Added PirateChainHTLC.getUnspentFundingTxid(), allowing a minimum amount to be specified.

This will ensure that the correct fundingTxid can be redeemed or refunded by the trade bot.

src/main/java/org/qortal/crosschain/PirateChainHTLC.java

@@ -236,6 +236,37 @@ public class PirateChainHTLC {
 		return null;
 	}
 
+	/**
+	 * Returns a string containing the unspent txid of the transaction that funded supplied <tt>p2shAddress</tt>
+	 * and is at least the value specified in <tt>minimumAmount</tt>
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public static String getUnspentFundingTxid(BitcoinyBlockchainProvider blockchain, String p2shAddress, long minimumAmount) throws ForeignBlockchainException {
+		byte[] ourScriptPubKey = addressToScriptPubKey(p2shAddress);
+
+		// Note: we can't include unconfirmed transactions here because the Pirate light wallet server requires a block range
+		List<UnspentOutput> unspentOutputs = blockchain.getUnspentOutputs(p2shAddress, false);
+		for (UnspentOutput unspentOutput : unspentOutputs) {
+
+			if (!Arrays.equals(ourScriptPubKey, unspentOutput.script)) {
+				// Not funding our specific HTLC script hash
+				continue;
+			}
+
+			if (unspentOutput.value < minimumAmount) {
+				// Not funding the required amount
+				continue;
+			}
+
+			return HashCode.fromBytes(unspentOutput.hash).toString();
+		}
+
+
+		// No valid unspent outputs, so must be already spent
+		return null;
+	}
+
 	/**
 	 * Returns HTLC status, given P2SH address and expected redeem/refund amount
 	 * <p>

src/test/java/org/qortal/test/crosschain/PirateChainTests.java

@@ -124,6 +124,21 @@ public class PirateChainTests extends Common {
 		assertEquals(expectedTxidBE, txid);
 	}
 
+	@Test
+	public void testGetTxidForUnspentAddressWithMinimumAmount() throws ForeignBlockchainException {
+		String p2shAddress = "ba6Q5HWrWtmfU2WZqQbrFdRYsafA45cUAt";
+		long p2shFee = 10000;
+		final long minimumAmount = 10000 + p2shFee;
+		String txid = PirateChainHTLC.getUnspentFundingTxid(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
+
+		// Reverse the byte order of the txid used by block explorers, to get to big-endian form
+		byte[] expectedTxidLE = HashCode.fromString("fea4b0c1abcf8f0f3ddc2fa2f9438501ee102aad62a9ff18a5ce7d08774755c0").asBytes();
+		Bytes.reverse(expectedTxidLE);
+		String expectedTxidBE = HashCode.fromBytes(expectedTxidLE).toString();
+
+		assertEquals(expectedTxidBE, txid);
+	}
+
 	@Test
 	public void testGetTxidForSpentAddress() throws ForeignBlockchainException {
 		String p2shAddress = "bE49izfVxz8odhu8c2BcUaVFUnt7NLFRgv"; //"t3KtVxeEb8srJofo6atMEpMpEP6TjEi8VqA";