#include "CLucene/StdHeader.h"
#include "PhraseScorer.h"

#include "PhraseQueue.h"
#include "PhrasePositions.h"
#include "HitCollector.h"
#include "Scorer.h"
#include "Similarity.h"

namespace lucene{ namespace search{


  PhraseScorer::PhraseScorer(TermPositions** tps, const int_t tpsLength, l_byte_t* n, float_t w):
    norms(n),
    weight(w),
    pq( *new PhraseQueue(tpsLength) )
  {
    // use PQ to build a sorted list of PhrasePositions
    for (int_t i = 0; i < tpsLength; i++)
      pq.put( new PhrasePositions(*tps[i], i) );
    pqToList();
  }
  PhraseScorer::~PhraseScorer() {
    /* DSR: The PriorityQueue $pq is actually empty at present, the elements
    ** having been transferred by pqToList() to the linked list starting with
    ** $first.  The nodes of that linked list are deleted by the destructor of
    ** $first, rather than the destructor of $pq. */
    delete first;
    delete &pq;
  }

  void PhraseScorer::score(HitCollector& results, const int_t end){
    while (last->doc < end) {			  // find doc w/ all the terms
      while (first->doc < last->doc) {		  // scan forward in first
        do {
          first->Next();
        } while (first->doc < last->doc);
        firstToLast();
        if (last->doc >= end)
          return;
      }

      // found doc with all terms
      float_t freq = phraseFreq();		  // check for phrase

      if (freq > 0.0) {
        float_t score = Similarity::tf(freq)*weight; // compute score
        score *= Similarity::normf(norms[first->doc]); // normalize
        results.collect(first->doc, score);	  // add to results
      }
      last->Next();				  // resume scanning
    }
  }


  void PhraseScorer::pqToList() {
    last = first = NULL;
    while (pq.top() != NULL) {
      PhrasePositions* pp = pq.pop();
      if (last != NULL) {			  // add next to end of list
        last->next = pp;
      } else
        first = pp;
      last = pp;
      pp->next = NULL;
    }
  }

  void PhraseScorer::firstToLast() {
    last->next = first;			  // move first to end of list
    last = first;
    first = first->next;
    last->next = NULL;
  }
}}