Function calculateWordMatchScore

Source

export function calculateWordMatchScore(
  titleWords: string[],
  searchWords: string[],
): number {
  const matchableTitleWords = filterMatchableWords(titleWords);
  const matchableSearchWords = filterMatchableWords(searchWords);

  if (matchableTitleWords.length === 0 || matchableSearchWords.length === 0) {
    return -1;
  }

  let matchingWords = 0;
  const matchedSearchWords = new Set<string>();

  for (const word of matchableTitleWords) {
    for (const searchWord of matchableSearchWords) {
      if (matchedSearchWords.has(searchWord)) continue;

      if (word === searchWord) {
        matchingWords += 1;
        matchedSearchWords.add(searchWord);
        break;
      }

      if (isPartialWordMatch(word, searchWord)) {
        matchingWords += 0.5;
        matchedSearchWords.add(searchWord);
        break;
      }
    }
  }

  const denominator = Math.max(
    2,
    Math.min(matchableTitleWords.length, matchableSearchWords.length),
  );
  const matchRatio = matchingWords / denominator;
  const adjustedMatchRatio = applyDensityPenalty(
    matchRatio,
    matchingWords,
    matchableTitleWords.length,
    matchableSearchWords.length,
  );

  if (adjustedMatchRatio >= WORD_MATCH_BASE_RATIO) {
    return (
      WORD_MATCH_BASE_RATIO + (adjustedMatchRatio - WORD_MATCH_BASE_RATIO) * 0.6
    );
  }

  const fallbackScore = getWordMatchFallbackScore(
    adjustedMatchRatio,
    matchableTitleWords.length,
    matchableSearchWords.length,
    matchingWords,
  );

  if (fallbackScore !== null) {
    return fallbackScore;
  }

  return -1;
}
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