Change eatery cache to a map flow

Author: caleb-bit

app/src/main/java/com/cornellappdev/android/eatery/data/repositories/EateryRepository.kt

@@ -7,9 +7,12 @@ import com.cornellappdev.android.eatery.data.models.Event
 import com.cornellappdev.android.eatery.ui.viewmodels.state.EateryApiResponse
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 import javax.inject.Singleton
@@ -95,8 +98,8 @@ class EateryRepository @Inject constructor(private val networkApi: NetworkApi) {
     /**
      * A map from eatery ids to the states representing their API loading calls.
      */
-    private val eateryApiCache: MutableMap<Int, MutableStateFlow<EateryApiResponse<Eatery>>> =
-        mutableMapOf()
+    private val eateryApiCache: MutableStateFlow<MutableMap<Int, EateryApiResponse<Eatery>>> =
+        MutableStateFlow(mutableMapOf())
 
     /**
      * Makes a new call to backend for the specified eatery. After calling,
@@ -105,31 +108,33 @@ class EateryRepository @Inject constructor(private val networkApi: NetworkApi) {
      */
     private fun pingEatery(eateryId: Int) {
         // If first time calling, make new state.
-        if (eateryApiCache[eateryId] == null) {
-            eateryApiCache[eateryId] = MutableStateFlow(EateryApiResponse.Pending)
-        }
-
-        eateryApiCache[eateryId]!!.value = EateryApiResponse.Pending
+        updateCache(eateryId, EateryApiResponse.Pending)
 
         CoroutineScope(Dispatchers.IO).launch {
             try {
                 val eatery = getEatery(eateryId = eateryId)
-                eateryApiCache[eateryId]!!.value = EateryApiResponse.Success(eatery)
+                updateCache(eateryId, EateryApiResponse.Success(eatery))
             } catch (_: Exception) {
-                eateryApiCache[eateryId]!!.value = EateryApiResponse.Error
+                updateCache(eateryId, EateryApiResponse.Error)
             }
         }
     }
 
+    private fun updateCache(eateryId: Int, response: EateryApiResponse<Eatery>) {
+        eateryApiCache.update {
+            (it + (eateryId to response)).toMutableMap()
+        }
+    }
+
     /**
      * Returns the [StateFlow] representing the API call for the specified eatery.
      * If ALL eateries are already loaded, then this simply instantly returns that.
      */
-    fun getEateryFlow(eateryId: Int): StateFlow<EateryApiResponse<Eatery>> {
+    fun getEateryFlow(eateryId: Int): Flow<EateryApiResponse<Eatery>> {
         lastEateryId = eateryId
-        if (!eateryApiCache.contains(eateryId)) {
+        if (!eateryApiCache.value.contains(eateryId)) {
             pingEatery(eateryId)
         }
-        return eateryApiCache[eateryId]!!
+        return eateryApiCache.map { it[eateryId]!! }
     }
 }

app/src/main/java/com/cornellappdev/android/eatery/ui/screens/SearchScreen.kt

@@ -109,7 +109,8 @@ fun SearchScreen(
         }
     }
 
-    ModalBottomSheetLayout(sheetState = modalBottomSheetState, sheetShape = RoundedCornerShape(
+    ModalBottomSheetLayout(
+        sheetState = modalBottomSheetState, sheetShape = RoundedCornerShape(
         bottomStart = 0.dp, bottomEnd = 0.dp, topStart = 12.dp, topEnd = 12.dp
     ), sheetElevation = 8.dp, sheetContent = {
         PaymentMethodsBottomSheet(selectedFilters = selectedPaymentMethodFilters, hide = {
@@ -242,7 +243,10 @@ fun SearchScreen(
                         )
 
                         recentSearches.forEach { eateryId ->
-                            val eateryResponse = searchViewModel.openEatery(eateryId).value
+                            val eateryResponse =
+                                searchViewModel.openEatery(eateryId).collectAsState(
+                                    initial = EateryApiResponse.Pending
+                                ).value
                             if (eateryResponse is EateryApiResponse.Success) {
                                 Box(
                                     Modifier.padding(
@@ -280,7 +284,8 @@ fun SearchScreen(
                                 horizontal = 16.dp, vertical = 12.dp
                             )
                         ) {
-                            EateryCard(eatery = eatery,
+                            EateryCard(
+                                eatery = eatery,
                                 isFavorite = favorites.any { favoriteEatery ->
                                     favoriteEatery.id == eatery.id
                                 },
@@ -309,14 +314,16 @@ fun SearchScreen(
 fun FavoriteItem(
     eatery: Eatery, onEateryClick: (eatery: Eatery) -> Unit
 ) {
-    Column(modifier = Modifier
-        .width(96.dp)
-        .clickable {
-            onEateryClick(eatery)
-        }) {
+    Column(
+        modifier = Modifier
+            .width(96.dp)
+            .clickable {
+                onEateryClick(eatery)
+            }) {
         // Use box to overlay the star over the eatery
         Box {
-            GlideImage(imageModel = { eatery.imageUrl ?: "" },
+            GlideImage(
+                imageModel = { eatery.imageUrl ?: "" },
                 modifier = Modifier
                     .fillMaxWidth()
                     .height(96.dp)

app/src/main/java/com/cornellappdev/android/eatery/ui/viewmodels/EateryDetailViewModel.kt

@@ -13,8 +13,8 @@ import com.cornellappdev.android.eatery.ui.components.general.MenuItemViewState
 import com.cornellappdev.android.eatery.ui.viewmodels.state.EateryApiResponse
 import com.cornellappdev.android.eatery.util.fromOffsetToDayOfWeek
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.launchIn
@@ -72,7 +72,7 @@ class EateryDetailViewModel @Inject constructor(
     /**
      * A flow emitting the loading status of the current eatery.
      */
-    private val eateryFlow: StateFlow<EateryApiResponse<Eatery>> =
+    private val eateryFlow: Flow<EateryApiResponse<Eatery>> =
         eateryRepository.getEateryFlow(eateryId)
 
     private val userSelectedMeal = MutableStateFlow<Event?>(null)