.Named;
import com.google.protobuf.ByteString;

import org.waveprotocol.wave.crypto.WaveSigner;
import org.waveprotocol.wave.examples.fedone.waveserver.CertificateManager.SignatureResultListener;
import org.waveprotocol.wave.federation.Proto.ProtocolSignedDelta;
import org.waveprotocol.wave.federation.Proto.ProtocolWaveletDelta;

import java.util.concurrent.ScheduledExecutorService;

@Singleton
public class DeltaSignerProvider  implements Provider<DeltaSigner> {

  private int maximumDeltaBundleSize;
  private int bundlingAccumulationDelayMs;
  private final WaveSigner waveSigner;
  private final ScheduledExecutorService executor;

  @Inject
  public DeltaSignerProvider(ScheduledExecutorService executor,
    @Named("maximum_delta_bundle_size") int maximumDeltaBundleSize,
    @Named("delta_bundling_accumulation_delay_ms") int bundlingAccumulationDelayMs,
    WaveSigner waveSigner) {

    Preconditions.checkArgument(maximumDeltaBundleSize > 0, "Max delta bundle size must be >= 1.");
    Preconditions.checkArgument(bundlingAccumulationDelayMs >= 0, "Delta bundling accumulation " +
    		"delay must be >= 0");
    this.executor = executor;
    this.waveSigner = waveSigner;
    this.maximumDeltaBundleSize = maximumDeltaBundleSize;
    this.bundlingAccumulationDelayMs = bundlingAccumulationDelayMs;
  }

  @Override
  public DeltaSigner get() {
    Preconditions.checkArgument(maximumDeltaBundleSize > 0);
    if (maximumDeltaBundleSize == 1) {
      return getSimpleDeltaSigner(waveSigner);
    } else {
      return new BundlingDeltaSigner(
          executor,
          waveSigner, maximumDeltaBundleSize,
          bundlingAccumulationDelayMs);
    }
  }

  /**
   * Simple signer, signs the delta and immediately calls the resultListener.
   * @return the signed delta with a non-bundle signature.
   */
  @VisibleForTesting
  static DeltaSigner getSimpleDeltaSigner(final WaveSigner waveSigner) {
    return new DeltaSigner() {

      @Override
      public void sign(ByteStringMessage<ProtocolWaveletDelta> delta,
          SignatureResultListener resultListener) {
        ProtocolSignedDelta.Builder signedDelta = ProtocolSignedDelta.newBuilder();
        ByteString deltaBytes =  delta.getByteString();
        signedDelta.setDelta(deltaBytes);
        signedDelta.addAllSignature(ImmutableList.of(waveSigner.sign(deltaBytes.toByteArray()).build()));
        resultListener.signatureResult(signedDelta.build());
      }

    };
  }
}