[wallet] Improve DD51 unit rendering and adapt tests accordingly

(cherry picked from commit c7b2cbe5c39192648336746a719ecdfa88221b28)

3 files changed, 74 insertions, 28 deletions

diff --git a/cashier/src/main/java/net/taler/cashier/SignedAmount.kt b/cashier/src/main/java/net/taler/cashier/SignedAmount.kt
index 4f624ae..45bc3af 100644
--- a/cashier/src/main/java/net/taler/cashier/SignedAmount.kt
+++ b/cashier/src/main/java/net/taler/cashier/SignedAmount.kt
@@ -23,8 +23,10 @@ data class SignedAmount(
     val amount: Amount
 ) {
 
-    override fun toString(): String {
-        return if (positive) "$amount" else "-$amount"
-    }
+    override fun toString() = toString(showSymbol = true)
 
+    fun toString(showSymbol: Boolean) = amount.toString(
+            showSymbol = showSymbol,
+            negative = !positive,
+    )
 }
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt b/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt
index d6188cf..1652056 100644
--- a/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt
+++ b/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt
@@ -23,6 +23,7 @@ import kotlinx.serialization.Serializer
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 import java.text.DecimalFormat
+import java.text.DecimalFormatSymbols
 import java.text.NumberFormat
 import kotlin.math.floor
 import kotlin.math.pow
@@ -214,32 +215,39 @@ public data class Amount(
     fun toString(
         showSymbol: Boolean = true,
         negative: Boolean = false,
+        symbols: DecimalFormatSymbols = DecimalFormat().decimalFormatSymbols,
     ): String {
-        val symbols = DecimalFormat().decimalFormatSymbols
-
-        val format = if (showSymbol) {
-            NumberFormat.getCurrencyInstance()
-        } else {
-            // Make sure monetary separators are the ones used!
-            symbols.decimalSeparator = symbols.monetaryDecimalSeparator
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
-                symbols.groupingSeparator = symbols.monetaryGroupingSeparator
+        // We clone the object to safely/cleanly modify it
+        val s = symbols.clone() as DecimalFormatSymbols
+        val amount = (if (negative) "-$amountStr" else amountStr).toBigDecimal()
+
+        // No currency spec, so we render normally
+        if (spec == null) {
+            val format = NumberFormat.getInstance()
+            format.maximumFractionDigits = MAX_FRACTION_LENGTH
+            format.minimumFractionDigits = 0
+            if (Build.VERSION.SDK_INT >= 34) {
+                s.groupingSeparator = s.monetaryGroupingSeparator
             }
+            s.decimalSeparator = s.monetaryDecimalSeparator
+            (format as DecimalFormat).decimalFormatSymbols = s
 
-            NumberFormat.getInstance()
+            val fmt = format.format(amount)
+            return if (showSymbol) "$fmt $currency" else fmt
         }
 
-        if (spec != null) {
-            symbols.currencySymbol = spec.symbol(this)
-            format.maximumFractionDigits = spec.numFractionalNormalDigits
-            format.minimumFractionDigits = spec.numFractionalTrailingZeroDigits
-        } else {
-            symbols.currencySymbol = currency
+        // There is currency spec, so we can do things right
+        val format = NumberFormat.getCurrencyInstance()
+        format.maximumFractionDigits = spec.numFractionalNormalDigits
+        format.minimumFractionDigits = spec.numFractionalTrailingZeroDigits
+        s.currencySymbol = spec.symbol(this)
+        (format as DecimalFormat).decimalFormatSymbols = s
+
+        val fmt = format.format(amount)
+        return if (showSymbol) fmt else {
+            // We should do better than manually removing the symbol here
+            fmt.replace(s.currencySymbol, "").trim()
         }
-
-        (format as DecimalFormat).decimalFormatSymbols = symbols
-
-        return format.format((if (negative) "-$amountStr" else amountStr).toBigDecimal())
     }
 
     override fun compareTo(other: Amount): Int {
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt b/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt
index 7072426..e7fb273 100644
--- a/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt
+++ b/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt
@@ -16,10 +16,12 @@
 
 package net.taler.common
 
+import android.os.Build
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertTrue
 import org.junit.Test
+import java.text.DecimalFormatSymbols
 import kotlin.random.Random
 
 class AmountTest {
@@ -41,7 +43,6 @@ class AmountTest {
         assertEquals("TESTKUDOS", amount.currency)
         assertEquals(23, amount.value)
         assertEquals((0.42 * 1e8).toInt(), amount.fraction)
-        assertEquals("23.42 TESTKUDOS", amount.toString())
 
         str = "EUR:500000000.00000001"
         amount = Amount.fromJSONString(str)
@@ -49,7 +50,6 @@ class AmountTest {
         assertEquals("EUR", amount.currency)
         assertEquals(500000000, amount.value)
         assertEquals(1, amount.fraction)
-        assertEquals("500000000.00000001 EUR", amount.toString())
 
         str = "EUR:1500000000.00000003"
         amount = Amount.fromJSONString(str)
@@ -57,14 +57,51 @@ class AmountTest {
         assertEquals("EUR", amount.currency)
         assertEquals(1500000000, amount.value)
         assertEquals(3, amount.fraction)
-        assertEquals("1500000000.00000003 EUR", amount.toString())
     }
 
     @Test
     fun testToString() {
+        val symbols = DecimalFormatSymbols.getInstance()
+        symbols.decimalSeparator = '.'
+        symbols.groupingSeparator = ','
+        symbols.monetaryDecimalSeparator = '.'
+        if (Build.VERSION.SDK_INT >= 34) {
+            symbols.monetaryGroupingSeparator = ','
+        }
+
+        val spec = CurrencySpecification(
+            name = "Bitcoin",
+            numFractionalInputDigits = 8,
+            numFractionalNormalDigits = 8,
+            numFractionalTrailingZeroDigits = 0,
+            altUnitNames = mapOf(
+                0 to "₿",
+                // TODO: uncomment when units get implemented
+                //  and then write tests for units, please
+//                -1 to "d₿",
+//                -2 to "c₿",
+//                -3 to "m₿",
+//                -6 to "µ₿",
+//                -8 to "sat",
+            ),
+        )
+
         Amount.fromString("BITCOINBTC", "0.00000001").let { amount ->
-            assertEquals("0.00000001 BITCOINBTC", amount.toString())
+            // Only the raw amount
             assertEquals("0.00000001", amount.amountStr)
+
+            // The amount without currency spec
+            assertEquals("0.00000001 BITCOINBTC", amount.toString(symbols = symbols))
+            assertEquals("0.00000001", amount.toString(symbols = symbols, showSymbol = false))
+            assertEquals("-0.00000001 BITCOINBTC", amount.toString(symbols = symbols, negative = true))
+            assertEquals("-0.00000001", amount.toString(symbols = symbols, showSymbol = false, negative = true))
+
+            // The amount with currency spec
+            val withSpec = amount.withSpec(spec)
+            assertEquals("₿0.00000001", withSpec.toString(symbols = symbols))
+            assertEquals("0.00000001", withSpec.toString(symbols = symbols, showSymbol = false))
+            assertEquals("-₿0.00000001", withSpec.toString(symbols = symbols, negative = true))
+            assertEquals("-0.00000001", withSpec.toString(symbols = symbols, showSymbol = false, negative = true))
         }
     }
 
@@ -76,7 +113,6 @@ class AmountTest {
         assertEquals(str, amount.toJSONString())
         assertEquals("TESTKUDOS123", amount.currency)
         assertEquals(maxValue, amount.value)
-        assertEquals("$maxValue.99999999 TESTKUDOS123", amount.toString())
 
         // longer currency not accepted
         assertThrows<AmountParserException>("longer currency was accepted") {