/*

 * Copyright (c) 2010, 2021, 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 java.lang;

import java.io.DataInputStream;

import java.io.InputStream;

import java.lang.ref.SoftReference;

import java.util.Arrays;

import java.util.Locale;

import java.util.zip.InflaterInputStream;

import java.security.AccessController;

import java.security.PrivilegedAction;

class CharacterName {

    private static SoftReference<CharacterName> refCharName;

    // codepoint -> bkIndex -> lookup -> offset/len

    private final byte[] strPool;

    private final int[] lookup;      // code point -> offset/len in strPool

    private final int[] bkIndices;   // code point -> lookup index

    // name -> hash -> hsIndices -> cpEntries -> code point

    private final int[] cpEntries;   // code points that have name in strPool

    private final int[] hsIndices;   // chain heads, hash indices into "cps"

    private CharacterName()  {

        try (@SuppressWarnings("removal") DataInputStream dis = new DataInputStream(new InflaterInputStream(

            AccessController.doPrivileged(new PrivilegedAction<>() {

                public InputStream run() {

                    return getClass().getResourceAsStream("uniName.dat");

                }

            })))) {

            int total = dis.readInt();

            int bkNum = dis.readInt();

            int cpNum = dis.readInt();

            int cpEnd = dis.readInt();

            byte ba[] = new byte[cpEnd];

            lookup = new int[bkNum * 256];

            bkIndices = new int[(Character.MAX_CODE_POINT + 1) >> 8];

            strPool = new byte[total - cpEnd];

            cpEntries = new int[cpNum * 3];

            hsIndices = new int[(cpNum / 2) | 1];

            Arrays.fill(bkIndices, -1);

            Arrays.fill(hsIndices, -1);

            dis.readFully(ba);

            dis.readFully(strPool);

            int nameOff = 0;

            int cpOff = 0;

            int cp = 0;

            int bk = -1;

            int prevBk = -1;   // prev bkNo;

            int idx = 0;

            int next = -1;

            int hash = 0;

            int hsh = 0;

            do {

                int len = ba[cpOff++] & 0xff;

                if (len == 0) {

                    len = ba[cpOff++] & 0xff;

                    // always big-endian

                    cp = ((ba[cpOff++] & 0xff) << 16) |

                         ((ba[cpOff++] & 0xff) <<  8) |

                         ((ba[cpOff++] & 0xff));

                }  else {

                    cp++;

                }

                // cp -> name

                int hi = cp >> 8;

                if (prevBk != hi) {

                    bk++;

                    bkIndices[hi] = bk;

                    prevBk = hi;

                }

                lookup[(bk << 8) + (cp & 0xff)] = (nameOff << 8) | len;

                // name -> cp

                hash = hashN(strPool, nameOff, len);

                hsh = (hash & 0x7fffffff) % hsIndices.length;

                next = hsIndices[hsh];

                hsIndices[hsh] = idx;

                idx = addCp(idx, hash, next, cp);

                nameOff += len;

            } while (cpOff < cpEnd);

        } catch (Exception x) {

            throw new InternalError(x.getMessage(), x);

        }

    }

    private static final int hashN(byte[] a, int off, int len) {

        int h = 1;

        while (len-- > 0) {

            h = 31 * h + a[off++];

        }

        return h;

    }

    private int addCp(int idx, int hash, int next, int cp) {

        cpEntries[idx++] = hash;

        cpEntries[idx++] = next;

        cpEntries[idx++] = cp;

        return idx;

    }

    private int getCpHash(int idx) { return cpEntries[idx]; }

    private int getCpNext(int idx) { return cpEntries[idx + 1]; }

    private int getCp(int idx)  { return cpEntries[idx + 2]; }

    public static CharacterName getInstance() {

        SoftReference<CharacterName> ref = refCharName;

        CharacterName cname = null;

        if (ref == null || (cname = ref.get()) == null) {

            cname = new CharacterName();

            refCharName = new SoftReference<>(cname);

        }

        return cname;

    }

    public String getName(int cp) {

        int off = 0;

        int bk = bkIndices[cp >> 8];

        if (bk == -1 || (off = lookup[(bk << 8) + (cp & 0xff)]) == 0)

            return null;

        @SuppressWarnings("deprecation")

        String result = new String(strPool, 0, off >>> 8, off & 0xff);  // ASCII

        return result;

    }

    public int getCodePoint(String name) {

        byte[] bname = name.getBytes(sun.nio.cs.ISO_8859_1.INSTANCE);

        int hsh = hashN(bname, 0, bname.length);

        int idx = hsIndices[(hsh & 0x7fffffff) % hsIndices.length];

        while (idx != -1) {

            if (getCpHash(idx) == hsh) {

                int cp = getCp(idx);

                int off = -1;

                int bk = bkIndices[cp >> 8];

                if (bk != -1 && (off = lookup[(bk << 8) + (cp & 0xff)]) != 0) {

                    int len = off & 0xff;

                    off = off >>> 8;

                    if (bname.length == len) {

                        int i = 0;

                        while (i < len && bname[i] == strPool[off++]) {

                            i++;

                        }

                        if (i == len) {

                            return cp;

                        }

                    }

                 }

            }

            idx = getCpNext(idx);

        }

        return -1;

    }

}