/*
 * Copyright (c) 2010, 2016, 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 (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(java.nio.charset.StandardCharsets.ISO_8859_1);
 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;
 }
}