/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package org.apache.http.client.entity;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.entity.HttpEntityWrapper;
import org.apache.http.util.Args;

/**
 * Common base class for decompressing {@link HttpEntity} implementations.
 *
 * @since 4.4
 */
public class DecompressingEntity extends HttpEntityWrapper {

    /**
     * Default buffer size.
     */
    private static final int BUFFER_SIZE = 1024 * 2;

    private final InputStreamFactory inputStreamFactory;
    /**
     * {@link #getContent()} method must return the same {@link InputStream}
     * instance when DecompressingEntity is wrapping a streaming entity.
     */
    private InputStream content;

    /**
     * Creates a new {@link DecompressingEntity}.
     *
     * @param wrapped the non-null {@link HttpEntity} to be wrapped
     * @param inputStreamFactory factory to create decompressing stream.
     */
    public DecompressingEntity(
            final HttpEntity wrapped,
            final InputStreamFactory inputStreamFactory) {
        super(wrapped);
        this.inputStreamFactory = inputStreamFactory;
    }

    private InputStream getDecompressingStream() throws IOException {
        final InputStream in = wrappedEntity.getContent();
        return new LazyDecompressingInputStream(in, inputStreamFactory);
    }

    @Override
    public InputStream getContent() throws IOException {
        if (wrappedEntity.isStreaming()) {
            if (content == null) {
                content = getDecompressingStream();
            }
            return content;
        } else {
            return getDecompressingStream();
        }
    }

    @Override
    public void writeTo(final OutputStream outstream) throws IOException {
        Args.notNull(outstream, "Output stream");
        final InputStream instream = getContent();
        try {
            final byte[] buffer = new byte[BUFFER_SIZE];
            int l;
            while ((l = instream.read(buffer)) != -1) {
                outstream.write(buffer, 0, l);
            }
        } finally {
            instream.close();
        }
    }

    @Override
    public Header getContentEncoding() {
        /* Content encoding is now 'identity' */
        return null;
    }

    @Override
    public long getContentLength() {
        /* length of decompressed content is not known */
        return -1;
    }

}