/*

 * Copyright 1996-1997 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.io;

/**

 * UCS2 (UTF16) -> UCS Transformation Format 8 (UTF-8) converter

 * It's represented like below.

 *

 * # Bits   Bit pattern

 * 1    7   0xxxxxxx

 * 2   11   110xxxxx 10xxxxxx

 * 3   16   1110xxxx 10xxxxxx 10xxxxxx

 * 4   21   11110xxx 10xxxxxx 10xxxxxx 10xxxxxx

 * 5   26   111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

 * 6   31   1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

 *

 *     UCS2 uses 1-3 / UTF16 uses 1-4 / UCS4 uses 1-6

 */

public class CharToByteUTF8 extends CharToByteConverter {

    private char highHalfZoneCode;

    public int flush(byte[] output, int outStart, int outEnd)

        throws MalformedInputException

    {

        if (highHalfZoneCode != 0) {

            highHalfZoneCode = 0;

            badInputLength = 0;

            throw new MalformedInputException();

        }

        byteOff = charOff = 0;

        return 0;

    }

    /**

     * Character conversion

     */

    public int convert(char[] input, int inOff, int inEnd,

                       byte[] output, int outOff, int outEnd)

        throws ConversionBufferFullException, MalformedInputException

    {

        char inputChar;

        byte[] outputByte = new byte[6];

        int inputSize;

        int outputSize;

        charOff = inOff;

        byteOff = outOff;

        if (highHalfZoneCode != 0) {

            inputChar = highHalfZoneCode;

            highHalfZoneCode = 0;

            if (input[inOff] >= 0xdc00 && input[inOff] <= 0xdfff) {

                // This is legal UTF16 sequence.

                int ucs4 = (highHalfZoneCode - 0xd800) * 0x400

                    + (input[inOff] - 0xdc00) + 0x10000;

                output[0] = (byte)(0xf0 | ((ucs4 >> 18)) & 0x07);

                output[1] = (byte)(0x80 | ((ucs4 >> 12) & 0x3f));

                output[2] = (byte)(0x80 | ((ucs4 >> 6) & 0x3f));

                output[3] = (byte)(0x80 | (ucs4 & 0x3f));

                charOff++;

                highHalfZoneCode = 0;

            } else {

                // This is illegal UTF16 sequence.

                badInputLength = 0;

                throw new MalformedInputException();

            }

        }

        while(charOff < inEnd) {

            inputChar = input[charOff];

            if (inputChar < 0x80) {

                outputByte[0] = (byte)inputChar;

                inputSize = 1;

                outputSize = 1;

            } else if (inputChar < 0x800) {

                outputByte[0] = (byte)(0xc0 | ((inputChar >> 6) & 0x1f));

                outputByte[1] = (byte)(0x80 | (inputChar & 0x3f));

                inputSize = 1;

                outputSize = 2;

            } else if (inputChar >= 0xd800 && inputChar <= 0xdbff) {

                // this is <high-half zone code> in UTF-16

                if (charOff + 1 >= inEnd) {

                    highHalfZoneCode = inputChar;

                    break;

                }

                // check next char is valid <low-half zone code>

                char lowChar = input[charOff + 1];

                if (lowChar < 0xdc00 || lowChar > 0xdfff) {

                    badInputLength = 1;

                    throw new MalformedInputException();

                }

                int ucs4 = (inputChar - 0xd800) * 0x400 + (lowChar - 0xdc00)

                    + 0x10000;

                outputByte[0] = (byte)(0xf0 | ((ucs4 >> 18)) & 0x07);

                outputByte[1] = (byte)(0x80 | ((ucs4 >> 12) & 0x3f));

                outputByte[2] = (byte)(0x80 | ((ucs4 >> 6) & 0x3f));

                outputByte[3] = (byte)(0x80 | (ucs4 & 0x3f));

                outputSize = 4;

                inputSize = 2;

            } else {

                outputByte[0] = (byte)(0xe0 | ((inputChar >> 12)) & 0x0f);

                outputByte[1] = (byte)(0x80 | ((inputChar >> 6) & 0x3f));

                outputByte[2] = (byte)(0x80 | (inputChar & 0x3f));

                inputSize = 1;

                outputSize = 3;

            }

            if (byteOff + outputSize > outEnd) {

                throw new ConversionBufferFullException();

            }

            for (int i = 0; i < outputSize; i++) {

                output[byteOff++] = outputByte[i];

            }

            charOff += inputSize;

        }

        return byteOff - outOff;

    }

    public boolean canConvert(char ch) {

        return true;

    }

    public int getMaxBytesPerChar() {

        return 3;

    }

    public void reset() {

        byteOff = charOff = 0;

        highHalfZoneCode = 0;

    }

    public String getCharacterEncoding() {

        return "UTF8";

    }

}