// 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.prf;

import com.google.crypto.tink.PrimitiveSet;
import com.google.crypto.tink.PrimitiveWrapper;
import com.google.crypto.tink.Registry;
import com.google.crypto.tink.proto.OutputPrefixType;
import com.google.errorprone.annotations.Immutable;
import java.security.GeneralSecurityException;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

PrfSetWrapper is the implementation of PrimitiveWrapper for the PrfSet primitive.
The returned primitive has instances of Prf for each key in the KeySet. The individual Prf instances can then be used to compute psuedo-random sequences from the underlying key. /**
 * PrfSetWrapper is the implementation of PrimitiveWrapper for the PrfSet primitive.
 *
 * <p>The returned primitive has instances of {@code Prf} for each key in the KeySet. The individual
 * Prf instances can then be used to compute psuedo-random sequences from the underlying key.
 */
@Immutable
public class PrfSetWrapper implements PrimitiveWrapper<PrfSet> {
  private static class WrappedPrfSet extends PrfSet {
    // This map is constructed using Collections.unmodifiableMap
    @SuppressWarnings("Immutable")
    private final Map<Integer, Prf> keyIdToPrfMap;

    private final int primaryKeyId;

    private WrappedPrfSet(PrimitiveSet<PrfSet> primitives) throws GeneralSecurityException {
      if (primitives.getRawPrimitives().isEmpty()) {
        throw new GeneralSecurityException("No primitives provided.");
      }
      if (primitives.getPrimary() == null) {
        throw new GeneralSecurityException("Primary key not set.");
      }

      primaryKeyId = primitives.getPrimary().getKeyId();
      List<PrimitiveSet.Entry<PrfSet>> entries = primitives.getRawPrimitives();
      Map<Integer, Prf> mutablePrfMap = new HashMap<>();
      for (PrimitiveSet.Entry<PrfSet> entry : entries) {
        if (!entry.getOutputPrefixType().equals(OutputPrefixType.RAW)) {
          throw new GeneralSecurityException(
              "Key " + entry.getKeyId() + " has non raw prefix type");
        }
        // PrfSets pushed into this wrapper should have have only one key with ID '0'.
        if (entry.getPrimitive().getPrfs().size() > 1) {
          throw new GeneralSecurityException(
              "More PRFs than expected in KeyTypeManager for key " + entry.getKeyId());
        }
        // Likewise, the key IDs of the PrfSet passed
        mutablePrfMap.put(
            entry.getKeyId(),
            entry.getPrimitive().getPrfs().get(entry.getPrimitive().getPrimaryId()));
      }
      keyIdToPrfMap = Collections.unmodifiableMap(mutablePrfMap);
    }

    @Override
    public int getPrimaryId() {
      return primaryKeyId;
    }

    @Override
    public Map<Integer, Prf> getPrfs() throws GeneralSecurityException {
      return keyIdToPrfMap;
    }
  }

  @Override
  public PrfSet wrap(PrimitiveSet<PrfSet> set) throws GeneralSecurityException {
    return new WrappedPrfSet(set);
  }

  @Override
  public Class<PrfSet> getPrimitiveClass() {
    return PrfSet.class;
  }

  public static void register() throws GeneralSecurityException {
    Registry.registerPrimitiveWrapper(new PrfSetWrapper());
  }
}