/*
 * Copyright ConsenSys AG.
 *
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
package org.hyperledger.besu.ethereum.privacy;

import org.hyperledger.besu.crypto.Hash;
import org.hyperledger.besu.ethereum.rlp.BytesValueRLPOutput;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

import org.apache.tuweni.bytes.Bytes;

public class PrivacyGroupUtil {

  public static String calculateEeaPrivacyGroupId(
      final Bytes privateFrom, final List<Bytes> privateFor) {
    final List<Bytes> privacyGroupIds = new ArrayList<>();
    privacyGroupIds.add(privateFrom);
    privacyGroupIds.addAll(privateFor);

    final List<byte[]> sortedPrivacyGroupIds =
        privacyGroupIds.stream()
            .distinct()
            .map(Bytes::toArray)
            .sorted(Comparator.comparing(Arrays::hashCode))
            .collect(Collectors.toList());

    final BytesValueRLPOutput bytesValueRLPOutput = new BytesValueRLPOutput();
    bytesValueRLPOutput.writeList(
        sortedPrivacyGroupIds,
        (privacyGroupId, rlpOutput) -> rlpOutput.writeBytes(Bytes.of(privacyGroupId)));

    return Hash.keccak256(bytesValueRLPOutput.encoded()).toBase64String();
  }
}
