Switch to more accurate fee estimation endpoint

The API endpoint for fee estimations has been changed to one that delivers more accurate fee estimations.

This is a temporary solution, until a more decentralized approach is found.

Fixes projects/issues/27

pricenode/src/main/java/bisq/price/mining/providers/BitcoinFeeRateProvider.java

@@ -42,8 +42,8 @@
 @Component
 class BitcoinFeeRateProvider extends FeeRateProvider {
 
-    private static final long MIN_FEE_RATE = 10; // satoshi/byte
-    private static final long MAX_FEE_RATE = 1000;
+    protected static final long MIN_FEE_RATE = 10; // satoshi/byte
+    protected static final long MAX_FEE_RATE = 1000;
 
     private static final int DEFAULT_MAX_BLOCKS = 2;
     private static final int DEFAULT_REFRESH_INTERVAL = 2;
@@ -63,9 +63,9 @@ protected FeeRate doGet() {
 
     private long getEstimatedFeeRate() {
         return getFeeRatePredictions()
-            .filter(p -> p.get("maxDelay") <= maxBlocks)
+            .filter(p -> p.getKey().equalsIgnoreCase("halfHourFee"))
+            .map(Map.Entry::getValue)
             .findFirst()
-            .map(p -> p.get("maxFee"))
             .map(r -> {
                 log.info("latest fee rate prediction is {} sat/byte", r);
                 return r;
@@ -75,19 +75,18 @@ private long getEstimatedFeeRate() {
             .orElse(MIN_FEE_RATE);
     }
 
-    private Stream<Map<String, Long>> getFeeRatePredictions() {
+    private Stream<Map.Entry<String, Long>> getFeeRatePredictions() {
         return restTemplate.exchange(
             RequestEntity
                 .get(UriComponentsBuilder
-                    // now using /fees/list because /fees/recommended estimates were too high
-                    .fromUriString("https://bitcoinfees.earn.com/api/v1/fees/list")
+                    // Temporarily call mempool.space centralized API endpoint
+                    // A more de-centralized solution discussed in https://github.com/bisq-network/projects/issues/27
+                    .fromUriString("https://mempool.space/api/v1/fees/recommended")
                     .build().toUri())
                 .header("User-Agent", "") // required to avoid 403
                 .build(),
-            new ParameterizedTypeReference<Map<String, List<Map<String, Long>>>>() {
-            }
-        ).getBody().entrySet().stream()
-            .flatMap(e -> e.getValue().stream());
+            new ParameterizedTypeReference<Map<String, Long>>() { }
+        ).getBody().entrySet().stream();
     }
 
     private static Optional<String[]> args(Environment env) {

pricenode/src/test/java/bisq/price/mining/providers/BitcoinFeeRateProviderTest.java

@@ -0,0 +1,45 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.price.mining.providers;
+
+import bisq.price.mining.FeeRate;
+
+import org.springframework.context.support.GenericXmlApplicationContext;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+
+public class BitcoinFeeRateProviderTest {
+
+    @Test
+    public void doGet_successfulCall() {
+
+        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
+        BitcoinFeeRateProvider feeRateProvider = new BitcoinFeeRateProvider(ctx.getEnvironment());
+
+        // Make a call to the API, retrieve the recommended fee rate
+        // If the API call fails, or the response body cannot be parsed, the test will fail with an exception
+        FeeRate retrievedFeeRate = feeRateProvider.doGet();
+
+        // Check that the FeeRateProvider returns a fee within the defined parameters
+        assertTrue(retrievedFeeRate.getPrice() >= BitcoinFeeRateProvider.MIN_FEE_RATE);
+        assertTrue(retrievedFeeRate.getPrice() <= BitcoinFeeRateProvider.MAX_FEE_RATE);
+    }
+
+}