use traversal to add elements, mostly to fix remote graph setups

when using remote graphs, Graph is actually just an empty shell and
can't be used to e.g. add elements.

open problems:
* marshalled classes can use the @id annotation to specify
the ID of a vertex, but we cannot set the id of a vertex inside a traversal
* same needs to be applied for edges

re #223

gremlin-scala/src/main/scala/gremlin/scala/GremlinScala.scala

@@ -669,12 +669,14 @@ class GremlinScala[End](val traversal: GraphTraversal[_, End]) {
   // -------------------
 
   /** set the property to the given value */
-  def property[A](key: Key[A], value: A)(implicit ev: End <:< Element) =
-    GremlinScala[End, Labels](traversal.property(key.name, value))
+  def property[A](keyValue: KeyValue[A])(
+      implicit ev: End <:< Element): GremlinScala.Aux[End, Labels] =
+    property(keyValue.key, keyValue.value)
 
   /** set the property to the given value */
-  def property[A](keyValue: KeyValue[A])(implicit ev: End <:< Element) =
-    GremlinScala[End, Labels](traversal.property(keyValue.key.name, keyValue.value))
+  def property[A](key: Key[A], value: A)(
+      implicit ev: End <:< Element): GremlinScala.Aux[End, Labels] =
+    GremlinScala[End, Labels](traversal.property(key.name, value))
 
   /** set the property to the value determined by the given traversal */
   def property[A](key: Key[A])(value: GremlinScala[End] => GremlinScala[A])(
@@ -859,12 +861,19 @@ class GremlinScala[End](val traversal: GraphTraversal[_, End]) {
     GremlinScala[Edge, Labels](traversal.bothE(labels: _*))
 
   /** may be used together with `from` / `to`, see TraversalSpec for examples */
-  def addE(label: String)(implicit ev: End <:< Vertex): GremlinScala.Aux[Edge, Labels] =
-    GremlinScala[Edge, Labels](traversal.addE(label))
-  def addE(label: StepLabel[Vertex])(implicit ev: End <:< Vertex): GremlinScala.Aux[Edge, Labels] =
-    GremlinScala[Edge, Labels](traversal.addE(label.name))
+  def addE(label: String, properties: KeyValue[_]*)(
+      implicit ev: End <:< Vertex): GremlinScala.Aux[Edge, Labels] = {
+    val newTrav = properties.foldLeft(traversal.addE(label)) { (trav, prop) =>
+      trav.property(prop.key.name, prop.value)
+    }
+    GremlinScala[Edge, Labels](newTrav)
+  }
 
-  /** modulator, use in conjunction with addE()
+  def addE(label: StepLabel[Vertex], properties: KeyValue[_]*)(
+      implicit ev: End <:< Vertex): GremlinScala.Aux[Edge, Labels] =
+    addE(label.name, properties: _*)
+
+  /** modulator, use in conjunction with addE
     * http://tinkerpop.apache.org/docs/current/reference/#from-step */
   def from(vertex: Vertex): GremlinScala.Aux[End, Labels] =
     GremlinScala[End, Labels](traversal.from(vertex))
@@ -884,8 +893,8 @@ class GremlinScala[End](val traversal: GraphTraversal[_, End]) {
     GremlinScala[End, Labels](
       traversal.from(fromTraversal(start).traversal.asInstanceOf[GraphTraversal[End, Vertex]]))
 
-  /** modulator, use in conjunction with addE()
-    * http://tinkerpop.apache.org/docs/current/reference/#from-step */
+  /** modulator, use in conjunction with addE
+    * http://tinkerpop.apache.org/docs/current/reference/#to-step */
   def to(vertex: Vertex): GremlinScala.Aux[End, Labels] =
     GremlinScala[End, Labels](traversal.to(vertex))
 

gremlin-scala/src/main/scala/gremlin/scala/ScalaGraph.scala

@@ -18,21 +18,22 @@ case class ScalaGraph(traversalSource: TraversalSource) {
   def configure(conf: TraversalSource => TraversalSource) =
     ScalaGraph(conf(TraversalSource(graph)))
 
-  def addVertex(label: String): Vertex = graph.addVertex(label)
+  def addVertex(): Vertex =
+    traversalSource.underlying.addV().next
 
-  def addVertex(): Vertex = graph.addVertex()
+  def addVertex(label: String): Vertex =
+    traversalSource.underlying.addV(label).next
 
-  def addVertex(label: String, properties: (String, Any)*): Vertex = {
-    val labelParam = Seq(T.label, label)
-    val params =
-      properties.flatMap(pair => Seq(pair._1, pair._2.asInstanceOf[AnyRef]))
-    graph.addVertex(labelParam ++ params: _*)
+  def addVertex(properties: (String, Any)*): Vertex = {
+    val traversal = traversalSource.underlying.addV()
+    properties.foreach { case (key, value) => traversal.property(key, value) }
+    traversal.next
   }
 
-  def addVertex(properties: (String, Any)*): Vertex = {
-    val params =
-      properties.flatMap(pair => Seq(pair._1, pair._2.asInstanceOf[AnyRef]))
-    graph.addVertex(params: _*)
+  def addVertex(label: String, properties: (String, Any)*): Vertex = {
+    val traversal = traversalSource.underlying.addV(label)
+    properties.foreach { case (key, value) => traversal.property(key, value) }
+    traversal.next
   }
 
   def addVertex(label: String, properties: Map[String, Any]): Vertex =
@@ -44,10 +45,13 @@ case class ScalaGraph(traversalSource: TraversalSource) {
   /**
     * Save an object's values into a new vertex
     * @param cc The case class to persist as a vertex
+    *
+    * Note: this doesn't work with remote graphs, since remote graphs require you to use
+    * traversal steps to add a vertex (e.g. addV), but there's no step to set the ID
     */
   def addVertex[CC <: Product: Marshallable](cc: CC): Vertex = {
     val fromCC = implicitly[Marshallable[CC]].fromCC(cc)
-    val idParam = fromCC.id.toSeq.flatMap(List(T.id, _))
+    val idParam = fromCC.id.toSeq.flatMap(List(T.id, _)) //TODO: this will break things
     val labelParam = Seq(T.label, fromCC.label)
     val params = fromCC.valueMap.toSeq.flatMap(pair => Seq(pair._1, pair._2.asInstanceOf[AnyRef]))
     graph.addVertex(idParam ++ labelParam ++ params: _*)
@@ -60,34 +64,37 @@ case class ScalaGraph(traversalSource: TraversalSource) {
   def +(label: String, properties: KeyValue[_]*): Vertex =
     addVertex(label, properties.map(v => (v.key.name, v.value)).toMap)
 
+  /** start a traversal with `addV` */
   @deprecated("use `traversal.addV`", "3.3.1.2")
   def addV(): GremlinScala.Aux[Vertex, HNil] =
     traversalSource.addV()
 
+  /** start a traversal with `addV` */
   @deprecated("use `traversal.addV`", "3.3.1.2")
   def addV(label: String): GremlinScala.Aux[Vertex, HNil] =
     traversalSource.addV(label)
 
   @deprecated("use `traversal.inject`", "3.3.1.2")
+  /** start a traversal with given `starts`` */
   def inject[S](starts: S*): GremlinScala.Aux[S, HNil] =
     traversalSource.inject(starts: _*)
 
-  // start traversal with all vertices
+  /** start traversal with all vertices */
   @deprecated("use `traversal.V`", "3.3.1.2")
   def V(): GremlinScala.Aux[Vertex, HNil] =
     traversalSource.V()
 
-  // start traversal with all edges
+  /** start traversal with all edges */
   @deprecated("use `traversal.E`", "3.3.1.2")
   def E(): GremlinScala.Aux[Edge, HNil] =
     traversalSource.E()
 
-  // start traversal with some vertices identified by given ids
+  /** start traversal with some vertices identified by given ids */
   @deprecated("use `traversal.V`", "3.3.1.2")
   def V(vertexIds: Any*): GremlinScala.Aux[Vertex, HNil] =
     traversalSource.V(vertexIds: _*)
 
-  // start traversal with some edges identified by given ids
+  /** start traversal with some edges identified by given ids */
   @deprecated("use `traversal.E`", "3.3.1.2")
   def E(edgeIds: Any*): GremlinScala.Aux[Edge, HNil] =
     traversalSource.E(edgeIds: _*)

gremlin-scala/src/main/scala/gremlin/scala/ScalaVertex.scala

@@ -56,15 +56,8 @@ case class ScalaVertex(vertex: Vertex) extends ScalaElement[Vertex] {
 
   def bothE(labels: String*) = start().bothE(labels: _*)
 
-  def addEdge(
-      label: String,
-      inVertex: Vertex,
-      properties: Seq[KeyValue[_]] = Nil
-  ): Edge = {
-    val params =
-      properties.toSeq.flatMap(pair => Seq(pair.key.name, pair.value.asInstanceOf[AnyRef]))
-    vertex.addEdge(label, inVertex.vertex, params: _*)
-  }
+  def addEdge(label: String, inVertex: Vertex, properties: KeyValue[_]*): Edge =
+    vertex.start.addE(label, properties: _*).to(inVertex).head
 
   def addEdge[CC <: Product: Marshallable](inVertex: Vertex, cc: CC): Edge = {
     val fromCC = implicitly[Marshallable[CC]].fromCC(cc)
@@ -74,27 +67,27 @@ case class ScalaVertex(vertex: Vertex) extends ScalaElement[Vertex] {
   }
 
   def <--(se: SemiEdge): Edge =
-    se.from.asScala.addEdge(se.label, vertex, se.properties)
+    se.from.asScala.addEdge(se.label, vertex, se.properties: _*)
 
   def <--(de: SemiDoubleEdge): (Edge, Edge) =
-    addEdge(de.label, de.right, de.properties) -> de.right.asScala
-      .addEdge(de.label, vertex, de.properties)
+    addEdge(de.label, de.right, de.properties: _*) -> de.right.asScala
+      .addEdge(de.label, vertex, de.properties: _*)
 
   def ---(label: String): SemiEdge = SemiEdge(vertex, label)
 
   def ---(label: String, properties: KeyValue[_]*): SemiEdge =
-    SemiEdge(vertex, label, properties)
+    SemiEdge(vertex, label, properties: _*)
 
   def ---(label: String, properties: Map[String, Any]): SemiEdge =
     SemiEdge(vertex, label, properties.map {
       case (key, value) => Key[Any](key) -> value
-    }.toSeq)
+    }.toSeq: _*)
 
   def ---[CC <: Product: Marshallable](cc: CC): SemiEdge = {
     val fromCC = implicitly[Marshallable[CC]].fromCC(cc)
     SemiEdge(vertex, fromCC.label, fromCC.valueMap.map { r =>
       Key[Any](r._1) -> r._2
-    }.toSeq)
+    }.toSeq: _*)
   }
 
   def vertices(direction: Direction, edgeLabels: String*): util.Iterator[Vertex] =

gremlin-scala/src/main/scala/gremlin/scala/SemiEdge.scala

@@ -1,7 +1,7 @@
 package gremlin.scala
 
-case class SemiEdge(from: Vertex, label: String, properties: Seq[KeyValue[_]] = Nil) {
-  def -->(to: Vertex) = from.asScala.addEdge(label, to, properties)
+case class SemiEdge(from: Vertex, label: String, properties: KeyValue[_]*) {
+  def -->(to: Vertex) = from.asScala.addEdge(label, to, properties: _*)
 }
 
-case class SemiDoubleEdge(right: Vertex, label: String, properties: Seq[KeyValue[_]] = Nil)
+case class SemiDoubleEdge(right: Vertex, label: String, properties: KeyValue[_]*)

gremlin-scala/src/main/scala/gremlin/scala/package.scala

@@ -164,7 +164,7 @@ package object scala {
     lazy val keyValues: KeyValues = labelAndValues.tail
     lazy val properties: List[KeyValue[_]] = keyValues.toList
 
-    def ---(from: Vertex) = SemiEdge(from, label, properties)
-    def -->(right: Vertex) = SemiDoubleEdge(right, label, properties)
+    def ---(from: Vertex) = SemiEdge(from, label, properties: _*)
+    def -->(right: Vertex) = SemiDoubleEdge(right, label, properties: _*)
   }
 }

gremlin-scala/src/test/scala/gremlin/scala/ElementSpec.scala

@@ -42,7 +42,7 @@ class ElementSpec extends TestBase {
       * TODO: `properties` should take `Key` as well
       */
     it("sets a property with multiple values") {
-      val v = graph.addV().property(Name, "marko").property(Name, "marko a. rodriguez").head
+      val v = graph.addVertex((Name.name -> "marko"), (Name.name -> "marko a. rodriguez"))
       graph.V(v).properties(Name.name).count.head shouldBe 2
 
       v.property(Cardinality.list, Name.name, "m. a. rodriguez")
@@ -166,8 +166,7 @@ class ElementSpec extends TestBase {
       val v1 = graph.addVertex()
       val v2 = graph.addVertex()
 
-      val e =
-        v1.asScala.addEdge("testLabel", v2, Seq(TestProperty -> "testValue"))
+      val e = v1.asScala.addEdge("testLabel", v2, TestProperty -> "testValue")
       e.label shouldBe "testLabel"
       e.value2(TestProperty) shouldBe "testValue"
       e.valueMap(TestProperty.name) shouldBe Map(TestProperty.name -> "testValue")

gremlin-scala/src/test/scala/gremlin/scala/TraversalSpec.scala

@@ -321,6 +321,7 @@ class TraversalSpec extends WordSpec with Matchers {
   }
 
   "group" should {
+
     "modulate by property key" in new Fixture {
       val results: JMap[Int, JCollection[Vertex]] =
         graph.V