fix: avoid duplicate rate writes

Author: ovitrif

app/src/main/java/to/bitkit/ui/screens/widgets/calculator/CalculatorViewModel.kt

@@ -46,6 +46,7 @@ class CalculatorViewModel @Inject constructor(
     val uiState: StateFlow<CalculatorUiState> = _uiState.asStateFlow()
     private var pendingValues: CalculatorValues? = null
     private var lastCurrencyKey: CalculatorCurrencyKey? = null
+    private var lastRates: ImmutableList<FxRate>? = null
     private var activeInput: MoneyType? = null
 
     val isCalculatorWidgetEnabled: StateFlow<Boolean> = widgetsRepo.widgetsDataFlow
@@ -164,14 +165,17 @@ class CalculatorViewModel @Inject constructor(
         val currencyKey = CalculatorCurrencyKey(
             selectedCurrency = currencyState.selectedCurrency,
             displayUnit = currencyState.displayUnit,
-            rates = currencyState.rates,
         )
         val previousCurrencyKey = lastCurrencyKey
+        val previousRates = lastRates
         lastCurrencyKey = currencyKey
+        lastRates = currencyState.rates
 
-        val currencyChanged = previousCurrencyKey != null && previousCurrencyKey != currencyKey
+        val currencyChanged = previousCurrencyKey != null &&
+            previousCurrencyKey.selectedCurrency != currencyKey.selectedCurrency
         val displayUnitChanged = previousCurrencyKey != null &&
             previousCurrencyKey.displayUnit != currencyKey.displayUnit
+        val ratesChanged = previousRates != null && previousRates != currencyState.rates
         val isInitialSync = previousCurrencyKey == null
         val nextActiveValues = deriveActiveValues(
             activeValues = activeValues,
@@ -188,7 +192,7 @@ class CalculatorViewModel @Inject constructor(
             )
         }
 
-        val shouldRefreshFiat = isInitialSync || currencyChanged || shouldHydrateFiatFromStoredBtc(
+        val shouldRefreshFiat = isInitialSync || currencyChanged || ratesChanged || shouldHydrateFiatFromStoredBtc(
             storedBtcValue = storedValues.btcValue,
             storedFiatValue = storedValues.fiatValue,
             currentFiatValue = nextActiveValues.fiatValue,
@@ -219,7 +223,10 @@ class CalculatorViewModel @Inject constructor(
         if (convertedFiat.isEmpty()) return persistCanonicalValues(activeValues, nextActiveValues)
 
         val updatedValues = nextActiveValues.copy(fiatValue = convertedFiat)
-        updateCalculatorValues(updatedValues)
+        persistCanonicalValuesIfNeeded(
+            activeValues = activeValues,
+            nextActiveValues = updatedValues,
+        )
         return updatedValues
     }
 
@@ -371,7 +378,6 @@ data class CalculatorUiState(
 private data class CalculatorCurrencyKey(
     val selectedCurrency: String,
     val displayUnit: BitcoinDisplayUnit,
-    val rates: ImmutableList<FxRate>,
 )
 
 internal fun shouldHydrateFiatFromStoredBtc(

app/src/test/java/to/bitkit/ui/screens/widgets/calculator/CalculatorViewModelTest.kt

@@ -35,6 +35,7 @@ class CalculatorViewModelTest : BaseUnitTest() {
     private var fiatConversionValue: String? = null
     private var fiatConversionFormatted: String? = null
     private var fiatToSatsValue = 12_345uL
+    private var updateCalculatorValuesCalls = 0
 
     private lateinit var sut: CalculatorViewModel
 
@@ -47,6 +48,7 @@ class CalculatorViewModelTest : BaseUnitTest() {
         fiatConversionValue = null
         fiatConversionFormatted = null
         fiatToSatsValue = 12_345uL
+        updateCalculatorValuesCalls = 0
 
         whenever(widgetsRepo.widgetsDataFlow).thenReturn(widgetsData)
         whenever(currencyRepo.currencyState).thenReturn(currencyState)
@@ -65,6 +67,7 @@ class CalculatorViewModelTest : BaseUnitTest() {
         }
         whenever(currencyRepo.convertFiatToSats(any<BigDecimal>(), anyOrNull())).thenAnswer { fiatToSatsValue }
         whenever { widgetsRepo.updateCalculatorValues(any()) }.thenAnswer {
+            updateCalculatorValuesCalls++
             val calculatorValues = it.getArgument<CalculatorValues>(0)
             widgetsData.value = widgetsData.value.copy(calculatorValues = calculatorValues)
             Unit
@@ -290,6 +293,25 @@ class CalculatorViewModelTest : BaseUnitTest() {
         assertEquals("7.50", widgetsData.value.calculatorValues.fiatValue)
     }
 
+    @Test
+    fun `rate refresh skips persist when fiat display value is unchanged`() = test {
+        sut = createSut()
+        advanceUntilIdle()
+
+        sut.onBtcInputChanged("10000")
+        advanceUntilIdle()
+
+        val updatesBeforeRateRefresh = updateCalculatorValuesCalls
+        currencyState.value = currencyState.value.copy(
+            rates = persistentListOf(fxRate(lastPrice = "62501")),
+        )
+        advanceUntilIdle()
+
+        assertEquals("10000", sut.uiState.value.btcValue)
+        assertEquals("6.25", sut.uiState.value.fiatValue)
+        assertEquals(updatesBeforeRateRefresh, updateCalculatorValuesCalls)
+    }
+
     @Test
     fun `currency change preserves fiat input as source`() = test {
         sut = createSut()