/*
 *  ******************************************************************************
 *  *
 *  *
 *  * 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.nd4j.linalg.api.ops.impl.transforms.gradient;

import org.nd4j.autodiff.samediff.SDVariable;
import org.nd4j.autodiff.samediff.SameDiff;
import org.nd4j.imports.NoOpNameFoundException;
import org.nd4j.linalg.api.buffer.DataType;
import org.nd4j.linalg.api.ops.DynamicCustomOp;
import org.nd4j.linalg.api.shape.LongShapeDescriptor;

import java.util.Collections;
import java.util.List;

/**
 *
 */
public class GradientBackwardsMarker extends DynamicCustomOp {
    public static final String OP_NAME = "gradientbackwards";

    public GradientBackwardsMarker(SameDiff sameDiff, SDVariable i_v1, SDVariable i_v2) {
        super(sameDiff, new SDVariable[]{i_v1, i_v2});
    }
    public GradientBackwardsMarker() {
    }

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

    /**
     * The opName of this operation
     *
     * @return the opName of this operation
     */
    @Override
    public String opName() {
        return OP_NAME;
    }

    @Override
    public String onnxName() {
        throw new NoOpNameFoundException("No onnx op opName found for " +  opName());
    }

    @Override
    public String tensorflowName() {
        throw new NoOpNameFoundException("No tensorflow op opName found for " +  opName());
    }

    @Override
    public List<SDVariable> doDiff(List<SDVariable> i_v) {
        return i_v;
    }

    @Override
    public List<DataType> calculateOutputDataTypes(List<DataType> dataTypes){
        //Dummy variable
        return Collections.singletonList(DataType.FLOAT);
    }

    @Override
    public List<LongShapeDescriptor> calculateOutputShape() {
        throw new UnsupportedOperationException("calculateOutputShape() is not supported for control flow ops.");
    }

    @Override
    public int getNumOutputs(){
        return 1;
    }
}
