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 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package sun.nio.cs.ext;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import sun.nio.cs.HistoricallyNamedCharset;
import sun.nio.cs.SingleByte;

import static sun.nio.cs.CharsetMapping.*;

public class SJIS
    extends Charset
    implements HistoricallyNamedCharset
{

    public SJIS() {
        super("Shift_JIS", ExtendedCharsets.aliasesFor("Shift_JIS"));
    }

    public String historicalName() {
        return "SJIS";
    }

    public boolean contains(Charset cs) {
        return ((cs.name().equals("US-ASCII"))
                || (cs instanceof JIS_X_0201)
                || (cs instanceof SJIS)
                || (cs instanceof JIS_X_0208));
    }

    public CharsetDecoder newDecoder() {
        return new Decoder(this);
    }

    public CharsetEncoder newEncoder() {
        // Need to force the replacement byte to 0x3f
        // because JIS_X_0208_Encoder defines its own
        // alternative 2 byte substitution to permit it
        // to exist as a self-standing Encoder

        byte[] replacementBytes = { (byte)0x3f };
        return new Encoder(this).replaceWith(replacementBytes);
    }

    // TBD: DB.Decoder impl currently does not use decodeSingle/
    // Double() (performance). If it does switch back to use the
    // decodeSingle/Double, SJIS.Decoder can simply extend it.
    static class Decoder extends CharsetDecoder
                         implements DelegatableDecoder {
        private static SingleByte.Decoder jis0201 =
            (SingleByte.Decoder)new JIS_X_0201().newDecoder();

        private static DoubleByte.Decoder jis0208 =
            (DoubleByte.Decoder)new JIS_X_0208().newDecoder();

        protected Decoder(Charset cs) {
            super(cs, 0.5f, 1.0f);
        }

        public char decodeSingle(int b) {
            return jis0201.decode(b);
        }

        public char decodeDouble(int c1, int c2) {
            int adjust = c2 < 0x9F ? 1 : 0;
            int rowOffset = c1 < 0xA0 ? 0x70 : 0xB0;
            int cellOffset = (adjust == 1) ? (c2 > 0x7F ? 0x20 : 0x1F) : 0x7E;
            int b1 = ((c1 - rowOffset) << 1) - adjust;
            int b2 = c2 - cellOffset;
            return jis0208.decodeDouble(b1, b2);
        }

        protected CoderResult decodeArrayLoop(ByteBuffer src, CharBuffer dst) {
            byte[] sa = src.array();
            int sp = src.arrayOffset() + src.position();
            int sl = src.arrayOffset() + src.limit();

            char[] da = dst.array();
            int dp = dst.arrayOffset() + dst.position();
            int dl = dst.arrayOffset() + dst.limit();

            try {
                while (sp < sl && dp < dl) {
                    int inSize = 1;
                    int b1 = sa[sp];    //  & 0xff;
                    char c = decodeSingle(b1);
                    if (c == UNMAPPABLE_DECODING) {
                        if (sl - sp < 2)
                            return CoderResult.UNDERFLOW;
                        int b2 = sa[sp + 1] & 0xff;
                        if ((c = decodeDouble(b1 & 0xff, b2)) == UNMAPPABLE_DECODING) {
                            return CoderResult.unmappableForLength(2);
                        }
                        inSize = 2;
                    }
                    da[dp++] = c;
                    sp += inSize;
                }
                return (sp >= sl) ? CoderResult.UNDERFLOW
                                  : CoderResult.OVERFLOW;
            } finally {
                src.position(sp - src.arrayOffset());
                dst.position(dp - dst.arrayOffset());
            }
        }

        protected CoderResult decodeBufferLoop(ByteBuffer src, CharBuffer dst) {
            int mark = src.position();
            try {
                while (src.hasRemaining() && dst.hasRemaining()) {
                    int b1 = src.get();    //  & 0xff;
                    char c = decodeSingle(b1);
                    int inSize = 1;
                    if (c == UNMAPPABLE_DECODING) {
                        if (src.remaining() < 1)
                            return CoderResult.UNDERFLOW;
                        int b2 = src.get() & 0xff;
                        if ((c = decodeDouble(b1 & 0xff, b2)) == UNMAPPABLE_DECODING) {
                            return CoderResult.unmappableForLength(2);
                        }
                        inSize = 2;
                    }
                    dst.put(c);
                    mark += inSize;
                }
                return src.hasRemaining()? CoderResult.OVERFLOW
                                         : CoderResult.UNDERFLOW;
            } finally {
                src.position(mark);
            }
        }

        public CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) {
            if (src.hasArray() && dst.hasArray())
                return decodeArrayLoop(src, dst);
            else
                return decodeBufferLoop(src, dst);
        }

        public void implReset() {
            super.implReset();
        }

        public CoderResult implFlush(CharBuffer out) {
            return super.implFlush(out);
        }
    }

    static class Encoder extends DoubleByte.Encoder_JISX0208 {
        private static SingleByte.Encoder jis0201 =
            (SingleByte.Encoder)new JIS_X_0201().newEncoder();

        private static DoubleByte.Encoder jis0208 =
            (DoubleByte.Encoder)new JIS_X_0208().newEncoder(); //init

        protected Encoder(Charset cs) {
            super(cs, JIS_X_0208.c2b, JIS_X_0208.c2bIndex);
        }

        public int encodeChar(char ch) {
            int bb;
            if ((bb = jis0201.encode(ch)) != UNMAPPABLE_ENCODING) {
                return bb;
            }
            bb = super.encodeChar(ch);

            if (bb == UNMAPPABLE_ENCODING || bb <= MAX_SINGLEBYTE)
                return UNMAPPABLE_ENCODING;
            /*
             * This algorithm for converting from JIS to SJIS comes from
             * Ken Lunde's "Understanding Japanese Information Processing",
             * pg 163.
             */
            int c1 = (bb >> 8) & 0xff;
            int c2 = bb & 0xff;
            int rowOffset = c1 < 0x5F ? 0x70 : 0xB0;
            int cellOffset = (c1 % 2 == 1) ? (c2 > 0x5F ? 0x20 : 0x1F) : 0x7E;
            return ((((c1 + 1 ) >> 1) + rowOffset) << 8) | (c2 + cellOffset);
        }
    }
}