/*-
 * ============LICENSE_START=======================================================
 * org.openecomp.aai
 * ================================================================================
 * Copyright (C) 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=========================================================
 */

package org.openecomp.aai.query.builder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Optional;
import java.util.Set;

import org.apache.tinkerpop.gremlin.process.traversal.P;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal.Admin;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
import org.apache.tinkerpop.gremlin.structure.Direction;
import org.apache.tinkerpop.gremlin.structure.Vertex;

import org.openecomp.aai.db.props.AAIProperties;
import org.openecomp.aai.exceptions.AAIException;
import org.openecomp.aai.introspection.Introspector;
import org.openecomp.aai.introspection.Loader;
import org.openecomp.aai.schema.enums.ObjectMetadata;
import org.openecomp.aai.schema.enums.PropertyMetadata;
import org.openecomp.aai.serialization.db.EdgeRule;
import org.openecomp.aai.serialization.db.EdgeRules;
import org.openecomp.aai.serialization.db.EdgeType;
import org.openecomp.aai.serialization.db.exceptions.NoEdgeRuleFoundException;

/**
 * The Class GraphTraversalBuilder.
 */
public abstract class GraphTraversalBuilder extends QueryBuilder {

	protected GraphTraversal<Vertex, Vertex> traversal = null;
	protected Admin<Vertex, Vertex> completeTraversal = null;
	private EdgeRules edgeRules = EdgeRules.getInstance();
	
	protected int parentStepIndex = 0;
	protected int containerStepIndex = 0;
	protected int stepIndex = 0;
	
	/**
	 * Instantiates a new graph traversal builder.
	 *
	 * @param loader the loader
	 */
	public GraphTraversalBuilder(Loader loader, GraphTraversalSource source) {
		super(loader, source);
		
		traversal = __.start();
		
	}
	
	/**
	 * Instantiates a new graph traversal builder.
	 *
	 * @param loader the loader
	 * @param start the start
	 */
	public GraphTraversalBuilder(Loader loader, GraphTraversalSource source, Vertex start) {
		super(loader, source, start);
		
		traversal = __.start();
		
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getVerticesByIndexedProperty(String key, Object value) {
	
		return this.getVerticesByProperty(key, value);
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getVerticesByIndexedProperty(String key, List<?> values) {
		return this.getVerticesByProperty(key, values);
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getVerticesByProperty(String key, Object value) {
		
		//this is because the index is registered as an Integer
		value = this.correctObjectType(value);
		
		traversal.has(key, value);
		
		stepIndex++;
		return this;
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getVerticesByProperty(final String key, final List<?> values) {
		
		//this is because the index is registered as an Integer
		List<Object> correctedValues = new ArrayList<>();
		for (Object item : values) {
			correctedValues.add(this.correctObjectType(item));
		}
		
		traversal.has(key, P.within(correctedValues));
		
		stepIndex++;
		return this;
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getChildVerticesFromParent(String parentKey, String parentValue, String childType) {
		traversal.has(parentKey, parentValue).has(AAIProperties.NODE_TYPE, childType);
		stepIndex++;
		return this;
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getTypedVerticesByMap(String type, LinkedHashMap<String, String> map) {
		
		for (String key : map.keySet()) {
			traversal.has(key, map.get(key));
			stepIndex++;
		}
		traversal.has(AAIProperties.NODE_TYPE, type);
		stepIndex++;
		return this;
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder createDBQuery(Introspector obj) {
		this.createKeyQuery(obj);
		this.createContainerQuery(obj);
		return this;
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder createKeyQuery(Introspector obj) {
		Set<String> keys = obj.getKeys();
		Object val;
		for (String key : keys) {
			val = obj.getValue(key);
			Optional<String> metadata = obj.getPropertyMetadata(key, PropertyMetadata.DB_ALIAS);
			if (metadata.isPresent()) {
				//use the db name for the field rather than the object model
				key = metadata.get();
			}
			if (val != null) {
				//this is because the index is registered as an Integer
				if (val.getClass().equals(Long.class)) {
					traversal.has(key,new Integer(val.toString()));
				} else {
					traversal.has(key, val);
				}
				stepIndex++;
			}
		}
		return this;
	}

	@Override
	public QueryBuilder exactMatchQuery(Introspector obj) {
		this.createKeyQuery(obj);
		allPropertiesQuery(obj);
		this.createContainerQuery(obj);
		return this;
	}
	
	private void allPropertiesQuery(Introspector obj) {
		Set<String> props = obj.getProperties();
		Set<String> keys = obj.getKeys();
		Object val;
		for (String prop : props) {
			if (obj.isSimpleType(prop) && !keys.contains(prop)) {
				val = obj.getValue(prop);
				if (val != null) {
					Optional<String> metadata = obj.getPropertyMetadata(prop, PropertyMetadata.DB_ALIAS);
					if (metadata.isPresent()) {
						//use the db name for the field rather than the object model
						prop = metadata.get();
					}
					//this is because the index is registered as an Integer
					if (val != null && val.getClass().equals(Long.class)) {
						traversal.has(prop,new Integer(val.toString()));
					} else {
						traversal.has(prop, val);
					}
					stepIndex++;
				}
			}
		}
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	
	public QueryBuilder createContainerQuery(Introspector obj) {
		String type = obj.getChildDBName();
		String abstractType = obj.getMetadata(ObjectMetadata.ABSTRACT);
		if (abstractType != null) {
			String[] inheritors = obj.getMetadata(ObjectMetadata.INHERITORS).split(",");
			traversal.has(AAIProperties.NODE_TYPE, P.within(inheritors));
		} else {
			traversal.has(AAIProperties.NODE_TYPE, type);
		}
		stepIndex++;
		markContainer();
		return this;
	}

	/**
	 * @throws NoEdgeRuleFoundException 
	 * @throws AAIException 
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder createEdgeTraversal(EdgeType type, Introspector parent, Introspector child) throws AAIException, NoEdgeRuleFoundException {
		String isAbstractType = parent.getMetadata(ObjectMetadata.ABSTRACT);
		if ("true".equals(isAbstractType)) {
			markParentBoundary();
			traversal.union(handleAbstractEdge(type, parent, child));
			stepIndex += 1;
		} else {
			this.edgeQuery(type, parent, child);
		}
		return this;
			
	}
	
	private Traversal<Vertex, Vertex>[] handleAbstractEdge(EdgeType type, Introspector abstractParent, Introspector child) throws AAIException, NoEdgeRuleFoundException {
		String childName = child.getDbName();
		String inheritorMetadata = abstractParent.getMetadata(ObjectMetadata.INHERITORS);
		String[] inheritors = inheritorMetadata.split(",");
		Traversal<Vertex, Vertex>[] unionTraversals = new Traversal[inheritors.length];
		int traversalIndex = 0;
		for (int i = 0; i < inheritors.length; i++) {
			String inheritor = inheritors[i];
			if (edgeRules.hasEdgeRule(inheritor, childName) || edgeRules.hasEdgeRule(childName, inheritor)) {
				EdgeRule rule = edgeRules.getEdgeRule(type, inheritor, childName);
				GraphTraversal<Vertex, Vertex> innerTraversal = __.start();
				if (rule.getDirection().equals(Direction.OUT)) {
					innerTraversal.out(rule.getLabel());
				} else {
					innerTraversal.in(rule.getLabel());
				}
				innerTraversal.has(AAIProperties.NODE_TYPE, childName);
				unionTraversals[traversalIndex] = innerTraversal;
				traversalIndex++;
			}
		}
		if (traversalIndex < inheritors.length) {
			Traversal<Vertex, Vertex>[] temp = Arrays.copyOfRange(unionTraversals, 0, traversalIndex);
			unionTraversals = temp;
		}
		return unionTraversals;
	}
	/**
	 * @throws NoEdgeRuleFoundException 
	 * @throws AAIException 
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder createEdgeTraversal(EdgeType type, Vertex parent, Introspector child) throws AAIException, NoEdgeRuleFoundException {
		
		String nodeType = parent.<String>property(AAIProperties.NODE_TYPE).orElse(null);
		Introspector parentObj = loader.introspectorFromName(nodeType);
		this.edgeQuery(type, parentObj, child);
		return this;
			
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder union(QueryBuilder... builder) {
		GraphTraversal<Vertex, Vertex>[] traversals = new GraphTraversal[builder.length];
		for (int i = 0; i < builder.length; i++) {
			traversals[i] = (GraphTraversal<Vertex, Vertex>)builder[i].getQuery();
		}
		this.traversal.union(traversals);
		stepIndex++;
		
		return this;
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder where(QueryBuilder... builder) {
		GraphTraversal<Vertex, Vertex>[] traversals = new GraphTraversal[builder.length];
		for (int i = 0; i < builder.length; i++) {
			this.traversal.where((GraphTraversal<Vertex, Vertex>)builder[i].getQuery());
			stepIndex++;
		}
		
		return this;
	}
	
	/**
	 * Edge query.
	 *
	 * @param outType the out type
	 * @param inType the in type
	 * @throws NoEdgeRuleFoundException 
	 * @throws AAIException 
	 */
	private void edgeQuery(EdgeType type, Introspector outObj, Introspector inObj) throws AAIException, NoEdgeRuleFoundException {
		String outType = outObj.getDbName();
		String inType = inObj.getDbName();
		
		if (outObj.isContainer()) {
			outType = outObj.getChildDBName();
		}
		if (inObj.isContainer()) {
			inType = inObj.getChildDBName();
		}
		markParentBoundary();
		EdgeRule rule = edgeRules.getEdgeRule(type, outType, inType);
		if (rule.getDirection().equals(Direction.OUT)) {
			traversal.out(rule.getLabel());
		} else {
			traversal.in(rule.getLabel());
		}
		stepIndex++;
		this.createContainerQuery(inObj);
	}
	
	@Override
	public QueryBuilder limit(long amount) {
		traversal.limit(amount);
		return this;
	}

	/**
	 * @{inheritDoc}
	 */
	@Override
	public <T> T getQuery() {
		return (T)this.traversal;
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public QueryBuilder getParentQuery() {

		return cloneQueryAtStep(parentStepIndex);
	}
	
	@Override
	public QueryBuilder getContainerQuery() {
		
		if (this.parentStepIndex == 0) {
			return removeQueryStepsBetween(0, containerStepIndex);
		} else {
			return cloneQueryAtStep(containerStepIndex);
		}
	}
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public void markParentBoundary() {
		parentStepIndex = stepIndex;
	}
	
	@Override
	public void markContainer() {
		containerStepIndex = stepIndex;
	}
	
	
	/**
	 * @{inheritDoc}
	 */
	@Override
	public Vertex getStart() {
		return this.start;
	}

	protected int getParentStepIndex() {
		return parentStepIndex;
	}

	protected int getContainerStepIndex() {
		return containerStepIndex;
	}

	protected int getStepIndex() {
		return stepIndex;
	}

	protected abstract QueryBuilder cloneQueryAtStep(int index);
	/**
	 * end is exclusive
	 * 
	 * @param start
	 * @param end
	 * @return
	 */
	protected abstract QueryBuilder removeQueryStepsBetween(int start, int end);
	
	private void executeQuery() {
		
		Admin<Vertex, Vertex> admin;
		if (start != null) {
			admin = source.V(start).asAdmin();
		} else {
			admin = source.V().asAdmin();

		}
		
		TraversalHelper.insertTraversal(admin.getEndStep(), traversal.asAdmin(), admin);
		
		this.completeTraversal = admin;
	}
	
	@Override
	public boolean hasNext() {
		if (this.completeTraversal == null) {
			executeQuery();
		}
		
		return this.completeTraversal.hasNext();
	}
	
	@Override
	public Vertex next() {
		if (this.completeTraversal == null) {
			executeQuery();
		}
		
		return this.completeTraversal.next();
	}
	
	@Override
	public List<Vertex> toList() {
		if (this.completeTraversal == null) {
			executeQuery();
		}
		
		return this.completeTraversal.toList();
	}

}