/*
 *  ******************************************************************************
 *  *
 *  *
 *  * This program and the accompanying materials are made available under the
 *  * terms of the Apache License, Version 2.0 which is available at
 *  * https://www.apache.org/licenses/LICENSE-2.0.
 *  *
 *  *  See the NOTICE file distributed with this work for additional
 *  *  information regarding copyright ownership.
 *  * 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.
 *  *
 *  * SPDX-License-Identifier: Apache-2.0
 *  *****************************************************************************
 */

package org.deeplearning4j.datasets.iterator.utilty;

import lombok.Getter;
import lombok.Setter;
import org.nd4j.linalg.dataset.DataSet;
import org.nd4j.linalg.dataset.api.DataSetPreProcessor;
import org.nd4j.linalg.dataset.api.iterator.DataSetIterator;

import java.util.List;
import java.util.NoSuchElementException;

public class SingletonDataSetIterator implements DataSetIterator {

    private final DataSet dataSet;
    private boolean hasNext = true;
    private boolean preprocessed = false;
    @Getter @Setter
    private DataSetPreProcessor preProcessor;

    /**
     * @param multiDataSet The underlying dataset to return
     */
    public SingletonDataSetIterator(DataSet multiDataSet) {
        this.dataSet = multiDataSet;
    }

    @Override
    public DataSet next(int num) {
        return next();
    }

    @Override
    public int inputColumns() {
        return 0;
    }

    @Override
    public int totalOutcomes() {
        return 0;
    }

    @Override
    public boolean resetSupported() {
        return true;
    }

    @Override
    public boolean asyncSupported() {
        return false;
    }

    @Override
    public void reset() {
        hasNext = true;
    }

    @Override
    public int batch() {
        return 0;
    }

    @Override
    public List<String> getLabels() {
        return null;
    }

    @Override
    public boolean hasNext() {
        return hasNext;
    }

    @Override
    public DataSet next() {
        if (!hasNext) {
            throw new NoSuchElementException("No elements remaining");
        }
        hasNext = false;
        if (preProcessor != null && !preprocessed) {
            preProcessor.preProcess(dataSet);
            preprocessed = true;
        }
        return dataSet;
    }

    @Override
    public void remove() {
        //No op
    }
}
