From 381a5cacb001453235e008976f6dc312fb149d37 Mon Sep 17 00:00:00 2001
From: Peter Gromov <peter@jetbrains.com>
Date: Tue, 23 Feb 2021 13:00:02 +0100
Subject: [PATCH] LUCENE-9805: Hunspell: fix space + mixed case heuristics on
 suggestions (#2420)

---
 .../apache/lucene/analysis/hunspell/ModifyingSuggester.java | 6 +++---
 .../src/test/org/apache/lucene/analysis/hunspell/sug.dic    | 6 +++++-
 .../src/test/org/apache/lucene/analysis/hunspell/sug.sug    | 1 +
 .../src/test/org/apache/lucene/analysis/hunspell/sug.wrong  | 3 ++-
 4 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/ModifyingSuggester.java b/lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/ModifyingSuggester.java
index 86e34c739e4..286d1ee69ee 100644
--- a/lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/ModifyingSuggester.java
+++ b/lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/ModifyingSuggester.java
@@ -70,18 +70,18 @@ class ModifyingSuggester {
       }
 
       List<String> adjusted =
-          result.stream().map(s -> capitalizeAfterSpace(low, s)).collect(Collectors.toList());
+          result.stream().map(s -> capitalizeAfterSpace(word, s)).collect(Collectors.toList());
       result.clear();
       result.addAll(adjusted);
     }
   }
 
   // aNew -> "a New" (instead of "a new")
-  private String capitalizeAfterSpace(String lowMisspelled, String candidate) {
+  private String capitalizeAfterSpace(String misspelled, String candidate) {
     int space = candidate.indexOf(' ');
     int tail = candidate.length() - space - 1;
     if (space > 0
-        && lowMisspelled.regionMatches(lowMisspelled.length() - tail, candidate, space + 1, tail)) {
+        && !misspelled.regionMatches(misspelled.length() - tail, candidate, space + 1, tail)) {
       return candidate.substring(0, space + 1)
           + Character.toUpperCase(candidate.charAt(space + 1))
           + candidate.substring(space + 2);
diff --git a/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.dic b/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.dic
index 6725561e81f..6ea06f1f10f 100644
--- a/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.dic
+++ b/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.dic
@@ -15,4 +15,8 @@ spite
 inspire
 Saiph
 sahib
-ship
\ No newline at end of file
+ship
+ESP
+esp
+s
+S
\ No newline at end of file
diff --git a/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.sug b/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.sug
index 4595756cc87..e7a52c43c02 100644
--- a/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.sug
+++ b/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.sug
@@ -13,3 +13,4 @@ McDonald
 permanent
 in, in a
 Saiph, Ship, Sahib
+ESP, ESP s, Esp, Esp s
\ No newline at end of file
diff --git a/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.wrong b/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.wrong
index d8875d8a571..356a08d8810 100644
--- a/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.wrong
+++ b/lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/sug.wrong
@@ -14,4 +14,5 @@ permqnent
 permanent-vacation
 permqnent-vacation
 ina
-Sahip
\ No newline at end of file
+Sahip
+ESPs
\ No newline at end of file