/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.xerces.impl.xpath.regex;

import java.text.CharacterIterator;

/**
 * Boyer-Moore searcher.
 * 
 * @xerces.internal
 *
 * @version $Id: BMPattern.java 572108 2007-09-02 18:48:31Z mrglavas $
 */
public class BMPattern {
    final char[] pattern;
    final int[] shiftTable;
    final boolean ignoreCase;

    public BMPattern(String pat, boolean ignoreCase) {
        this(pat, 256, ignoreCase);
    }

    public BMPattern(String pat, int tableSize, boolean ignoreCase) {
        this.pattern = pat.toCharArray();
        this.shiftTable = new int[tableSize];
        this.ignoreCase = ignoreCase;

        int length = pattern.length;
        for (int i = 0;  i < this.shiftTable.length;  i ++)
            this.shiftTable[i] = length;

        for (int i = 0;  i < length;  i ++) {
            char ch = this.pattern[i];
            int diff = length-i-1;
            int index = ch % this.shiftTable.length;
            if (diff < this.shiftTable[index])
                this.shiftTable[index] = diff;
            if (this.ignoreCase) {
                ch = Character.toUpperCase(ch);
                index = ch % this.shiftTable.length;
                if (diff < this.shiftTable[index])
                    this.shiftTable[index] = diff;
                ch = Character.toLowerCase(ch);
                index = ch % this.shiftTable.length;
                if (diff < this.shiftTable[index])
                    this.shiftTable[index] = diff;
            }
        }
    }

    /**
     *
     * @return -1 if <var>iterator</var> does not contain this pattern.
     */
    public int matches(CharacterIterator iterator, int start, int limit) {
        if (this.ignoreCase)  return this.matchesIgnoreCase(iterator, start, limit);
        int plength = this.pattern.length;
        if (plength == 0)  return start;
        int index = start+plength;
        while (index <= limit) {
            int pindex = plength;
            int nindex = index+1;
            char ch;
            do {
                if ((ch = iterator.setIndex(--index)) != this.pattern[--pindex])
                    break;
                if (pindex == 0)
                    return index;
            } while (pindex > 0);
            index += this.shiftTable[ch % this.shiftTable.length]+1;
            if (index < nindex)  index = nindex;
        }
        return -1;
    }

    /**
     *
     * @return -1 if <var>str</var> does not contain this pattern.
     */
    public int matches(String str, int start, int limit) {
        if (this.ignoreCase)  return this.matchesIgnoreCase(str, start, limit);
        int plength = this.pattern.length;
        if (plength == 0)  return start;
        int index = start+plength;
        while (index <= limit) {
            //System.err.println("Starts at "+index);
            int pindex = plength;
            int nindex = index+1;
            char ch;
            do {
                if ((ch = str.charAt(--index)) != this.pattern[--pindex])
                    break;
                if (pindex == 0)
                    return index;
            } while (pindex > 0);
            index += this.shiftTable[ch % this.shiftTable.length]+1;
            if (index < nindex)  index = nindex;
        }
        return -1;
    }
    /**
     *
     * @return -1 if <var>chars</char> does not contain this pattern.
     */
    public int matches(char[] chars, int start, int limit) {
        if (this.ignoreCase)  return this.matchesIgnoreCase(chars, start, limit);
        int plength = this.pattern.length;
        if (plength == 0)  return start;
        int index = start+plength;
        while (index <= limit) {
            //System.err.println("Starts at "+index);
            int pindex = plength;
            int nindex = index+1;
            char ch;
            do {
                if ((ch = chars[--index]) != this.pattern[--pindex])
                    break;
                if (pindex == 0)
                    return index;
            } while (pindex > 0);
            index += this.shiftTable[ch % this.shiftTable.length]+1;
            if (index < nindex)  index = nindex;
        }
        return -1;
    }

    int matchesIgnoreCase(CharacterIterator iterator, int start, int limit) {
        int plength = this.pattern.length;
        if (plength == 0)  return start;
        int index = start+plength;
        while (index <= limit) {
            int pindex = plength;
            int nindex = index+1;
            char ch;
            do {
                char ch1 = ch = iterator.setIndex(--index);
                char ch2 = this.pattern[--pindex];
                if (ch1 != ch2) {
                    ch1 = Character.toUpperCase(ch1);
                    ch2 = Character.toUpperCase(ch2);
                    if (ch1 != ch2 && Character.toLowerCase(ch1) != Character.toLowerCase(ch2))
                        break;
                }
                if (pindex == 0)
                    return index;
            } while (pindex > 0);
            index += this.shiftTable[ch % this.shiftTable.length]+1;
            if (index < nindex)  index = nindex;
        }
        return -1;
    }
    
    int matchesIgnoreCase(String text, int start, int limit) {
        int plength = this.pattern.length;
        if (plength == 0)  return start;
        int index = start+plength;
        while (index <= limit) {
            int pindex = plength;
            int nindex = index+1;
            char ch;
            do {
                char ch1 = ch = text.charAt(--index);
                char ch2 = this.pattern[--pindex];
                if (ch1 != ch2) {
                    ch1 = Character.toUpperCase(ch1);
                    ch2 = Character.toUpperCase(ch2);
                    if (ch1 != ch2 && Character.toLowerCase(ch1) != Character.toLowerCase(ch2))
                        break;
                }
                if (pindex == 0)
                    return index;
            } while (pindex > 0);
            index += this.shiftTable[ch % this.shiftTable.length]+1;
            if (index < nindex)  index = nindex;
        }
        return -1;
    }
    int matchesIgnoreCase(char[] chars, int start, int limit) {
        int plength = this.pattern.length;
        if (plength == 0)  return start;
        int index = start+plength;
        while (index <= limit) {
            int pindex = plength;
            int nindex = index+1;
            char ch;
            do {
                char ch1 = ch = chars[--index];
                char ch2 = this.pattern[--pindex];
                if (ch1 != ch2) {
                    ch1 = Character.toUpperCase(ch1);
                    ch2 = Character.toUpperCase(ch2);
                    if (ch1 != ch2 && Character.toLowerCase(ch1) != Character.toLowerCase(ch2))
                        break;
                }
                if (pindex == 0)
                    return index;
            } while (pindex > 0);
            index += this.shiftTable[ch % this.shiftTable.length]+1;
            if (index < nindex)  index = nindex;
        }
        return -1;
    }

    /*
    public static void main(String[] argv) {
        try {
            int[] shiftTable = new int[256];
            initializeBoyerMoore(argv[0], shiftTable, true);
            int o = -1;
            CharacterIterator ite = new java.text.StringCharacterIterator(argv[1]);
            long start = System.currentTimeMillis();
            //for (int i = 0;  i < 10000;  i ++)
                o = searchIgnoreCasesWithBoyerMoore(ite, 0, argv[0], shiftTable);
            start = System.currentTimeMillis()-start;
            System.out.println("Result: "+o+", Elapsed: "+start);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }*/
}

