Debounce performing search depending on searchquery length

android/quest/src/main/java/org/smartregister/fhircore/quest/ui/register/RegisterViewModel.kt

@@ -17,6 +17,7 @@
 package org.smartregister.fhircore.quest.ui.register
 
 import android.graphics.Bitmap
+import androidx.annotation.VisibleForTesting
 import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableLongStateOf
@@ -33,10 +34,13 @@
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlin.math.ceil
+import kotlin.time.Duration.Companion.milliseconds
+import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asSharedFlow
+import kotlinx.coroutines.flow.debounce
 import kotlinx.coroutines.flow.emptyFlow
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
@@ -78,10 +82,12 @@
 import org.smartregister.fhircore.engine.util.extension.encodeJson
 import org.smartregister.fhircore.quest.data.register.RegisterPagingSource
 import org.smartregister.fhircore.quest.data.register.model.RegisterPagingSourceState
+import org.smartregister.fhircore.quest.ui.shared.models.SearchQuery
 import org.smartregister.fhircore.quest.util.extensions.referenceToBitmap
 import org.smartregister.fhircore.quest.util.extensions.toParamDataMap
 import timber.log.Timber
 
+@OptIn(FlowPreview::class)
 @HiltViewModel
 class RegisterViewModel
 @Inject
@@ -112,6 +118,29 @@
   }
   private val decodedImageMap = mutableStateMapOf<String, Bitmap>()
 
+  private val _searchQueryFlow: MutableSharedFlow<SearchQuery> = MutableSharedFlow()
+
+  @VisibleForTesting
+  val debouncedSearchQueryFlow =
+    _searchQueryFlow.debounce {
+      val searchText = it.query
+      when (searchText.length) {
+        0 -> 2.milliseconds // when search is cleared
+        1,
+        2, -> 1000.milliseconds
+        else -> 500.milliseconds
+      }
+    }
+
+  init {
+    viewModelScope.launch {
+      debouncedSearchQueryFlow.collect {
+        val registerId = registerUiState.value.registerId
+        performSearch(registerId, it)
+      }
+    }
+  }
+
   /**
    * This function paginates the register data. An optional [clearCache] resets the data in the
    * cache (this is necessary after a questionnaire has been submitted to refresh the register with
@@ -191,26 +220,7 @@
     when (event) {
       // Search using name or patient logicalId or identifier. Modify to add more search params
       is RegisterEvent.SearchRegister -> {
-        if (event.searchQuery.isBlank()) {
-          val regConfig = retrieveRegisterConfiguration(registerId)
-          val searchByDynamicQueries = !regConfig.searchBar?.dataFilterFields.isNullOrEmpty()
-          if (searchByDynamicQueries) {
-            registerFilterState.value = RegisterFilterState() // Reset queries
-          }
-          when {
-            regConfig.infiniteScroll ->
-              registerData.value = retrieveCompleteRegisterData(registerId, searchByDynamicQueries)
-            else ->
-              retrieveRegisterUiState(
-                registerId = registerId,
-                screenTitle = registerUiState.value.screenTitle,
-                params = registerUiState.value.params.toTypedArray(),
-                clearCache = searchByDynamicQueries,
-              )
-          }
-        } else {
-          filterRegisterData(event.searchQuery.query)
-        }
+        viewModelScope.launch { _searchQueryFlow.emit(event.searchQuery) }
       }
       is RegisterEvent.MoveToNextPage -> {
         currentPage.value = currentPage.value.plus(1)
@@ -224,6 +234,30 @@
     }
   }
 
+  @VisibleForTesting
+  fun performSearch(registerId: String, searchQuery: SearchQuery) {
+    if (searchQuery.isBlank()) {
+      val regConfig = retrieveRegisterConfiguration(registerId)
+      val searchByDynamicQueries = !regConfig.searchBar?.dataFilterFields.isNullOrEmpty()
+      if (searchByDynamicQueries) {
+        registerFilterState.value = RegisterFilterState() // Reset queries
+      }
+      when {
+        regConfig.infiniteScroll ->
+          registerData.value = retrieveCompleteRegisterData(registerId, searchByDynamicQueries)
+        else ->
+          retrieveRegisterUiState(
+            registerId = registerId,
+            screenTitle = registerUiState.value.screenTitle,
+            params = registerUiState.value.params.toTypedArray(),
+            clearCache = searchByDynamicQueries,
+          )
+      }
+    } else {
+      filterRegisterData(searchQuery.query)
+    }
+  }
+
   fun filterRegisterData(searchText: String) {
     val searchBar = registerUiState.value.registerConfiguration?.searchBar
     val registerId = registerUiState.value.registerId

android/quest/src/test/java/org/smartregister/fhircore/quest/ui/register/RegisterViewModelTest.kt

@@ -29,6 +29,10 @@ import io.mockk.runs
 import io.mockk.spyk
 import io.mockk.verify
 import javax.inject.Inject
+import kotlin.time.Duration.Companion.milliseconds
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.advanceTimeBy
+import kotlinx.coroutines.test.advanceUntilIdle
 import kotlinx.coroutines.test.runTest
 import org.hl7.fhir.r4.model.Coding
 import org.hl7.fhir.r4.model.DateType
@@ -114,14 +118,18 @@ class RegisterViewModelTest : RobolectricTest() {
   @Test
   @kotlinx.coroutines.ExperimentalCoroutinesApi
   fun testRetrieveRegisterUiState() = runTest {
-    every { registerViewModel.retrieveRegisterConfiguration(any()) } returns
+    val registerConfig =
       RegisterConfiguration(
         appId = "app",
         id = registerId,
         fhirResource =
           FhirResourceConfig(baseResource = ResourceConfig(resource = ResourceType.Patient)),
         pageSize = 10,
       )
+    configurationRegistry.configCacheMap[registerId] = registerConfig
+    registerViewModel.registerUiState.value =
+      registerViewModel.registerUiState.value.copy(registerId = registerId)
+
     every { registerViewModel.paginateRegisterData(any(), any()) } just runs
     coEvery { registerRepository.countRegisterData(any()) } returns 200
     registerViewModel.retrieveRegisterUiState(
@@ -143,23 +151,78 @@ class RegisterViewModelTest : RobolectricTest() {
   }
 
   @Test
-  fun testOnEventSearchRegister() {
-    every { registerViewModel.retrieveRegisterConfiguration(any()) } returns
+  @kotlinx.coroutines.ExperimentalCoroutinesApi
+  fun testDebounceSearchQueryFlow() = runTest {
+    val registerConfig =
       RegisterConfiguration(
         appId = "app",
         id = registerId,
         fhirResource =
           FhirResourceConfig(baseResource = ResourceConfig(resource = ResourceType.Patient)),
         pageSize = 10,
       )
-    every { registerViewModel.registerUiState } returns
-      mutableStateOf(RegisterUiState(registerId = registerId))
+    configurationRegistry.configCacheMap[registerId] = registerConfig
+    registerViewModel.registerUiState.value =
+      registerViewModel.registerUiState.value.copy(registerId = registerId)
+    coEvery { registerRepository.countRegisterData(any()) } returns 0L
+
+    val results = mutableListOf<String>()
+    val debounceJob = launch {
+      registerViewModel.debouncedSearchQueryFlow.collect { results.add(it.query) }
+    }
+    advanceUntilIdle()
+
     // Search with empty string should paginate the data
     registerViewModel.onEvent(RegisterEvent.SearchRegister(SearchQuery.emptyText))
+
+    advanceTimeBy(3.milliseconds)
+    Assert.assertTrue(results.isNotEmpty())
+    Assert.assertTrue(results.last().isBlank())
+
+    registerViewModel.onEvent(RegisterEvent.SearchRegister(SearchQuery("K")))
+    registerViewModel.onEvent(RegisterEvent.SearchRegister(SearchQuery("Kh")))
+    registerViewModel.onEvent(RegisterEvent.SearchRegister(SearchQuery("Kha")))
+    registerViewModel.onEvent(RegisterEvent.SearchRegister(SearchQuery("Khan")))
+
+    advanceTimeBy(1010.milliseconds)
+    Assert.assertEquals(2, results.size)
+    Assert.assertEquals("Khan", results.last())
+    debounceJob.cancel()
+  }
+
+  @Test
+  fun testPerformSearchWithEmptyQuery() = runTest {
+    val registerConfig =
+      RegisterConfiguration(
+        appId = "app",
+        id = registerId,
+        fhirResource =
+          FhirResourceConfig(baseResource = ResourceConfig(resource = ResourceType.Patient)),
+        pageSize = 10,
+      )
+    configurationRegistry.configCacheMap[registerId] = registerConfig
+    coEvery { registerRepository.countRegisterData(any()) } returns 0L
+
+    // Search with empty string should paginate the data
+    registerViewModel.performSearch(registerId, SearchQuery.emptyText)
     verify { registerViewModel.retrieveRegisterUiState(any(), any(), any(), any()) }
+  }
+
+  @Test
+  fun testPerformSearchWithNonEmptyQuery() = runTest {
+    val registerConfig =
+      RegisterConfiguration(
+        appId = "app",
+        id = registerId,
+        fhirResource =
+          FhirResourceConfig(baseResource = ResourceConfig(resource = ResourceType.Patient)),
+        pageSize = 10,
+      )
+    configurationRegistry.configCacheMap[registerId] = registerConfig
+    coEvery { registerRepository.countRegisterData(any()) } returns 0L
 
     // Search for the word 'Khan' should call the filterRegisterData function
-    registerViewModel.onEvent(RegisterEvent.SearchRegister(SearchQuery("Khan")))
+    registerViewModel.performSearch(registerId, SearchQuery("Khan"))
     verify { registerViewModel.filterRegisterData(any()) }
   }