Support for applications recording exchange rate that was valid when transaction was sent. Use the new SendRequest.exchangeRate register.

Includes a test.

core/src/main/java/com/google/bitcoin/core/Transaction.java

@@ -22,6 +22,7 @@ import com.google.bitcoin.crypto.TransactionSignature;
 import com.google.bitcoin.script.Script;
 import com.google.bitcoin.script.ScriptBuilder;
 import com.google.bitcoin.script.ScriptOpCodes;
+import com.google.bitcoin.utils.ExchangeRate;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.primitives.Ints;
 import com.google.common.primitives.Longs;
@@ -152,6 +153,13 @@ public class Transaction extends ChildMessage implements Serializable {
 
     private Purpose purpose = Purpose.UNKNOWN;
 
+    /**
+     * This field can be used by applications to record the exchange rate that was valid when the transaction happened.
+     * It's optional.
+     */
+    @Nullable
+    private ExchangeRate exchangeRate;
+
     public Transaction(NetworkParameters params) {
         super(params);
         version = 1;
@@ -1259,4 +1267,19 @@ public class Transaction extends ChildMessage implements Serializable {
     public void setPurpose(Purpose purpose) {
         this.purpose = purpose;
     }
+
+    /**
+     * Getter for {@link #exchangeRate}.
+     */
+    @Nullable
+    public ExchangeRate getExchangeRate() {
+        return exchangeRate;
+    }
+
+    /**
+     * Setter for {@link #exchangeRate}.
+     */
+    public void setExchangeRate(ExchangeRate exchangeRate) {
+        this.exchangeRate = exchangeRate;
+    }
 }

core/src/main/java/com/google/bitcoin/core/Wallet.java

@@ -29,6 +29,7 @@ import com.google.bitcoin.signers.TransactionSigner;
 import com.google.bitcoin.store.UnreadableWalletException;
 import com.google.bitcoin.store.WalletProtobufSerializer;
 import com.google.bitcoin.utils.BaseTaggableObject;
+import com.google.bitcoin.utils.ExchangeRate;
 import com.google.bitcoin.utils.ListenerRegistration;
 import com.google.bitcoin.utils.Threading;
 import com.google.bitcoin.wallet.*;
@@ -3010,6 +3011,11 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
          */
         public boolean useDummySignatures = true;
 
+        /**
+         * If not null, this exchange rate is recorded with the transaction during completion.
+         */
+        public ExchangeRate exchangeRate = null;
+
         // Tracks if this has been passed to wallet.completeTx already: just a safety check.
         private boolean completed;
 
@@ -3375,6 +3381,8 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
             // transaction lists more appropriately, especially when the wallet starts to generate transactions itself
             // for internal purposes.
             req.tx.setPurpose(Transaction.Purpose.USER_PAYMENT);
+            // Record the exchange rate that was valid when the transaction was completed.
+            req.tx.setExchangeRate(req.exchangeRate);
             req.completed = true;
             req.fee = calculatedFee;
             log.info("  completed: {}", req.tx);

core/src/main/java/com/google/bitcoin/store/WalletProtobufSerializer.java

@@ -24,6 +24,8 @@ import com.google.bitcoin.crypto.KeyCrypterScrypt;
 import com.google.bitcoin.script.Script;
 import com.google.bitcoin.signers.LocalTransactionSigner;
 import com.google.bitcoin.signers.TransactionSigner;
+import com.google.bitcoin.utils.ExchangeRate;
+import com.google.bitcoin.utils.Fiat;
 import com.google.bitcoin.wallet.KeyChainGroup;
 import com.google.bitcoin.wallet.WalletTransaction;
 import com.google.common.collect.Lists;
@@ -290,6 +292,14 @@ public class WalletProtobufSerializer {
                 throw new RuntimeException("New tx purpose serialization not implemented.");
         }
         txBuilder.setPurpose(purpose);
+
+        ExchangeRate exchangeRate = tx.getExchangeRate();
+        if (exchangeRate != null) {
+            Protos.ExchangeRate.Builder exchangeRateBuilder = Protos.ExchangeRate.newBuilder()
+                    .setCoinValue(exchangeRate.coin.value).setFiatValue(exchangeRate.fiat.value)
+                    .setFiatCurrencyCode(exchangeRate.fiat.currencyCode);
+            txBuilder.setExchangeRate(exchangeRateBuilder);
+        }
         
         return txBuilder.build();
     }
@@ -576,6 +586,12 @@ public class WalletProtobufSerializer {
             tx.setPurpose(Transaction.Purpose.USER_PAYMENT);
         }
 
+        if (txProto.hasExchangeRate()) {
+            Protos.ExchangeRate exchangeRateProto = txProto.getExchangeRate();
+            tx.setExchangeRate(new ExchangeRate(Coin.valueOf(exchangeRateProto.getCoinValue()), Fiat.valueOf(
+                    exchangeRateProto.getFiatCurrencyCode(), exchangeRateProto.getFiatValue())));
+        }
+
         // Transaction should now be complete.
         Sha256Hash protoHash = byteStringToHash(txProto.getHash());
         if (!tx.getHash().equals(protoHash))

core/src/test/java/com/google/bitcoin/core/WalletTest.java

@@ -28,6 +28,8 @@ import com.google.bitcoin.testing.FakeTxBuilder;
 import com.google.bitcoin.testing.MockTransactionBroadcaster;
 import com.google.bitcoin.testing.NopTransactionSigner;
 import com.google.bitcoin.testing.TestWithWallet;
+import com.google.bitcoin.utils.ExchangeRate;
+import com.google.bitcoin.utils.Fiat;
 import com.google.bitcoin.utils.Threading;
 import com.google.bitcoin.wallet.*;
 import com.google.bitcoin.wallet.WalletTransaction.Pool;
@@ -2555,4 +2557,12 @@ public class WalletTest extends TestWithWallet {
         assertTrue(wallet.getTransactionSigners().get(1).isReady());
     }
 
+    @Test
+    public void sendRequestExchangeRate() throws Exception {
+        receiveATransaction(wallet, myAddress);
+        SendRequest sendRequest = SendRequest.to(myAddress, Coin.COIN);
+        sendRequest.exchangeRate = new ExchangeRate(Fiat.parseFiat("EUR", "500"));
+        wallet.completeTx(sendRequest);
+        assertEquals(sendRequest.exchangeRate, sendRequest.tx.getExchangeRate());
+    }
 }

core/src/wallet.proto

@@ -263,7 +263,10 @@ message Transaction {
   }
   optional Purpose purpose = 10 [default = UNKNOWN];
 
-  // Next tag: 12
+  // Exchange rate that was valid when the transaction was sent.
+  optional ExchangeRate exchange_rate = 12;
+
+  // Next tag: 13
 }
 
 /** The parameters used in the scrypt key derivation function.
@@ -366,3 +369,15 @@ message Wallet {
 
   // Next tag: 18
 }
+
+/** An exchange rate between Bitcoin and some fiat currency. */
+message ExchangeRate {
+  // This much of satoshis (1E-8 fractions)…
+  required int64 coin_value = 1;
+  // …is worth this much of fiat (1E-4 fractions).
+  required int64 fiat_value = 2;
+  // ISO 4217 currency code (if available) of the fiat currency.
+  required string fiat_currency_code = 3;
+
+  // Next tag: 4
+}