/*
 * Copyright 2013 Websquared, Inc.
 * 
 * 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 org.fastcatsearch.ir.filter.function;

import java.io.IOException;

import org.apache.lucene.util.BytesRef;
import org.fastcatsearch.ir.filter.FilterException;
import org.fastcatsearch.ir.filter.FilterFunction;
import org.fastcatsearch.ir.io.DataRef;
import org.fastcatsearch.ir.query.Filter;
import org.fastcatsearch.ir.query.RankInfo;
import org.fastcatsearch.ir.settings.FieldIndexSetting;
import org.fastcatsearch.ir.settings.FieldSetting;


/**
 * 패턴과 데이터비교시.
 * 패턴길이 > 데이터길이 이면 비교하지 않고 불일치처리.
 * @author swsong
 *
 */
public class SuffixFilter extends PatternFilterFunction {

	public SuffixFilter(Filter filter, FieldIndexSetting fieldIndexSetting, FieldSetting fieldSetting) throws FilterException {
		super(filter, fieldIndexSetting, fieldSetting, false);
	}
	public SuffixFilter(Filter filter, FieldIndexSetting fieldIndexSetting, FieldSetting fieldSetting, boolean isBoostFunction) throws FilterException {
		super(filter, fieldIndexSetting, fieldSetting, isBoostFunction);
	}
	
	@Override
	public boolean filtering(RankInfo rankInfo, DataRef dataRef) throws IOException {
		while(dataRef.next()){
			
			BytesRef bytesRef = dataRef.bytesRef();
			for (int j = 0; j < patternCount; j++) {
				BytesRef patternBuf = patternList[j];
				int plen = patternBuf.length;
				
				//Prefix에서도 패턴이 데이터보다  크면 match확인필요없음. 다음으로 진행.
				if(plen > bytesRef.length()) {
					continue;
				}
				
				if(plen > 0){
					if(byteEqualsReverse(patternBuf, bytesRef)){
						if(isBoostFunction){
							//boost옵션이 있다면 점수를 올려주고 리턴한다.
							rankInfo.addScore(boostScore);
							if(rankInfo.isExplain()) {
								rankInfo.explain(fieldIndexId, boostScore, "SUFFIX_BOOST_FILTER");
							}
						}
						return true;
					}
						
					//여기까지 왔다면 매칭되지 않은것이다.
					//다음패턴으로 이동.
				}
					
			} // for (int j = 0; j < patternCount; j++) {
			
		}
		
		return isBoostFunction;
		
	}
	
	private boolean byteEqualsReverse(BytesRef patternBuf, BytesRef dataBuf){
		//예) fieldSize가 5인 dataBuf에 ABC는 ABC00으로 들어있다.
		//0이 아닌 유효데이터 마지막 위치 확인. 뒤에서부터.
		int dataLastOffset = 0;
		for (dataLastOffset = dataBuf.length() - 1; dataLastOffset >= 0; dataLastOffset--) {
			if (dataBuf.get(dataLastOffset) != 0) {
				break;
			}
		}
		if(dataLastOffset < 0){
			//빈 데이터.
			return false;
		}
		//뒤에서 부터 매칭테스트.
		int offset = patternBuf.length() - 1;
		for (int k = 0; k < patternBuf.length(); k++) {
			if (patternBuf.get(offset - k) != dataBuf.get(dataLastOffset - k)) {
				return false;
			}
		}
		
		return true;
	}
	
}