/*
 * 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.juneau.http.entity;

import static org.apache.juneau.commons.utils.AssertionUtils.*;
import static org.apache.juneau.commons.utils.IoUtils.*;
import static org.apache.juneau.commons.utils.Utils.*;

import java.io.*;
import java.nio.charset.*;
import java.util.*;
import java.util.function.*;

import org.apache.juneau.commons.io.*;
import org.apache.juneau.http.header.*;

/**
 * A streamed, non-repeatable entity that obtains its content from an {@link Reader}.
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommonBasics">juneau-rest-common Basics</a>
 * </ul>
 */
@SuppressWarnings("resource")
public class ReaderEntity extends BasicHttpEntity {
   private byte[] byteCache;
   private String stringCache;

   /**
    * Constructor.
    */
   public ReaderEntity() {}

   /**
    * Constructor.
    *
    * @param contentType The entity content type.
    * @param content The entity contents.
    */
   public ReaderEntity(ContentType contentType, Reader content) {
      super(contentType, content);
   }

   /**
    * Copy constructor.
    *
    * @param copyFrom The bean being copied.
    */
   protected ReaderEntity(ReaderEntity copyFrom) {
      super(copyFrom);
   }

   @Override /* Overridden from AbstractHttpEntity */
   public byte[] asBytes() throws IOException {
      if (isCached() && byteCache == null)
         byteCache = readBytes(content());
      if (nn(byteCache))
         return byteCache;
      return readBytes(content());
   }

   @Override /* Overridden from AbstractHttpEntity */
   public String asString() throws IOException {
      if (isCached() && stringCache == null)
         stringCache = read(content(), getMaxLength());
      if (nn(stringCache))
         return stringCache;
      return read(content());
   }

   @Override
   public ReaderEntity copy() {
      return new ReaderEntity(this);
   }

   @Override /* Overridden from HttpEntity */
   public InputStream getContent() throws IOException {
      if (isCached())
         return new ByteArrayInputStream(asBytes());
      return new ReaderInputStream(content(), getCharset());
   }

   @Override /* Overridden from HttpEntity */
   public long getContentLength() {
      if (isCached())
         return asSafeBytes().length;
      return super.getContentLength();
   }

   @Override /* Overridden from HttpEntity */
   public boolean isRepeatable() { return isCached(); }

   @Override /* Overridden from HttpEntity */
   public boolean isStreaming() { return ! isCached(); }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setCached() throws IOException {
      super.setCached();
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setCharset(Charset value) {
      super.setCharset(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setChunked() {
      super.setChunked();
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setChunked(boolean value) {
      super.setChunked(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContent(Object value) {
      super.setContent(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContent(Supplier<?> value) {
      super.setContent(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContentEncoding(ContentEncoding value) {
      super.setContentEncoding(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContentEncoding(String value) {
      super.setContentEncoding(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContentLength(long value) {
      super.setContentLength(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContentType(ContentType value) {
      super.setContentType(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setContentType(String value) {
      super.setContentType(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setMaxLength(int value) {
      super.setMaxLength(value);
      return this;
   }

   @Override /* Overridden from BasicHttpEntity */
   public ReaderEntity setUnmodifiable() {
      super.setUnmodifiable();
      return this;
   }

   /**
    * Writes bytes from the {@code InputStream} this entity was constructed
    * with to an {@code OutputStream}.  The content length
    * determines how many bytes are written.  If the length is unknown ({@code -1}), the
    * stream will be completely consumed (to the end of the stream).
    */
   @Override
   public void writeTo(OutputStream out) throws IOException {
      assertArgNotNull("out", out);

      if (isCached()) {
         out.write(asBytes());
      } else {
         var osw = new OutputStreamWriter(out, getCharset());
         pipe(content(), osw);
         osw.flush();
      }
      out.flush();
   }

   private Reader content() {
      return Objects.requireNonNull(contentOrElse((Reader)null), "Reader is null.");
   }
}