/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/util/EntityUtils.java $
 * $Revision: 569637 $
 * $Date: 2007-08-25 00:36:59 -0700 (Sat, 25 Aug 2007) $
 *
 * ====================================================================
 * 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.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;

import org.apache.http.HeaderElement;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
import org.apache.http.protocol.HTTP;

/**
 * Static helpers for dealing with {@link HttpEntity entities}.
 *
 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
 *
 * @version $Revision: 569637 $
 * 
 * @since 4.0
 */
public final class EntityUtils {

    /** Disabled default constructor. */
    private EntityUtils() {
    }
    
    public static byte[] toByteArray(final HttpEntity entity) throws IOException {
        if (entity == null) {
            throw new IllegalArgumentException("HTTP entity may not be null");
        }
        InputStream instream = entity.getContent();
        if (instream == null) {
            return new byte[] {};
        }
        if (entity.getContentLength() > Integer.MAX_VALUE) {
            throw new IllegalArgumentException("HTTP entity too large to be buffered in memory");
        }
        int i = (int)entity.getContentLength();
        if (i < 0) {
            i = 4096;
        }
        ByteArrayBuffer buffer = new ByteArrayBuffer(i);
        try {
            byte[] tmp = new byte[4096];
            int l;
            while((l = instream.read(tmp)) != -1) {
                buffer.append(tmp, 0, l);
            }
        } finally {
            instream.close();
        }
        return buffer.toByteArray();
    }
        
    public static String getContentCharSet(final HttpEntity entity)
        throws ParseException {

        if (entity == null) {
            throw new IllegalArgumentException("HTTP entity may not be null");
        }
        String charset = null;
        if (entity.getContentType() != null) { 
            HeaderElement values[] = entity.getContentType().getElements();
            if (values.length > 0) {
                NameValuePair param = values[0].getParameterByName("charset");
                if (param != null) {
                    charset = param.getValue();
                }
            }
        }
        return charset;
    }

    public static String toString(
            final HttpEntity entity, final String defaultCharset) throws IOException, ParseException {
        if (entity == null) {
            throw new IllegalArgumentException("HTTP entity may not be null");
        }
        InputStream instream = entity.getContent();
        if (instream == null) {
            return "";
        }
        if (entity.getContentLength() > Integer.MAX_VALUE) {
            throw new IllegalArgumentException("HTTP entity too large to be buffered in memory");
        }
        int i = (int)entity.getContentLength();
        if (i < 0) {
            i = 4096;
        }
        String charset = getContentCharSet(entity);
        if (charset == null) {
            charset = defaultCharset;
        }
        if (charset == null) {
            charset = HTTP.DEFAULT_CONTENT_CHARSET;
        }
        Reader reader = new InputStreamReader(instream, charset);
        CharArrayBuffer buffer = new CharArrayBuffer(i); 
        try {
            char[] tmp = new char[1024];
            int l;
            while((l = reader.read(tmp)) != -1) {
                buffer.append(tmp, 0, l);
            }
        } finally {
            reader.close();
        }
        return buffer.toString();
    }

    public static String toString(final HttpEntity entity)
        throws IOException, ParseException {
        return toString(entity, null);
    }
    
}