/*******************************************************************************
 * Copyright (c) 2015-2018 Skymind, Inc.
 *
 * 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.
 *
 * 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.nn.conf.layers;

import lombok.*;
import org.deeplearning4j.nn.api.Layer;
import org.deeplearning4j.nn.api.ParamInitializer;
import org.deeplearning4j.nn.api.layers.LayerConstraint;
import org.deeplearning4j.nn.conf.NeuralNetConfiguration;
import org.deeplearning4j.nn.conf.inputs.InputType;
import org.deeplearning4j.nn.conf.memory.LayerMemoryReport;
import org.deeplearning4j.nn.layers.recurrent.LSTMHelpers;
import org.deeplearning4j.nn.params.LSTMParamInitializer;
import org.deeplearning4j.optimize.api.TrainingListener;
import org.nd4j.linalg.activations.IActivation;
import org.nd4j.linalg.activations.impl.ActivationSigmoid;
import org.nd4j.linalg.api.buffer.DataType;
import org.nd4j.linalg.api.ndarray.INDArray;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;

/**
 * LSTM recurrent neural network layer without peephole connections. Supports CuDNN acceleration - see <a
 * href="https://deeplearning4j.org/docs/latest/deeplearning4j-config-cudnn">https://deeplearning4j.org/docs/latest/deeplearning4j-config-cudnn</a> for details
 *
 * @author Alex Black
 * @see GravesLSTM GravesLSTM class for an alternative LSTM (with peephole connections)
 */
@Data
@NoArgsConstructor
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public class LSTM extends AbstractLSTM {

    private double forgetGateBiasInit;
    private IActivation gateActivationFn = new ActivationSigmoid();

    private LSTM(Builder builder) {
        super(builder);
        this.forgetGateBiasInit = builder.forgetGateBiasInit;
        this.gateActivationFn = builder.gateActivationFn;
        initializeConstraints(builder);
    }

    @Override
    protected void initializeConstraints(org.deeplearning4j.nn.conf.layers.Layer.Builder<?> builder) {
        super.initializeConstraints(builder);
        if (((Builder) builder).recurrentConstraints != null) {
            if (constraints == null) {
                constraints = new ArrayList<>();
            }
            for (LayerConstraint c : ((Builder) builder).recurrentConstraints) {
                LayerConstraint c2 = c.clone();
                c2.setParams(Collections.singleton(LSTMParamInitializer.RECURRENT_WEIGHT_KEY));
                constraints.add(c2);
            }
        }
    }

    @Override
    public Layer instantiate(NeuralNetConfiguration conf, Collection<TrainingListener> trainingListeners,
                             int layerIndex, INDArray layerParamsView, boolean initializeParams, DataType networkDataType) {
        LayerValidation.assertNInNOutSet("LSTM", getLayerName(), layerIndex, getNIn(), getNOut());
        org.deeplearning4j.nn.layers.recurrent.LSTM ret = new org.deeplearning4j.nn.layers.recurrent.LSTM(conf, networkDataType);
        ret.setListeners(trainingListeners);
        ret.setIndex(layerIndex);
        ret.setParamsViewArray(layerParamsView);
        Map<String, INDArray> paramTable = initializer().init(conf, layerParamsView, initializeParams);
        ret.setParamTable(paramTable);
        ret.setConf(conf);
        return ret;
    }

    @Override
    public ParamInitializer initializer() {
        return LSTMParamInitializer.getInstance();
    }

    @Override
    public LayerMemoryReport getMemoryReport(InputType inputType) {
        //TODO - CuDNN etc
        return LSTMHelpers.getMemoryReport(this, inputType);
    }

    @NoArgsConstructor
    public static class Builder extends AbstractLSTM.Builder<Builder> {


        @SuppressWarnings("unchecked")
        public LSTM build() {
            return new LSTM(this);
        }
    }

}
