/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 *
 * ECOMP is a trademark and service mark of AT&T Intellectual Property.
 */
package org.onap.aai.serialization.tinkerpop;

import org.apache.tinkerpop.gremlin.process.traversal.step.util.Tree;
import org.apache.tinkerpop.gremlin.structure.*;
import org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertex;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

/**
 * Represents a {@link Vertex} that is disconnected from a {@link Graph} however, 
 * traversals are supported as they are backed by a Tree with saturated {@link Vertex} and {@link Edge} objects.
 * These objects are not mutable and can only be used to read information out.
 *
 */

public class TreeBackedVertex extends DetachedVertex implements Vertex {

	private static final long serialVersionUID = -976854460992756953L;
	private final Tree<Element> tree;
	private final Vertex self;
	public TreeBackedVertex (Vertex v, Tree<Element> tree) {
		super(v, true);
		this.self = v;
		this.tree = tree;
	}
	
	 @Override
    public Iterator<Edge> edges(final Direction direction, final String... edgeLabels) {
		final List<Element> edges = tree.getObjectsAtDepth(2);
		final List<Tree<Element>> trees = tree.getTreesAtDepth(2);
		final List<Tree<Element>> vTrees = tree.getTreesAtDepth(3);
        return edges.stream().map( ele -> (Edge)ele).filter(e -> {
			if (Direction.IN.equals(direction)) {
				return e.inVertex().equals(self);
			} else if (Direction.OUT.equals(direction)) {
				return e.outVertex().equals(self);
			} else {
				return true;
			}
		}).filter(e -> {
			boolean result = false;
			if (edgeLabels.length == 0) {
				return true;
			}
			for (String label : edgeLabels) {
				if (label.equals(e.label())) {
					result = true;
					break;
				}
			}
			return result;
		}).map(e -> {
			Tree<Element> eTree = new Tree<>();
			for (Tree<Element> tree : trees) {
				if (tree.keySet().contains(e)) {
					eTree = tree;
					break;
				}
			}
			TreeBackedVertex in = null;
			TreeBackedVertex out = null;
			if (e.inVertex().equals(self)) {
				in = this;
				out = this.createForVertex(e.outVertex(), vTrees);
			} else if (e.outVertex().equals(self)) {
				out = this;
				in = this.createForVertex(e.inVertex(), vTrees);
			}
			return (Edge)new TreeBackedEdge(e, in, out);
		}).iterator();

    }
	 
	private TreeBackedVertex createForVertex(Vertex v, List<Tree<Element>> trees) {
		Tree<Element> vTree = new Tree<>();
		for (Tree<Element> tree : trees) {
			if (tree.keySet().contains(v)) {
				vTree = tree;
				break;
			}
		}
		
		return new TreeBackedVertex((Vertex)vTree.keySet().iterator().next(), vTree);
	}
    @Override
    public Iterator<Vertex> vertices(final Direction direction, final String... labels) {
    	final List<Tree<Element>> vertexElements = tree.getTreesAtDepth(3);
		final List<Element> edgeElements = tree.getObjectsAtDepth(2);
		return edgeElements.stream().map( ele -> (Edge)ele).filter(e -> {
			boolean result = false;
			if (labels.length == 0) {
				return true;
			}
			for (String label : labels) {
				if (label.equals(e.label())) {
					result = true;
					break;
				}
			}
			return result;
		}).filter(e -> {
			if (Direction.IN.equals(direction) && e.inVertex().equals(self)) {
				return true;
			} else if (Direction.OUT.equals(direction) && e.outVertex().equals(self)) {
				return true;
			} else if (Direction.BOTH.equals(direction)){
				return true;
			} else {
				return false;
			}
		}).map(e -> {
			final List<Vertex> list;
			if (Direction.IN.equals(direction)) {
				list = Collections.singletonList(e.outVertex());
			} else if (Direction.OUT.equals(direction)){
				list = Collections.singletonList(e.inVertex());
			} else {
				list = new ArrayList<>();
				Iterator<Vertex> itr = e.bothVertices();
				while (itr.hasNext()) {
    				list.add(itr.next());
				}
			}
			return list;
			
		}).flatMap(list -> list.stream()).map(v -> {
			Tree<Element> vTree = new Tree<Element>();
			for (Tree<Element> tree : vertexElements) {
				if (tree.keySet().contains(v)) {
					vTree = tree;
					break;
				}
			}
			
			return (Vertex)new TreeBackedVertex(v, vTree);
		}).iterator();
	}
	
}