/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache POI" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache POI", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * 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.poi.util;

import java.io.IOException;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.List;
import java.util.ArrayList;

/**
 * Utilities to read hex from files.
 *
 * @author Marc Johnson
 * @author Glen Stampoultzis (glens at apache.org)
 */
public class HexRead
{
    /**
     * This method reads hex data from a filename and returns a byte array.
     * The file may contain line comments that are preceeded with a # symbol.
     *
     * @param filename  The filename to read
     * @return The bytes read from the file.
     * @throws IOException If there was a problem while reading the file.
     */
    public static byte[] readData( String filename )
            throws IOException
    {
        File file = new File( filename );
        FileInputStream stream = new FileInputStream( file );
        try
        {
            return readData(stream, -1);
        }
        finally
        {
            stream.close();
        }
    }

    /**
     * Same as readData(String) except that this method allows you to specify sections within
     * a file.  Sections are referenced using section headers in the form:
     * <pre>
     *  [sectioname]
     * </pre>
     *
     * @see #readData(String)
     */
    public static byte[] readData(String filename, String section)
        throws IOException
    {
        File file = new File( filename );
        FileInputStream stream = new FileInputStream( file );
        try
        {
            StringBuffer sectionText = new StringBuffer();
            boolean inSection = false;
            int c = stream.read();
            while (c != -1)
            {
                switch(c)
                {
                    case '[':
                        inSection = true;
                        break;
                    case '\n': case '\r':
                        inSection = false;
                        sectionText = new StringBuffer();
                        break;
                    case ']':
                        inSection = false;
                        if (sectionText.toString().equals(section))
                            return readData(stream, '[');
                        sectionText = new StringBuffer();
                        break;
                    default:
                        if (inSection)
                            sectionText.append((char)c);
                }

                c = stream.read();
            }
        }
        finally
        {
            stream.close();
        }
        throw new IOException("Section '" + section + "' not found");
    }

    static private byte[] readData( FileInputStream stream, int eofChar ) throws IOException
    {
        int characterCount = 0;
        byte b = (byte) 0;
        List bytes = new ArrayList();
        boolean done = false;

        while ( !done )
        {
            int count = stream.read();
            char baseChar = 'a';

            if ( count == eofChar)
                break;

            switch ( count )
            {

                case '#':
                    readToEOL(stream);
                    break;
                case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
                    b <<= 4;
                    b += (byte) ( count - '0' );
                    characterCount++;
                    if ( characterCount == 2 )
                    {
                        bytes.add( new Byte( b ) );
                        characterCount = 0;
                        b = (byte) 0;
                    }
                    break;

                case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
                    baseChar = 'A';

                case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
                    b <<= 4;
                    b += (byte) ( count + 10 - baseChar );
                    characterCount++;
                    if ( characterCount == 2 )
                    {
                        bytes.add( new Byte( b ) );
                        characterCount = 0;
                        b = (byte) 0;
                    }
                    break;

                case -1:
                    done = true;
                    break;

                default :
                    break;
            }
        }
        Byte[] polished = (Byte[]) bytes.toArray( new Byte[0] );
        byte[] rval = new byte[polished.length];

        for ( int j = 0; j < polished.length; j++ )
        {
            rval[j] = polished[j].byteValue();
        }
        return rval;
    }

    static private void readToEOL( InputStream stream ) throws IOException
    {
        int c = stream.read();
        while ( c != -1 && c != '\n' && c != '\r')
        {
            c = stream.read();
        }
    }


}