Refactor takeoffer reply proto & ErrorMessageHandler

- Add description msg TakeOfferReply proto, and fromProto method
  to core.offer.enum AvailabilityResult.  The description field
  maps a client usable error message to the enum.

- Adjust GrpcErrorMessageHandler to add AvailabilityResult.description()
  to takeoffer reply.

- Refactor (split up) GrpcClient's takeOffer.  Add getTakeOfferReply()
  to give clients a chance to make choices based on the reply's
  AvailabilityResult when the takeoffer command did not result in a
  trade. (Some errors are fatal, some not.)

cli/src/main/java/bisq/cli/GrpcClient.java

@@ -53,6 +53,7 @@ import bisq.proto.grpc.SendBtcRequest;
 import bisq.proto.grpc.SetTxFeeRatePreferenceRequest;
 import bisq.proto.grpc.SetWalletPasswordRequest;
 import bisq.proto.grpc.StopRequest;
+import bisq.proto.grpc.TakeOfferReply;
 import bisq.proto.grpc.TakeOfferRequest;
 import bisq.proto.grpc.TradeInfo;
 import bisq.proto.grpc.TxFeeRateInfo;
@@ -309,41 +310,21 @@ public final class GrpcClient {
                 .collect(Collectors.toList());
     }
 
-    public TradeInfo takeOffer(String offerId, String paymentAccountId, String takerFeeCurrencyCode) {
+    public TakeOfferReply getTakeOfferReply(String offerId, String paymentAccountId, String takerFeeCurrencyCode) {
         var request = TakeOfferRequest.newBuilder()
                 .setOfferId(offerId)
                 .setPaymentAccountId(paymentAccountId)
                 .setTakerFeeCurrencyCode(takerFeeCurrencyCode)
                 .build();
-        var reply = grpcStubs.tradesService.takeOffer(request);
-        if (reply.hasTrade()) {
+        return grpcStubs.tradesService.takeOffer(request);
+    }
+
+    public TradeInfo takeOffer(String offerId, String paymentAccountId, String takerFeeCurrencyCode) {
+        var reply = getTakeOfferReply(offerId, paymentAccountId, takerFeeCurrencyCode);
+        if (reply.hasTrade())
             return reply.getTrade();
-        } else {
-            // If there is no trade, there should be a reason in the AvailabilityResult.
-            // Convert the enum to a user error message before throwing the exception.
-            switch (reply.getAvailabilityResult()) {
-                case MARKET_PRICE_NOT_AVAILABLE:
-                    throw new IllegalStateException("could not take offer because market price for calculating trade price is unavailable");
-                case PRICE_OUT_OF_TOLERANCE:
-                    throw new IllegalStateException("could not take offer because taker's price is outside tolerance");
-                case PRICE_CHECK_FAILED:
-                    throw new IllegalStateException("could not take offer because trade price check failed");
-                case NO_ARBITRATORS:
-                    throw new IllegalStateException("could not take offer because no arbitrators are available");
-                case NO_MEDIATORS:
-                    throw new IllegalStateException("could not take offer because no mediators are available");
-                case NO_REFUND_AGENTS:
-                    throw new IllegalStateException("could not take offer because no refund agents are available");
-                case USER_IGNORED:
-                    throw new IllegalStateException("could not take offer from ignored user");
-                case MAKER_DENIED_API_USER:
-                    throw new IllegalStateException("could not take offer because maker is api user");
-                case UNCONF_TX_LIMIT_HIT:
-                    throw new IllegalStateException("could not take offer because you have too many unconfirmed transactions at this moment");
-                default:
-                    throw new IllegalStateException("programmer error: could not take offer for unknown reason");
-            }
-        }
+        else
+            throw new IllegalStateException(reply.getAvailabilityResultDescription());
     }
 
     public TradeInfo getTrade(String tradeId) {

core/src/main/java/bisq/core/offer/AvailabilityResult.java

@@ -18,17 +18,31 @@
 package bisq.core.offer;
 
 public enum AvailabilityResult {
-    UNKNOWN_FAILURE,
-    AVAILABLE,
-    OFFER_TAKEN,
-    PRICE_OUT_OF_TOLERANCE,
-    MARKET_PRICE_NOT_AVAILABLE,
-    @SuppressWarnings("unused") NO_ARBITRATORS,
-    NO_MEDIATORS,
-    USER_IGNORED,
-    @SuppressWarnings("unused") MISSING_MANDATORY_CAPABILITY,
-    @SuppressWarnings("unused") NO_REFUND_AGENTS,
-    UNCONF_TX_LIMIT_HIT,
-    MAKER_DENIED_API_USER,
-    PRICE_CHECK_FAILED
+    UNKNOWN_FAILURE("cannot take offer for unknown reason"),
+    AVAILABLE("offer available"),
+    OFFER_TAKEN("offer taken"),
+    PRICE_OUT_OF_TOLERANCE("cannot take offer because taker's price is outside tolerance"),
+    MARKET_PRICE_NOT_AVAILABLE("cannot take offer because market price for calculating trade price is unavailable"),
+    @SuppressWarnings("unused") NO_ARBITRATORS("cannot take offer because no arbitrators are available"),
+    NO_MEDIATORS("cannot take offer because no mediators are available"),
+    USER_IGNORED("cannot take offer because user is ignored"),
+    @SuppressWarnings("unused") MISSING_MANDATORY_CAPABILITY("description not available"),
+    @SuppressWarnings("unused") NO_REFUND_AGENTS("cannot take offer because no refund agents are available"),
+    UNCONF_TX_LIMIT_HIT("cannot take offer because you have too many unconfirmed transactions at this moment"),
+    MAKER_DENIED_API_USER("cannot take offer because maker is api user"),
+    PRICE_CHECK_FAILED("cannot take offer because trade price check failed");
+
+    private final String description;
+
+    AvailabilityResult(String description) {
+        this.description = description;
+    }
+
+    public String description() {
+        return description;
+    }
+
+    public static AvailabilityResult fromProto(protobuf.AvailabilityResult proto) {
+        return AvailabilityResult.valueOf(proto.name());
+    }
 }

daemon/src/main/java/bisq/daemon/grpc/GrpcErrorMessageHandler.java

@@ -92,9 +92,10 @@ public class GrpcErrorMessageHandler implements ErrorMessageHandler {
         // The client should look at the grpc reply object's AvailabilityResult
         // field if reply.hasTrade = false, and use it give the user a human readable msg.
         try {
-            AvailabilityResult availabilityResult = getAvailabilityResult(errorMessage);
+            AvailabilityResult availabilityResultProto = getAvailabilityResult(errorMessage);
             var reply = TakeOfferReply.newBuilder()
-                    .setAvailabilityResult(availabilityResult)
+                    .setAvailabilityResult(availabilityResultProto)
+                    .setAvailabilityResultDescription(getAvailabilityResultDescription(availabilityResultProto))
                     .build();
             @SuppressWarnings("unchecked")
             var takeOfferResponseObserver = (StreamObserver<TakeOfferReply>) responseObserver;
@@ -116,6 +117,10 @@ public class GrpcErrorMessageHandler implements ErrorMessageHandler {
                                 format("Could not find an AvailabilityResult in error message:%n%s", errorMessage)));
     }
 
+    private String getAvailabilityResultDescription(AvailabilityResult proto) {
+        return bisq.core.offer.AvailabilityResult.fromProto(proto).description();
+    }
+
     private boolean isTakeOfferError() {
         return fullMethodName.equals(getTakeOfferMethod().getFullMethodName());
     }

proto/src/main/proto/grpc.proto

@@ -278,6 +278,7 @@ message TakeOfferRequest {
 message TakeOfferReply {
     TradeInfo trade = 1;
     AvailabilityResult availabilityResult = 2;
+    string availabilityResultDescription = 3;
 }
 
 message ConfirmPaymentStartedRequest {