/*

 * ====================================================================

 * 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.impl.entity;



import org.apache.http.Header;

import org.apache.http.HeaderElement;

import org.apache.http.HttpException;

import org.apache.http.HttpMessage;

import org.apache.http.ParseException;

import org.apache.http.ProtocolException;

import org.apache.http.entity.ContentLengthStrategy;

import org.apache.http.params.HttpParams;

import org.apache.http.params.CoreProtocolPNames;

import org.apache.http.protocol.HTTP;



/**

 * The lax implementation of the content length strategy. This class will ignore 

 * unrecognized transfer encodings and malformed <code>Content-Length</code> 

 * header values if the {@link CoreProtocolPNames#STRICT_TRANSFER_ENCODING} 

 * parameter of the given message is not set or set to <code>false</code>. 

 * <p>

 * This class recognizes "chunked" and "identitiy" transfer-coding only.

 * <p>

 * The following parameters can be used to customize the behavior of this class: 

 * <ul>

 *  <li>{@link org.apache.http.params.CoreProtocolPNames#STRICT_TRANSFER_ENCODING}</li>

 * </ul>

 * 

 * @since 4.0

 */

public class LaxContentLengthStrategy implements ContentLengthStrategy {



    public LaxContentLengthStrategy() {

        super();

    }



    public long determineLength(final HttpMessage message) throws HttpException {

        if (message == null) {

            throw new IllegalArgumentException("HTTP message may not be null");

        }



        HttpParams params = message.getParams(); 

        boolean strict = params.isParameterTrue(CoreProtocolPNames.STRICT_TRANSFER_ENCODING);

        

        Header transferEncodingHeader = message.getFirstHeader(HTTP.TRANSFER_ENCODING);

        Header contentLengthHeader = message.getFirstHeader(HTTP.CONTENT_LEN);

        // We use Transfer-Encoding if present and ignore Content-Length.

        // RFC2616, 4.4 item number 3

        if (transferEncodingHeader != null) {

            HeaderElement[] encodings = null;

            try {

                encodings = transferEncodingHeader.getElements();

            } catch (ParseException px) {

                throw new ProtocolException

                    ("Invalid Transfer-Encoding header value: " +

                     transferEncodingHeader, px);

            }

            if (strict) {

                // Currently only chunk and identity are supported

                for (int i = 0; i < encodings.length; i++) {

                    String encoding = encodings[i].getName();

                    if (encoding != null && encoding.length() > 0 

                        && !encoding.equalsIgnoreCase(HTTP.CHUNK_CODING)

                        && !encoding.equalsIgnoreCase(HTTP.IDENTITY_CODING)) {

                        throw new ProtocolException("Unsupported transfer encoding: " + encoding);

                    }

                }

            }

            // The chunked encoding must be the last one applied RFC2616, 14.41

            int len = encodings.length;

            if (HTTP.IDENTITY_CODING.equalsIgnoreCase(transferEncodingHeader.getValue())) {

                return IDENTITY;                            

            } else if ((len > 0) && (HTTP.CHUNK_CODING.equalsIgnoreCase(

                    encodings[len - 1].getName()))) { 

                return CHUNKED;

            } else {

                if (strict) {

                    throw new ProtocolException("Chunk-encoding must be the last one applied");

                }

                return IDENTITY;                            

            }

        } else if (contentLengthHeader != null) {

            long contentlen = -1;

            Header[] headers = message.getHeaders(HTTP.CONTENT_LEN);

            if (strict && headers.length > 1) {

                throw new ProtocolException("Multiple content length headers");

            }

            for (int i = headers.length - 1; i >= 0; i--) {

                Header header = headers[i];

                try {

                    contentlen = Long.parseLong(header.getValue());

                    break;

                } catch (NumberFormatException e) {

                    if (strict) {

                        throw new ProtocolException("Invalid content length: " + header.getValue());

                    }

                }

                // See if we can have better luck with another header, if present

            }

            if (contentlen >= 0) {

                return contentlen;

            } else {

                return IDENTITY;

            }

        } else {

            return IDENTITY;

        }

    }

        

}