/**
 * 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.atlas.repository.graphdb.janus;

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

import org.apache.atlas.repository.graphdb.AtlasEdge;
import org.apache.atlas.repository.graphdb.AtlasElement;
import org.apache.atlas.repository.graphdb.AtlasSchemaViolationException;
import org.apache.atlas.repository.graphdb.AtlasVertex;
import org.apache.atlas.repository.graphdb.janus.graphson.AtlasGraphSONMode;
import org.apache.atlas.repository.graphdb.janus.graphson.AtlasGraphSONUtility;
import org.apache.tinkerpop.gremlin.structure.Element;
import org.apache.tinkerpop.gremlin.structure.Property;
import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;

import com.google.common.base.Function;
import com.google.common.collect.Lists;
import org.janusgraph.core.SchemaViolationException;
import org.janusgraph.core.JanusGraphElement;

/**
 * Janus implementation of AtlasElement.
 *
 * @param <T> the implementation class of the wrapped Janus element
 * that is stored.
 */
public class AtlasJanusElement<T extends Element> implements AtlasElement {

    private T element;
    protected AtlasJanusGraph graph;

    public AtlasJanusElement(AtlasJanusGraph graph, T element) {
        this.element = element;
        this.graph = graph;
    }

    @Override
    public <T> T getProperty(String propertyName, Class<T> clazz) {

        //add explicit logic to return null if the property does not exist
        //This is the behavior Atlas expects.  Janus throws an exception
        //in this scenario.
        Property p = getWrappedElement().property(propertyName);
        if (p.isPresent()) {
            Object propertyValue= p.value();
            if (propertyValue == null) {
                return null;
            }
            if (AtlasEdge.class == clazz) {
                return (T)graph.getEdge(propertyValue.toString());
            }
            if (AtlasVertex.class == clazz) {
                return (T)graph.getVertex(propertyValue.toString());
            }
            return (T)propertyValue;

        }
        return null;
    }



    /**
     * Gets all of the values of the given property.
     * @param propertyName
     * @return
     */
    @Override
    public <T> Collection<T> getPropertyValues(String propertyName, Class<T> type) {
        return Collections.singleton(getProperty(propertyName, type));
    }

    @Override
    public Set<String> getPropertyKeys() {
        return getWrappedElement().keys();
    }

    @Override
    public void removeProperty(String propertyName) {
        Iterator<? extends Property<String>> it = getWrappedElement().properties(propertyName);
        while(it.hasNext()) {
            Property<String> property = it.next();
            property.remove();
        }
    }

    @Override
    public void setProperty(String propertyName, Object value) {
        try {
            if (value == null) {
                Object existingVal = getProperty(propertyName, Object.class);
                if (existingVal != null) {
                    removeProperty(propertyName);
                }
            } else {
                getWrappedElement().property(propertyName, value);
            }
        } catch(SchemaViolationException e) {
            throw new AtlasSchemaViolationException(e);
        }
    }

    @Override
    public Object getId() {
        return element.id();
    }

    @Override
    public T getWrappedElement() {
        return element;
    }


    @Override
    public JSONObject toJson(Set<String> propertyKeys) throws JSONException {

        return AtlasGraphSONUtility.jsonFromElement(this, propertyKeys, AtlasGraphSONMode.NORMAL);
    }

    @Override
    public int hashCode() {
        int result = 37;
        result = 17*result + getClass().hashCode();
        result = 17*result + getWrappedElement().hashCode();
        return result;
    }

    @Override
    public boolean equals(Object other) {

        if (other == null) {
            return false;
        }

        if (other.getClass() != getClass()) {
            return false;
        }
        AtlasJanusElement otherElement = (AtlasJanusElement) other;
        return getWrappedElement().equals(otherElement.getWrappedElement());
    }

    @Override
    public List<String> getListProperty(String propertyName) {
        List<String> value =  getProperty(propertyName, List.class);
        return value;
    }

    @Override
    public void setListProperty(String propertyName, List<String> values) {
        setProperty(propertyName, values);

    }

    @Override
    public boolean exists() {
        try {
            return !((JanusGraphElement)element).isRemoved();
        } catch(IllegalStateException e) {
            return false;
        }

    }

    @Override
    public <T> void setJsonProperty(String propertyName, T value) {
        setProperty(propertyName, value);
    }

    @Override
    public <T> T getJsonProperty(String propertyName) {
        return (T)getProperty(propertyName, String.class);
    }

    @Override
    public String getIdForDisplay() {
        return getId().toString();
    }


    @Override
    public <V> List<V> getListProperty(String propertyName, Class<V> elementType) {

        List<String> value = getListProperty(propertyName);

        if (value == null || value.isEmpty()) {
            return (List<V>)value;
        }

        if (AtlasEdge.class.isAssignableFrom(elementType)) {


            return (List<V>)Lists.transform(value, new Function<String, AtlasEdge>(){

                @Override
                public AtlasEdge apply(String input) {
                    return graph.getEdge(input);
                }
            });
        }

        if (AtlasVertex.class.isAssignableFrom(elementType)) {

            return (List<V>)Lists.transform(value, new Function<String, AtlasVertex>(){

                @Override
                public AtlasVertex apply(String input) {
                    return graph.getVertex(input);
                }
            });
        }

        return (List<V>)value;
    }


    @Override
    public void setPropertyFromElementsIds(String propertyName, List<AtlasElement> values) {
        List<String> propertyValue = new ArrayList<>(values.size());
        for(AtlasElement value: values) {
            propertyValue.add(value.getId().toString());
        }
        setProperty(propertyName, propertyValue);
    }


    @Override
    public void setPropertyFromElementId(String propertyName, AtlasElement value) {
        setProperty(propertyName, value.getId().toString());

    }


    @Override
    public boolean isIdAssigned() {
        return true;
    }

}
