[HACK][POS] Prepopulate orders cache after opening POS

RELEASE-NOTES.txt

@@ -16,6 +16,7 @@
 - [*][Woo POS] Automatically scroll to newly created orders when returning to the Orders screen [https://github.com/woocommerce/woocommerce-android/pull/14990]
 - [Internal] Restore coupon drawable files mistakenly removed in previous release [https://github.com/woocommerce/woocommerce-android/pull/15005]
 - [*] Fixed a rare crash that occurred when displaying shipping rates for a selected package [https://github.com/woocommerce/woocommerce-android/pull/15032]
+- [*][Woo POS] Prepopulate orders cache after opening POS to improve performance [https://github.com/woocommerce/woocommerce-android/pull/15066]
 
 23.7
 -----

WooCommerce/src/main/kotlin/com/woocommerce/android/ui/woopos/home/WooPosHomeViewModel.kt

@@ -14,11 +14,13 @@ import com.woocommerce.android.ui.woopos.home.ParentToChildrenEvent.SearchEvent.
 import com.woocommerce.android.ui.woopos.home.ParentToChildrenEvent.SearchEvent.RecentSearchSelected
 import com.woocommerce.android.ui.woopos.home.WooPosHomeState.DialogState
 import com.woocommerce.android.ui.woopos.home.WooPosHomeState.ScreenPositionState
+import com.woocommerce.android.ui.woopos.orders.WooPosOrdersDataSource
 import com.woocommerce.android.ui.woopos.util.analytics.WooPosAnalyticsEvent
 import com.woocommerce.android.ui.woopos.util.analytics.WooPosAnalyticsEvent.Event.BackToCartTapped
 import com.woocommerce.android.ui.woopos.util.analytics.WooPosAnalyticsTracker
 import com.woocommerce.android.viewmodel.getStateFlow
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.SharedFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -31,8 +33,13 @@ class WooPosHomeViewModel @Inject constructor(
     private val parentToChildrenEventSender: WooPosParentToChildrenEventSender,
     private val analyticsTracker: WooPosAnalyticsTracker,
     private val soundHelper: WooPosSoundHelper,
+    private val ordersDataSource: WooPosOrdersDataSource,
     savedStateHandle: SavedStateHandle,
 ) : ViewModel() {
+    companion object {
+        private const val ORDERS_CACHE_WARMUP_DELAY_MS = 5000L
+    }
+
     private val _state = savedStateHandle.getStateFlow(
         scope = viewModelScope,
         key = "home_state",
@@ -54,6 +61,7 @@ class WooPosHomeViewModel @Inject constructor(
         viewModelScope.launch {
             soundHelper.preloadChaChing()
         }
+        prepopulateOrdersCache()
     }
 
     override fun onCleared() {
@@ -255,6 +263,15 @@ class WooPosHomeViewModel @Inject constructor(
         }
     }
 
+    private fun prepopulateOrdersCache() {
+        viewModelScope.launch {
+            delay(ORDERS_CACHE_WARMUP_DELAY_MS)
+            ordersDataSource.loadOrders(
+                pageSize = WooPosOrdersDataSource.POS_ORDERS_CACHE_PREPOPULATION_SIZE
+            ).collect {}
+        }
+    }
+
     private fun handleOrderCreated(event: ChildToParentEvent.OrderCreated) {
         sendEventToChildren(
             OrderCreated(

WooCommerce/src/main/kotlin/com/woocommerce/android/ui/woopos/orders/WooPosOrdersDataSource.kt

@@ -51,17 +51,18 @@ class WooPosOrdersDataSource @Inject constructor(
 
     companion object {
         const val POS_ORDERS_PAGE_SIZE = 25
+        const val POS_ORDERS_CACHE_PREPOPULATION_SIZE = 5
         private const val UNKNOWN_ERROR = "Unknown error"
     }
 
-    fun loadOrders(): Flow<LoadOrdersResult> = flow {
+    fun loadOrders(pageSize: Int = POS_ORDERS_PAGE_SIZE): Flow<LoadOrdersResult> = flow {
         val cached = ordersCache.getAll()
         if (cached.isNotEmpty()) {
             val cachedWithRefunds = fetchRefundsForOrders(cached)
             emit(LoadOrdersResult.SuccessCache(cachedWithRefunds))
         }
 
-        val result = loadFirstPage()
+        val result = loadFirstPage(pageSize = pageSize)
         result.onSuccess { orders ->
             ordersCache.setAll(orders)
             val ordersWithRefunds = fetchRefundsForOrders(orders)
@@ -123,18 +124,24 @@ class WooPosOrdersDataSource @Inject constructor(
         ordersCache.setAll(updated)
     }
 
-    private suspend fun loadFirstPage(searchQuery: String? = null): Result<List<Order>> {
+    private suspend fun loadFirstPage(
+        searchQuery: String? = null,
+        pageSize: Int = POS_ORDERS_PAGE_SIZE
+    ): Result<List<Order>> {
         page.set(1)
         canLoadMore.set(false)
-        return fetchAndMap(searchQuery)
+        return fetchAndMap(searchQuery, pageSize)
     }
 
     private suspend fun loadNextPage(searchQuery: String? = null): Result<List<Order>> {
         return fetchAndMap(searchQuery)
     }
 
-    private suspend fun fetchAndMap(searchQuery: String? = null): Result<List<Order>> {
-        val result = fetchOrdersFromRemote(page.get(), searchQuery)
+    private suspend fun fetchAndMap(
+        searchQuery: String? = null,
+        pageSize: Int = POS_ORDERS_PAGE_SIZE
+    ): Result<List<Order>> {
+        val result = fetchOrdersFromRemote(page.get(), searchQuery, pageSize)
         return if (result.isError) {
             Result.failure(result.error.toThrowable())
         } else {
@@ -146,10 +153,11 @@ class WooPosOrdersDataSource @Inject constructor(
 
     private suspend fun fetchOrdersFromRemote(
         page: Int,
-        searchQuery: String?
+        searchQuery: String?,
+        count: Int = POS_ORDERS_PAGE_SIZE
     ) = restClient.fetchOrders(
         site = selectedSite.get(),
-        count = POS_ORDERS_PAGE_SIZE,
+        count = count,
         page = page,
         orderBy = OrderBy.DATE,
         sortOrder = OrderRestClient.SortOrder.DESCENDING,

WooCommerce/src/main/kotlin/com/woocommerce/android/ui/woopos/orders/WooPosOrdersViewModel.kt

@@ -445,7 +445,10 @@ class WooPosOrdersViewModel @Inject constructor(
                                 searchInputState = WooPosSearchInputState.Closed
                             )
                         } else {
-                            replaceOrders(result.ordersWithRefunds)
+                            replaceOrders(
+                                ordersWithRefunds = result.ordersWithRefunds,
+                                paginationState = WooPosPaginationState.Loading
+                            )
                         }
                     }
 

WooCommerce/src/test/kotlin/com/woocommerce/android/ui/woopos/home/WooPosHomeViewModelTest.kt

@@ -7,16 +7,19 @@ import com.woocommerce.android.ui.woopos.home.ParentToChildrenEvent.OrderSuccess
 import com.woocommerce.android.ui.woopos.home.WooPosHomeUIEvent.ExitPosClicked
 import com.woocommerce.android.ui.woopos.home.WooPosHomeUIEvent.SystemBackClicked
 import com.woocommerce.android.ui.woopos.home.items.WooPosItemsViewModel.ItemClickedData
+import com.woocommerce.android.ui.woopos.orders.WooPosOrdersDataSource
 import com.woocommerce.android.ui.woopos.util.WooPosCoroutineTestRule
 import com.woocommerce.android.ui.woopos.util.analytics.WooPosAnalyticsEvent.Event.BackToCartTapped
 import com.woocommerce.android.ui.woopos.util.analytics.WooPosAnalyticsEvent.Event.ExitConfirmed
 import com.woocommerce.android.ui.woopos.util.analytics.WooPosAnalyticsTracker
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.emptyFlow
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.test.runTest
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.Rule
+import org.mockito.kotlin.any
 import org.mockito.kotlin.argThat
 import org.mockito.kotlin.mock
 import org.mockito.kotlin.verify
@@ -37,6 +40,7 @@ class WooPosHomeViewModelTest {
     private val parentToChildrenEventSender: WooPosParentToChildrenEventSender = mock()
     private val analyticsTracker: WooPosAnalyticsTracker = mock()
     private val soundHelper: WooPosSoundHelper = mock()
+    private val ordersDataSource: WooPosOrdersDataSource = mock()
 
     @Test
     fun `when order created, then pass event to cart`() =
@@ -342,11 +346,13 @@ class WooPosHomeViewModelTest {
     }
 
     private fun createViewModel(): WooPosHomeViewModel {
+        whenever(ordersDataSource.loadOrders(any())).thenReturn(emptyFlow())
         return WooPosHomeViewModel(
             childrenToParentEventReceiver,
             parentToChildrenEventSender,
             analyticsTracker,
             soundHelper,
+            ordersDataSource,
             SavedStateHandle()
         )
     }