/*
 * Copyright 2019-2023 The Polypheny Project
 *
 * Licensed 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.
 *
 * This file incorporates code covered by the following terms:
 *
 * 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.polypheny.db.adapter.geode.simple;


import java.util.Iterator;
import lombok.extern.slf4j.Slf4j;
import org.apache.calcite.linq4j.Enumerator;
import org.apache.geode.cache.client.ClientCache;
import org.apache.geode.cache.query.QueryService;
import org.apache.geode.cache.query.SelectResults;


/**
 * Geode Simple Enumerator.
 *
 * @param <E> Element type
 */
@Slf4j
public abstract class GeodeSimpleEnumerator<E> implements Enumerator<E> {

    private Iterator results;

    private E current;
    private ClientCache clientCache;


    public GeodeSimpleEnumerator( ClientCache clientCache, String regionName ) {
        this.clientCache = clientCache;
        QueryService queryService = clientCache.getQueryService();
        String oql = "select * from /" + regionName.trim();
        try {
            results = ((SelectResults) queryService.newQuery( oql ).execute()).iterator();
        } catch ( Exception e ) {
            log.error( "Caught exception", e );
            results = null;
        }
    }


    @Override
    public E current() {
        return current;
    }


    @Override
    public boolean moveNext() {
        if ( results.hasNext() ) {
            current = convert( results.next() );
            return true;
        }
        current = null;
        return false;
    }


    @Override
    public void reset() {
        throw new UnsupportedOperationException();
    }


    @Override
    public void close() {
        /*clientCache.close(); */
    }


    public abstract E convert( Object obj );

}

