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/*
 * Copyright 2015 The FireNio Project
 *
 * Licensed 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 com.firenio.codec.http11;

import com.firenio.collection.IntArray;
import com.firenio.common.Util;

//关键字：前缀，后缀，部分匹配表
public class KMPUtil {

    private char[] match_array;

    private int[] match_table;

    private String match_value;

    public KMPUtil(String value) {
        this.initialize(value);
    }

    public static void main(String[] args) {

        String s1 = "1111111111111111111211111111112111121111211111111";

        String match = "1112";

        KMPUtil kmp = new KMPUtil(match);

        System.out.println(kmp.match_all(s1));

    }

    private void initialize(String value) {
        if (Util.isNullOrBlank(value)) {
            throw new IllegalArgumentException("null value");
        }
        this.match_value = value;
        this.match_array = match_value.toCharArray();
        this.match_table = new int[match_value.length()];
        this.initialize_part_match_table();
    }

    private void initialize_part_match_table() {
        int length = this.match_value.length();
        // 直接从两位开始比较
        for (int i = 2; i < length; i++) {
            match_table[i] = initialize_part_match_table0(match_array, i);
        }
    }

    private int initialize_part_match_table0(char[] array, int length) {
        int e = 0;
        WORD:
        for (int i = 1; i < length; i++) {
            int t = 0;
            int p = 0;
            int s = length - i;
            for (int j = 0; j < i; j++) {
                if (array[p++] != array[s++]) {
                    continue WORD;
                }
                t++;
            }
            e = t;
        }
        return e;
    }

    public int match(String value) {
        return match(value, 0);
    }

    public int match(String value, int begin) {
        if (Util.isNullOrBlank(value) || begin < 0) {
            return -1;
        }
        if (value.length() - begin < this.match_array.length) {
            return -1;
        }
        int    source_length = value.length();
        int    index         = begin;
        int    match_length  = this.match_array.length;
        char[] match_array   = this.match_array;
        int[]  match_table   = this.match_table;
        LOOP:
        for (; index < source_length; ) {
            for (int i = 0; i < match_length; i++) {
                if (value.charAt(index + i) != match_array[i]) {
                    if (i == 0) {
                        index++;
                    } else {
                        index += (i - match_table[i]);
                    }
                    continue LOOP;
                }
            }
            return index;
        }
        return -1;
    }

    public IntArray match_all(String value) {
        if (Util.isNullOrBlank(value)) {
            return null;
        }
        if (value.length() < match_value.length()) {
            return null;
        }
        IntArray matchs = new IntArray();
        if (value.equals(match_value)) {
            matchs.add(0);
            return matchs;
        }
        int    source_length = value.length();
        int    index         = 0;
        int    match_length  = this.match_array.length;
        char[] match_array   = this.match_array;
        int[]  match_table   = this.match_table;
        LOOP:
        for (; index < source_length; ) {
            if (source_length - index < match_length) {
                break;
            }
            for (int i = 0; i < match_length; i++) {
                if (value.charAt(index + i) != match_array[i]) {
                    if (i == 0) {
                        index++;
                    } else {
                        index += (i - match_table[i]);
                    }
                    continue LOOP;
                }
            }
            matchs.add(index);
            index += match_length;
        }
        return matchs;
    }
}