/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
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 * CDDL HEADER END
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/*
 * Copyright (c) 2001 by Sun Microsystems, Inc.
 * All rights reserved.
 *
 */

//  IANACharCode.java: SLPv1 Character encoding support
//  Author:           James Kempf
//  Created On:       Fri Sep 11 13:24:02 1998
//  Last Modified By: James Kempf
//  Last Modified On: Wed Oct 28 14:33:02 1998
//  Update Count:     7
//


package com.sun.slp;

import java.util.*;
import java.io.*;

/**
 * The IANACharCode class supports static methods for decoding IANA
 * character codes into strings appropriate for the Java Writer subclass
 * encoding String arguments, and for encoding the String descriptions
 * of character codings into the integer codes. Ideally, Java itself
 * should support this.
 *
 * @author James Kempf
 */

abstract class IANACharCode extends Object {

    // Character code descriptors. These can be used with the Java
    //  character encoding utilities. For Unicode, we use little on
    //  input,

    static final String ASCII = "Default";
    static final String LATIN1 = "latin1";
    static final String UTF8 = "UTF8";
    static final String UNICODE = "Unicode";
    static final String UNICODE_LITTLE = "UnicodeLittle";
    static final String UNICODE_BIG = "UnicodeBig";
    static final String UNICODE_BIG_NO_HDR = "UnicodeBigNoHdr";

    // Error code for misidentified character set.

    static final short CHARSET_NOT_UNDERSTOOD = 5;

    // Character codes.

    protected static final int CHAR_ASCII   = 3;
    protected static final int CHAR_LATIN1  = 4;
    protected static final int CHAR_UTF8    = 6;
    protected static final int CHAR_UNICODE = 1000;

    // First two bytes indicate that string is big/little endian Unicode.
    //  If this flag isn't set, then big endian is assumed and we
    //  must add the big endian bytes on every call.

    protected static final byte[] UNICODE_LITTLE_FLAG =
                                        {(byte)0xFF, (byte)0xFE};

    protected static final byte[] UNICODE_BIG_FLAG =
                                        {(byte)0xFE, (byte)0xFF};

    /**
     * Encode the String describing a character encoding into
     * the approprate integer descriptor code.
     *
     * @param encoding The String describing the encoding.
     * @exception ServiceLocationCharSetNotUnderstoodException Thrown if the
     *                  String is not recognized.
     */

    static int encodeCharacterEncoding(String encoding)
        throws ServiceLocationException {

        if (encoding.equals(ASCII)) {
            return CHAR_ASCII;
        } else if (encoding.equals(LATIN1)) {
            return CHAR_LATIN1;
        } else if (encoding.equals(UTF8)) {
            return CHAR_UTF8;
        } else if (encoding.equals(UNICODE)) {
            return CHAR_UNICODE;
        } else if (encoding.equals(UNICODE_BIG)) {
            return CHAR_UNICODE;
        } else if (encoding.equals(UNICODE_LITTLE)) {
            return CHAR_UNICODE;
        } else if (encoding.equals(UNICODE_BIG_NO_HDR)) {
            return CHAR_UNICODE;
        }

        throw
            new ServiceLocationException(
                                CHARSET_NOT_UNDERSTOOD,
                                "v1_unsupported_encoding",
                                new Object[] {encoding});
    }

    /**
     * Decode the integer describing a character encoding into
     * the approprate String descriptor.
     *
     * @param code The integer coding the String set.
     * @exception ServiceLocationCharSetNotUnderstoodException Thrown if the
     *                  integer is not recognized.
     */

    static String decodeCharacterEncoding(int code)
        throws ServiceLocationException {

        switch (code) {
        case CHAR_ASCII:        return ASCII;
        case CHAR_LATIN1:       return LATIN1;
        case CHAR_UTF8: return UTF8;
        case CHAR_UNICODE:      return UNICODE;
        }

        throw
            new ServiceLocationException(
                                CHARSET_NOT_UNDERSTOOD,
                                "v1_unsupported_encoding",
                                new Object[] {Integer.toString(code)});
    }

    /**
     * Return a string of integers giving the character's encoding in
     * the character set passed in as encoding.
     *
     * @param c The character to escape.
     * @param encoding The character set encoding to use.
     * @return The character as a string of integers for the encoding.
     * @exception ServiceLocationException Thrown if the encoding is not
     *           recognized, if the character's encoding
     *           has more than 8 bytes or if the sign bit gets turned on.
     */

    static String escapeChar(char c, String encoding)
        throws ServiceLocationException {

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        try {
            OutputStreamWriter osw = new OutputStreamWriter(baos, encoding);

            osw.write(c);
            osw.flush();

        } catch (UnsupportedEncodingException ex) {

            throw
                new ServiceLocationException(
                                CHARSET_NOT_UNDERSTOOD,
                                "v1_unsupported_encoding",
                                new Object[] {encoding});

        } catch (IOException ex) {

        }

        byte b[] = baos.toByteArray();
        int code = 0;

        // Assemble the character code based on the encoding type.

        if (encoding.equals(UNICODE) ||
            encoding.equals(UNICODE_BIG) ||
            encoding.equals(UNICODE_LITTLE)) {

            code = (int)(b[0] & 0xFF);          // control bytes...
            code = (int)(code | ((b[1] & 0xFF) << 8));
            code = (int)(code | ((b[2] & 0xFF) << 16));
            code = (int)(code | ((b[3] & 0xFF) << 24));

            if (b.length <= 4) {
                throw
                    new ServiceLocationException(
                                ServiceLocationException.PARSE_ERROR,
                                "v1_charcode_error",
                                new Object[] {Character.valueOf(c), encoding});
            }

        } else if (encoding.equals(ASCII) || encoding.equals(LATIN1)) {

            code = (int)(b[0] & 0xFF);

            if (b.length > 1) {
                throw
                    new ServiceLocationException(
                                ServiceLocationException.PARSE_ERROR,
                                "v1_charcode_error",
                                new Object[] {Character.valueOf(c), encoding});
            }
        } else if (encoding.equals(UTF8)) {

            if (b.length > 3) {
                throw
                    new ServiceLocationException(
                                ServiceLocationException.PARSE_ERROR,
                                "v1_charcode_error",
                                new Object[] {Character.valueOf(c), encoding});
            }


            code = (int)(b[0] & 0xFF);

            if (b.length > 1) {
                code = (int)(code | ((b[1] & 0xFF) << 8));
            }

            if (b.length > 2) {
                code = (int)(code | ((b[2] & 0xFF) << 16));
            }
        }

        return Integer.toString(code);
    }

    /**
     * Unescape the character encoded as the string.
     *
     * @param ch The character as a string of Integers.
     * @param encoding The character set encoding to use.
     * @return The character.
     * @exception ServiceLocationException Thrown if the string can't
     *           be parsed into an integer or if the encoding isn't
     *           recognized.
     */

    static String unescapeChar(String ch, String encoding)
        throws ServiceLocationException {

        int code = 0;

        try {
            code = Integer.parseInt(ch);

        } catch (NumberFormatException ex) {
            throw
                new ServiceLocationException(
                                ServiceLocationException.PARSE_ERROR,
                                "v1_stringcode_error",
                                new Object[] {ch, encoding});

        }

        // Convert to bytes. We need to taylor the array size to the
        //  number of bytes because otherwise, in encodings that
        //  take less bytes, the resulting string will have garbage
        //  in it.

        String str = null;
        byte b0 = 0, b1 = 0, b2 = 0, b3 = 0;
        byte b[] = null;

        b0 = (byte) (code & 0xFF);
        b1 = (byte) ((code >> 8) & 0xFF);
        b2 = (byte) ((code >> 16) & 0xFF);
        b3 = (byte) ((code >> 24) & 0xFf);

        // We create an array sized to the encoding.

        if (encoding.equals(UNICODE_BIG) ||
            encoding.equals(UNICODE_LITTLE)) {
            b = new byte[4];
            b[0] = b0;
            b[1] = b1;
            b[2] = b2;
            b[3] = b3;

        } else if (encoding.equals(LATIN1) || encoding.equals(ASCII)) {
            // single byte
            b = new byte[1];
            b[0] = b0;

            if (b1 != 0 || b2 != 0) {
                throw
                    new ServiceLocationException(
                                ServiceLocationException.PARSE_ERROR,
                                "v1_stringcode_error",
                                new Object[] {ch, encoding});
            }


        } else if (encoding.equals(UTF8)) {// vari-byte

            if (b3 != 0) {
                throw
                    new ServiceLocationException(
                                ServiceLocationException.PARSE_ERROR,
                                "v1_stringcode_error",
                                new Object[] {ch, encoding});
            }

            if (b2 != 0) {
                b = new byte[3];
                b[2] = b2;
                b[1] = b1;
                b[0] = b0;
            } else if (b1 != 0) {
                b = new byte[2];
                b[1] = b1;
                b[0] = b0;
            } else {
                b = new byte[1];
                b[0] = b0;
            }
        }

        // Make a string out of it.

        try {
            str = new String(b, encoding);

        } catch (UnsupportedEncodingException ex) {
            Assert.slpassert(false,
                          "v1_unsupported_encoding",
                          new Object[] {encoding});
        }

        return str;
    }

    // Determine from the flag bytes whether this is big or little endian
    //  Unicode. If there are no flag bytes, then just return UNICODE.

    static String getUnicodeEndianess(byte[] bytes) {

        if (bytes.length >= 2) {

            if (bytes[0] == UNICODE_LITTLE_FLAG[0] &&
                bytes[1] == UNICODE_LITTLE_FLAG[1]) {
                return UNICODE_LITTLE;

            } else if (bytes[0] == UNICODE_BIG_FLAG[0] &&
                       bytes[1] == UNICODE_BIG_FLAG[1]) {
                return UNICODE_BIG;

            }
        }

        // We can`t tell from the byte header, so it's big endian. But
        //  since we need to add the byte header, we say we don't know.

        return UNICODE;

    }

    // Add the big endian flag to a Unicode string.

    static byte[] addBigEndianFlag(byte[] bytes) {

        byte[] flaggedBytes = new byte[bytes.length + 2];

        flaggedBytes[0] = UNICODE_BIG_FLAG[0];
        flaggedBytes[1] = UNICODE_BIG_FLAG[1];

        System.arraycopy(flaggedBytes, 2, bytes, 0, bytes.length);

        return flaggedBytes;

    }
}