/*
 * Copyright 2014, Stratio.
 *
 * 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.stratio.cassandra.index.service;

import org.apache.cassandra.dht.Token;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.lucene.index.FilteredTermsEnum;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.MultiTermQuery;
import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.BytesRef;

import java.io.IOException;

/**
 * Generic query for retrieving a range of tokens in combination with {@link TokenMapperGeneric}.
 *
 * @author Andres de la Pena <adelapena@stratio.com>
 */
public class TokenRangeQuery extends MultiTermQuery {

    private final TokenMapperGeneric tokenMapper; // The token mapper
    private final Token lower; // The lower accepted token
    private final Token upper; // The upper accepted token
    private final boolean includeLower; // If the lower token must be included if not null
    private final boolean includeUpper; // If the upper token must be included if not null

    /**
     * Builds a new {@link TokenRangeQuery}.
     *
     * @param lower        The lower accepted {@link Token}. Maybe null meaning no lower limit.
     * @param upper        The upper accepted {@link Token}. Maybe null meaning no lower limit.
     * @param includeLower If the {@code lowerValue} is included in the range.
     * @param includeUpper If the {@code upperValue} is included in the range.
     * @param tokenMapper  The used {@link TokenMapperGeneric}.
     */
    public TokenRangeQuery(Token lower,
                           Token upper,
                           boolean includeLower,
                           boolean includeUpper,
                           TokenMapperGeneric tokenMapper) {
        super(TokenMapperGeneric.FIELD_NAME);
        this.tokenMapper = tokenMapper;
        this.lower = lower;
        this.upper = upper;
        this.includeLower = includeLower;
        this.includeUpper = includeUpper;
    }

    /** {@inheritDoc} */
    @Override
    protected TermsEnum getTermsEnum(Terms terms, AttributeSource atts) throws IOException {
        TermsEnum termsEnum = terms.iterator(null);
        return new TokenDataRangeFilteredTermsEnum(termsEnum);
    }

    /** {@inheritDoc} */
    @Override
    public String toString(String field) {
        return new ToStringBuilder(this).append("field", field)
                                        .append("lower", lower)
                                        .append("upper", upper)
                                        .append("includeLower", includeLower)
                                        .append("includeUpper", includeUpper)
                                        .toString();
    }

    /**
     * {@link FilteredTermsEnum} for generic tokens.
     */
    private class TokenDataRangeFilteredTermsEnum extends FilteredTermsEnum {

        /**
         * Builds a new {@link TokenDataRangeFilteredTermsEnum} for the specified {@link TermsEnum}.
         *
         * @param termsEnum The {@link TermsEnum} to be filtered.
         */
        public TokenDataRangeFilteredTermsEnum(TermsEnum termsEnum) {
            super(termsEnum);
            setInitialSeekTerm(new BytesRef());
        }

        /** {@inheritDoc} */
        @Override
        @SuppressWarnings("unchecked")
        protected AcceptStatus accept(BytesRef term) {
            Token token = tokenMapper.token(term);
            if (includeLower ? token.compareTo(lower) < 0 : token.compareTo(lower) <= 0) {
                return AcceptStatus.NO;
            } else if (includeUpper ? token.compareTo(upper) > 0 : token.compareTo(upper) >= 0) {
                return AcceptStatus.NO;
            } else {
                return AcceptStatus.YES;
            }
        }
    }
}