Cache balance and load it on startup

app/src/main/java/to/bitkit/data/AppStorage.kt

@@ -2,7 +2,12 @@ package to.bitkit.data
 
 import android.content.Context
 import android.content.SharedPreferences
+import androidx.core.content.edit
 import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.serialization.encodeToString
+import to.bitkit.di.json
+import to.bitkit.models.BalanceState
+import to.bitkit.utils.Logger
 import javax.inject.Inject
 import kotlin.reflect.KProperty
 
@@ -19,14 +24,36 @@ class AppStorage @Inject constructor(
     var bolt11: String by SharedPrefDelegate(Key.BOLT11)
     var bip21: String by SharedPrefDelegate(Key.BIP21)
 
+    fun cacheBalance(balanceState: BalanceState) {
+        try {
+            val jsonData = json.encodeToString(balanceState)
+            sharedPreferences.edit { putString(Key.BALANCE.name, jsonData) }
+
+        } catch (e: Throwable) {
+            Logger.debug("Failed to cache balance: $e")
+        }
+    }
+
+    fun loadBalance(): BalanceState? {
+        val jsonData = sharedPreferences.getString(Key.BALANCE.name, null) ?: return null
+
+        return try {
+            json.decodeFromString(jsonData)
+        } catch (e: Throwable) {
+            Logger.debug("Failed to load cached balance: $e")
+            null
+        }
+    }
+
     enum class Key {
         ONCHAIN_ADDRESS,
         BOLT11,
         BIP21,
+        BALANCE,
     }
 
     fun clear() {
-        sharedPreferences.edit().clear().apply()
+        sharedPreferences.edit { clear() }
     }
 }
 
@@ -36,6 +63,6 @@ private class SharedPrefDelegate(private val key: AppStorage.Key) {
     }
 
     operator fun setValue(thisRef: AppStorage, property: KProperty<*>, value: String) {
-        thisRef.sharedPreferences.edit().putString(key.name, value).apply()
+        thisRef.sharedPreferences.edit { putString(key.name, value) }
     }
 }

app/src/main/java/to/bitkit/models/BalanceState.kt

@@ -1,5 +1,8 @@
 package to.bitkit.models
 
+import kotlinx.serialization.Serializable
+
+@Serializable
 data class BalanceState(
     val totalOnchainSats: ULong = 0uL,
     val totalLightningSats: ULong = 0uL,

app/src/main/java/to/bitkit/ui/ContentView.kt

@@ -18,6 +18,7 @@ import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
 import androidx.lifecycle.compose.LocalLifecycleOwner
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.navigation.NavController
 import androidx.navigation.NavGraphBuilder
 import androidx.navigation.NavHostController
@@ -185,7 +186,7 @@ fun ContentView(
             walletViewModel.isRestoringWallet = false
         }
     } else {
-        val balance by walletViewModel.balanceState.collectAsState()
+        val balance by walletViewModel.balanceState.collectAsStateWithLifecycle()
         val currencies by currencyViewModel.uiState.collectAsState()
 
         CompositionLocalProvider(

app/src/main/java/to/bitkit/viewmodels/WalletViewModel.kt

@@ -61,7 +61,7 @@ class WalletViewModel @Inject constructor(
     private val _uiState = MutableStateFlow(MainUiState())
     val uiState = _uiState.asStateFlow()
 
-    private val _balanceState = MutableStateFlow(BalanceState())
+    private val _balanceState = MutableStateFlow(appStorage.loadBalance() ?: BalanceState())
     val balanceState = _balanceState.asStateFlow()
 
     private var _nodeLifecycleState: NodeLifecycleState = NodeLifecycleState.Stopped
@@ -195,13 +195,15 @@ class WalletViewModel @Inject constructor(
         lightningService.balances?.let { balance ->
             _uiState.update { it.copy(balanceDetails = balance) }
             val totalSats = balance.totalLightningBalanceSats + balance.totalOnchainBalanceSats
-            _balanceState.update {
-                it.copy(
-                    totalOnchainSats = balance.totalOnchainBalanceSats,
-                    totalLightningSats = balance.totalLightningBalanceSats,
-                    totalSats = totalSats,
-                )
-            }
+
+            val newBalance = BalanceState(
+                totalOnchainSats = balance.totalOnchainBalanceSats,
+                totalLightningSats = balance.totalLightningBalanceSats,
+                totalSats = totalSats,
+            )
+            _balanceState.update { newBalance }
+            appStorage.cacheBalance(newBalance)
+
             if (totalSats > 0u) {
                 viewModelScope.launch {
                     settingsStore.setShowEmptyState(false)