Updated on 2026-08-14

core/ui/src/main/java/com/tangem/core/ui/format/bigdecimal/BigDecimalFiatFormat.kt

@@ -242,6 +242,33 @@ fun BigDecimalFiatFormat.anyDecimals(decimals: Int): BigDecimalFormat = BigDecim
         .replace(formatterCurrency.getSymbol(locale), fiatCurrencySymbol)
 }
 
+/**
+ * Formats fiat amount following the pattern:
+ *
+ * 123 -> $123
+ *
+ * 123.1 -> $123.10
+ *
+ * 123.10 -> $123.10
+ *
+ * 123.456 -> $123.46
+ */
+fun BigDecimalFiatFormat.optionalDecimals(): BigDecimalFormat = BigDecimalFormat { value ->
+    val formatterCurrency = getJavaCurrencyByCode(fiatCurrencyCode)
+
+    val hasFraction = value.stripTrailingZeros().scale() > 0
+    val defaultDigits = formatterCurrency.defaultFractionDigits
+    val formatter = NumberFormat.getCurrencyInstance(locale).apply {
+        currency = formatterCurrency
+        minimumFractionDigits = if (hasFraction) defaultDigits else 0
+        maximumFractionDigits = defaultDigits
+        roundingMode = RoundingMode.HALF_UP
+    }
+
+    formatter.format(value)
+        .replace(formatterCurrency.getSymbol(locale), fiatCurrencySymbol)
+}
+
 // == Helpers ==
 
 private fun BigDecimal.isLessThanThreshold() = this > BigDecimal.ZERO && this < FIAT_FORMAT_THRESHOLD

core/ui/src/test/kotlin/com/tangem/core/ui/format/bigdecimal/BigDecimalFiatFormatTest.kt

@@ -2,6 +2,9 @@ package com.tangem.core.ui.format.bigdecimal
 
 import com.google.common.truth.Truth
 import org.junit.Test
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.MethodSource
 import java.math.BigDecimal
 import java.util.Locale
 
@@ -342,4 +345,37 @@ internal class BigDecimalFiatFormatTest {
         Truth.assertThat(formatted)
             .isEqualTo("-" + "0.50".addUsdSymbolLeft())
     }
+
+    @ParameterizedTest
+    @MethodSource("provideTestCasesForOptionalDecimals")
+    fun `GIVEN amount WHEN format with optionalDecimals THEN correct answer`(
+        amount: String,
+        answer: String,
+    ) {
+        val testValue = BigDecimal(amount)
+
+        val formatted = testValue.format {
+            fiat(
+                fiatCurrencyCode = usdCurrencyCode,
+                fiatCurrencySymbol = usdSymbol,
+                locale = testLocale,
+            ).optionalDecimals()
+        }
+
+        Truth.assertThat(formatted).isEqualTo(answer)
+    }
+
+    private companion object {
+        @JvmStatic
+        fun provideTestCasesForOptionalDecimals() = listOf(
+            Arguments.of("123", "$123"),
+            Arguments.of("123.1", "$123.10"),
+            Arguments.of("123.10", "$123.10"),
+            Arguments.of("123.456", "$123.46"),
+            Arguments.of("0", "$0"),
+            Arguments.of("0.1", "$0.10"),
+            Arguments.of("0.12", "$0.12"),
+            Arguments.of("0.127", "$0.13"),
+        )
+    }
 }