Refactor joining nested queries to search filter queries

engine/src/androidTest/java/com/google/android/fhir/db/impl/DatabaseImplTest.kt

@@ -2530,6 +2530,92 @@ class DatabaseImplTest {
     assertThat(result.map { it.resource.logicalId }).containsExactly("100").inOrder()
   }
 
+  @Test
+  fun search_patient_with_given_disjoint_and_has_diabetes() {
+    runBlocking {
+      val jane =
+        Patient().apply {
+          id = "jane-001"
+          addName(
+            HumanName().apply {
+              addGiven("Jane")
+              family = "Doe"
+            },
+          )
+        }
+      val john =
+        Patient().apply {
+          id = "john-001"
+          addName(
+            HumanName().apply {
+              addGiven("John")
+              family = "Doe"
+            },
+          )
+        }
+      val jade =
+        Patient().apply {
+          id = "jade-001"
+          addName(
+            HumanName().apply {
+              addGiven("Jade")
+              family = "Doe"
+            },
+          )
+        }
+
+      val diabetes1 =
+        Condition().apply {
+          subject = Reference("Patient/${jane.logicalId}")
+          code = CodeableConcept(Coding("http://snomed.info/sct", "44054006", "Diabetes"))
+        }
+      val diabetes2 =
+        Condition().apply {
+          subject = Reference("Patient/${john.logicalId}")
+          code = CodeableConcept(Coding("http://snomed.info/sct", "44054006", "Diabetes"))
+        }
+      val diabetes3 =
+        Condition().apply {
+          subject = Reference("Patient/${jade.logicalId}")
+          code = CodeableConcept(Coding("http://snomed.info/sct", "44054006", "Diabetes"))
+        }
+      database.insert(jane, jade, john, diabetes1, diabetes2, diabetes3)
+
+      val result =
+        database.search<Patient>(
+          Search(ResourceType.Patient)
+            .apply {
+              has<Condition>(Condition.SUBJECT) {
+                filter(
+                  Condition.CODE,
+                  { value = of(Coding("http://snomed.info/sct", "44054006", "Diabetes")) },
+                )
+              }
+
+              filter(
+                Patient.GIVEN,
+                {
+                  value = "John"
+                  modifier = StringFilterModifier.MATCHES_EXACTLY
+                },
+              )
+
+              filter(
+                Patient.GIVEN,
+                {
+                  value = "Jane"
+                  modifier = StringFilterModifier.MATCHES_EXACTLY
+                },
+              )
+              operation = Operation.OR
+            }
+            .getQuery(),
+        )
+
+      assertThat(result.map { it.resource.logicalId }).containsExactly("jane-001", "john-001")
+    }
+  }
+
   @Test
   fun search_patient_return_single_patient_who_has_diabetic_careplan() = runBlocking {
     val patient =

engine/src/main/java/com/google/android/fhir/search/MoreSearch.kt

@@ -366,14 +366,8 @@ internal fun Search.getQuery(
   var filterStatement = ""
   val filterArgs = mutableListOf<Any>()
   val nestedSearchQuery = nestedSearches.nestedQuery(type, operation)
-  val filterQuery =
-    getFilterQueries().let {
-      if (nestedSearchQuery != null) {
-        it + nestedSearchQuery
-      } else {
-        it
-      }
-    }
+  val filterQuery = getFilterQueries() + (nestedSearchQuery?.let { listOf(it) } ?: emptyList())
+
   val filterJoinOperator =
     when (operation) {
       Operation.OR -> "\nUNION\n"

engine/src/test/java/com/google/android/fhir/search/SearchTest.kt

@@ -1961,6 +1961,87 @@ class SearchTest {
       )
   }
 
+  @Test
+  fun search_patient_multiple_given_disjoint_has_condition_diabetes() {
+    val query =
+      Search(ResourceType.Patient)
+        .apply {
+          has<Condition>(Condition.SUBJECT) {
+            filter(
+              Condition.CODE,
+              { value = of(Coding("http://snomed.info/sct", "44054006", "Diabetes")) },
+            )
+          }
+
+          filter(
+            Patient.GIVEN,
+            {
+              value = "John"
+              modifier = StringFilterModifier.MATCHES_EXACTLY
+            },
+          )
+
+          filter(
+            Patient.GIVEN,
+            {
+              value = "Jane"
+              modifier = StringFilterModifier.MATCHES_EXACTLY
+            },
+          )
+          operation = Operation.OR
+        }
+        .getQuery()
+
+    assertThat(query.query)
+      .isEqualTo(
+        """
+        SELECT a.resourceUuid, a.serializedResource
+        FROM ResourceEntity a
+        WHERE a.resourceType = ?
+        AND a.resourceUuid IN (
+        SELECT resourceUuid FROM StringIndexEntity
+        WHERE resourceType = ? AND index_name = ? AND index_value = ?
+        UNION
+        SELECT resourceUuid FROM StringIndexEntity
+        WHERE resourceType = ? AND index_name = ? AND index_value = ?
+        INTERSECT
+        SELECT resourceUuid
+        FROM ResourceEntity a
+        WHERE a.resourceType = ? AND a.resourceId IN (
+        SELECT substr(a.index_value, 9)
+        FROM ReferenceIndexEntity a
+        WHERE a.resourceType = ? AND a.index_name = ?
+        AND a.resourceUuid IN (
+        SELECT resourceUuid FROM TokenIndexEntity
+        WHERE resourceType = ? AND index_name = ? AND (index_value = ? AND IFNULL(index_system,'') = ?)
+        )
+        )
+        )
+                """
+          .trimIndent(),
+      )
+
+    assertThat(query.args)
+      .isEqualTo(
+        listOf(
+          "Patient",
+          "Patient",
+          "given",
+          "John",
+          "Patient",
+          "given",
+          "Jane",
+          "Patient",
+          "Condition",
+          "subject",
+          "Condition",
+          "code",
+          "44054006",
+          "http://snomed.info/sct",
+        ),
+      )
+  }
+
   @Test
   fun practitioner_has_patient_has_condition_diabetes_and_hypertension() {
     val query =