From 141a95bc09316fb353a10bdda8e8d9d92ff3fe21 Mon Sep 17 00:00:00 2001
From: Austin Littley <austin@swirldslabs.com>
Date: Tue, 19 Dec 2023 11:34:32 -0500
Subject: [PATCH] Create hasher classes

Signed-off-by: Austin Littley <austin@swirldslabs.com>
---
 .../platform/event/hashing/EventHasher.java   | 50 ++++++++++++++++
 .../wiring/components/EventHasherWiring.java  | 57 +++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/event/hashing/EventHasher.java
 create mode 100644 platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/wiring/components/EventHasherWiring.java

diff --git a/platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/event/hashing/EventHasher.java b/platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/event/hashing/EventHasher.java
new file mode 100644
index 000000000000..a651b0a66853
--- /dev/null
+++ b/platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/event/hashing/EventHasher.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2023 Hedera Hashgraph, LLC
+ *
+ * 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.
+ */
+
+package com.swirlds.platform.event.hashing;
+
+import com.swirlds.common.context.PlatformContext;
+import com.swirlds.common.crypto.Cryptography;
+import com.swirlds.platform.event.GossipEvent;
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * Hashes events.
+ */
+public class EventHasher {
+    private final Cryptography cryptography;
+
+    /**
+     * Constructs a new event hasher.
+     *
+     * @param platformContext the platform context
+     */
+    public EventHasher(@NonNull final PlatformContext platformContext) {
+        this.cryptography = platformContext.getCryptography();
+    }
+
+    /**
+     * Hashes the event and builds the event descriptor.
+     *
+     * @param event the event to hash
+     * @return the hashed event
+     */
+    public GossipEvent hashEvent(@NonNull final GossipEvent event) {
+        cryptography.digestSync(event.getHashedData());
+        event.buildDescriptor();
+        return event;
+    }
+}
diff --git a/platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/wiring/components/EventHasherWiring.java b/platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/wiring/components/EventHasherWiring.java
new file mode 100644
index 000000000000..30ada78247f6
--- /dev/null
+++ b/platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/wiring/components/EventHasherWiring.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2023 Hedera Hashgraph, LLC
+ *
+ * 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.
+ */
+
+package com.swirlds.platform.wiring.components;
+
+import com.swirlds.common.wiring.schedulers.TaskScheduler;
+import com.swirlds.common.wiring.wires.input.BindableInputWire;
+import com.swirlds.common.wiring.wires.input.InputWire;
+import com.swirlds.common.wiring.wires.output.OutputWire;
+import com.swirlds.platform.event.GossipEvent;
+import com.swirlds.platform.event.hashing.EventHasher;
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * Wiring for the {@link EventHasher}.
+ *
+ * @param eventInput    the input wire for events to be hashed
+ * @param eventOutput   the output wire for hashed events
+ * @param flushRunnable the runnable to flush the hasher
+ */
+public record EventHasherWiring(
+        @NonNull InputWire<GossipEvent> eventInput,
+        @NonNull OutputWire<GossipEvent> eventOutput,
+        @NonNull Runnable flushRunnable) {
+    /**
+     * Create a new instance of this wiring.
+     *
+     * @param taskScheduler the task scheduler for this wiring
+     * @return the new wiring instance
+     */
+    public static EventHasherWiring create(@NonNull final TaskScheduler<GossipEvent> taskScheduler) {
+        return new EventHasherWiring(
+                taskScheduler.buildInputWire("events to hash"), taskScheduler.getOutputWire(), taskScheduler::flush);
+    }
+
+    /**
+     * Bind an event hasher to this wiring.
+     *
+     * @param hasher the event hasher to bind
+     */
+    public void bind(@NonNull final EventHasher hasher) {
+        ((BindableInputWire<GossipEvent, GossipEvent>) eventInput).bind(hasher::hashEvent);
+    }
+}