Don't allow more than one (active) trade-bot entry per trade-offer

src/main/java/org/qortal/controller/tradebot/AcctTradeBot.java

@@ -1,5 +1,7 @@
 package org.qortal.controller.tradebot;
 
+import java.util.List;
+
 import org.qortal.api.model.crosschain.TradeBotCreateRequest;
 import org.qortal.crosschain.ACCT;
 import org.qortal.crosschain.ForeignBlockchainException;
@@ -11,7 +13,10 @@ import org.qortal.repository.Repository;
 
 public interface AcctTradeBot {
 
-	public enum ResponseResult { OK, BALANCE_ISSUE, NETWORK_ISSUE }
+	public enum ResponseResult { OK, BALANCE_ISSUE, NETWORK_ISSUE, TRADE_ALREADY_EXISTS }
+
+	/** Returns list of state names for trade-bot entries that have ended, e.g. redeemed, refunded or cancelled. */
+	public List<String> getEndStates();
 
 	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException;
 

src/main/java/org/qortal/controller/tradebot/BitcoinACCTv1TradeBot.java

@@ -6,6 +6,7 @@ import static java.util.stream.Collectors.toMap;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -110,6 +111,10 @@ public class BitcoinACCTv1TradeBot implements AcctTradeBot {
 
 	private static BitcoinACCTv1TradeBot instance;
 
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDING_B, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
 	private BitcoinACCTv1TradeBot() {
 	}
 
@@ -120,6 +125,11 @@ public class BitcoinACCTv1TradeBot implements AcctTradeBot {
 		return instance;
 	}
 
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
 	/**
 	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for BTC.
 	 * <p>

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv1TradeBot.java

@@ -3,8 +3,10 @@ package org.qortal.controller.tradebot;
 import static java.util.Arrays.stream;
 import static java.util.stream.Collectors.toMap;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -102,6 +104,10 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 
 	private static LitecoinACCTv1TradeBot instance;
 
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
 	private LitecoinACCTv1TradeBot() {
 	}
 
@@ -112,6 +118,11 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 		return instance;
 	}
 
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
 	/**
 	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for LTC.
 	 * <p>

src/main/java/org/qortal/controller/tradebot/TradeBot.java

@@ -176,6 +176,10 @@ public class TradeBot implements Listener {
 			return ResponseResult.NETWORK_ISSUE;
 		}
 
+		// Check Alice doesn't already have an existing, on-going trade-bot entry for this AT.
+		if (repository.getCrossChainRepository().existsTradeWithAtExcludingStates(atData.getATAddress(), acctTradeBot.getEndStates()))
+			return ResponseResult.TRADE_ALREADY_EXISTS;
+
 		return acctTradeBot.startResponse(repository, atData, acct, crossChainTradeData, foreignKey, receivingAddress);
 	}
 

src/main/java/org/qortal/repository/CrossChainRepository.java

@@ -8,6 +8,9 @@ public interface CrossChainRepository {
 
 	public TradeBotData getTradeBotData(byte[] tradePrivateKey) throws DataException;
 
+	/** Returns true if there is an existing trade-bot entry relating to given AT address, excluding trade-bot entries with given states. */
+	public boolean existsTradeWithAtExcludingStates(String atAddress, List<String> excludeStates) throws DataException;
+
 	public List<TradeBotData> getAllTradeBotData() throws DataException;
 
 	public void save(TradeBotData tradeBotData) throws DataException;

src/main/java/org/qortal/repository/hsqldb/HSQLDBCrossChainRepository.java

@@ -3,6 +3,7 @@ package org.qortal.repository.hsqldb;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 import org.qortal.data.crosschain.TradeBotData;
@@ -68,6 +69,36 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 		}
 	}
 
+	@Override
+	public boolean existsTradeWithAtExcludingStates(String atAddress, List<String> excludeStates) throws DataException {
+		if (excludeStates == null)
+			excludeStates = Collections.emptyList();
+
+		StringBuilder whereClause = new StringBuilder(256);
+		whereClause.append("at_address = ?");
+
+		Object[] bindParams = new Object[1 + excludeStates.size()];
+		bindParams[0] = atAddress;
+
+		if (!excludeStates.isEmpty()) {
+			whereClause.append(" AND trade_state NOT IN (?");
+			bindParams[1] = excludeStates.get(0);
+
+			for (int i = 1; i < excludeStates.size(); ++i) {
+				whereClause.append(", ?");
+				bindParams[1 + i] = excludeStates.get(i);
+			}
+
+			whereClause.append(")");
+		}
+
+		try {
+			return this.repository.exists("TradeBotStates", whereClause.toString(), bindParams);
+		} catch (SQLException e) {
+			throw new DataException("Unable to check for trade-bot state in repository", e);
+		}
+	}
+
 	@Override
 	public List<TradeBotData> getAllTradeBotData() throws DataException {
 		String sql = "SELECT trade_private_key, acct_name, trade_state, trade_state_value, "