source: AnnotationManagerN4J/src/main/java/de/mpiwg/itgroup/annotations/neo4j/AnnotationStore.java @ 12:5928c5d9aae8

/**
 * 
 */
package de.mpiwg.itgroup.annotations.neo4j;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

import org.apache.log4j.Logger;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.index.Index;
import org.neo4j.graphdb.index.IndexHits;

import de.mpiwg.itgroup.annotations.Actor;
import de.mpiwg.itgroup.annotations.Annotation;
import de.mpiwg.itgroup.annotations.Annotation.FragmentTypes;
import de.mpiwg.itgroup.annotations.Group;
import de.mpiwg.itgroup.annotations.Person;

/**
 * @author casties
 * 
 */
public class AnnotationStore {

    protected static Logger logger = Logger.getLogger(AnnotationStore.class);

    protected GraphDatabaseService graphDb;

    public static enum NodeTypes {
        ANNOTATION, PERSON, TARGET
    }

    protected List<Index<Node>> nodeIndexes;

    public static enum RelationTypes implements RelationshipType {
        ANNOTATES, CREATED, PERMITS_ADMIN, PERMITS_DELETE, PERMITS_UPDATE, PERMITS_READ
    }

    public static String ANNOTATION_URI_BASE = "http://entities.mpiwg-berlin.mpg.de/annotations/";

    public AnnotationStore(GraphDatabaseService graphDb) {
        super();
        this.graphDb = graphDb;
        nodeIndexes = new ArrayList<Index<Node>>(3);
        // List.set(enum.ordinal(), val) seems not to work.
        nodeIndexes.add(NodeTypes.ANNOTATION.ordinal(), graphDb.index().forNodes("annotations"));
        nodeIndexes.add(NodeTypes.PERSON.ordinal(), graphDb.index().forNodes("persons"));
        nodeIndexes.add(NodeTypes.TARGET.ordinal(), graphDb.index().forNodes("targets"));
    }

    protected Index<Node> getNodeIndex(NodeTypes type) {
        return nodeIndexes.get(type.ordinal());
    }

    /**
     * Returns the Annotation with the given id.
     * 
     * @param id
     * @return
     */
    public Annotation getAnnotationById(String id) {
        Node annotNode = getNodeIndex(NodeTypes.ANNOTATION).get("id", id).getSingle();
        Annotation annot = createAnnotationFromNode(annotNode);
        return annot;
    }

    /**
     * Returns an Annotation object from an annotation-Node.
     * 
     * @param annotNode
     * @return
     */
    public Annotation createAnnotationFromNode(Node annotNode) {
        Annotation annot = new Annotation();
        annot.setUri((String) annotNode.getProperty("id", null));
        annot.setBodyText((String) annotNode.getProperty("bodyText", null));
        annot.setBodyUri((String) annotNode.getProperty("bodyUri", null));
        // get annotation target from relation
        Relationship targetRel = getRelation(annotNode, RelationTypes.ANNOTATES, null);
        if (targetRel != null) {
            Node target = targetRel.getEndNode();
            annot.setTargetBaseUri((String) target.getProperty("uri", null));
        } else {
            logger.error("annotation "+annotNode+" has no target node!");
        }
        annot.setTargetFragment((String) annotNode.getProperty("targetFragment", null));
        String ft = (String) annotNode.getProperty("fragmentType", null);
        if (ft != null) {
            annot.setFragmentType(FragmentTypes.valueOf(ft));
        }
        // get creator from relation
        Relationship creatorRel = getRelation(annotNode, RelationTypes.CREATED, null);
        if (creatorRel != null) {
            Node creatorNode = creatorRel.getStartNode();
            Actor creator = createActorFromNode(creatorNode);
            annot.setCreator(creator);
        } else {
            logger.error("annotation "+annotNode+" has no creator node!");
        }
        // get creation date
        annot.setCreated((String) annotNode.getProperty("created", null));
        // get permissions
        Relationship adminRel = getRelation(annotNode, RelationTypes.PERMITS_ADMIN, null);
        if (adminRel != null) {
            Node adminNode = adminRel.getEndNode();
            //FIXME
        }
        
        return annot;
    }

    /**
     * Returns an Actor object from a node.
     * 
     * @param actorNode
     * @return
     */
    protected Actor createActorFromNode(Node actorNode) {
        String uri = (String) actorNode.getProperty("uri", null);
        String name = (String) actorNode.getProperty("name", null);
        String type = (String) actorNode.getProperty("TYPE", null);
        Actor creator = null;
        if (type != null && type.equals("PERSON")) {
            creator = new Person(uri, name);
        } else if (type != null && type.equals("GROUP")) {
            creator = new Group(uri, name);
        }
        return creator;
    }

    /**
     * Store a new annotation in the store or update an existing one. Returns
     * the stored annotation.
     * 
     * @param annot
     * @return
     */
    public Annotation storeAnnotation(Annotation annot) {
        Node annotNode = null;
        Transaction tx = graphDb.beginTx();
        try {
            /*
             * create or get the annotation
             */
            String id = annot.getUri();
            if (id == null) {
                id = createRessourceURI("annot:");
            }
            annotNode = getOrCreateAnnotationNode(id);

            /*
             * the annotation body
             */
            String bodyText = annot.getBodyText();
            if (bodyText != null) {
                annotNode.setProperty("bodyText", bodyText);
            }
            String bodyUri = annot.getBodyUri();
            if (bodyUri != null) {
                annotNode.setProperty("bodyUri", bodyUri);
            }

            /*
             * the annotation target
             */
            String targetBaseUri = annot.getTargetBaseUri();
            if (targetBaseUri != null) {
                Node target = getOrCreateTargetNode(targetBaseUri);
                getOrCreateRelation(annotNode, RelationTypes.ANNOTATES, target);
            }

            /*
             * The fragment part of the annotation target.
             */
            String targetFragment = annot.getTargetFragment();
            FragmentTypes fragmentType = annot.getFragmentType();
            if (targetFragment != null) {
                annotNode.setProperty("targetFragment", targetFragment);
                annotNode.setProperty("fragmentType", fragmentType.name());
            }

            /*
             * The creator of this annotation.
             */
            Actor creator = annot.getCreator();
            if (creator != null) {
                Node creatorNode = getOrCreatePersonNode(creator);
                getOrCreateRelation(creatorNode, RelationTypes.CREATED, annotNode);
            }

            /*
             * The creation date of this annotation.
             */
            String created = annot.getCreated();
            if (created != null) {
                annotNode.setProperty("created", created);
            }

            /*
             * Permissions for this annotation.
             */
            setPermissionRelation(annotNode, RelationTypes.PERMITS_ADMIN, annot.getAdminPermission());
            setPermissionRelation(annotNode, RelationTypes.PERMITS_DELETE, annot.getDeletePermission());
            setPermissionRelation(annotNode, RelationTypes.PERMITS_UPDATE, annot.getUpdatePermission());
            setPermissionRelation(annotNode, RelationTypes.PERMITS_READ, annot.getReadPermission());

            tx.success();
        } finally {
            tx.finish();
        }

        // re-read and return annotation
        Annotation storedAnnot = createAnnotationFromNode(annotNode);
        return storedAnnot;
    }

    /**
     * Deletes the annotation with the given id.
     * 
     * @param id
     */
    public void deleteById(String id) {
        Node annotNode = getNodeIndex(NodeTypes.ANNOTATION).get("id", id).getSingle();
        if (annotNode != null) {
            // delete related objects
            Transaction tx = graphDb.beginTx();
            try {
                for (Relationship rel : annotNode.getRelationships()) {
                    // delete relation and the related node if it has no other
                    // relations
                    Node other = rel.getOtherNode(annotNode);
                    rel.delete();
                    if (!other.hasRelationship()) {
                        deleteNode(other);
                    }
                }
                if (!annotNode.hasRelationship()) {
                    deleteNode(annotNode);
                } else {
                    logger.error("deleteById: unable to delete: Node still has relations.");
                }
                tx.success();
            } finally {
                tx.finish();
            }
        }
    }

    /**
     * Returns all annotations with the given uri and/or user.
     * 
     * @param uri
     * @param userUri
     * @param limit
     * @param offset
     * @return
     */
    public List<Annotation> searchByUriUser(String targetUri, String userUri, String limit, String offset) {
        List<Annotation> annotations = new ArrayList<Annotation>();
        if (targetUri != null) {
            // there should be only one
            Node target = getNodeIndex(NodeTypes.TARGET).get("uri", targetUri).getSingle();
            if (target != null) {
                Iterable<Relationship> relations = target.getRelationships(RelationTypes.ANNOTATES);
                for (Relationship relation : relations) {
                    Node ann = relation.getStartNode();
                    if (ann.getProperty("TYPE", "").equals("ANNOTATION")) {
                        Annotation annot = createAnnotationFromNode(ann);
                        annotations.add(annot);
                    } else {
                        logger.error("ANNOTATES relation does not start with ANNOTATION: " + ann);
                    }
                }
            }
        }
        if (userUri != null) {
            // there should be only one
            Node person = getNodeIndex(NodeTypes.PERSON).get("uri", userUri).getSingle();
            if (person != null) {
                Iterable<Relationship> relations = person.getRelationships(RelationTypes.CREATED);
                for (Relationship relation : relations) {
                    Node ann = relation.getEndNode();
                    if (ann.getProperty("TYPE", "").equals("ANNOTATION")) {
                        Annotation annot = createAnnotationFromNode(ann);
                        annotations.add(annot);
                    } else {
                        logger.error("CREATED relation does not end with ANNOTATION: " + ann);
                    }
                }
            }
        }
        return annotations;
    }

    protected Relationship getOrCreateRelation(Node start, RelationshipType type, Node end) {
        if (start.hasRelationship()) {
            // there are relations
            Iterable<Relationship> rels = start.getRelationships(type, Direction.OUTGOING);
            for (Relationship rel : rels) {
                if (rel.getEndNode().equals(end)) {
                    // relation exists
                    return rel;
                }
            }
        }
        // create new one
        Relationship rel;
        Transaction tx = graphDb.beginTx();
        try {
            rel = start.createRelationshipTo(end, type);
            tx.success();
        } finally {
            tx.finish();
        }
        return rel;
    }

    protected Node getOrCreateAnnotationNode(String id) {
        Index<Node> idx = getNodeIndex(NodeTypes.ANNOTATION);
        IndexHits<Node> annotations = idx.get("id", id);
        Node annotation = annotations.getSingle();
        if (annotation == null) {
            // does not exist yet
            Transaction tx = graphDb.beginTx();
            try {
                annotation = graphDb.createNode();
                annotation.setProperty("TYPE", NodeTypes.ANNOTATION.name());
                annotation.setProperty("id", id);
                idx.add(annotation, "id", id);
                tx.success();
            } finally {
                tx.finish();
            }
        }
        return annotation;
    }

    protected Node getOrCreateTargetNode(String uri) {
        Index<Node> idx = getNodeIndex(NodeTypes.TARGET);
        IndexHits<Node> targets = idx.get("uri", uri);
        Node target = targets.getSingle();
        if (target == null) {
            // does not exist yet
            Transaction tx = graphDb.beginTx();
            try {
                target = graphDb.createNode();
                target.setProperty("TYPE", NodeTypes.TARGET.name());
                target.setProperty("uri", uri);
                idx.add(target, "uri", uri);
                tx.success();
            } finally {
                tx.finish();
            }
        }
        return target;
    }

    protected Node getOrCreatePersonNode(Actor actor) {
        /*
         * // Person is identified by URI Index<Node> idx =
         * getNodeIndex(NodeTypes.PERSON); IndexHits<Node> persons =
         * idx.get("uri", uri); Node person = persons.getSingle(); if (person ==
         * null) { // does not exist yet Transaction tx = graphDb.beginTx(); try
         * { person = graphDb.createNode(); person.setProperty("TYPE",
         * NodeTypes.PERSON.name()); person.setProperty("uri", uri);
         * idx.add(person, "uri", uri); if (name != null) {
         * person.setProperty("name", name); } tx.success(); } finally {
         * tx.finish(); } } return person;
         */
        return null;
    }

    /**
     * Create or update permissions relations for an annotation.
     * 
     * @param annotNode
     * @param type
     * @param annot
     */
    protected void setPermissionRelation(Node annotNode, RelationTypes type, Actor actor) {
        Node newActorNode = null;
        if (actor != null) {
            newActorNode = getOrCreatePersonNode(actor);
        }
        Relationship rel = getRelation(annotNode, type, null);
        if (rel != null) {
            // relation exists
            Node oldActorNode = rel.getEndNode();
            if (!oldActorNode.equals(newActorNode)) {
                // new admin is different
                rel.delete();
                if (newActorNode != null) {
                    rel = getOrCreateRelation(annotNode, type, newActorNode);
                }
            }
        } else {
            // no relation yet
            if (newActorNode != null) {
                rel = getOrCreateRelation(annotNode, type, newActorNode);
            }
        }
    }

    /**
     * Unindexes and deletes given Node if it has no relations.
     * 
     * @param node
     */
    protected void deleteNode(Node node) {
        Transaction tx = graphDb.beginTx();
        try {
            if (node.hasRelationship()) {
                logger.error("deleteNode: unable to delete: Node still has relations.");
            } else {
                String ts = (String) node.getProperty("TYPE", null);
                try {
                    NodeTypes type = NodeTypes.valueOf(ts);
                    getNodeIndex(type).remove(node);
                } catch (Exception e) {
                    logger.error("deleteNode: unable to get TYPE of node: " + node);
                }
                node.delete();
            }
            tx.success();
        } finally {
            tx.finish();
        }
    }

    protected Relationship getRelation(Node start, RelationTypes type, Direction direction) {
        Iterable<Relationship> rels;
        if (direction == null) {
            // ignore direction
            rels = start.getRelationships(type);
        } else {
            rels = start.getRelationships(type, direction);
        }
        for (Relationship rel : rels) {
            return rel;
        }
        return null;
    }

    /**
     * Erzeuge eine urn aus der aktuellen Zeit in millis
     * 
     * @return
     */
    private String createRessourceURI(String prefix) {

        Calendar cal = Calendar.getInstance();

        long time = cal.getTimeInMillis();

        return String.format("%s%s%s", ANNOTATION_URI_BASE, prefix, time);

    }

}