package org.apache.lucene.index;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import org.apache.lucene.search.WildcardTermEnum;
import java.util.HashSet;
import java.util.Iterator;
import java.io.IOException;
/**
  A wildcard term is used in the PhrasePrefix class.
  The class holds the wildcard term with special characters
  until the query is prepared. Then the wildcard term is equated
  with a set of terms in the index. 
  Effectively this class is a term with one field but with multiple
  text fields. The internal multiple fields are hidden.
  */

public class WildcardTerm extends Term {
    private HashSet whs=null;

    /** Constructs a Term with the given field and text. */
    public WildcardTerm(String fld, String txt) {
        super(fld, txt);
    }

    /** Compares two terms, returning true iff they have the same
      field and text. */
    public boolean equals(Object o) {
        if (o == null)
            return false;
        //if term has not been expanded yet match against the wildcard pattern
        if (whs == null) {
            Term other = (Term)o;
            return field == other.field && text.equals(other.text);
        } else {
            Term other = (Term)o;
            if (whs.contains(other) ) {
                return true;
            } else { 
                return false;
            }
        }
    }

    public String toString() {
        if (whs==null) {
            return "WildcardTerm<" + field + ":" + text + ">";
        } else {
            StringBuffer sb = new StringBuffer();
            sb.append("WildcardTerm<" + field + ":" + text + "(");
            for (Iterator i=whs.iterator();i.hasNext();){
                sb.append( ((Term)i.next()).text );
                if (i.hasNext() )
                    sb.append("|");
            }
            sb.append(")>");
            return sb.toString();
        }
    }

    public void reset() {
        whs.clear();
        whs=null;
    }

    /**
     * Given an Indexreader we can now expand the wildcard term to
     * all words in the index that match the specified wildcard term.
     */
    public void prepare(IndexReader reader) {
        if (reader == null ) {
            return;
        }
        //WildcardTermEnum does not need a call to next to be valid
        WildcardTermEnum wt;
        if (whs!= null) {
            whs.clear();
        } else {
            whs=new HashSet();
        }
        //creates enum of all words in index that match wildcard pattern
        try {
            wt = new WildcardTermEnum(reader,new Term(field,text));
        } catch (IOException e) {
            return;
        }
        while (!wt.endEnum()) {
            whs.add(wt.term());
            try {
                wt.next();
            } catch (IOException e) {
                break;
            }
        }
        if (whs.size() <1) {
            whs=null;
        }
    }

    /**
     * Return internal hashset as array of Terms
     */
    public Term[] getTerms() {
        if (whs == null) {
            return null;
        } else {
            Term[] terms = new Term[whs.size()];
            int j=0;
            for (Iterator i=whs.iterator();i.hasNext();){
                terms[j]=(Term)i.next();
                j++;
            }
            return terms;
        }
    }
}