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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.ArrayIndexExpression;
import net.sf.jasperreports.engine.json.expression.member.MemberExpression;

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

import com.fasterxml.jackson.databind.JsonNode;

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

    private ArrayIndexExpression expression;

    public ArrayIndexExpressionEvaluator(EvaluationContext evaluationContext, ArrayIndexExpression expression) {
        super(evaluationContext);
        this.expression = expression;
    }

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

        JsonNodeContainer result = new JsonNodeContainer();

        switch(expression.getDirection()) {
            case DOWN:
                // this only make sense for containers with appropriate size
                if (expression.getIndex() >= 0 && expression.getIndex() < contextNode.getContainerSize()) {
                    List containerNodes = contextNode.getContainerNodes();
                    JRJsonNode nodeAtIndex = containerNodes.get(expression.getIndex());

                    if (applyFilter(nodeAtIndex)) {
                        result.add(nodeAtIndex);
                    }
                }
                break;
            case ANYWHERE_DOWN:
                List nodes = contextNode.getContainerNodes();

                for (JRJsonNode node: nodes) {
                    result.addNodes(goAnywhereDown(node));
                }

                break;
        }

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

        return null;

    }

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

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

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

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

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

            addChildrenToStack(stackNode, stack);

            // process the current stack item
            if (stackDataNode.isArray()) {
                if (log.isDebugEnabled()) {
                    log.debug("processing stack element: " + stackDataNode);
                }

                if (expression.getIndex() >= 0 && expression.getIndex() < stackDataNode.size()) {
                    JsonNode nodeAtIndex = stackDataNode.get(expression.getIndex());
                    JRJsonNode child = stackNode.createChild(nodeAtIndex);

                    if (applyFilter(child)) {
                        result.add(child);
                    }
                }
            }
        }

        return result;
    }

}