Proof of Stake banner (#3757)

* i did it for the gram

Signed-off-by: Justin Florentine <justin+github@florentine.us>

besu/src/main/java/org/hyperledger/besu/controller/BesuControllerBuilder.java

@@ -20,6 +20,7 @@
 import org.hyperledger.besu.config.GenesisConfigOptions;
 import org.hyperledger.besu.consensus.merge.FinalizedBlockHashSupplier;
 import org.hyperledger.besu.consensus.merge.MergeContext;
+import org.hyperledger.besu.consensus.merge.PandaPrinter;
 import org.hyperledger.besu.consensus.qbft.pki.PkiBlockCreationConfiguration;
 import org.hyperledger.besu.crypto.NodeKey;
 import org.hyperledger.besu.datatypes.Hash;
@@ -340,6 +341,7 @@ public BesuController build() {
     final boolean fastSyncEnabled =
         EnumSet.of(SyncMode.FAST, SyncMode.X_SNAP).contains(syncConfig.getSyncMode());
     final SyncState syncState = new SyncState(blockchain, ethPeers, fastSyncEnabled);
+    syncState.subscribeTTDReached(new PandaPrinter());
 
     final TransactionPool transactionPool =
         TransactionPoolFactory.createTransactionPool(

consensus/merge/src/main/java/org/hyperledger/besu/consensus/merge/PandaPrinter.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright Hyperledger Besu Contributors.
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ */
+
+package org.hyperledger.besu.consensus.merge;
+
+import org.hyperledger.besu.plugin.services.BesuEvents.TTDReachedListener;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class PandaPrinter implements TTDReachedListener {
+
+  private static final Logger LOG = LoggerFactory.getLogger(PandaPrinter.class);
+  private static final String pandaBanner = PandaPrinter.loadBanner();
+
+  private static String loadBanner() {
+    Class<PandaPrinter> c = PandaPrinter.class;
+    InputStream is = c.getResourceAsStream("/ProofOfPanda3.txt");
+    StringBuilder resultStringBuilder = new StringBuilder();
+    try (BufferedReader br =
+        new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8))) {
+      String line;
+      while ((line = br.readLine()) != null) {
+        resultStringBuilder.append(line).append("\n");
+      }
+    } catch (IOException e) {
+      LOG.error("Couldn't load hilarious panda banner");
+    }
+    return resultStringBuilder.toString();
+  }
+
+  @Override
+  public void onTTDReached(final boolean reached) {
+    if (reached) {
+      LOG.info("\n" + pandaBanner);
+    }
+  }
+}