/*
 * Copyright (c) 2001, 2005, 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.
 *
 * 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.
 */

import java.nio.CharBuffer;
import java.nio.ByteBuffer;
import java.nio.charset.*;
import sun.nio.cs.ext.EUC_TW;

public abstract class X11CNS11643 extends Charset {
    private final int plane;
    public X11CNS11643 (int plane, String name) {
        super(name, null);
        switch (plane) {
        case 1:
            this.plane = 0; // CS1
            break;
        case 2:
        case 3:
            this.plane = plane;
            break;
        default:
            throw new IllegalArgumentException
                ("Only planes 1, 2, and 3 supported");
        }
    }

    public CharsetEncoder newEncoder() {
        return new Encoder(this, plane);
    }

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

    public boolean contains(Charset cs) {
        return cs instanceof X11CNS11643;
    }

    private class Encoder extends EUC_TW_OLD.Encoder {
        private int plane;
        public Encoder(Charset cs, int plane) {
            super(cs);
            this.plane = plane;
        }
        public boolean canEncode(char c) {
            if (c <= 0x7F) {
                return false;
            }
            int p = getNative(c) >> 16;
            if (p == 1 && plane == 0 ||
                p == 2 && plane == 2 ||
                p == 3 && plane == 3)
                return true;
            return false;
        }

        public boolean isLegalReplacement(byte[] repl) {
            return true;
        }

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

            try {
                while (sp < sl) {
                    char c = sa[sp];
                    if (c >= '\uFFFE' || c <= '\u007f')
                        return CoderResult.unmappableForLength(1);
                    int cns = getNative(c);
                    int p = cns >> 16;
                    if (p == 1 && plane == 0 ||
                        p == 2 && plane == 2 ||
                        p == 3 && plane == 3) {
                        if (dl - dp < 2)
                            return CoderResult.OVERFLOW;
                        da[dp++] = (byte) ((cns  >> 8) & 0x7f);
                        da[dp++] = (byte) (cns & 0x7f);
                        sp++;
                        continue;
                    }
                    return CoderResult.unmappableForLength(1);
                }
                return CoderResult.UNDERFLOW;
            } finally {
                src.position(sp - src.arrayOffset());
                dst.position(dp - dst.arrayOffset());
            }
        }
    }

    private class Decoder extends EUC_TW_OLD.Decoder {
        private String table;
        protected Decoder(Charset cs, int plane) {
            super(cs);
            switch (plane) {
            case 0:
                table = unicodeCNS1;
                break;
            case 2:
                table = unicodeCNS2;
                break;
            case 3:
                table = unicodeCNS3;
                break;
            default:
                throw new IllegalArgumentException
                    ("Only planes 1, 2, and 3 supported");
            }
        }

        //we only work on array backed buffer.
        protected CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) {
            byte[] sa = src.array();
            int sp = src.arrayOffset() + src.position();
            int sl = src.arrayOffset() + src.limit();
            assert (sp <= sl);
            sp = (sp <= sl ? sp : sl);

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

            try {
                while (sp < sl) {
                    if ( sl - sp < 2) {
                        return CoderResult.UNDERFLOW;
                    }
                    byte b1 = sa[sp];
                    byte b2 = sa[sp + 1];
                    char c = replacement().charAt(0);

                    if (table == unicodeCNS3) {
                        char[] cc = convToSurrogate((byte)(b1 | 0x80),
                                                    (byte)(b2 | 0x80),
                                                    table);
                        if (cc != null && cc[0] == '\u0000')
                            c = cc[1];
                    } else {
                        c = convToUnicode((byte)(b1 | 0x80),
                                           (byte)(b2 | 0x80),
                                           table);
                    }
                    if (c == replacement().charAt(0)
                        //to keep the compatibility with b2cX11CNS11643
                        /*|| c == '\u0000'*/) {
                        return CoderResult.unmappableForLength(2);
                    }
                    if (dl - dp < 1)
                        return CoderResult.OVERFLOW;
                    da[dp++] = c;
                    sp +=2;
                }
                return CoderResult.UNDERFLOW;
            } finally {
                src.position(sp - src.arrayOffset());
                dst.position(dp - dst.arrayOffset());
            }
        }
    }
}