package com.browseengine.bobo.query;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.apache.lucene.index.AtomicReader;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Scorer;
import com.browseengine.bobo.api.BoboSegmentReader;
import com.browseengine.bobo.facets.data.FacetDataCache;
import com.browseengine.bobo.facets.data.TermLongList;
import com.browseengine.bobo.util.BigSegmentedArray;
public class RecencyBoostScorerBuilder implements ScorerBuilder {
private final float _maxFactor;
private final TimeUnit _timeunit;
private final float _min;
private final float _max;
private final long _cutoffInMillis;
private final float _A;
private final String _timeFacetName;
private final long _now;
public RecencyBoostScorerBuilder(String timeFacetName, float maxFactor, long cutoff,
TimeUnit timeunit) {
this(timeFacetName, maxFactor, timeunit.convert(System.currentTimeMillis(),
TimeUnit.MILLISECONDS), cutoff, timeunit);
}
public RecencyBoostScorerBuilder(String timeFacetName, float maxFactor, long from, long cutoff,
TimeUnit timeunit) {
_timeFacetName = timeFacetName;
_maxFactor = maxFactor;
_min = 1.0f;
_max = _maxFactor + _min;
_timeunit = timeunit;
_cutoffInMillis = _timeunit.toMillis(cutoff);
_A = (_min - _max) / (((float) _cutoffInMillis) * ((float) _cutoffInMillis));
_now = timeunit.toMillis(from);
}
@Override
public Explanation explain(AtomicReader reader, int doc, Explanation innerExplaination)
throws IOException {
if (reader instanceof BoboSegmentReader) {
BoboSegmentReader boboReader = (BoboSegmentReader) reader;
Object dataObj = boboReader.getFacetData(_timeFacetName);
if (dataObj instanceof FacetDataCache<?>) {
@SuppressWarnings("unchecked")
FacetDataCache<Long> facetDataCache = (FacetDataCache<Long>) (boboReader
.getFacetData(_timeFacetName));
final BigSegmentedArray orderArray = facetDataCache.orderArray;
final TermLongList termList = (TermLongList) facetDataCache.valArray;
Explanation finalExpl = new Explanation();
finalExpl.addDetail(innerExplaination);
float rawScore = innerExplaination.getValue();
long timeVal = termList.getPrimitiveValue(orderArray.get(doc));
float timeScore = computeTimeFactor(timeVal);
float finalScore = combineScores(timeScore, rawScore);
finalExpl.setValue(finalScore);
finalExpl.setDescription("final score = (time score: " + timeScore + ") * (raw score: "
+ rawScore + "), timeVal: " + timeVal);
return finalExpl;
} else {
throw new IllegalStateException(
"underlying facet data must be of type FacetDataCache<Long>");
}
} else {
throw new IllegalStateException("reader not instance of " + BoboSegmentReader.class);
}
}
@Override
public Scorer createScorer(final Scorer innerScorer, AtomicReader reader,
boolean scoreDocsInOrder, boolean topScorer) throws IOException {
if (reader instanceof BoboSegmentReader) {
BoboSegmentReader boboReader = (BoboSegmentReader) reader;
Object dataObj = boboReader.getFacetData(_timeFacetName);
if (dataObj instanceof FacetDataCache<?>) {
@SuppressWarnings("unchecked")
FacetDataCache<Long> facetDataCache = (FacetDataCache<Long>) (boboReader
.getFacetData(_timeFacetName));
final BigSegmentedArray orderArray = facetDataCache.orderArray;
final TermLongList termList = (TermLongList) facetDataCache.valArray;
return new Scorer(innerScorer.getWeight()) {
@Override
public float score() throws IOException {
float rawScore = innerScorer.score();
long timeVal = termList.getRawValue(orderArray.get(innerScorer.docID()));
float timeScore = computeTimeFactor(timeVal);
return combineScores(timeScore, rawScore);
}
@Override
public int advance(int target) throws IOException {
return innerScorer.advance(target);
}
@Override
public int docID() {
return innerScorer.docID();
}
@Override
public int nextDoc() throws IOException {
return innerScorer.nextDoc();
}
@Override
public int freq() throws IOException {
// TODO Auto-generated method stub
return 0;
}
@Override
public long cost() {
// TODO Auto-generated method stub
return 0;
}
};
} else {
throw new IllegalStateException(
"underlying facet data must be of type FacetDataCache<Long>");
}
} else {
throw new IllegalStateException("reader not instance of " + BoboSegmentReader.class);
}
}
protected float computeTimeFactor(long timeVal) {
long xVal = _now - timeVal;
if (xVal > _cutoffInMillis) {
return _min;
} else {
float xValFloat = xVal;
return _A * xValFloat * xValFloat + _max;
}
}
private static float combineScores(float timeScore, float rawScore) {
return timeScore * rawScore;
}
}