perf: optimize screen load times with progressive un-gating and SWR caching (#1192)

app/src/main/java/com/m57/hermescontrol/ui/providers/ProvidersScreen.kt

@@ -46,6 +46,7 @@ import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.m57.hermescontrol.R
+import com.m57.hermescontrol.data.local.AuthManager
 import com.m57.hermescontrol.data.model.OAuthProvider
 import com.m57.hermescontrol.data.model.OAuthStartResponse
 import com.m57.hermescontrol.theme.LocalHermesStatusColors
@@ -65,9 +66,13 @@ fun ProvidersScreen(
     viewModel: ProvidersViewModel = viewModel { ProvidersViewModel() },
 ) {
     val state by viewModel.uiState.collectAsStateWithLifecycle()
+    val dataScope by AuthManager.dataScopeFlow.collectAsStateWithLifecycle()
     val context = LocalContext.current
 
-    LaunchedEffect(Unit) { viewModel.load() }
+    LaunchedEffect(dataScope) {
+        viewModel.clearScopeOwnedState()
+        viewModel.load()
+    }
 
     ToastEffect(toastMessage = state.toastMessage, onClearToast = viewModel::clearToast)
 
@@ -98,7 +103,7 @@ fun ProvidersScreen(
         title = { Text(stringResource(R.string.screen_providers)) },
         navigationIcon = onOpenDrawer?.let { NavIcon.Menu(it) },
         isRefreshing = state.isLoading,
-        onRefresh = { viewModel.load() },
+        onRefresh = { viewModel.load(forceRefresh = true) },
     ) { paddingValues ->
         when {
             state.isLoading && state.providers.isEmpty() -> {

app/src/main/java/com/m57/hermescontrol/ui/providers/ProvidersViewModel.kt

@@ -2,8 +2,10 @@ package com.m57.hermescontrol.ui.providers
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import com.m57.hermescontrol.data.local.SwrCache
 import com.m57.hermescontrol.data.model.OAuthPollResponse
 import com.m57.hermescontrol.data.model.OAuthProvider
+import com.m57.hermescontrol.data.model.OAuthProvidersResponse
 import com.m57.hermescontrol.data.model.OAuthStartResponse
 import com.m57.hermescontrol.data.model.OAuthSubmitRequest
 import com.m57.hermescontrol.data.remote.ApiClient
@@ -12,6 +14,7 @@ import com.m57.hermescontrol.data.remote.NetworkResult
 import com.m57.hermescontrol.data.remote.safeApiCall
 import com.m57.hermescontrol.ui.common.ToastHost
 import com.m57.hermescontrol.ui.common.safeLaunchLoad
+import com.m57.hermescontrol.ui.common.safeLaunchSwrLoad
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -66,9 +69,35 @@ class ProvidersViewModel :
     val uiState: StateFlow<ProvidersUiState> = _uiState.asStateFlow()
 
     private var pollJob: Job? = null
+    private val providersCache = SwrCache<String, OAuthProvidersResponse>()
 
-    fun load() {
-        safeLaunchLoad(
+    fun clearScopeOwnedState() {
+        pollJob?.cancel()
+        _uiState.update {
+            it.copy(
+                isLoading = false,
+                providers = emptyList(),
+                errorMessage = null,
+                flowPhase = OAuthFlowPhase.IDLE,
+                flowProvider = null,
+                flowErrorMessage = null,
+            )
+        }
+    }
+
+    fun load(forceRefresh: Boolean = false) {
+        safeLaunchSwrLoad(
+            cache = providersCache,
+            forceRefresh = forceRefresh,
+            onCacheHit = { data ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        providers = data.providers.orEmpty(),
+                        errorMessage = null,
+                    )
+                }
+            },
             apiCall = { safeApiCall { ApiClient.hermesApi.getOAuthProviders() } },
             onStart = {
                 _uiState.update { it.copy(isLoading = true, errorMessage = null) }
@@ -105,7 +134,7 @@ class ProvidersViewModel :
                         toastMessage = "Disconnected",
                     )
                 }
-                load()
+                load(forceRefresh = true)
             },
             onError = { error ->
                 _uiState.update {
@@ -301,7 +330,7 @@ class ProvidersViewModel :
 
     private fun finishFlow(status: String) {
         pollJob?.cancel()
-        load()
+        load(forceRefresh = true)
         // Stay on DONE so the dialog can show a success confirmation; the Screen's
         // Done button calls dismissFlow() to reset to IDLE. (Setting IDLE here would
         // conflate with DONE via StateFlow and unmount the dialog before the user sees it.)