feat: migrate FiatRateCache to DataStore

app/build.gradle.kts

@@ -58,6 +58,7 @@ dependencies {
     androidTestImplementation(libs.androidx.junit)
     debugImplementation(libs.androidx.compose.ui.test.manifest)
     debugImplementation(libs.androidx.compose.ui.tooling)
+
     // Networking
     implementation(libs.retrofit2.retrofit)
     implementation(libs.converter.gson)
@@ -71,6 +72,9 @@ dependencies {
     implementation(libs.androidx.lifecycle.viewmodel.ktx)
     implementation(libs.androidx.lifecycle.viewmodel.compose)
 
+    // DataStore
+    implementation(libs.androidx.datastore.preferences)
+
     // Room
     implementation(libs.room.runtime)
     implementation(libs.room.ktx)

app/src/main/java/com/bitcointxoko/gudariwallet/data/FiatDataStore.kt

@@ -0,0 +1,116 @@
+package com.bitcointxoko.gudariwallet.data
+
+import android.content.Context
+import android.util.Log
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.emptyPreferences
+import androidx.datastore.preferences.core.floatPreferencesKey
+import androidx.datastore.preferences.core.longPreferencesKey
+import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.preferencesDataStore
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.first
+import java.io.IOException
+
+private const val TAG = "FiatDataStore"
+private const val DATASTORE_NAME = "fiat_prefs"
+
+// Top-level extension — one instance per process
+private val Context.fiatDataStore: DataStore<Preferences> by preferencesDataStore(
+    name = DATASTORE_NAME
+)
+
+class FiatDataStore(context: Context) {
+
+    private val dataStore = context.applicationContext.fiatDataStore
+    private val gson = Gson()
+
+    // ── Key factories ─────────────────────────────────────────────────────────
+
+    private fun rateKey(currency: String)        = floatPreferencesKey("fiat_rate_$currency")
+    private fun rateFetchedAtKey(currency: String) = longPreferencesKey("fiat_rate_fetched_at_$currency")
+    private val currenciesKey                    = stringPreferencesKey("fiat_currencies_json")
+
+    // ── Rate ──────────────────────────────────────────────────────────────────
+
+    /**
+     * Returns the last persisted rate for [currency], or null if none exists.
+     * Used as a cold-start fallback while a fresh network fetch is in flight.
+     */
+    suspend fun getPersistedRate(currency: String): Double? {
+        val prefs = dataStore.data
+            .catch { e ->
+                if (e is IOException) {
+                    Log.w(TAG, "FIAT [RATE STALE ] read error — ${e.message}")
+                    emit(emptyPreferences())
+                } else throw e
+            }
+            .first()
+        val value = prefs[rateKey(currency)]?.toDouble()
+        if (value != null && value > 0.0) {
+            Log.d(TAG, "FIAT [RATE STALE ] $currency — using persisted rate $value")
+        }
+        return value?.takeIf { it > 0.0 }
+    }
+
+    /**
+     * Persists a freshly fetched [rate] for [currency].
+     * Always called alongside the in-memory update in [FiatRateCache.putRate].
+     */
+    suspend fun persistRate(currency: String, rate: Double) {
+        runCatching {
+            dataStore.edit { prefs ->
+                prefs[rateKey(currency)]          = rate.toFloat()
+                prefs[rateFetchedAtKey(currency)] = System.currentTimeMillis()
+            }
+        }.onFailure { e ->
+            Log.w(TAG, "FIAT [RATE FRESH ] persist failed for $currency — ${e.message}")
+        }
+        Log.d(TAG, "FIAT [RATE FRESH ] $currency = $rate — persisted to DataStore")
+    }
+
+    // ── Currency list ─────────────────────────────────────────────────────────
+
+    /**
+     * Returns the persisted currency list, or null if none has been stored yet.
+     */
+    suspend fun getPersistedCurrencies(): List<String>? {
+        val prefs = dataStore.data
+            .catch { e ->
+                if (e is IOException) {
+                    Log.w(TAG, "FIAT [CURRENCIES] read error — ${e.message}")
+                    emit(emptyPreferences())
+                } else throw e
+            }
+            .first()
+        val json = prefs[currenciesKey] ?: return null
+        return runCatching {
+            val type = object : TypeToken<List<String>>() {}.type
+            val list: List<String> = gson.fromJson(json, type)
+            Log.d(TAG, "FIAT [CURRENCIES] DataStore hit (${list.size} currencies)")
+            list
+        }.getOrElse { e ->
+            Log.w(TAG, "FIAT [CURRENCIES] parse failed — ${e.message}")
+            null
+        }
+    }
+
+    /**
+     * Persists [currencies] to DataStore.
+     */
+    suspend fun persistCurrencies(currencies: List<String>) {
+        if (currencies.isEmpty()) return
+        runCatching {
+            dataStore.edit { prefs ->
+                prefs[currenciesKey] = gson.toJson(currencies)
+            }
+        }.onFailure { e ->
+            Log.w(TAG, "FIAT [CURRENCIES] persist failed — ${e.message}")
+        }
+        Log.d(TAG, "FIAT [CURRENCIES] persisted ${currencies.size} currencies to DataStore")
+    }
+}

app/src/main/java/com/bitcointxoko/gudariwallet/data/FiatRateCache.kt

@@ -1,24 +1,19 @@
 package com.bitcointxoko.gudariwallet.data
 
-import android.content.SharedPreferences
 import android.util.Log
-import androidx.core.content.edit
-import com.google.gson.Gson
-import com.google.gson.reflect.TypeToken
 
 private const val TAG = "FiatRateCache"
 
 /**
- * Two-tier (in-memory + SharedPreferences) cache for fiat exchange rates
+ * Two-tier (in-memory + DataStore) cache for fiat exchange rates
  * and the supported-currency list.
  *
- * Receives the already-open [prefs] instance from [BalancePrefsStore] so that
+ * Disk persistence is delegated to [FiatDataStore]; this class owns
- * all wallet prefs stay in a single file.
+ * only the in-memory (L1) layer and the cache-coordination logic.
  */
-class FiatRateCache(store: BalancePrefsStore) {
+class FiatRateCache(private val fiatDataStore: FiatDataStore) {
-    private val prefs = store.prefs
 
-    // ── Rate ─────────────────────────────────────────────────────────────────
+    // ── Rate ──────────────────────────────────────────────────────────────────
 
     private var cachedRate         : Double? = null
     private var rateLastFetchedAt  : Long    = 0L
@@ -26,9 +21,10 @@ class FiatRateCache(store: BalancePrefsStore) {
 
     /**
      * Returns a fresh in-memory rate for [currency] if it is younger than
-     * [ttlMs], then falls back to the last persisted float, then returns null.
+     * [ttlMs], then falls back to the last persisted value via DataStore,
+     * then returns null.
      */
-    fun getRate(currency: String, ttlMs: Long): Double? {
+    suspend fun getRate(currency: String, ttlMs: Long): Double? {
         val now = System.currentTimeMillis()
         val age = now - rateLastFetchedAt
 
@@ -37,9 +33,9 @@ class FiatRateCache(store: BalancePrefsStore) {
             return cachedRate
         }
 
-        // Cold-start fallback: last persisted rate
+        // Cold-start fallback: last persisted rate from DataStore
-        val persisted = prefs.getFloat("fiat_rate_$currency", 0f).toDouble()
+        val persisted = fiatDataStore.getPersistedRate(currency)
-        if (persisted > 0.0) {
+        if (persisted != null) {
             Log.d(TAG, "FIAT [RATE STALE ] $currency — using persisted rate $persisted")
             return persisted
         }
@@ -50,15 +46,12 @@ class FiatRateCache(store: BalancePrefsStore) {
     /**
      * Stores a freshly fetched [rate] for [currency] in memory and on disk.
      */
-    fun putRate(currency: String, rate: Double) {
+    suspend fun putRate(currency: String, rate: Double) {
         val now = System.currentTimeMillis()
         cachedRate         = rate
         rateLastFetchedAt  = now
         cachedRateCurrency = currency
-        prefs.edit {
+        fiatDataStore.persistRate(currency, rate)
-            putFloat("fiat_rate_$currency", rate.toFloat())
-            putLong("fiat_rate_fetched_at_$currency", now)
-        }
         Log.d(TAG, "FIAT [RATE FRESH ] 1 $currency = $rate sats — cached + persisted")
     }
 
@@ -72,38 +65,32 @@ class FiatRateCache(store: BalancePrefsStore) {
     // ── Currency list ─────────────────────────────────────────────────────────
 
     private var cachedCurrencies: List<String>? = null
-    private val gson = Gson()
 
     /**
-     * Returns the cached currency list (memory → disk → null).
+     * Returns the cached currency list (memory → DataStore → null).
      * Callers are responsible for fetching from the network on a null result.
      */
-    fun getCurrencies(): List<String>? {
+    suspend fun getCurrencies(): List<String>? {
         cachedCurrencies?.let {
             Log.d(TAG, "FIAT [CURRENCIES] in-memory hit (${it.size} currencies)")
             return it
         }
 
-        val json = prefs.getString("fiat_currencies_json", null) ?: return null
+        val persisted = fiatDataStore.getPersistedCurrencies()
-        return runCatching {
+        if (persisted != null) {
-            val type = object : TypeToken<List<String>>() {}.type
+            cachedCurrencies = persisted
-            val list: List<String> = gson.fromJson(json, type)
-            Log.d(TAG, "FIAT [CURRENCIES] prefs hit (${list.size} currencies)")
-            list.also { cachedCurrencies = it }
-        }.getOrElse { e ->
-            Log.w(TAG, "FIAT [CURRENCIES] prefs parse failed — ${e.message}")
-            null
         }
+        return persisted
     }
 
     /** Stores [currencies] in memory and on disk. */
-    fun putCurrencies(currencies: List<String>) {
+    suspend fun putCurrencies(currencies: List<String>) {
         if (currencies.isEmpty()) return
         cachedCurrencies = currencies
-        prefs.edit { putString("fiat_currencies_json", gson.toJson(currencies)) }
+        fiatDataStore.persistCurrencies(currencies)
         Log.d(TAG, "FIAT [CURRENCIES] cached ${currencies.size} currencies")
     }
 
     val currentRate: Double?
         get() = cachedRate.takeIf { cachedRateCurrency.isNotBlank() }
-}
+}

app/src/main/java/com/bitcointxoko/gudariwallet/ui/WalletViewModelFactory.kt

@@ -7,9 +7,9 @@ import com.bitcointxoko.gudariwallet.api.LNbitsClient
 import com.bitcointxoko.gudariwallet.api.NodeAliasClient
 import com.bitcointxoko.gudariwallet.data.BalancePrefsStore
 import com.bitcointxoko.gudariwallet.data.LNbitsNodeAliasRepository
+import com.bitcointxoko.gudariwallet.data.FiatDataStore
 import com.bitcointxoko.gudariwallet.data.LNbitsWalletRepository
 import com.bitcointxoko.gudariwallet.data.LnurlCacheRepository
-import com.bitcointxoko.gudariwallet.data.NodeAliasRepository
 import com.bitcointxoko.gudariwallet.data.PaymentCacheRepository
 import com.bitcointxoko.gudariwallet.security.EncryptedSecretStore
 import com.bitcointxoko.gudariwallet.service.NodeAliasService
@@ -30,10 +30,11 @@ class WalletViewModelFactory(private val app: Application) : ViewModelProvider.F
         val paymentCache = PaymentCacheRepository(app)
 
         val aliasRepo    = LNbitsNodeAliasRepository(nodeAliasSvc)
+        val fiatDataStore = FiatDataStore(app)
         val repo         = LNbitsWalletRepository(api = api, secrets = secrets)
         val balancePrefs = BalancePrefsStore(app)
         val balanceVm    = BalanceViewModel(repo, balancePrefs)
-        val fiatVm       = FiatViewModel(repo, balancePrefs, balanceVm)
+        val fiatVm       = FiatViewModel(repo, balancePrefs, balanceVm, fiatDataStore)
         val receiveVm  = ReceiveViewModel(repo)
         val sendVm     = SendViewModel(
             repo = repo,

app/src/main/java/com/bitcointxoko/gudariwallet/ui/fiat/FiatViewModel.kt

@@ -4,10 +4,12 @@ import android.util.Log
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.bitcointxoko.gudariwallet.data.BalancePrefsStore
+import com.bitcointxoko.gudariwallet.data.FiatDataStore
 import com.bitcointxoko.gudariwallet.data.FiatRateCache
 import com.bitcointxoko.gudariwallet.data.WalletRepository
 import com.bitcointxoko.gudariwallet.ui.BalanceState
 import com.bitcointxoko.gudariwallet.ui.balance.BalanceViewModel
+import com.bitcointxoko.gudariwallet.util.WalletConstants.RATE_TTL_MS
 import com.bitcointxoko.gudariwallet.util.satsToFiat
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
@@ -17,15 +19,15 @@ import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 
 private const val TAG = "FiatViewModel"
-private const val RATE_TTL_MS = 5 * 60 * 1_000L   // 5 minutes
 
 class FiatViewModel(
     private val repo        : WalletRepository,
     private val balancePrefs: BalancePrefsStore,
     private val balanceVm   : BalanceViewModel,
+    fiatDataStore           : FiatDataStore,
 ) : ViewModel() {
 
-    private val fiatCache = FiatRateCache(balancePrefs)
+    private val fiatCache = FiatRateCache(fiatDataStore)
 
     val fiatRate: Double?
         get() = fiatCache.currentRate
@@ -33,7 +35,7 @@ class FiatViewModel(
     val fiatCurrency: String?
         get() = _selectedCurrency.value
 
-    // ── Balance hidden ───────────────────────────────────────────────────────
+    // ── Balance hidden ────────────────────────────────────────────────────────
     private val _balanceHidden = MutableStateFlow(balancePrefs.isBalanceHidden)
     val balanceHidden: StateFlow<Boolean> = _balanceHidden
 
@@ -43,8 +45,9 @@ class FiatViewModel(
         balancePrefs.setBalanceHidden(next)
     }
 
-    // ── Selected currency ────────────────────────────────────────────────────
+    // ── Selected currency ─────────────────────────────────────────────────────
-    private val _selectedCurrency = MutableStateFlow(balancePrefs.selectedCurrency)
+    private val _selectedCurrency =
+        MutableStateFlow(balancePrefs.selectedCurrency)
     val selectedCurrency: StateFlow<String?> = _selectedCurrency
 
     fun setSelectedCurrency(currency: String?) {
@@ -60,8 +63,7 @@ class FiatViewModel(
         }
     }
 
-    // ── Sats-per-fiat-unit derived flow ──────────────────────────────────────
+    // ── Sats-per-fiat-unit derived flow ───────────────────────────────────────
-    // Used by UnitWheelPicker to convert between sats and fiat amounts.
     val fiatSatsPerUnit: StateFlow<Double?> = balanceVm.balanceState
         .mapNotNull { state ->
             (state as? BalanceState.Success)?.let { s ->
@@ -76,13 +78,12 @@ class FiatViewModel(
             initialValue = null
         )
 
-    // ── Called by BalanceViewModel after every successful balance refresh ────
+    // ── Called by BalanceViewModel after every successful balance refresh ─────
-    // Keeps fiat display in sync whenever the balance changes.
     fun onBalanceRefreshed() {
         viewModelScope.launch { fetchAndApplyFiatRate() }
     }
 
-    // ── Rate fetch + apply ───────────────────────────────────────────────────
+    // ── Rate fetch + apply ────────────────────────────────────────────────────
     private suspend fun fetchAndApplyFiatRate() {
         val currency = _selectedCurrency.value ?: return
 
@@ -103,7 +104,7 @@ class FiatViewModel(
         balanceVm.applyFiat(fiat, currency)
     }
 
-    // ── Currency list ────────────────────────────────────────────────────────
+    // ── Currency list ─────────────────────────────────────────────────────────
     suspend fun getSupportedCurrencies(): List<String> {
         fiatCache.getCurrencies()?.let { return it }
         return fetchAndCacheCurrencies()

app/src/main/java/com/bitcointxoko/gudariwallet/util/WalletConstants.kt

@@ -42,4 +42,7 @@ object WalletConstants {
     const val BALANCE_PREFS_KEY         = "last_balance_sats"
     const val BALANCE_PREFS_SAVED_AT    = "last_balance_saved_at"
     const val BALANCE_CACHE_TTL_MS      = 3_600_000L              // 1 hour
+
+    // ── Fiat cache ─────────────────────────────────────────────────────────
+    const val RATE_TTL_MS = 5 * 60 * 1_000L   // 5 minutes
 }

gradle/libs.versions.toml

@@ -21,8 +21,7 @@ navigationCompose = "2.8.9"
 appcompat = "1.7.0"
 ksp = "2.2.10-2.0.2"
 room = "2.7.1"
-
+datastore = "1.2.1"
-
 
 [libraries]
 androidx-biometric = { module = "androidx.biometric:biometric", version.ref = "biometric" }
@@ -57,7 +56,7 @@ androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version
 room-runtime = { group = "androidx.room", name = "room-runtime", version.ref = "room" }
 room-ktx = { group = "androidx.room", name = "room-ktx", version.ref = "room" }
 room-compiler = { group = "androidx.room", name = "room-compiler", version.ref = "room" }
-
+androidx-datastore-preferences = { group = "androidx.datastore", name = "datastore-preferences", version.ref = "datastore" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }