From b3dfeccb5f480c43210f9c0b56a75bdb375bf536 Mon Sep 17 00:00:00 2001
From: Andrew Valencik <andrew.valencik@gmail.com>
Date: Sat, 22 Feb 2025 19:39:14 -0500
Subject: [PATCH] Add topN arg to Scorer, use for SearchRequest.size

---
 .../pink/cozydev/protosearch/Scorer.scala     | 31 +++++++++++++++----
 .../protosearch/SearchInterpreter.scala       |  2 +-
 .../cozydev/protosearch/ScorerSuite.scala     | 14 ++++++++-
 .../pink/cozydev/protosearch/JsInterop.scala  |  2 +-
 4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/core/src/main/scala/pink/cozydev/protosearch/Scorer.scala b/core/src/main/scala/pink/cozydev/protosearch/Scorer.scala
index 88735611..ed81267f 100644
--- a/core/src/main/scala/pink/cozydev/protosearch/Scorer.scala
+++ b/core/src/main/scala/pink/cozydev/protosearch/Scorer.scala
@@ -20,7 +20,6 @@ import cats.data.NonEmptyList
 import cats.syntax.all.*
 import pink.cozydev.lucille.Query
 
-import scala.collection.mutable.HashMap
 import pink.cozydev.protosearch.internal.PositionalIter
 
 import java.util.regex.PatternSyntaxException
@@ -29,7 +28,7 @@ case class Scorer(index: MultiIndex, defaultOR: Boolean = true) {
 
   private val defaultIdx: Index = index.indexes(index.schema.defaultField)
 
-  def score(qs: Query, docs: Set[Int]): Either[String, List[(Int, Double)]] = {
+  def score(qs: Query, docs: Set[Int], topN: Int): Either[String, List[(Int, Double)]] = {
     def accScore(
         idx: Index,
         queries: NonEmptyList[Query],
@@ -57,7 +56,7 @@ case class Scorer(index: MultiIndex, defaultOR: Boolean = true) {
         case q: Query.Boost => Left(s"Unsupported Boost in Scorer: $q")
         case q: Query.WildCard => Left(s"Unsupported WildCard in Scorer: $q")
       }
-    accScore(defaultIdx, NonEmptyList.one(qs)).map(combineMaps)
+    accScore(defaultIdx, NonEmptyList.one(qs)).map(ms => combineMaps(ms, topN))
   }
 
   private def phraseScore(
@@ -124,11 +123,31 @@ case class Scorer(index: MultiIndex, defaultOR: Boolean = true) {
     }
   }
 
-  private def combineMaps(ms: NonEmptyList[Map[Int, Double]]): List[(Int, Double)] = {
-    val mb = HashMap.empty ++ ms.head
+  private val ord = Ordering[(Double, Int)].on[(Int, Double)](idScore => (-idScore._2, idScore._1))
+
+  private def combineMaps(ms: NonEmptyList[Map[Int, Double]], topN: Int): List[(Int, Double)] = {
+    // Combine scores by Id
+    val mb = scala.collection.mutable.HashMap.empty[Int, Double] ++ ms.head
     ms.tail.foreach(m1 =>
       m1.foreach { case (k: Int, v: Double) => mb.update(k, v + mb.getOrElse(k, 0.0)) }
     )
-    mb.toList.sortBy(idScore => (-idScore._2, idScore._1))
+    // Sort scores
+    val arr = new Array[Tuple2[Int, Double]](mb.size)
+    var i = 0
+    mb.foreach { docScore =>
+      arr(i) = docScore
+      i += 1
+    }
+    java.util.Arrays.sort(arr, ord)
+    // Build list of topN
+    val bldr = List.newBuilder[(Int, Double)]
+    val resultSize = if (mb.size < topN) mb.size else topN
+    bldr.sizeHint(resultSize)
+    var n = 0
+    while (n < resultSize) {
+      bldr += arr(n)
+      n += 1
+    }
+    bldr.result()
   }
 }
diff --git a/core/src/main/scala/pink/cozydev/protosearch/SearchInterpreter.scala b/core/src/main/scala/pink/cozydev/protosearch/SearchInterpreter.scala
index 02949426..7644d47b 100644
--- a/core/src/main/scala/pink/cozydev/protosearch/SearchInterpreter.scala
+++ b/core/src/main/scala/pink/cozydev/protosearch/SearchInterpreter.scala
@@ -36,7 +36,7 @@ final case class SearchInterpreter(
       parseQ.flatMap(q =>
         indexSearcher
           .search(q)
-          .flatMap(ds => scorer.score(q, ds))
+          .flatMap(ds => scorer.score(q, ds, request.size))
       )
 
     val lstB = List.newBuilder[Hit]
diff --git a/core/src/test/scala/pink/cozydev/protosearch/ScorerSuite.scala b/core/src/test/scala/pink/cozydev/protosearch/ScorerSuite.scala
index eded8b7b..98f1d6e1 100644
--- a/core/src/test/scala/pink/cozydev/protosearch/ScorerSuite.scala
+++ b/core/src/test/scala/pink/cozydev/protosearch/ScorerSuite.scala
@@ -38,7 +38,7 @@ class ScorerSuite extends munit.FunSuite {
   def score(q: String, docs: Set[Int]): Either[String, List[(Int, Double)]] =
     QueryParser
       .parse(q)
-      .flatMap(q => scorer.score(q, docs))
+      .flatMap(q => scorer.score(q, docs, 10))
 
   def ordered(hits: Either[String, List[(Int, Double)]]): List[Int] =
     hits.fold(_ => Nil, ds => ds.map(_._1))
@@ -74,4 +74,16 @@ class ScorerSuite extends munit.FunSuite {
     assertEquals(ordered(hits), List(1))
   }
 
+  test("scorer with topN=1 returns only top doc") {
+    val q = "Tale OR Two" // has 3 matches
+    val hits = QueryParser.parse(q).flatMap(q => scorer.score(q, allDocs, topN = 1))
+    assertEquals(ordered(hits), List(1))
+  }
+
+  test("scorer topN can be bigger than number of matches") {
+    val q = "Tale OR Two" // has 3 matches
+    val hits = QueryParser.parse(q).flatMap(q => scorer.score(q, allDocs, topN = 999))
+    assertEquals(ordered(hits), List(1, 0, 2))
+  }
+
 }
diff --git a/jsinterop/src/main/scala/pink/cozydev/protosearch/JsInterop.scala b/jsinterop/src/main/scala/pink/cozydev/protosearch/JsInterop.scala
index 6963e651..cc9bc91f 100644
--- a/jsinterop/src/main/scala/pink/cozydev/protosearch/JsInterop.scala
+++ b/jsinterop/src/main/scala/pink/cozydev/protosearch/JsInterop.scala
@@ -41,7 +41,7 @@ class Querier(val mIndex: MultiIndex) {
 
   @JSExport
   def search(query: String): js.Array[JsHit] = {
-    val req = SearchRequest(query, 10, highlightFields, resultFields, true)
+    val req = SearchRequest(query, size = 10, highlightFields, resultFields, lastTermPrefix = true)
     val hits = searcher
       .search(req)
       .fold(