src/main/java/de/ids_mannheim/korap/collection/CollectionBuilder.java

package de.ids_mannheim.korap.collection;

import java.util.*;
import java.io.IOException;

import org.apache.lucene.index.Term;
import org.apache.lucene.queries.TermsFilter;
import org.apache.lucene.search.*;
import org.apache.lucene.search.NumericRangeFilter;
import de.ids_mannheim.korap.util.KrillDate;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import de.ids_mannheim.korap.KrillCollection;
import de.ids_mannheim.korap.collection.BooleanGroupFilter;

/*
 * TODO: Optimize!
 * - Remove identical object in Boolean groups
 * - Flatten boolean groups
 * - create "between" ranges for multiple date objects
 */

public class CollectionBuilder {

    // Logger
    private final static Logger log = LoggerFactory
            .getLogger(KrillCollection.class);

    // This advices the java compiler to ignore all loggings
    public static final boolean DEBUG = false;


    public CollectionBuilder.Interface term (String field, String term) {
        return new CollectionBuilder.Term(field, term);
    };


    public CollectionBuilder.Interface re (String field, String term) {
        return new CollectionBuilder.Term(field, term, true);
    };


    public CollectionBuilder.Interface since (String field, String date) {
        int since = new KrillDate(date).floor();

        if (since == 0 || since == KrillDate.BEGINNING)
            return null;

        return new CollectionBuilder.Range(field, since, KrillDate.END);
    };


    public CollectionBuilder.Interface till (String field, String date) {
        try {
            int till = new KrillDate(date).ceil();
            if (till == 0 || till == KrillDate.END)
                return null;

            return new CollectionBuilder.Range(field, KrillDate.BEGINNING, till);
        }
        catch (NumberFormatException e) {
            log.warn("Parameter of till(date) is invalid");
        };
        return null;
    };


    // This will be optimized away in future versions
    public CollectionBuilder.Interface between (String field, String start,
            String end) {
        CollectionBuilder.Interface startObj = this.since(field, start);
        if (startObj == null)
            return null;

        CollectionBuilder.Interface endObj = this.till(field, end);
        if (endObj == null)
            return null;

        return this.andGroup().with(startObj).with(endObj);
    };


    public CollectionBuilder.Interface date (String field, String date) {
        KrillDate dateDF = new KrillDate(date);

        if (dateDF.year == 0)
            return null;

        if (dateDF.day == 0 || dateDF.month == 0) {
            int begin = dateDF.floor();
            int end = dateDF.ceil();

            if (end == 0
                    || (begin == KrillDate.BEGINNING && end == KrillDate.END))
                return null;

            return new CollectionBuilder.Range(field, begin, end);
        };

        return new CollectionBuilder.Range(field, dateDF.floor(), dateDF.ceil());
    };


    public CollectionBuilder.Group andGroup () {
        return new CollectionBuilder.Group(false);
    };


    public CollectionBuilder.Group orGroup () {
        return new CollectionBuilder.Group(true);
    };

    public interface Interface {
        public String toString ();


        public Filter toFilter ();


        public boolean isNegative ();


        public CollectionBuilder.Interface not ();
    };

    public class Term implements CollectionBuilder.Interface {
        private boolean isNegative = false;
        private boolean regex = false;
        private String field;
        private String term;


        public Term (String field, String term) {
            this.field = field;
            this.term = term;
        };


        public Term (String field, String term, boolean regex) {
            this.field = field;
            this.term = term;
            this.regex = regex;
        };


        public Filter toFilter () {
            // Regular expression
            if (this.regex)
                return new QueryWrapperFilter(
                        new RegexpQuery(new org.apache.lucene.index.Term(
                                this.field, this.term)));

            // Simple term
            return new TermsFilter(new org.apache.lucene.index.Term(this.field,
                    this.term));
        };


        public String toString () {
            Filter filter = this.toFilter();
            if (filter == null)
                return "";
            return filter.toString();
        };


        public boolean isNegative () {
            return this.isNegative;
        };


        public CollectionBuilder.Interface not () {
            this.isNegative = true;
            return this;
        };
    };

    public class Group implements CollectionBuilder.Interface {
        private boolean isOptional = false;
        private boolean isNegative = true;


        public boolean isNegative () {
            return this.isNegative;
        };


        public boolean isOptional () {
            return this.isOptional;
        };

        private ArrayList<CollectionBuilder.Interface> operands;


        public Group (boolean optional) {
            this.isOptional = optional;
            this.operands = new ArrayList<CollectionBuilder.Interface>(3);
        };


        public Group with (CollectionBuilder.Interface cb) {
            if (cb == null)
                return this;

            if (!cb.isNegative())
                this.isNegative = false;
            this.operands.add(cb);
            return this;
        };


        public Group with (String field, String term) {
            if (field == null || term == null)
                return this;
            return this.with(new CollectionBuilder.Term(field, term));
        };


        public Filter toFilter () {
            if (this.operands == null || this.operands.isEmpty())
                return null;

            if (this.operands.size() == 1)
                return this.operands.get(0).toFilter();

            // BooleanFilter bool = new BooleanFilter();
            BooleanGroupFilter bool = new BooleanGroupFilter(this.isOptional);

            Iterator<CollectionBuilder.Interface> i = this.operands.iterator();
            while (i.hasNext()) {
                CollectionBuilder.Interface cb = i.next();
                if (cb.isNegative()) {
                    bool.without(cb.toFilter());
                }
                else {
                    bool.with(cb.toFilter());
                };
            };

            return bool;
        };


        public String toString () {
            Filter filter = this.toFilter();
            if (filter == null)
                return "";
            return filter.toString();
        };


        public CollectionBuilder.Interface not () {
            this.isNegative = true;
            return this;
        };
    };

    public class Range implements CollectionBuilder.Interface {
        private boolean isNegative = false;
        private String field;
        private int start, end;


        public Range (String field, int start, int end) {
            this.field = field;
            this.start = start;
            this.end = end;
        };


        public boolean isNegative () {
            return this.isNegative;
        };


        public String toString () {
            Filter filter = this.toFilter();
            if (filter == null)
                return "";
            return filter.toString();
        };


        public Filter toFilter () {
            return NumericRangeFilter.newIntRange(this.field, this.start,
                    this.end, true, true);
        };


        public CollectionBuilder.Interface not () {
            this.isNegative = true;
            return this;
        };
    };
};