Add Regtest mode for Litecoin (#20)

core/src/main/java/org/libdohj/params/AbstractLitecoinParams.java

@@ -16,26 +16,16 @@
 
 package org.libdohj.params;
 
-import java.math.BigInteger;
-import org.bitcoinj.core.AltcoinBlock;
-
-import org.bitcoinj.core.Block;
-import org.bitcoinj.core.Coin;
-import static org.bitcoinj.core.Coin.COIN;
-import org.bitcoinj.core.NetworkParameters;
-import org.bitcoinj.core.Sha256Hash;
-import org.bitcoinj.core.VerificationException;
+import org.bitcoinj.core.*;
 import org.bitcoinj.store.BlockStore;
 import org.bitcoinj.store.BlockStoreException;
-import org.bitcoinj.core.StoredBlock;
-import org.bitcoinj.core.Utils;
 import org.bitcoinj.utils.MonetaryFormat;
 import org.libdohj.core.AltcoinNetworkParameters;
 import org.libdohj.core.AltcoinSerializer;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
+import java.math.BigInteger;
+import static org.bitcoinj.core.Coin.COIN;
 
 /**
  * Common parameters for Litecoin networks.
@@ -51,7 +41,7 @@ public abstract class AbstractLitecoinParams extends NetworkParameters implement
     public static final int LITE_TARGET_TIMESPAN = (int) (3.5 * 24 * 60 * 60); // 3.5 days
     public static final int LITE_TARGET_SPACING = (int) (2.5 * 60); // 2.5 minutes
     public static final int LITE_INTERVAL = LITE_TARGET_TIMESPAN / LITE_TARGET_SPACING;
-    
+
     /**
      * The maximum number of coins to be generated
      */
@@ -82,6 +72,8 @@ public abstract class AbstractLitecoinParams extends NetworkParameters implement
     public static final String ID_LITE_MAINNET = "org.litecoin.production";
     /** The string returned by getId() for the testnet. */
     public static final String ID_LITE_TESTNET = "org.litecoin.test";
+    /** The string returned by getId() for regtest. */
+    public static final String ID_LITE_REGTEST = "regtest";
 
     public static final int LITECOIN_PROTOCOL_VERSION_MINIMUM = 70002;
     public static final int LITECOIN_PROTOCOL_VERSION_CURRENT = 70003;
@@ -249,7 +241,7 @@ public abstract class AbstractLitecoinParams extends NetworkParameters implement
     }
 
     /**
-     * 
+     *
      * @param previousHeight Height of the block immediately previous to the one we're calculating difficulty of.
      * @param previousBlockTime Time of the block immediately previous to the one we're calculating difficulty of.
      * @param lastDifficultyTarget Compact difficulty target of the last retarget block.

core/src/main/java/org/libdohj/params/LitecoinRegTestParams.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.libdohj.params;
+
+import org.bitcoinj.core.Block;
+import org.bitcoinj.core.StoredBlock;
+import org.bitcoinj.core.VerificationException;
+import org.bitcoinj.store.BlockStore;
+import org.bitcoinj.store.BlockStoreException;
+
+import java.math.BigInteger;
+
+import static com.google.common.base.Preconditions.checkState;
+
+/**
+ * Network parameters for the regression test mode of bitcoind in which all blocks are trivially solvable.
+ */
+public class LitecoinRegTestParams extends LitecoinTestNet3Params {
+    private static final BigInteger MAX_TARGET = new BigInteger("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16);
+
+    public LitecoinRegTestParams() {
+        super();
+        // Difficulty adjustments are disabled for regtest.
+        // By setting the block interval for difficulty adjustments to Integer.MAX_VALUE we make sure difficulty never changes.
+        interval = Integer.MAX_VALUE;
+        maxTarget = MAX_TARGET;
+        subsidyDecreaseBlockCount = 150;
+        port = 19444;
+        id = ID_LITE_REGTEST;
+        packetMagic = 0xfabfb5da;
+    }
+
+    @Override
+    public boolean allowEmptyPeerChain() {
+        return true;
+    }
+
+    private static Block genesis;
+
+
+    /**
+     * Extract from Litecoin source code, definition of regtest params.
+     * https://github.com/litecoin-project/litecoin/blob/edc66b374ea68107c721062152dd95e6aa037d53/src/chainparams.cpp
+     */
+    @Override
+    public Block getGenesisBlock() {
+        synchronized (LitecoinRegTestParams.class) {
+            if (genesis == null) {
+                genesis = super.getGenesisBlock();
+                genesis.setNonce(0);
+                genesis.setDifficultyTarget(0x207fffffL);
+                genesis.setTime(1296688602L);
+                checkState(genesis.getVersion() == 1);
+                checkState(genesis.getMerkleRoot().toString().equals("97ddfbbae6be97fd6cdf3e7ca13232a3afff2353e29badfab7f73011edd4ced9"));
+                checkState(genesis.getHashAsString().toLowerCase().equals("530827f38f93b43ed12af0b3ad25a288dc02ed74d6d7857862df51fc56c416f9"));
+                genesis.verifyHeader();
+            }
+            return genesis;
+        }
+    }
+
+    private static LitecoinRegTestParams instance;
+
+    public static synchronized LitecoinRegTestParams get() {
+        if (instance == null) {
+            instance = new LitecoinRegTestParams();
+        }
+        return instance;
+    }
+
+    @Override
+    public String getPaymentProtocolId() {
+        return ID_LITE_REGTEST;
+    }
+
+    @Override
+    /** the testnet rules don't work for regtest, where difficulty stays the same */
+    public long calculateNewDifficultyTarget(StoredBlock storedPrev, Block nextBlock, BlockStore blockStore)
+            throws VerificationException, BlockStoreException {
+        final Block prev = storedPrev.getHeader();
+        return prev.getDifficultyTarget();
+    }
+}

core/src/test/java/org/libdohj/params/LitecoinRegTestParamsTest.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2015 J. Ross Nicoll
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.libdohj.params;
+
+import org.bitcoinj.core.Block;
+import org.bitcoinj.core.Context;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ *
+ * @author Mike Rosseel
+ */
+public class LitecoinRegTestParamsTest {
+    private static final LitecoinRegTestParams params = LitecoinRegTestParams.get();
+
+    @Before
+    public void setUp() throws Exception {
+        Context context = new Context(params);
+    }
+
+    @Test
+    public void testRegTestGenesisBlock() {
+        Block genesis = params.getGenesisBlock();
+        assertEquals("530827f38f93b43ed12af0b3ad25a288dc02ed74d6d7857862df51fc56c416f9", genesis.getHashAsString());
+    }
+}