Make EventNode#toString return a graph of the current node state

Signed-off-by: TheMode <themode@outlook.fr>

src/main/java/net/minestom/server/event/EventNodeImpl.java

@@ -218,6 +218,46 @@ non-sealed class EventNodeImpl<T extends Event> implements EventNode<T> {
         return parent;
     }
 
+    @Override
+    public String toString() {
+        return createStringGraph(createGraph());
+    }
+
+    Graph createGraph() {
+        synchronized (GLOBAL_CHILD_LOCK) {
+            List<Graph> children = this.children.stream().map(EventNodeImpl::createGraph).toList();
+            return new Graph(getName(), getEventType().getSimpleName(), getPriority(), children);
+        }
+    }
+
+    static String createStringGraph(Graph graph) {
+        StringBuilder buffer = new StringBuilder();
+        genToStringTree(buffer, "", "", graph);
+        return buffer.toString();
+    }
+
+    private static void genToStringTree(StringBuilder buffer, String prefix, String childrenPrefix, Graph graph) {
+        buffer.append(prefix);
+        buffer.append(String.format("%s - EventType: %s - Priority: %d", graph.name(), graph.eventType(), graph.priority()));
+        buffer.append('\n');
+        var nextNodes = graph.children();
+        for (Iterator<? extends @NotNull Graph> iterator = nextNodes.iterator(); iterator.hasNext(); ) {
+            Graph next = iterator.next();
+            if (iterator.hasNext()) {
+                genToStringTree(buffer, childrenPrefix + '\u251C' + '\u2500' + " ", childrenPrefix + '\u2502' + "   ", next);
+            } else {
+                genToStringTree(buffer, childrenPrefix + '\u2514' + '\u2500' + " ", childrenPrefix + "    ", next);
+            }
+        }
+    }
+
+    record Graph(String name, String eventType, int priority,
+                 List<Graph> children) {
+        public Graph {
+            children = children.stream().sorted(Comparator.comparingInt(Graph::priority)).toList();
+        }
+    }
+
     private void invalidateEventsFor(EventNodeImpl<? super T> node) {
         for (Class<? extends T> eventType : listenerMap.keySet()) {
             node.invalidateEvent(eventType);

src/test/java/net/minestom/server/event/EventNodeGraphTest.java

@@ -0,0 +1,55 @@
+package net.minestom.server.event;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class EventNodeGraphTest {
+
+    @Test
+    public void single() {
+        EventNode<Event> node = EventNode.all("main");
+        verifyGraph(node, new EventNodeImpl.Graph("main", "Event", 0, List.of()));
+    }
+
+    @Test
+    public void singleChild() {
+        EventNode<Event> node = EventNode.all("main");
+        node.addChild(EventNode.all("child"));
+        verifyGraph(node, new EventNodeImpl.Graph("main", "Event", 0,
+                List.of(new EventNodeImpl.Graph("child", "Event", 0, List.of())
+                )));
+    }
+
+    @Test
+    public void childrenPriority() {
+        {
+            EventNode<Event> node = EventNode.all("main");
+            node.addChild(EventNode.all("child1").setPriority(5));
+            node.addChild(EventNode.all("child2").setPriority(10));
+            verifyGraph(node, new EventNodeImpl.Graph("main", "Event", 0,
+                    List.of(new EventNodeImpl.Graph("child1", "Event", 5, List.of()),
+                            new EventNodeImpl.Graph("child2", "Event", 10, List.of())
+                    )));
+        }
+        {
+            EventNode<Event> node = EventNode.all("main");
+            node.addChild(EventNode.all("child2").setPriority(10));
+            node.addChild(EventNode.all("child1").setPriority(5));
+            verifyGraph(node, new EventNodeImpl.Graph("main", "Event", 0,
+                    List.of(new EventNodeImpl.Graph("child1", "Event", 5, List.of()),
+                            new EventNodeImpl.Graph("child2", "Event", 10, List.of())
+                    )));
+        }
+    }
+
+    void verifyGraph(EventNode<?> n, EventNodeImpl.Graph graph) {
+        EventNodeImpl<?> node = (EventNodeImpl<?>) n;
+        var nodeGraph = node.createGraph();
+        assertEquals(graph, nodeGraph, "Graphs are not equals");
+        assertEquals(EventNodeImpl.createStringGraph(graph), EventNodeImpl.createStringGraph(nodeGraph), "String graphs are not equals");
+        assertEquals(n.toString(), EventNodeImpl.createStringGraph(nodeGraph), "The node does not use createStringGraph");
+    }
+}