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/*******************************************************************************
 * 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.datavec.api.transform.sequence;


import lombok.Data;
import lombok.EqualsAndHashCode;
import org.datavec.api.transform.schema.Schema;
import org.datavec.api.transform.schema.SequenceSchema;
import org.nd4j.shade.jackson.annotation.JsonIgnoreProperties;
import org.nd4j.shade.jackson.annotation.JsonProperty;

import java.util.Arrays;
import java.util.Collection;

/**
 * Convert a set of values to a sequence. Two approaches are supported:

 * (a) if "singleStepsequenceMode" is true - convert each record independently, to a "sequence" of length 1

 * (b) otherwise - performa  "group and sort" operations. For example, group by one or more columns, and then
 *     sort each value within the group by some mechanism. For example, group by customer, sort by time.
 *
 * @author Alex Black
 */
@Data
@EqualsAndHashCode(exclude = {"inputSchema"})
@JsonIgnoreProperties({"inputSchema"})
public class ConvertToSequence {

    private boolean singleStepSequencesMode;
    private final String[] keyColumns;
    private final SequenceComparator comparator; //For sorting values within collected (unsorted) sequence
    private Schema inputSchema;

    /**
     *
     * @param keyColumn The value to use as the key for inferring which examples belong to what sequence
     * @param comparator The comparator to use when deciding the order of each possible time step in the sequence
     */
    public ConvertToSequence(String keyColumn, SequenceComparator comparator){
        this(false, new String[]{keyColumn}, comparator);
    }

    /**
     *
     * @param keyColumns The value or values to use as the key (multiple values: compound key)  for inferring which
     *                   examples belong to what sequence
     * @param comparator The comparator to use when deciding the order of each possible time step in the sequence
     */
    public ConvertToSequence(Collection keyColumns, SequenceComparator comparator) {
        this(false, keyColumns.toArray(new String[keyColumns.size()]), comparator);
    }

    /**
     *
     * @param keyColumns The value or values to use as the key (multiple values: compound key)  for inferring which
     *                   examples belong to what sequence
     * @param comparator The comparator to use when deciding the order of each possible time step in the sequence
     */
    public ConvertToSequence(@JsonProperty("singleStepSequencesMode") boolean singleStepSequencesMode,
                             @JsonProperty("keyColumn") String[] keyColumns,
                             @JsonProperty("comparator") SequenceComparator comparator) {
        this.singleStepSequencesMode = singleStepSequencesMode;
        this.keyColumns = keyColumns;
        this.comparator = comparator;
    }

    public SequenceSchema transform(Schema schema) {
        return new SequenceSchema(schema.getColumnMetaData());
    }

    public void setInputSchema(Schema schema) {
        this.inputSchema = schema;
        if(!singleStepSequencesMode){
            comparator.setSchema(transform(schema));
        }
    }

    @Override
    public String toString() {
        if(singleStepSequencesMode) {
            return "ConvertToSequence()";
        } else if(keyColumns.length == 1){
            return "ConvertToSequence(keyColumn=\"" + keyColumns[0] + "\",comparator=" + comparator + ")";
        } else {
            return "ConvertToSequence(keyColumns=\"" + Arrays.toString(keyColumns) + "\",comparator=" + comparator + ")";
        }
    }

}