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package com.browseengine.bobo.query.scoring;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.log4j.Logger;
import org.apache.lucene.index.AtomicReader;
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Weight;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.util.Bits;

import com.browseengine.bobo.api.BoboSegmentReader;
import com.browseengine.bobo.api.BrowseSelection;
import com.browseengine.bobo.docidset.RandomAccessDocIdSet;
import com.browseengine.bobo.facets.FacetHandler;
import com.browseengine.bobo.facets.filter.RandomAccessFilter;
import com.browseengine.bobo.query.MatchAllDocIdSetIterator;

public class FacetTermQuery extends Query {
  private static final Logger logger = Logger.getLogger(FacetTermQuery.class);

  private final String _name;
  private final BrowseSelection _sel;
  private final FacetTermScoringFunctionFactory _scoringFactory;
  private final Map _boostMap;

  public FacetTermQuery(BrowseSelection sel, Map boostMap) {
    this(sel, boostMap, new DefaultFacetTermScoringFunctionFactory());
  }

  public FacetTermQuery(BrowseSelection sel, Map boostMap,
      FacetTermScoringFunctionFactory scoringFactory) {
    _name = sel.getFieldName();
    _sel = sel;
    _scoringFactory = scoringFactory;
    _boostMap = boostMap;
  }

  public String getName() {
    return _name;
  }

  public Map getBoostMap() {
    return _boostMap;
  }

  @Override
  public String toString(String fieldname) {
    return String.valueOf(_sel);
  }

  @Override
  public Weight createWeight(IndexSearcher searcher) throws IOException {
    return new FacetTermWeight(searcher.getSimilarity());
  }

  @SuppressWarnings({ "rawtypes", "unchecked" })
  @Override
  public void extractTerms(Set terms) {
    String[] vals = _sel.getValues();
    for (String val : vals) {
      terms.add(new Term(_name, val));
    }
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null) return false;
    if (getClass() != obj.getClass()) return false;
    if (!(obj instanceof FacetTermQuery)) return false;

    FacetTermQuery other = (FacetTermQuery) obj;
    if (!this.toString().equals(other.toString())) return false;
    if (!_name.equals(other.getName())) return false;

    Map _boostMap_1 = this._boostMap;
    Map _boostMap_2 = other.getBoostMap();

    if (_boostMap_1.size() != _boostMap_2.size()) return false;
    Iterator it_map = _boostMap_1.keySet().iterator();
    while (it_map.hasNext()) {
      String key_1 = it_map.next();
      if (!_boostMap_2.containsKey(key_1)) return false;
      else {
        float boost_1 = _boostMap_1.get(key_1);
        float boost_2 = _boostMap_2.get(key_1);

        if (Float.floatToIntBits(boost_1) != Float.floatToIntBits(boost_2)) return false;
      }
    }

    return true;
  }

  private class FacetTermWeight extends Weight {
    Similarity _similarity;

    public FacetTermWeight(Similarity sim) {
      _similarity = sim;
    }

    @Override
    public Explanation explain(AtomicReaderContext context, int docid) throws IOException {
      BoboSegmentReader boboReader = (BoboSegmentReader) (context.reader());
      FacetHandler fhandler = boboReader.getFacetHandler(FacetTermQuery.this._name);
      if (fhandler != null) {
        BoboDocScorer scorer = null;
        if (fhandler instanceof FacetScoreable) {
          scorer = ((FacetScoreable) fhandler).getDocScorer(boboReader, _scoringFactory, _boostMap);
          Explanation exp1 = scorer.explain(docid);
          Explanation exp2 = new Explanation(getBoost(), "boost");
          Explanation expl = new Explanation();
          expl.setDescription("product of:");
          expl.setValue(exp1.getValue() * exp2.getValue());
          expl.addDetail(exp1);
          expl.addDetail(exp2);
          return expl;
        } else {
          return null;
        }
      }
      return null;
    }

    @Override
    public Query getQuery() {
      return FacetTermQuery.this;
    }

    private final DocIdSetIterator buildIterator(final RandomAccessDocIdSet docset,
        final BoboSegmentReader reader, final Bits acceptDocs) {
      return new DocIdSetIterator() {
        private int doc = -1;
        private final int maxDoc = reader.maxDoc();

        @Override
        public int advance(int target) throws IOException {
          doc = target;
          while (doc < maxDoc) {
            if (acceptDocs != null && !acceptDocs.get(doc)) {
              ++doc;
              continue;
            }
            if (!docset.get(doc)) {
              ++doc;
              continue;
            }
            break;
          }
          if (doc >= maxDoc) {
            doc = DocIdSetIterator.NO_MORE_DOCS;
          }
          return doc;
        }

        @Override
        public int docID() {
          return doc;
        }

        @Override
        public int nextDoc() throws IOException {
          ++doc;
          while (doc < maxDoc) {
            if (acceptDocs != null && !acceptDocs.get(doc)) {
              ++doc;
              continue;
            }
            if (!docset.get(doc)) {
              ++doc;
              continue;
            }
            break;
          }
          if (doc >= maxDoc) {
            doc = DocIdSetIterator.NO_MORE_DOCS;
          }
          return doc;
        }

        @Override
        public long cost() {
          // TODO Auto-generated method stub
          return 0;
        }

      };
    }

    @Override
    public Scorer scorer(AtomicReaderContext context, boolean scoreDocsInOrder, boolean topScorer,
        Bits acceptDocs) throws IOException {
      AtomicReader reader = context.reader();
      if (reader instanceof BoboSegmentReader) {
        BoboSegmentReader boboReader = (BoboSegmentReader) reader;
        FacetHandler fhandler = boboReader.getFacetHandler(FacetTermQuery.this._name);
        if (fhandler != null) {
          DocIdSetIterator dociter = null;
          RandomAccessFilter filter = fhandler.buildFilter(FacetTermQuery.this._sel);
          if (filter != null) {
            RandomAccessDocIdSet docset = filter.getRandomAccessDocIdSet(boboReader);
            if (docset != null) {
              dociter = buildIterator(docset, boboReader, acceptDocs);
            }
          }
          if (dociter == null) {
            dociter = new MatchAllDocIdSetIterator(reader, acceptDocs);
          }
          BoboDocScorer scorer = null;
          if (fhandler instanceof FacetScoreable) {
            scorer = ((FacetScoreable) fhandler).getDocScorer(boboReader, _scoringFactory,
              _boostMap);
          }
          return new FacetTermScorer(_similarity, dociter, scorer);
        } else {
          logger.error("FacetHandler is not defined for the field: " + FacetTermQuery.this._name);
        }
        return null;
      } else {
        throw new IOException("index reader not instance of " + BoboSegmentReader.class);
      }
    }

    @Override
    public float getValueForNormalization() throws IOException {
      // TODO Auto-generated method stub
      return 0;
    }

    @Override
    public void normalize(float norm, float topLevelBoost) {
      // TODO Auto-generated method stub

    }
  }

  private class FacetTermScorer extends Scorer {
    private final DocIdSetIterator _docSetIter;
    private final BoboDocScorer _scorer;

    protected FacetTermScorer(Similarity similarity, DocIdSetIterator docidsetIter,
        BoboDocScorer scorer) {
      super(new FacetTermWeight(similarity));
      _docSetIter = docidsetIter;
      _scorer = scorer;
    }

    @Override
    public float score() throws IOException {
      return _scorer == null ? 1.0f : _scorer.score(_docSetIter.docID()) * getBoost();
    }

    @Override
    public int docID() {
      return _docSetIter.docID();
    }

    @Override
    public int nextDoc() throws IOException {
      return _docSetIter.nextDoc();
    }

    @Override
    public int advance(int target) throws IOException {
      return _docSetIter.advance(target);
    }

    @Override
    public int freq() throws IOException {
      // TODO Auto-generated method stub
      return 0;
    }

    @Override
    public long cost() {
      // TODO Auto-generated method stub
      return 0;
    }

  }

}