rdf.scala.utils/src/main/scala/org/apache/clerezza/rdf/scala/utils/RichGraphNode.scala

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.clerezza.rdf.scala.utils

import org.apache.clerezza.rdf.ontologies.RDF
import org.apache.clerezza.rdf.utils.GraphNode
import java.util.Iterator
import _root_.scala.collection.JavaConversions._
import _root_.scala.reflect.Manifest
import org.apache.clerezza.rdf.core.impl.SimpleMGraph
import org.apache.clerezza.rdf.core.{TripleCollection, UriRef, Resource, Literal, TypedLiteral, LiteralFactory, NonLiteral, BNode}
import org.apache.clerezza.rdf.utils.UnionMGraph


/**
 * A RichGraphNode decorates A GraphNode with additional method to be part on a DSL-style scala library.
 *
 * The default constructor is same a the GraphNode constructor, i.e. it takes the node and its context
 * Triple-collection
 *
 * @param resource the node represented by this RichGraphNode
 * @param graph the TripleCollection that describes the resource
 */
class RichGraphNode(resource: Resource, graph: TripleCollection ) extends GraphNode(resource, graph) {

  /**
   * Construct a RichGraphNode given an existing [[GraphNde]]
   *
   * @param node The GraphNode to be wrapped
   */
   def this(node: GraphNode) = this(node.getNode, node.getGraph)
   
  /**
   * Operator syntax shortcut to get all objects as <code>RichGraphNode</code>
   *
   * @return all objects of the specified property of the node wrapped by this object
   */
  def /(property: UriRef): CollectedIter[RichGraphNode] = {
    new CollectedIter[RichGraphNode](() => new GraphNodeIter(getObjects(property)), readLock)
  }

  /**
   * Operator syntax shortcut to get all subjects as <code>RichGraphNode</code>ref
   *
   * @param property the property for which the subjects pointing to this node by that property are requested
   * @return the matching resources
   */
  def /-(property: UriRef): CollectedIter[RichGraphNode] = {
    new CollectedIter[RichGraphNode](() => new GraphNodeIter(getSubjects(property)), readLock)
  }

  /**
   * Get the elements of the rdf:List represented by this node
   * @return a List with the elements of the rdf:List represented by this node
   */
  def !! = (for (listElem <- asList) yield {
    new RichGraphNode(new GraphNode(listElem, getGraph))
  }).toList

  /**
   * get a specified of the rdf:List represented by this node
   *
   * @return the specified index value
   */
  def %!!(index: Int) = new RichGraphNode(new GraphNode(asList.get(index),
                                                        getGraph))

  /**
   * produces a default String representation for the node, this is the lexical form of literals,
   * the unicode-string for UriRef and for BNodes the value returned by toString
   *
   * @return the default string representation of the node
   */
  def * : String = {
    getNode() match {
      case lit: Literal => lit.getLexicalForm
      case uri: UriRef => uri.getUnicodeString
      case wrappedNode => wrappedNode.toString
    }
  }

  private def asClass[T](clazz : Class[T]) : T= {
    val typedLiteral = getNode().asInstanceOf[TypedLiteral]
    clazz match {
      case c if(c == classOf[Boolean])  => LiteralFactory.getInstance().createObject(
          classOf[java.lang.Boolean], typedLiteral).booleanValue.asInstanceOf[T]
      case _ => LiteralFactory.getInstance().createObject(clazz, typedLiteral)
    }
  }

  /**
   * Creates an instance of specified Class-Type representing the value of the literal wrapped by this
   * <code>GraphNode</code>
   *
   * @return the literal represented by this node as instance of the specified type
   */
  def as[T](implicit m: Manifest[T]): T = {
    asClass(m.erasure.asInstanceOf[Class[T]])
  }

  /**
   * Operator syntax shortcut to get the <code>Resource</code> wrapped by this
   * <code>GraphNode</code>
   *
   * @return the node represented by this GraphNode as Resource, same as <code>getNode</code>
   */
  def ! = {
    getNode()
  }

  private class GraphNodeIter[T <: Resource](base: Iterator[T]) extends Iterator[RichGraphNode] {
    override def hasNext() = {
        base.hasNext();
    }

    override def next() : RichGraphNode = {
      new RichGraphNode(new GraphNode(base.next(), getGraph));
    }

    override def remove() {
      base.remove()
    }
  }

  /**
   *Sets the RDF:type of the subject */
  def a(rdfclass: UriRef): RichGraphNode = {
    addProperty(RDF.`type`, rdfclass)
    return this
  }

  /*
   * create an RichGraphNode from this one where the backing graph is protected from writes by a new
   * SimpleGraph.
   */
  def protect(): RichGraphNode = new RichGraphNode(getNode, new UnionMGraph(new SimpleMGraph(), graph))


  /**
   * relate the subject via the given relation to....
   */
  def --(rel: Resource): DashTuple = new DashTuple(rel)

  def --(rel: RichGraphNode): DashTuple = new DashTuple(rel.getNode)


  /**
   * relate the subject via the inverse of the given relation to....
   */
  def <--(tuple: RichGraphNode#DashTuple): RichGraphNode = {
    val inversePropertyRes = tuple.first.getNode
    val inverseProperty: UriRef =  inversePropertyRes match {
      case p: UriRef => p
      case _ => throw new RuntimeException("DashTuple must be a UriRef")
    }
    RichGraphNode.this.addInverseProperty(inverseProperty, tuple.second)
    RichGraphNode.this
  }


  /** class for Inverse relations with the current RichGraphNode.ref as object */
  //TODO add support for adding many for symmetry reasons
//  class InverseDashTuple(rel: DashTuple) {
//
//    /**
//     * ...to the following non literal
//     */
//    def --(subj: NonLiteral): RichGraphNode = {
//      RichGraphNode.this.addInverseProperty(rel, subj)
//      RichGraphNode.this
//    }
//
//    /**
//     * ...to the following resource (given as a string)
//     */
//    def --(subj: String): RichGraphNode = --(new UriRef(subj))
//
//    /**
//     * ...to the following EzGraphNode
//     * (useful for opening a new parenthesis and specifying other things in more detail
//     */
//    def --(subj: GraphNode): RichGraphNode = {
//      --(subj.getNode.asInstanceOf[NonLiteral])
//    }
//    // since we can only have inverses from non literals (howto deal with bndoes?)
//  }

  /**
   *  class for relations with the current RichGraphNode.ref as subject
   */
  class DashTuple(val second: Resource) {

    val first = RichGraphNode.this
    /**
     * ...to the following non resource
     */
    def -->(obj: Resource): RichGraphNode = {
      val property = second match {
        case u: UriRef => u;
        case _ => throw new RuntimeException("Property must be a UriRef")
      }
      RichGraphNode.this.addProperty(property, obj)
      RichGraphNode.this
    }


    /**
     * ...to the EzGraphNode, which is useful for opening a parenthesis.
     */
    def -->(sub: GraphNode): RichGraphNode = {
      //RichGraphNode.this + sub
      -->(sub.getNode)
    }
    /**
     * Add one relation for each member of the iterable collection
     */
    def -->>[T <: Resource](uris: Iterable[T]): RichGraphNode = {
      for (u <- uris) -->(u)
      RichGraphNode.this
    }
  }
}