/*
 * 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.tika.parser.wordperfect;

import java.io.IOException;

/**
 * Extracts WordPerfect Prefix Area data from a WordPerfect document.
 * Applies to both 5.x and 6+ documents.
 * @author Pascal Essiembre
 */
final class WPPrefixAreaExtractor {

    private WPPrefixAreaExtractor() {
        super();
    }

    //WP5.x:
    //  Prefix Area:            16 bytes (standard header)
    
    //WP6.x:
    //  Prefix Area:            30 bytes (16 standard header + 14 index header)
    
    public static WPPrefixArea extract(WPInputStream in) 
            throws IOException {
        WPPrefixArea prefixArea = new WPPrefixArea();

        in.mark(30);
        prefixArea.setFileId(in.readWPString(4));         // 1-4
        prefixArea.setDocAreaPointer(in.readWPLong());    // 5-8
        prefixArea.setProductType(in.readWP());           // 9
        prefixArea.setFileType(in.readWPChar());          // 10
        prefixArea.setMajorVersion(in.readWP());          // 11
        prefixArea.setMinorVersion(in.readWP());          // 12
        prefixArea.setEncrypted(in.readWPShort() != 0);   // 13-14
        prefixArea.setIndexAreaPointer(in.readWPShort()); // 15-16

        // only applies to 6.x:
        prefixArea.setFileSize(-1);
        if (prefixArea.getMajorVersion() == WPPrefixArea.WP6_MAJOR_VERSION) {
            try {
                in.skip(4); // 4 reserved bytes: skip     // 17-20
                prefixArea.setFileSize(in.readWPLong());      // 21-24
            } catch (IOException e) {
                // May fail if no index header, which is fine.
            }
        }
        
        in.reset();

        return prefixArea;
    }
}