add Neo4J access module

.gitignore

@@ -1,3 +1,5 @@
+arebac-neo4j/db
+
 # Created by https://www.toptal.com/developers/gitignore/api/eclipse,java,maven
 # Edit at https://www.toptal.com/developers/gitignore?templates=eclipse,java,maven
 

arebac-neo4j/pom.xml

@@ -0,0 +1,25 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>io.github.danthe1st</groupId>
+		<artifactId>AReBAC</artifactId>
+		<version>0.0.1-SNAPSHOT</version>
+	</parent>
+	<artifactId>arebac-neo4j</artifactId>
+	<name>AReBAC-Neo4J</name>
+
+	<dependencies>
+		<dependency>
+			<groupId>io.github.danthe1st</groupId>
+			<artifactId>arebac-core</artifactId>
+			<version>${project.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.neo4j</groupId>
+			<artifactId>neo4j</artifactId>
+			<version>5.22.0</version>
+		</dependency>
+	</dependencies>
+</project>

arebac-neo4j/src/main/java/io/github/danthe1st/arebac/neo4j/graph/Neo4jDB.java

@@ -0,0 +1,47 @@
+package io.github.danthe1st.arebac.neo4j.graph;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import io.github.danthe1st.arebac.data.commongraph.attributed.AttributedGraph;
+import org.neo4j.graphdb.Direction;
+import org.neo4j.graphdb.Node;
+import org.neo4j.graphdb.Relationship;
+import org.neo4j.graphdb.ResourceIterable;
+import org.neo4j.graphdb.Transaction;
+
+public class Neo4jDB implements AttributedGraph<Neo4jNode, Neo4jEdge> {
+	private final Transaction tx;
+
+	public Neo4jDB(Transaction tx) {
+		this.tx = tx;
+	}
+
+	@Override
+	public Neo4jNode findNodeById(String id) {
+		return new Neo4jNode(tx.getNodeByElementId(id));
+	}
+
+	@Override
+	public Collection<Neo4jEdge> findOutgoingEdges(Neo4jNode node) {
+		return findEdges(node, Direction.OUTGOING);
+	}
+
+	@Override
+	public Collection<Neo4jEdge> findIncomingEdges(Neo4jNode node) {
+		return findEdges(node, Direction.INCOMING);
+	}
+
+	private Collection<Neo4jEdge> findEdges(Neo4jNode node, Direction direction) {
+		Node internalNode = node.getDBNode();
+		ResourceIterable<Relationship> relationships = internalNode.getRelationships(direction);
+		List<Neo4jEdge> edges = new ArrayList<>();
+		for(Relationship relationship : relationships){
+			edges.add(new Neo4jEdge(relationship));
+		}
+		return Collections.unmodifiableList(edges);
+	}
+
+}

arebac-neo4j/src/main/java/io/github/danthe1st/arebac/neo4j/graph/Neo4jEdge.java

@@ -0,0 +1,51 @@
+package io.github.danthe1st.arebac.neo4j.graph;
+
+import io.github.danthe1st.arebac.data.commongraph.attributed.AttributeValue;
+import io.github.danthe1st.arebac.data.commongraph.attributed.AttributedGraphEdge;
+import org.neo4j.graphdb.Relationship;
+
+public class Neo4jEdge implements AttributedGraphEdge<Neo4jNode> {
+	private final Relationship relationship;
+
+	public Neo4jEdge(Relationship relationship) {
+		this.relationship = relationship;
+	}
+
+	@Override
+	public Neo4jNode source() {
+		return new Neo4jNode(relationship.getStartNode());
+	}
+
+	@Override
+	public Neo4jNode target() {
+		return new Neo4jNode(relationship.getEndNode());
+	}
+
+	@Override
+	public String id() {
+		return relationship.getElementId();
+	}
+
+	@Override
+	public String edgeType() {
+		return relationship.getType().name();
+	}
+
+	@Override
+	public AttributeValue<?> getAttribute(String key) {
+		if(!relationship.hasProperty(key)){
+			return null;
+		}
+		Object property = relationship.getProperty(key);
+		return switch(property) {
+		case String s -> AttributeValue.attribute(s);
+		case Boolean b -> AttributeValue.attribute(b);
+		case Integer l -> AttributeValue.attribute(l);
+		default -> throw new UnsupportedOperationException("unknown property type");
+		};
+	}
+
+	public Relationship getDBEdge() {
+		return relationship;
+	}
+}

arebac-neo4j/src/main/java/io/github/danthe1st/arebac/neo4j/graph/Neo4jNode.java

@@ -0,0 +1,50 @@
+package io.github.danthe1st.arebac.neo4j.graph;
+
+import java.util.Iterator;
+
+import io.github.danthe1st.arebac.data.commongraph.attributed.AttributeValue;
+import io.github.danthe1st.arebac.data.commongraph.attributed.AttributedNode;
+import org.neo4j.graphdb.Label;
+import org.neo4j.graphdb.Node;
+
+public class Neo4jNode implements AttributedNode {
+	private static final String NODE_TYPE = "_NO_LABEL";
+
+	private final Node node;
+
+	public Neo4jNode(Node node) {
+		this.node = node;
+	}
+
+	@Override
+	public String id() {
+		return node.getElementId();
+	}
+
+	@Override
+	public String nodeType() {
+		Iterator<Label> labelIt = node.getLabels().iterator();
+		if(labelIt.hasNext()){
+			return labelIt.next().name();
+		}
+		return NODE_TYPE;
+	}
+
+	@Override
+	public AttributeValue<?> getAttribute(String key) {
+		if(!node.hasProperty(key)){
+			return null;
+		}
+		Object property = node.getProperty(key);
+		return switch(property) {
+		case String s -> AttributeValue.attribute(s);
+		case Boolean b -> AttributeValue.attribute(b);
+		case Integer l -> AttributeValue.attribute(l);
+		default -> throw new UnsupportedOperationException("unknown property type");
+		};
+	}
+
+	public Node getDBNode() {
+		return node;
+	}
+}

pom.xml

@@ -11,6 +11,7 @@
 	</properties>
 	<modules>
 		<module>arebac-core</module>
+		<module>arebac-neo4j</module>
 	</modules>
 	<build>
 		<plugins>