Fix case insensitive and escaped query on wildcard

CHANGELOG.md

@@ -86,6 +86,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Bound the size of cache in deprecation logger ([16702](https://github.com/opensearch-project/OpenSearch/issues/16702))
 - Ensure consistency of system flag on IndexMetadata after diff is applied ([#16644](https://github.com/opensearch-project/OpenSearch/pull/16644))
 - Skip remote-repositories validations for node-joins when RepositoriesService is not in sync with cluster-state ([#16763](https://github.com/opensearch-project/OpenSearch/pull/16763))
+- Fix case insensitive and escaped query on wildcard ([#16827](https://github.com/opensearch-project/OpenSearch/pull/16827))
 - Fix _list/shards API failing when closed indices are present ([#16606](https://github.com/opensearch-project/OpenSearch/pull/16606))
 - Fix remote shards balance ([#15335](https://github.com/opensearch-project/OpenSearch/pull/15335))
 - Always use `constant_score` query for `match_only_text` field ([#16964](https://github.com/opensearch-project/OpenSearch/pull/16964))

rest-api-spec/src/main/resources/rest-api-spec/test/search/270_wildcard_fieldtype_queries.yml

@@ -62,6 +62,19 @@ setup:
         id: 7
         body:
           my_field: "ABCD"
+  - do:
+      index:
+        index: test
+        id: 8
+        body:
+          my_field: "*"
+
+  - do:
+      index:
+        index: test
+        id: 9
+        body:
+          my_field: "\\*"
   - do:
       indices.refresh: {}
 
@@ -223,7 +236,7 @@ setup:
             wildcard:
               my_field:
                 value: "*"
-  - match: { hits.total.value: 6 }
+  - match: { hits.total.value: 8 }
 ---
 "regexp match-all works":
   - do:
@@ -234,7 +247,7 @@ setup:
             regexp:
               my_field:
                 value: ".*"
-  - match: { hits.total.value: 6 }
+  - match: { hits.total.value: 8 }
 ---
 "terms query on wildcard field matches":
   - do:
@@ -270,3 +283,113 @@ setup:
   - match: { hits.total.value: 2 }
   - match: { hits.hits.0._id: "5" }
   - match: { hits.hits.1._id: "7" }
+---
+"case insensitive regexp query on wildcard field":
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            regexp:
+              my_field:
+                value: "AbCd"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "5" }
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            regexp:
+              my_field:
+                value: "AbCd"
+                case_insensitive: true
+  - match: { hits.total.value: 2 }
+  - match: { hits.hits.0._id: "5" }
+  - match: { hits.hits.1._id: "7" }
+---
+"wildcard query works on values contains escaped characters":
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            wildcard:
+              my_field:
+                value: "\\*"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "8" }
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            wildcard:
+              my_field:
+                value: "\\\\\\*"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "9" }
+---
+"regexp query works on values contains escaped characters":
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            regexp:
+              my_field:
+                value: "\\*"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "8" }
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            regexp:
+              my_field:
+                value: "\\\\\\*"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "9"}
+---
+"term query contains escaped characters":
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            term:
+              my_field: "\\*"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "9" }
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            term:
+              my_field: "*"
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "8"}
+---
+"terms query contains escaped characters":
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            terms: { my_field: ["*"] }
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "8" }
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            terms: { my_field: [ "\\*" ] }
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "9" }