content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF 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
   *
   *        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.apache.causeway.commons.io;
  
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.function.Function;
  
  import org.springframework.util.function.ThrowingConsumer;
  
  import org.apache.causeway.commons.functional.Try;
  import org.apache.causeway.commons.internal.exceptions._Exceptions;
  
  import org.jspecify.annotations.NonNull;
  
  /**
   * General purpose byte data peer that acts as source and sink at the same time.
   *
   * @since 2.0 {@index}
   */
  public interface DataPeer extends DataSink, DataSource {
  
      static DataPeer inMemory() {
          return inMemory(32);
      }
  
      static DataPeer inMemory(final int initialBufferSize) {
  
          var byteArrayHolder = new ArrayList<byte[]>(1);
  
          return new DataPeer() {
              @Override
              public <T> Try<T> tryReadAll(final @NonNull Function<InputStream, Try<T>> consumingMapper) {
                  var in = DataSource.ofBytes(bytes());
                  return in.tryReadAll(consumingMapper);
              }
  
              @Override
              public void writeAll(final @NonNull ThrowingConsumer<OutputStream> outputStreamConsumer) {
                  if(!byteArrayHolder.isEmpty()) {
                      throw _Exceptions.illegalState("Cannot writeAll to an in-memory DataPeer, that was already written to.");
                  }
                  var out = DataSink.ofByteArrayConsumer(byteArrayHolder::add, initialBufferSize);
                  out.writeAll(outputStreamConsumer);
              }
  
              @Override
              public byte[] bytes() {
                  return byteArrayHolder.isEmpty()
                          ? new byte[0]
                          : byteArrayHolder.get(0);
              }
  
          };
      }
  
  }
  