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/*
 * JasperReports - Free Java Reporting Library.
 * Copyright (C) 2001 - 2019 TIBCO Software Inc. All rights reserved.
 * http://www.jaspersoft.com
 *
 * Unless you have purchased a commercial license agreement from Jaspersoft,
 * the following license terms apply:
 *
 * This program is part of JasperReports.
 *
 * JasperReports is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * JasperReports is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with JasperReports. If not, see .
 */
package net.sf.jasperreports.engine.json.expression.member.evaluation;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;

import net.sf.jasperreports.engine.json.JRJsonNode;
import net.sf.jasperreports.engine.json.JsonNodeContainer;
import net.sf.jasperreports.engine.json.expression.EvaluationContext;
import net.sf.jasperreports.engine.json.expression.member.MemberExpression;
import net.sf.jasperreports.engine.json.expression.member.ObjectConstructionExpression;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

/**
 * @author Narcis Marcu ([email protected])
 */
public class ObjectConstructionExpressionEvaluator extends AbstractMemberExpressionEvaluator {
    private static final Log log = LogFactory.getLog(ObjectConstructionExpressionEvaluator.class);

    private ObjectConstructionExpression expression;

    public ObjectConstructionExpressionEvaluator(EvaluationContext evaluationContext, ObjectConstructionExpression expression) {
        super(evaluationContext);
        this.expression = expression;
    }

    @Override
    public JsonNodeContainer evaluate(JsonNodeContainer contextNode) {
        if (log.isDebugEnabled()) {
            log.debug("---> evaluating expression [" + expression +
                    "] on a node with (size: " + contextNode.getSize() +
                    ", cSize: " + contextNode.getContainerSize() + ")");
        }

        JsonNodeContainer result = new JsonNodeContainer();

        switch(expression.getDirection()) {
            case DOWN:
                for (JRJsonNode node: contextNode.getNodes()) {
                    result.addNodes(goDown(node));
                }

                break;
            case ANYWHERE_DOWN:
                for (JRJsonNode node: contextNode.getNodes()) {
                    result.addNodes(goAnywhereDown(node));
                }

                break;
        }

        if (result.getSize() > 0) {
            return result;
        }

        return null;
    }

    @Override
    public MemberExpression getMemberExpression() {
        return expression;
    }

    private List goDown(JRJsonNode jrJsonNode) {
        List result = new ArrayList<>();
        JsonNode dataNode = jrJsonNode.getDataNode();

        // advance into object
        if (dataNode.isObject()) {
            JRJsonNode deeperNode = constructNewObjectNodeWithKeys(jrJsonNode);
            if (deeperNode != null) {
                result.add(deeperNode);
            }
        }
        // advance into array
        else if (dataNode.isArray()) {
            for (JsonNode node : dataNode) {
                JRJsonNode childWithKeys = constructNewObjectNodeWithKeys(jrJsonNode.createChild(node));

                if (childWithKeys != null) {
                    result.add(childWithKeys);
                }
            }
        }

        return result;
    }

    private JRJsonNode constructNewObjectNodeWithKeys(JRJsonNode from) {
        ObjectNode newNode = getEvaluationContext().getObjectMapper().createObjectNode();

        for (String objectKey: expression.getObjectKeys()) {
            JsonNode deeperNode = from.getDataNode().get(objectKey);

            if (deeperNode != null && (deeperNode.isObject() || deeperNode.isValueNode() || deeperNode.isArray())) {
                JRJsonNode deeperChild = from.createChild(deeperNode);

                if (applyFilter(deeperChild)) {
                    newNode.put(objectKey, deeperNode);
                }
            }
        }

        if (newNode.size() > 0) {
            return from.createChild(newNode);
        }

        return null;
    }

    private List goAnywhereDown(JRJsonNode jrJsonNode) {
        List result = new ArrayList<>();
        Deque stack = new ArrayDeque<>();

        if (log.isDebugEnabled()) {
            log.debug("initial stack population with: " + jrJsonNode.getDataNode());
        }

        // populate the stack initially
        stack.push(jrJsonNode);

        while (!stack.isEmpty()) {
            JRJsonNode stackNode = stack.pop();
            JsonNode stackDataNode = stackNode.getDataNode();

            addChildrenToStack(stackNode, stack);

            if (log.isDebugEnabled()) {
                log.debug("processing stack element: " + stackDataNode);
            }

            // process the current stack item
            if (stackDataNode.isObject()) {
                JRJsonNode childWithKeys = constructNewObjectNodeWithKeys(stackNode);

                if (childWithKeys != null) {
                    result.add(childWithKeys);
                }
            }
        }

        return result;
    }

}