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/**
 * 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.metamodel.neo4j;

import static org.apache.metamodel.neo4j.Neo4jDataContext.*;

import java.util.ArrayList;
import java.util.List;

import org.apache.metamodel.data.AbstractDataSet;
import org.apache.metamodel.data.DefaultRow;
import org.apache.metamodel.data.Row;
import org.apache.metamodel.data.SimpleDataSetHeader;
import org.apache.metamodel.query.SelectItem;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

final class Neo4jDataSet extends AbstractDataSet {

    private final JSONObject _resultJSONObject;
    private int _currentRowIndex;
    private Row _row;

    public Neo4jDataSet(final List selectItems, final JSONObject resultJSONObject) {
        super(selectItems);
        _resultJSONObject = resultJSONObject;
        _currentRowIndex = 0;
    }

    @Override
    public boolean next() {
        try {
            final JSONArray resultsArray = _resultJSONObject.getJSONArray(NEO4J_KEY_RESPONSE_RESULTS);

            if (resultsArray.length() > 0) {
                final JSONObject results = resultsArray.getJSONObject(0);
                final JSONArray data = results.getJSONArray(NEO4J_KEY_DATA);

                if (_currentRowIndex < data.length()) {
                    final JSONObject row = data.getJSONObject(_currentRowIndex);
                    final JSONArray jsonValues = row.getJSONArray(NEO4J_KEY_RESPONSE_ROW);
                    final Object[] objectValues = new Object[jsonValues.length()];

                    for (int i = 0; i < jsonValues.length(); i++) {
                        final Object value = jsonValues.get(i);

                        if (value instanceof JSONArray) {
                            objectValues[i] = convertJSONArrayToList((JSONArray) value);
                        } else {
                            objectValues[i] = value;
                        }
                    }

                    _row = new DefaultRow(new SimpleDataSetHeader(getSelectItems()), objectValues);
                    _currentRowIndex++;

                    return true;
                }
            } else {
                final JSONArray errorArray = _resultJSONObject.getJSONArray("errors");
                final JSONObject error = errorArray.getJSONObject(0);
                throw new IllegalStateException(error.toString());
            }
        } catch (final JSONException e) {
            throw new IllegalStateException(e);
        }
        return false;
    }

    private List convertJSONArrayToList(final JSONArray jsonArray) throws JSONException {
        final List list = new ArrayList<>();

        for (int i = 0; i < jsonArray.length(); i++) {
            final Object item = jsonArray.get(i);

            if (item != null) {
                list.add(item.toString());
            }
        }

        return list;
    }

    @Override
    public Row getRow() {
        return _row;
    }
}