From e4818d4f3e2f95aa1b14bf9379efde2eaa8f9185 Mon Sep 17 00:00:00 2001
From: "J. Neugebauer" <ngb@helmholtz-bi.de>
Date: Thu, 7 Jul 2022 21:45:08 +0200
Subject: [PATCH] =?UTF-8?q?Abstraktion=20f=C3=BCr=20Listener=20API=20erste?=
 =?UTF-8?q?llt?=
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EventGenerator soll als einheitlicher Unterbau zur Umstzung von Listener Patterns dienen. Damit sollen Listener wie AudioListener oder AnimationListener umgesetzt werden.
---
 src/schule/ngb/zm/events/EventGenerator.java  | 50 ++++++++++++++
 src/schule/ngb/zm/events/Listener.java        |  7 ++
 .../ngb/zm/events/EventGeneratorTest.java     | 65 +++++++++++++++++++
 3 files changed, 122 insertions(+)
 create mode 100644 src/schule/ngb/zm/events/EventGenerator.java
 create mode 100644 src/schule/ngb/zm/events/Listener.java
 create mode 100644 test/src/schule/ngb/zm/events/EventGeneratorTest.java

diff --git a/src/schule/ngb/zm/events/EventGenerator.java b/src/schule/ngb/zm/events/EventGenerator.java
new file mode 100644
index 0000000..f8834a0
--- /dev/null
+++ b/src/schule/ngb/zm/events/EventGenerator.java
@@ -0,0 +1,50 @@
+package schule.ngb.zm.events;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.function.BiConsumer;
+
+public class EventGenerator<E, L extends Listener<E>> {
+
+	private CopyOnWriteArraySet<L> listeners;
+
+	private ConcurrentMap<String, BiConsumer<E, L>> eventRegistry;
+
+	public EventGenerator() {
+		listeners = new CopyOnWriteArraySet<>();
+		eventRegistry = new ConcurrentHashMap<>();
+	}
+
+	public void registerEventType( String eventKey, BiConsumer<E, L> dispatcher ) {
+		if( !eventRegistered(eventKey) ) {
+			eventRegistry.put(eventKey, dispatcher);
+		}
+	}
+
+	public void addListener( L listener ) {
+		listeners.add(listener);
+	}
+
+	public void removeListener( L listener ) {
+		listeners.remove(listener);
+	}
+
+	public boolean hasListeners() {
+		return !listeners.isEmpty();
+	}
+
+	public boolean eventRegistered( String eventKey ) {
+		return eventRegistry.containsKey(eventKey);
+	}
+
+	public void dispatchEvent( String eventKey, final E event ) {
+		if( eventRegistered(eventKey) ) {
+			final BiConsumer<E, L> dispatcher = eventRegistry.get(eventKey);
+			listeners.stream().forEach(( listener ) -> {
+				dispatcher.accept(event, listener);
+			});
+		}
+	}
+
+}
diff --git a/src/schule/ngb/zm/events/Listener.java b/src/schule/ngb/zm/events/Listener.java
new file mode 100644
index 0000000..54c6025
--- /dev/null
+++ b/src/schule/ngb/zm/events/Listener.java
@@ -0,0 +1,7 @@
+package schule.ngb.zm.events;
+
+public interface Listener<E> {
+
+
+
+}
diff --git a/test/src/schule/ngb/zm/events/EventGeneratorTest.java b/test/src/schule/ngb/zm/events/EventGeneratorTest.java
new file mode 100644
index 0000000..f10979b
--- /dev/null
+++ b/test/src/schule/ngb/zm/events/EventGeneratorTest.java
@@ -0,0 +1,65 @@
+package schule.ngb.zm.events;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class EventGeneratorTest {
+
+	class TestEvent {
+
+		private String data;
+
+		private String type;
+
+		public TestEvent( String data, boolean isStart ) {
+			this.data = data;
+			this.type = isStart ? "start" : "stop";
+		}
+
+		public String getData() {
+			return data;
+		}
+
+		public String getType() {
+			return type;
+		}
+
+	}
+
+	interface TestListener extends Listener<TestEvent> {
+
+		void startEvent( TestEvent t );
+
+		void stopEvent( TestEvent t );
+
+	}
+
+	@Test
+	void eventRegistry() {
+		EventGenerator<TestEvent, TestListener> gen = new EventGenerator<>();
+
+		gen.registerEventType("start", ( event, listener ) -> listener.startEvent(event));
+		gen.registerEventType("stop", ( event, listener ) -> listener.stopEvent(event));
+
+		gen.addListener(new TestListener() {
+			@Override
+			public void startEvent( TestEvent t ) {
+				assertEquals("start", t.getType());
+				assertTrue(t.getData().startsWith("Start Event"));
+			}
+
+			@Override
+			public void stopEvent( TestEvent t ) {
+				assertEquals("stop", t.getType());
+				assertTrue(t.getData().startsWith("Stop Event"));
+			}
+		});
+
+		gen.dispatchEvent("start", new TestEvent("Start Event 1", true));
+		gen.dispatchEvent("stop", new TestEvent("Stop Event 1", false));
+		gen.dispatchEvent("stop", new TestEvent("Stop Event 2", false));
+		gen.dispatchEvent("start", new TestEvent("Start Event 2", true));
+	}
+
+}