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/*
 Copyright 2013 Red Hat, Inc. and/or its affiliates.

 This file is part of lightblue.

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see .
 */
package com.redhat.lightblue.eval;

import java.util.Iterator;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.redhat.lightblue.crud.CrudConstants;
import com.redhat.lightblue.metadata.ArrayElement;
import com.redhat.lightblue.metadata.ArrayField;
import com.redhat.lightblue.metadata.FieldTreeNode;
import com.redhat.lightblue.metadata.ObjectArrayElement;
import com.redhat.lightblue.query.ArrayMatchExpression;
import com.redhat.lightblue.util.Path;

public class ArrayMatchEvaluator extends QueryEvaluator {
    private final Path field;
    private final QueryEvaluator ev;
    private final ObjectArrayElement elem;

    public ArrayMatchEvaluator(ArrayMatchExpression expr,
                               FieldTreeNode context) {
        // field needs to be resolved relative to the current context
        field = expr.getArray();
        FieldTreeNode node = context.resolve(field);
        if (node == null) {
            throw new EvaluationError(expr);
        }
        if (node instanceof ArrayField) {
            ArrayElement el = ((ArrayField) node).getElement();
            if (el instanceof ObjectArrayElement) {
                elem = (ObjectArrayElement) el;
                ev = QueryEvaluator.getInstance(expr.getElemMatch(), elem);
            } else {
                throw new EvaluationError(expr, CrudConstants.ERR_EXPECTED_OBJECT_ARRAY + field);
            }
        } else {
            throw new EvaluationError(expr, CrudConstants.ERR_EXPECTED_ARRAY + field);
        }
    }

    @Override
    public boolean evaluate(QueryEvaluationContext ctx) {
        boolean ret = false;
        JsonNode node = ctx.getNode(field);
        if (node instanceof ArrayNode) {
            ArrayNode array = (ArrayNode) node;
            int index = 0;
            QueryEvaluationContext nestedCtx = null;
            for (Iterator itr = array.elements(); itr.hasNext();) {
                JsonNode arrayElem = itr.next();
                if (index == 0) {
                    nestedCtx = ctx.firstElementNestedContext(arrayElem, field);
                } else {
                    nestedCtx.elementNestedContext(arrayElem, index);
                }
                if (ev.evaluate(nestedCtx)) {
                    ret = true;
                }
                index++;
            }
        }
        ctx.setResult(ret);
        return ret;
    }
}