/*

 * Copyright (c) 2009, 2013, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.nio.cs;

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 java.util.Arrays;

import sun.nio.cs.Surrogate;

import sun.nio.cs.ArrayDecoder;

import sun.nio.cs.ArrayEncoder;

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

/*

 * Four types of "DoubleByte" charsets are implemented in this class

 * (1)DoubleByte

 *    The "mostly widely used" multibyte charset, a combination of

 *    a singlebyte character set (usually the ASCII charset) and a

 *    doublebyte character set. The codepoint values of singlebyte

 *    and doublebyte don't overlap. Microsoft's multibyte charsets

 *    and IBM's "DBCS_ASCII" charsets, such as IBM1381, 942, 943,

 *    948, 949 and 950 are such charsets.

 *

 * (2)DoubleByte_EBCDIC

 *    IBM EBCDIC Mix multibyte charset. Use SO and SI to shift (switch)

 *    in and out between the singlebyte character set and doublebyte

 *    character set.

 *

 * (3)DoubleByte_SIMPLE_EUC

 *    It's a "simple" form of EUC encoding scheme, only have the

 *    singlebyte character set G0 and one doublebyte character set

 *    G1 are defined, G2 (with SS2) and G3 (with SS3) are not used.

 *    So it is actually the same as the "typical" type (1) mentioned

 *    above, except it return "malformed" for the SS2 and SS3 when

 *    decoding.

 *

 * (4)DoubleByte ONLY

 *    A "pure" doublebyte only character set. From implementation

 *    point of view, this is the type (1) with "decodeSingle" always

 *    returns unmappable.

 *

 * For simplicity, all implementations share the same decoding and

 * encoding data structure.

 *

 * Decoding:

 *

 *    char[][] b2c;

 *    char[] b2cSB;

 *    int b2Min, b2Max

 *

 *    public char decodeSingle(int b) {

 *        return b2cSB.[b];

 *    }

 *

 *    public char decodeDouble(int b1, int b2) {

 *        if (b2 < b2Min || b2 > b2Max)

 *            return UNMAPPABLE_DECODING;

 *         return b2c[b1][b2 - b2Min];

 *    }

 *

 *    (1)b2Min, b2Max are the corresponding min and max value of the

 *       low-half of the double-byte.

 *    (2)The high 8-bit/b1 of the double-byte are used to indexed into

 *       b2c array.

 *

 * Encoding:

 *

 *    char[] c2b;

 *    char[] c2bIndex;

 *

 *    public int encodeChar(char ch) {

 *        return c2b[c2bIndex[ch >> 8] + (ch & 0xff)];

 *    }

 *

 */

public class DoubleByte {

    public static final char[] B2C_UNMAPPABLE;

    static {

        B2C_UNMAPPABLE = new char[0x100];

        Arrays.fill(B2C_UNMAPPABLE, UNMAPPABLE_DECODING);

    }

    public static class Decoder extends CharsetDecoder

                                implements DelegatableDecoder, ArrayDecoder

    {

        final char[][] b2c;

        final char[] b2cSB;

        final int b2Min;

        final int b2Max;

        final boolean isASCIICompatible;

        // for SimpleEUC override

        protected CoderResult crMalformedOrUnderFlow(int b) {

            return CoderResult.UNDERFLOW;

        }

        protected CoderResult crMalformedOrUnmappable(int b1, int b2) {

            if (b2c[b1] == B2C_UNMAPPABLE ||                // isNotLeadingByte(b1)

                b2c[b2] != B2C_UNMAPPABLE ||                // isLeadingByte(b2)

                decodeSingle(b2) != UNMAPPABLE_DECODING) {  // isSingle(b2)

                return CoderResult.malformedForLength(1);

            }

            return CoderResult.unmappableForLength(2);

        }

        public Decoder(Charset cs, float avgcpb, float maxcpb,

                       char[][] b2c, char[] b2cSB,

                       int b2Min, int b2Max,

                       boolean isASCIICompatible) {

            super(cs, avgcpb, maxcpb);

            this.b2c = b2c;

            this.b2cSB = b2cSB;

            this.b2Min = b2Min;

            this.b2Max = b2Max;

            this.isASCIICompatible = isASCIICompatible;

        }

        public Decoder(Charset cs, char[][] b2c, char[] b2cSB, int b2Min, int b2Max,

                       boolean isASCIICompatible) {

            this(cs, 0.5f, 1.0f, b2c, b2cSB, b2Min, b2Max, isASCIICompatible);

        }

        public Decoder(Charset cs, char[][] b2c, char[] b2cSB, int b2Min, int b2Max) {

            this(cs, 0.5f, 1.0f, b2c, b2cSB, b2Min, b2Max, false);

        }

        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) {

                    // inline the decodeSingle/Double() for better performance

                    int inSize = 1;

                    int b1 = sa[sp] & 0xff;

                    char c = b2cSB[b1];

                    if (c == UNMAPPABLE_DECODING) {

                        if (sl - sp < 2)

                            return crMalformedOrUnderFlow(b1);

                        int b2 = sa[sp + 1] & 0xff;

                        if (b2 < b2Min || b2 > b2Max ||

                            (c = b2c[b1][b2 - b2Min]) == UNMAPPABLE_DECODING) {

                            return crMalformedOrUnmappable(b1, b2);

                        }

                        inSize++;

                    }

                    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 = b2cSB[b1];

                    int inSize = 1;

                    if (c == UNMAPPABLE_DECODING) {

                        if (src.remaining() < 1)

                            return crMalformedOrUnderFlow(b1);

                        int b2 = src.get() & 0xff;

                        if (b2 < b2Min || b2 > b2Max ||

                            (c = b2c[b1][b2 - b2Min]) == UNMAPPABLE_DECODING)

                            return crMalformedOrUnmappable(b1, b2);

                        inSize++;

                    }

                    dst.put(c);

                    mark += inSize;

                }

                return src.hasRemaining()? CoderResult.OVERFLOW

                                         : CoderResult.UNDERFLOW;

            } finally {

                src.position(mark);

            }

        }

        // Make some protected methods public for use by JISAutoDetect

        public CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) {

            if (src.hasArray() && dst.hasArray())

                return decodeArrayLoop(src, dst);

            else

                return decodeBufferLoop(src, dst);

        }

        @Override

        public int decode(byte[] src, int sp, int len, char[] dst) {

            int dp = 0;

            int sl = sp + len;

            char repl = replacement().charAt(0);

            while (sp < sl) {

                int b1 = src[sp++] & 0xff;

                char c = b2cSB[b1];

                if (c == UNMAPPABLE_DECODING) {

                    if (sp < sl) {

                        int b2 = src[sp++] & 0xff;

                        if (b2 < b2Min || b2 > b2Max ||

                            (c = b2c[b1][b2 - b2Min]) == UNMAPPABLE_DECODING) {

                            }

                        }

                    }

                    if (c == UNMAPPABLE_DECODING) {

                         c = repl;

                    }

                }

                dst[dp++] = c;

            }

            return dp;

        }

        @Override

        public boolean isASCIICompatible() {

            return isASCIICompatible;

        }

        public void implReset() {

            super.implReset();

        }

        public CoderResult implFlush(CharBuffer out) {

            return super.implFlush(out);

        }

        // decode loops are not using decodeSingle/Double() for performance

        // reason.

        public char decodeSingle(int b) {

            return b2cSB[b];

        }

        public char decodeDouble(int b1, int b2) {

            if (b1 < 0 || b1 > b2c.length ||

                b2 < b2Min || b2 > b2Max)

                return UNMAPPABLE_DECODING;

            return  b2c[b1][b2 - b2Min];

        }

    }

    // IBM_EBCDIC_DBCS

    public static class Decoder_EBCDIC extends Decoder {

        private static final int SBCS = 0;

        private static final int DBCS = 1;

        private static final int SO = 0x0e;

        private static final int SI = 0x0f;

        private int  currentState;

        public Decoder_EBCDIC(Charset cs,

                              char[][] b2c, char[] b2cSB, int b2Min, int b2Max,

                              boolean isASCIICompatible) {

            super(cs, b2c, b2cSB, b2Min, b2Max, isASCIICompatible);

        }

        public Decoder_EBCDIC(Charset cs,

                              char[][] b2c, char[] b2cSB, int b2Min, int b2Max) {

            super(cs, b2c, b2cSB, b2Min, b2Max, false);

        }

        public void implReset() {

            currentState = SBCS;

        }

        // Check validity of dbcs ebcdic byte pair values

        //

        // First byte : 0x41 -- 0xFE

        // Second byte: 0x41 -- 0xFE

        // Doublebyte blank: 0x4040

        //

        // The validation implementation in "old" DBCS_IBM_EBCDIC and sun.io

        // as

        //            if ((b1 != 0x40 || b2 != 0x40) &&

        //                (b2 < 0x41 || b2 > 0xfe)) {...}

        // is not correct/complete (range check for b1)

        //

        private static boolean isDoubleByte(int b1, int b2) {

            return (0x41 <= b1 && b1 <= 0xfe && 0x41 <= b2 && b2 <= 0xfe)

                   || (b1 == 0x40 && b2 == 0x40); // DBCS-HOST SPACE

        }

        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 {

                // don't check dp/dl together here, it's possible to

                // decdoe a SO/SI without space in output buffer.

                while (sp < sl) {

                    int b1 = sa[sp] & 0xff;

                    int inSize = 1;

                    if (b1 == SO) {  // Shift out

                        if (currentState != SBCS)

                            return CoderResult.malformedForLength(1);

                        else

                            currentState = DBCS;

                    } else if (b1 == SI) {

                        if (currentState != DBCS)

                            return CoderResult.malformedForLength(1);

                        else

                            currentState = SBCS;

                    } else {

                        char c =  UNMAPPABLE_DECODING;

                        if (currentState == SBCS) {

                            c = b2cSB[b1];

                            if (c == UNMAPPABLE_DECODING)

                                return CoderResult.unmappableForLength(1);

                        } else {

                            if (sl - sp < 2)

                                return CoderResult.UNDERFLOW;

                            int b2 = sa[sp + 1] & 0xff;

                            if (b2 < b2Min || b2 > b2Max ||

                                (c = b2c[b1][b2 - b2Min]) == UNMAPPABLE_DECODING) {

                                if (!isDoubleByte(b1, b2))

                                    return CoderResult.malformedForLength(2);

                                return CoderResult.unmappableForLength(2);

                            }

                            inSize++;

                        }

                        if (dl - dp < 1)

                            return CoderResult.OVERFLOW;

                        da[dp++] = c;

                    }

                    sp += inSize;

                }

                return CoderResult.UNDERFLOW;

            } 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()) {

                    int b1 = src.get() & 0xff;

                    int inSize = 1;

                    if (b1 == SO) {  // Shift out

                        if (currentState != SBCS)

                            return CoderResult.malformedForLength(1);

                        else

                            currentState = DBCS;

                    } else if (b1 == SI) {

                        if (currentState != DBCS)

                            return CoderResult.malformedForLength(1);

                        else

                            currentState = SBCS;

                    } else {

                        char c = UNMAPPABLE_DECODING;

                        if (currentState == SBCS) {

                            c = b2cSB[b1];

                            if (c == UNMAPPABLE_DECODING)

                                return CoderResult.unmappableForLength(1);

                        } else {

                            if (src.remaining() < 1)

                                return CoderResult.UNDERFLOW;

                            int b2 = src.get()&0xff;

                            if (b2 < b2Min || b2 > b2Max ||

                                (c = b2c[b1][b2 - b2Min]) == UNMAPPABLE_DECODING) {

                                if (!isDoubleByte(b1, b2))

                                    return CoderResult.malformedForLength(2);

                                return CoderResult.unmappableForLength(2);

                            }

                            inSize++;

                        }

                        if (dst.remaining() < 1)

                            return CoderResult.OVERFLOW;

                        dst.put(c);

                    }

                    mark += inSize;

                }

                return CoderResult.UNDERFLOW;

            } finally {

                src.position(mark);

            }

        }

        @Override

        public int decode(byte[] src, int sp, int len, char[] dst) {

            int dp = 0;

            int sl = sp + len;

            currentState = SBCS;

            char repl = replacement().charAt(0);

            while (sp < sl) {

                int b1 = src[sp++] & 0xff;

                if (b1 == SO) {  // Shift out

                    if (currentState != SBCS)

                        dst[dp++] = repl;

                    else

                        currentState = DBCS;

                } else if (b1 == SI) {

                    if (currentState != DBCS)

                        dst[dp++] = repl;

                    else

                        currentState = SBCS;

                } else {

                    char c =  UNMAPPABLE_DECODING;

                    if (currentState == SBCS) {

                        c = b2cSB[b1];

                        if (c == UNMAPPABLE_DECODING)

                            c = repl;

                    } else {

                        if (sl == sp) {

                            c = repl;

                        } else {

                            int b2 = src[sp++] & 0xff;

                            if (b2 < b2Min || b2 > b2Max ||

                                (c = b2c[b1][b2 - b2Min]) == UNMAPPABLE_DECODING) {

                                c = repl;

                            }

                        }

                    }

                    dst[dp++] = c;

                }

            }

            return dp;

        }

    }

    // DBCS_ONLY

    public static class Decoder_DBCSONLY extends Decoder {

        static final char[] b2cSB_UNMAPPABLE;

        static {

            b2cSB_UNMAPPABLE = new char[0x100];

            Arrays.fill(b2cSB_UNMAPPABLE, UNMAPPABLE_DECODING);

        }

        public Decoder_DBCSONLY(Charset cs, char[][] b2c, char[] b2cSB, int b2Min, int b2Max,

                                boolean isASCIICompatible) {

            super(cs, 0.5f, 1.0f, b2c, b2cSB_UNMAPPABLE, b2Min, b2Max, isASCIICompatible);

        }

        public Decoder_DBCSONLY(Charset cs, char[][] b2c, char[] b2cSB, int b2Min, int b2Max) {

            super(cs, 0.5f, 1.0f, b2c, b2cSB_UNMAPPABLE, b2Min, b2Max, false);

        }

    }

    // EUC_SIMPLE

    // The only thing we need to "override" is to check SS2/SS3 and

    // return "malformed" if found

    public static class Decoder_EUC_SIM extends Decoder {

        private final int SS2 =  0x8E;

        private final int SS3 =  0x8F;

        public Decoder_EUC_SIM(Charset cs,

                               char[][] b2c, char[] b2cSB, int b2Min, int b2Max,

                               boolean isASCIICompatible) {

            super(cs, b2c, b2cSB, b2Min, b2Max, isASCIICompatible);

        }

        // No support provided for G2/G3 for SimpleEUC

        protected CoderResult crMalformedOrUnderFlow(int b) {

            if (b == SS2 || b == SS3 )

                return CoderResult.malformedForLength(1);

            return CoderResult.UNDERFLOW;

        }

        protected CoderResult crMalformedOrUnmappable(int b1, int b2) {

            if (b1 == SS2 || b1 == SS3 )

                return CoderResult.malformedForLength(1);

            return CoderResult.unmappableForLength(2);

        }

        @Override

        public int decode(byte[] src, int sp, int len, char[] dst) {

            int dp = 0;

            int sl = sp + len;

            char repl = replacement().charAt(0);

            while (sp < sl) {

                int b1 = src[sp++] & 0xff;

                char c = b2cSB[b1];

                if (c == UNMAPPABLE_DECODING) {