Improve JCR repository lifecycle

[lgpl/argeo-commons.git] / org.argeo.cms.jcr / src / org / argeo / jcr / Jcr.java

package org.argeo.jcr;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigDecimal;
import java.text.MessageFormat;
import java.time.Instant;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Collections;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Iterator;
import java.util.List;

import javax.jcr.Binary;
import javax.jcr.ItemNotFoundException;
import javax.jcr.Node;
import javax.jcr.NodeIterator;
import javax.jcr.Property;
import javax.jcr.PropertyType;
import javax.jcr.Repository;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.Value;
import javax.jcr.Workspace;
import javax.jcr.nodetype.NodeType;
import javax.jcr.query.Query;
import javax.jcr.query.QueryManager;
import javax.jcr.security.Privilege;
import javax.jcr.version.Version;
import javax.jcr.version.VersionHistory;
import javax.jcr.version.VersionIterator;
import javax.jcr.version.VersionManager;

import org.apache.commons.io.IOUtils;

/**
 * Utility class whose purpose is to make using JCR less verbose by
 * systematically using unchecked exceptions and returning <code>null</code>
 * when something is not found. This is especially useful when writing user
 * interfaces (such as with SWT) where listeners and callbacks expect unchecked
 * exceptions. Loosely inspired by Java's <code>Files</code> singleton.
 */
public class Jcr {
        /**
         * The name of a node which will be serialized as XML text, as per section 7.3.1
         * of the JCR 2.0 specifications.
         */
        public final static String JCR_XMLTEXT = "jcr:xmltext";
        /**
         * The name of a property which will be serialized as XML text, as per section
         * 7.3.1 of the JCR 2.0 specifications.
         */
        public final static String JCR_XMLCHARACTERS = "jcr:xmlcharacters";
        /**
         * <code>jcr:name</code>, when used in another context than
         * {@link Property#JCR_NAME}, typically to name a node rather than a property.
         */
        public final static String JCR_NAME = "jcr:name";
        /**
         * <code>jcr:path</code>, when used in another context than
         * {@link Property#JCR_PATH}, typically to name a node rather than a property.
         */
        public final static String JCR_PATH = "jcr:path";
        /**
         * <code>jcr:primaryType</code> with prefix instead of namespace (as in
         * {@link Property#JCR_PRIMARY_TYPE}.
         */
        public final static String JCR_PRIMARY_TYPE = "jcr:primaryType";
        /**
         * <code>jcr:mixinTypes</code> with prefix instead of namespace (as in
         * {@link Property#JCR_MIXIN_TYPES}.
         */
        public final static String JCR_MIXIN_TYPES = "jcr:mixinTypes";
        /**
         * <code>jcr:uuid</code> with prefix instead of namespace (as in
         * {@link Property#JCR_UUID}.
         */
        public final static String JCR_UUID = "jcr:uuid";
        /**
         * <code>jcr:created</code> with prefix instead of namespace (as in
         * {@link Property#JCR_CREATED}.
         */
        public final static String JCR_CREATED = "jcr:created";
        /**
         * <code>jcr:createdBy</code> with prefix instead of namespace (as in
         * {@link Property#JCR_CREATED_BY}.
         */
        public final static String JCR_CREATED_BY = "jcr:createdBy";
        /**
         * <code>jcr:lastModified</code> with prefix instead of namespace (as in
         * {@link Property#JCR_LAST_MODIFIED}.
         */
        public final static String JCR_LAST_MODIFIED = "jcr:lastModified";
        /**
         * <code>jcr:lastModifiedBy</code> with prefix instead of namespace (as in
         * {@link Property#JCR_LAST_MODIFIED_BY}.
         */
        public final static String JCR_LAST_MODIFIED_BY = "jcr:lastModifiedBy";

        /**
         * @see Node#isNodeType(String)
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static boolean isNodeType(Node node, String nodeTypeName) {
                try {
                        return node.isNodeType(nodeTypeName);
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get whether " + node + " is of type " + nodeTypeName, e);
                }
        }

        /**
         * @see Node#hasNodes()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static boolean hasNodes(Node node) {
                try {
                        return node.hasNodes();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get whether " + node + " has children.", e);
                }
        }

        /**
         * @see Node#getParent()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Node getParent(Node node) {
                try {
                        return isRoot(node) ? null : node.getParent();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get parent of " + node, e);
                }
        }

        /**
         * @see Node#getParent()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String getParentPath(Node node) {
                return getPath(getParent(node));
        }

        /**
         * Whether this node is the root node.
         * 
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static boolean isRoot(Node node) {
                try {
                        return node.getDepth() == 0;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get depth of " + node, e);
                }
        }

        /**
         * @see Node#getPath()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String getPath(Node node) {
                try {
                        return node.getPath();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get path of " + node, e);
                }
        }

        /**
         * @see Node#getSession()
         * @see Session#getWorkspace()
         * @see Workspace#getName()
         */
        public static String getWorkspaceName(Node node) {
                return session(node).getWorkspace().getName();
        }

        /**
         * @see Node#getIdentifier()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String getIdentifier(Node node) {
                try {
                        return node.getIdentifier();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get identifier of " + node, e);
                }
        }

        /**
         * @see Node#getName()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String getName(Node node) {
                try {
                        return node.getName();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get name of " + node, e);
                }
        }

        /**
         * Returns the node name with its current index (useful for re-ordering).
         * 
         * @see Node#getName()
         * @see Node#getIndex()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String getIndexedName(Node node) {
                try {
                        return node.getName() + "[" + node.getIndex() + "]";
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get name of " + node, e);
                }
        }

        /**
         * @see Node#getProperty(String)
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Property getProperty(Node node, String property) {
                try {
                        if (node.hasProperty(property))
                                return node.getProperty(property);
                        else
                                return null;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get property " + property + " of " + node, e);
                }
        }

        /**
         * @see Node#getIndex()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static int getIndex(Node node) {
                try {
                        return node.getIndex();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get index of " + node, e);
                }
        }

        /**
         * If node has mixin {@link NodeType#MIX_TITLE}, return
         * {@link Property#JCR_TITLE}, otherwise return {@link #getName(Node)}.
         */
        public static String getTitle(Node node) {
                if (Jcr.isNodeType(node, NodeType.MIX_TITLE))
                        return get(node, Property.JCR_TITLE);
                else
                        return Jcr.getName(node);
        }

        /** Accesses a {@link NodeIterator} as an {@link Iterable}. */
        @SuppressWarnings("unchecked")
        public static Iterable<Node> iterate(NodeIterator nodeIterator) {
                return new Iterable<Node>() {

                        @Override
                        public Iterator<Node> iterator() {
                                return nodeIterator;
                        }
                };
        }

        /**
         * @return the children as an {@link Iterable} for use in for-each llops.
         * @see Node#getNodes()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Iterable<Node> nodes(Node node) {
                try {
                        return iterate(node.getNodes());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get children of " + node, e);
                }
        }

        /**
         * @return the children as a (possibly empty) {@link List}.
         * @see Node#getNodes()
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static List<Node> getNodes(Node node) {
                List<Node> nodes = new ArrayList<>();
                try {
                        if (node.hasNodes()) {
                                NodeIterator nit = node.getNodes();
                                while (nit.hasNext())
                                        nodes.add(nit.nextNode());
                                return nodes;
                        } else
                                return nodes;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get children of " + node, e);
                }
        }

        /**
         * @return the child or <code>null</node> if not found
         * @see Node#getNode(String)
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Node getNode(Node node, String child) {
                try {
                        if (node.hasNode(child))
                                return node.getNode(child);
                        else
                                return null;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get child of " + node, e);
                }
        }

        /**
         * @return the node at this path or <code>null</node> if not found
         * @see Session#getNode(String)
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Node getNode(Session session, String path) {
                try {
                        if (session.nodeExists(path))
                                return session.getNode(path);
                        else
                                return null;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get node " + path, e);
                }
        }

        /**
         * Add a node to this parent, setting its primary type and its mixins.
         * 
         * @param parent      the parent node
         * @param name        the name of the node, if <code>null</code>, the primary
         *                    type will be used (typically for XML structures)
         * @param primaryType the primary type, if <code>null</code>
         *                    {@link NodeType#NT_UNSTRUCTURED} will be used.
         * @param mixins      the mixins
         * @return the created node
         * @see Node#addNode(String, String)
         * @see Node#addMixin(String)
         */
        public static Node addNode(Node parent, String name, String primaryType, String... mixins) {
                if (name == null && primaryType == null)
                        throw new IllegalArgumentException("Both node name and primary type cannot be null");
                try {
                        Node newNode = parent.addNode(name == null ? primaryType : name,
                                        primaryType == null ? NodeType.NT_UNSTRUCTURED : primaryType);
                        for (String mixin : mixins) {
                                newNode.addMixin(mixin);
                        }
                        return newNode;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot add node " + name + " to " + parent, e);
                }
        }

        /**
         * Add an {@link NodeType#NT_BASE} node to this parent.
         * 
         * @param parent the parent node
         * @param name   the name of the node, cannot be <code>null</code>
         * @return the created node
         * 
         * @see Node#addNode(String)
         */
        public static Node addNode(Node parent, String name) {
                if (name == null)
                        throw new IllegalArgumentException("Node name cannot be null");
                try {
                        Node newNode = parent.addNode(name);
                        return newNode;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot add node " + name + " to " + parent, e);
                }
        }

        /**
         * Add mixins to a node.
         * 
         * @param node   the node
         * @param mixins the mixins
         * @return the created node
         * @see Node#addMixin(String)
         */
        public static void addMixin(Node node, String... mixins) {
                try {
                        for (String mixin : mixins) {
                                node.addMixin(mixin);
                        }
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot add mixins " + Arrays.asList(mixins) + " to " + node, e);
                }
        }

        /**
         * Removes this node.
         * 
         * @see Node#remove()
         */
        public static void remove(Node node) {
                try {
                        node.remove();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot remove node " + node, e);
                }
        }

        /**
         * @return the node with htis id or <code>null</node> if not found
         * @see Session#getNodeByIdentifier(String)
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Node getNodeById(Session session, String id) {
                try {
                        return session.getNodeByIdentifier(id);
                } catch (ItemNotFoundException e) {
                        return null;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get node with id " + id, e);
                }
        }

        /**
         * Set a property to the given value, or remove it if the value is
         * <code>null</code>.
         * 
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static void set(Node node, String property, Object value) {
                try {
                        if (!node.hasProperty(property)) {
                                if (value != null) {
                                        if (value instanceof List) {// multiple
                                                List<?> lst = (List<?>) value;
                                                String[] values = new String[lst.size()];
                                                for (int i = 0; i < lst.size(); i++) {
                                                        values[i] = lst.get(i).toString();
                                                }
                                                node.setProperty(property, values);
                                        } else {
                                                node.setProperty(property, value.toString());
                                        }
                                }
                                return;
                        }
                        Property prop = node.getProperty(property);
                        if (value == null) {
                                prop.remove();
                                return;
                        }

                        // multiple
                        if (value instanceof List) {
                                List<?> lst = (List<?>) value;
                                String[] values = new String[lst.size()];
                                // TODO better cast?
                                for (int i = 0; i < lst.size(); i++) {
                                        values[i] = lst.get(i).toString();
                                }
                                if (!prop.isMultiple())
                                        prop.remove();
                                node.setProperty(property, values);
                                return;
                        }

                        // single
                        if (prop.isMultiple()) {
                                prop.remove();
                                node.setProperty(property, value.toString());
                                return;
                        }

                        if (value instanceof String)
                                prop.setValue((String) value);
                        else if (value instanceof Long)
                                prop.setValue((Long) value);
                        else if (value instanceof Integer)
                                prop.setValue(((Integer) value).longValue());
                        else if (value instanceof Double)
                                prop.setValue((Double) value);
                        else if (value instanceof Float)
                                prop.setValue(((Float) value).doubleValue());
                        else if (value instanceof Calendar)
                                prop.setValue((Calendar) value);
                        else if (value instanceof BigDecimal)
                                prop.setValue((BigDecimal) value);
                        else if (value instanceof Boolean)
                                prop.setValue((Boolean) value);
                        else if (value instanceof byte[])
                                JcrUtils.setBinaryAsBytes(prop, (byte[]) value);
                        else if (value instanceof Instant) {
                                Instant instant = (Instant) value;
                                GregorianCalendar calendar = new GregorianCalendar();
                                calendar.setTime(Date.from(instant));
                                prop.setValue(calendar);
                        } else // try with toString()
                                prop.setValue(value.toString());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot set property " + property + " of " + node + " to " + value, e);
                }
        }

        /**
         * Get property as {@link String}.
         * 
         * @return the value of
         *         {@link Node#getProperty(String)}.{@link Property#getString()} or
         *         <code>null</code> if the property does not exist.
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String get(Node node, String property) {
                return get(node, property, null);
        }

        /**
         * Get property as a {@link String}. If the property is multiple it returns the
         * first value.
         * 
         * @return the value of
         *         {@link Node#getProperty(String)}.{@link Property#getString()} or
         *         <code>defaultValue</code> if the property does not exist.
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static String get(Node node, String property, String defaultValue) {
                try {
                        if (node.hasProperty(property)) {
                                Property p = node.getProperty(property);
                                if (!p.isMultiple())
                                        return p.getString();
                                else {
                                        Value[] values = p.getValues();
                                        if (values.length == 0)
                                                return defaultValue;
                                        else
                                                return values[0].getString();
                                }
                        } else
                                return defaultValue;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot retrieve property " + property + " from " + node, e);
                }
        }

        /**
         * Get property as a {@link Value}.
         * 
         * @return {@link Node#getProperty(String)} or <code>null</code> if the property
         *         does not exist.
         * @throws JcrException caused by {@link RepositoryException}
         */
        public static Value getValue(Node node, String property) {
                try {
                        if (node.hasProperty(property))
                                return node.getProperty(property).getValue();
                        else
                                return null;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot retrieve property " + property + " from " + node, e);
                }
        }

        /**
         * Get property doing a best effort to cast it as the target object.
         * 
         * @return the value of {@link Node#getProperty(String)} or
         *         <code>defaultValue</code> if the property does not exist.
         * @throws IllegalArgumentException if the value could not be cast
         * @throws JcrException             in case of unexpected
         *                                  {@link RepositoryException}
         */
        @SuppressWarnings("unchecked")
        public static <T> T getAs(Node node, String property, T defaultValue) {
                try {
                        // TODO deal with multiple
                        if (node.hasProperty(property)) {
                                Property p = node.getProperty(property);
                                try {
                                        if (p.isMultiple()) {
                                                throw new UnsupportedOperationException("Multiple values properties are not supported");
                                        }
                                        Value value = p.getValue();
                                        return (T) get(value);
                                } catch (ClassCastException e) {
                                        throw new IllegalArgumentException(
                                                        "Cannot cast property of type " + PropertyType.nameFromValue(p.getType()), e);
                                }
                        } else {
                                return defaultValue;
                        }
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot retrieve property " + property + " from " + node, e);
                }
        }
        
        public static <T> T getAs(Node node, String property, Class<T> clss) {
                if(String.class.isAssignableFrom(clss)) {
                        return (T)get(node,property);
                }       else    if(Long.class.isAssignableFrom(clss)) {
                        return (T)get(node,property);
                }else {
                        throw new IllegalArgumentException("Unsupported format "+clss);
                }
        }

        /**
         * Get a multiple property as a list, doing a best effort to cast it as the
         * target list.
         * 
         * @return the value of {@link Node#getProperty(String)}.
         * @throws IllegalArgumentException if the value could not be cast
         * @throws JcrException             in case of unexpected
         *                                  {@link RepositoryException}
         */
        public static <T> List<T> getMultiple(Node node, String property) {
                try {
                        if (node.hasProperty(property)) {
                                Property p = node.getProperty(property);
                                return getMultiple(p);
                        } else {
                                return null;
                        }
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot retrieve multiple values property " + property + " from " + node, e);
                }
        }

        /**
         * Get a multiple property as a list, doing a best effort to cast it as the
         * target list.
         */
        @SuppressWarnings("unchecked")
        public static <T> List<T> getMultiple(Property p) {
                try {
                        List<T> res = new ArrayList<>();
                        if (!p.isMultiple()) {
                                res.add((T) get(p.getValue()));
                                return res;
                        }
                        Value[] values = p.getValues();
                        for (Value value : values) {
                                res.add((T) get(value));
                        }
                        return res;
                } catch (ClassCastException | RepositoryException e) {
                        throw new IllegalArgumentException("Cannot get property " + p, e);
                }
        }

        /** Cast a {@link Value} to a standard Java object. */
        public static Object get(Value value) {
                Binary binary = null;
                try {
                        switch (value.getType()) {
                        case PropertyType.STRING:
                                return value.getString();
                        case PropertyType.DOUBLE:
                                return (Double) value.getDouble();
                        case PropertyType.LONG:
                                return (Long) value.getLong();
                        case PropertyType.BOOLEAN:
                                return (Boolean) value.getBoolean();
                        case PropertyType.DATE:
                                return value.getDate();
                        case PropertyType.BINARY:
                                binary = value.getBinary();
                                byte[] arr = null;
                                try (InputStream in = binary.getStream(); ByteArrayOutputStream out = new ByteArrayOutputStream();) {
                                        IOUtils.copy(in, out);
                                        arr = out.toByteArray();
                                } catch (IOException e) {
                                        throw new RuntimeException("Cannot read binary from " + value, e);
                                }
                                return arr;
                        default:
                                return value.getString();
                        }
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot cast value from " + value, e);
                } finally {
                        if (binary != null)
                                binary.dispose();
                }
        }

        /**
         * Retrieves the {@link Session} related to this node.
         * 
         * @deprecated Use {@link #getSession(Node)} instead.
         */
        @Deprecated
        public static Session session(Node node) {
                return getSession(node);
        }

        /** Retrieves the {@link Session} related to this node. */
        public static Session getSession(Node node) {
                try {
                        return node.getSession();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot retrieve session related to " + node, e);
                }
        }

        /** Retrieves the root node related to this session. */
        public static Node getRootNode(Session session) {
                try {
                        return session.getRootNode();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get root node for " + session, e);
                }
        }

        /** Whether this item exists. */
        public static boolean itemExists(Session session, String path) {
                try {
                        return session.itemExists(path);
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot check whether " + path + " exists", e);
                }
        }

        /**
         * Saves the {@link Session} related to this node. Note that all other unrelated
         * modifications in this session will also be saved.
         */
        public static void save(Node node) {
                try {
                        Session session = node.getSession();
//                      if (node.isNodeType(NodeType.MIX_LAST_MODIFIED)) {
//                              set(node, Property.JCR_LAST_MODIFIED, Instant.now());
//                              set(node, Property.JCR_LAST_MODIFIED_BY, session.getUserID());
//                      }
                        if (session.hasPendingChanges())
                                session.save();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot save session related to " + node + " in workspace "
                                        + session(node).getWorkspace().getName(), e);
                }
        }

        /** Login to a JCR repository. */
        public static Session login(Repository repository, String workspace) {
                try {
                        return repository.login(workspace);
                } catch (RepositoryException e) {
                        throw new IllegalArgumentException("Cannot login to repository", e);
                }
        }

        /** Safely and silently logs out a session. */
        public static void logout(Session session) {
                try {
                        if (session != null)
                                if (session.isLive())
                                        session.logout();
                } catch (Exception e) {
                        // silent
                }
        }

        /** Safely and silently logs out the underlying session. */
        public static void logout(Node node) {
                Jcr.logout(session(node));
        }

        /*
         * SECURITY
         */
        /**
         * Add a single privilege to a node.
         * 
         * @see Privilege
         */
        public static void addPrivilege(Node node, String principal, String privilege) {
                try {
                        Session session = node.getSession();
                        JcrUtils.addPrivilege(session, node.getPath(), principal, privilege);
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot add privilege " + privilege + " to " + node, e);
                }
        }

        /*
         * VERSIONING
         */
        /** Get checked out status. */
        public static boolean isCheckedOut(Node node) {
                try {
                        return node.isCheckedOut();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot retrieve checked out status of " + node, e);
                }
        }

        /** @see VersionManager#checkpoint(String) */
        public static void checkpoint(Node node) {
                try {
                        versionManager(node).checkpoint(node.getPath());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot check in " + node, e);
                }
        }

        /** @see VersionManager#checkin(String) */
        public static void checkin(Node node) {
                try {
                        versionManager(node).checkin(node.getPath());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot check in " + node, e);
                }
        }

        /** @see VersionManager#checkout(String) */
        public static void checkout(Node node) {
                try {
                        versionManager(node).checkout(node.getPath());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot check out " + node, e);
                }
        }

        /** Get the {@link VersionManager} related to this node. */
        public static VersionManager versionManager(Node node) {
                try {
                        return node.getSession().getWorkspace().getVersionManager();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get version manager from " + node, e);
                }
        }

        /** Get the {@link VersionHistory} related to this node. */
        public static VersionHistory getVersionHistory(Node node) {
                try {
                        return versionManager(node).getVersionHistory(node.getPath());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get version history from " + node, e);
                }
        }

        /**
         * The linear versions of this version history in reverse order and without the
         * root version.
         */
        public static List<Version> getLinearVersions(VersionHistory versionHistory) {
                try {
                        List<Version> lst = new ArrayList<>();
                        VersionIterator vit = versionHistory.getAllLinearVersions();
                        while (vit.hasNext())
                                lst.add(vit.nextVersion());
                        lst.remove(0);
                        Collections.reverse(lst);
                        return lst;
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get linear versions from " + versionHistory, e);
                }
        }

        /** The frozen node related to this {@link Version}. */
        public static Node getFrozenNode(Version version) {
                try {
                        return version.getFrozenNode();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get frozen node from " + version, e);
                }
        }

        /** Get the base {@link Version} related to this node. */
        public static Version getBaseVersion(Node node) {
                try {
                        return versionManager(node).getBaseVersion(node.getPath());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get base version from " + node, e);
                }
        }

        /*
         * FILES
         */
        /**
         * Returns the size of this file.
         * 
         * @see NodeType#NT_FILE
         */
        public static long getFileSize(Node fileNode) {
                try {
                        if (!fileNode.isNodeType(NodeType.NT_FILE))
                                throw new IllegalArgumentException(fileNode + " must be a file.");
                        return getBinarySize(fileNode.getNode(Node.JCR_CONTENT).getProperty(Property.JCR_DATA).getBinary());
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get file size of " + fileNode, e);
                }
        }

        /** Returns the size of this {@link Binary}. */
        public static long getBinarySize(Binary binaryArg) {
                try {
                        try (Bin binary = new Bin(binaryArg)) {
                                return binary.getSize();
                        }
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get file size of binary " + binaryArg, e);
                }
        }

        // QUERY
        /** Creates a JCR-SQL2 query using {@link MessageFormat}. */
        public static Query createQuery(QueryManager qm, String sql, Object... args) {
                // fix single quotes
                sql = sql.replaceAll("'", "''");
                String query = MessageFormat.format(sql, args);
                try {
                        return qm.createQuery(query, Query.JCR_SQL2);
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot create JCR-SQL2 query from " + query, e);
                }
        }

        /** Executes a JCR-SQL2 query using {@link MessageFormat}. */
        public static NodeIterator executeQuery(QueryManager qm, String sql, Object... args) {
                Query query = createQuery(qm, sql, args);
                try {
                        return query.execute().getNodes();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot execute query " + sql + " with arguments " + Arrays.asList(args), e);
                }
        }

        /** Executes a JCR-SQL2 query using {@link MessageFormat}. */
        public static NodeIterator executeQuery(Session session, String sql, Object... args) {
                QueryManager queryManager;
                try {
                        queryManager = session.getWorkspace().getQueryManager();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get query manager from session " + session, e);
                }
                return executeQuery(queryManager, sql, args);
        }

        /**
         * Executes a JCR-SQL2 query using {@link MessageFormat}, which must return a
         * single node at most.
         * 
         * @return the node or <code>null</code> if not found.
         */
        public static Node getNode(QueryManager qm, String sql, Object... args) {
                NodeIterator nit = executeQuery(qm, sql, args);
                if (nit.hasNext()) {
                        Node node = nit.nextNode();
                        if (nit.hasNext())
                                throw new IllegalStateException(
                                                "Query " + sql + " with arguments " + Arrays.asList(args) + " returned more than one node.");
                        return node;
                } else {
                        return null;
                }
        }

        /**
         * Executes a JCR-SQL2 query using {@link MessageFormat}, which must return a
         * single node at most.
         * 
         * @return the node or <code>null</code> if not found.
         */
        public static Node getNode(Session session, String sql, Object... args) {
                QueryManager queryManager;
                try {
                        queryManager = session.getWorkspace().getQueryManager();
                } catch (RepositoryException e) {
                        throw new JcrException("Cannot get query manager from session " + session, e);
                }
                return getNode(queryManager, sql, args);
        }

        /** Singleton. */
        private Jcr() {

        }
}