From 0bdfa7b6355505d8a5c4ccac41624df59251277c Mon Sep 17 00:00:00 2001
From: Mike Hearn <hearn@google.com>
Date: Wed, 9 Jan 2013 23:41:32 +0100
Subject: [PATCH] Better formatting in Utils.bitcoinValueToFriendlyString

---
 .../java/com/google/bitcoin/core/Utils.java    | 18 ++++++++++++++----
 .../com/google/bitcoin/core/UtilsTest.java     |  1 +
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/com/google/bitcoin/core/Utils.java b/core/src/main/java/com/google/bitcoin/core/Utils.java
index 6e295d62..36ce8444 100644
--- a/core/src/main/java/com/google/bitcoin/core/Utils.java
+++ b/core/src/main/java/com/google/bitcoin/core/Utils.java
@@ -294,15 +294,25 @@ public class Utils {
     }
 
     /**
-     * Returns the given value in nanocoins as a 0.12 type string.
+     * Returns the given value in nanocoins as a 0.12 type string. More digits after the decimal place will be used
+     * if necessary, but two will always be present.
      */
     public static String bitcoinValueToFriendlyString(BigInteger value) {
+        // TODO: This API is crap. This method should go away when we encapsulate money values.
         boolean negative = value.compareTo(BigInteger.ZERO) < 0;
         if (negative)
             value = value.negate();
-        BigInteger coins = value.divide(COIN);
-        BigInteger cents = value.remainder(COIN);
-        return String.format("%s%d.%02d", negative ? "-" : "", coins.intValue(), cents.intValue() / 1000000);
+        BigDecimal bd = new BigDecimal(value, 8);
+        String formatted = bd.toPlainString();   // Don't use scientific notation.
+        // Drop unnecessary zeros from the end.
+        int toDelete = 0;
+        for (int i = formatted.length() - 1; i > 1; i--) {
+            if (formatted.charAt(i) == '0')
+                toDelete++;
+            else
+                break;
+        }
+        return (negative ? "-" : "") + formatted.substring(0, formatted.length() - toDelete);
     }
     
     /**
diff --git a/core/src/test/java/com/google/bitcoin/core/UtilsTest.java b/core/src/test/java/com/google/bitcoin/core/UtilsTest.java
index c014ddcc..2517493c 100644
--- a/core/src/test/java/com/google/bitcoin/core/UtilsTest.java
+++ b/core/src/test/java/com/google/bitcoin/core/UtilsTest.java
@@ -51,6 +51,7 @@ public class UtilsTest {
     @Test
     public void testFormatting() {
         assertEquals("1.23", bitcoinValueToFriendlyString(toNanoCoins(1, 23)));
+        assertEquals("0.001", bitcoinValueToFriendlyString(BigInteger.valueOf(COIN.longValue() / 1000)));
         assertEquals("-1.23", bitcoinValueToFriendlyString(toNanoCoins(1, 23).negate()));
     }