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/*
 *  Copyright © 2017-2019 Cask Data, Inc.
 *
 *  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.
 */

package io.cdap.directives.row;

import io.cdap.cdap.api.annotation.Description;
import io.cdap.cdap.api.annotation.Name;
import io.cdap.cdap.api.annotation.Plugin;
import io.cdap.wrangler.api.Arguments;
import io.cdap.wrangler.api.Directive;
import io.cdap.wrangler.api.DirectiveExecutionException;
import io.cdap.wrangler.api.DirectiveParseException;
import io.cdap.wrangler.api.ExecutorContext;
import io.cdap.wrangler.api.Row;
import io.cdap.wrangler.api.annotations.Categories;
import io.cdap.wrangler.api.lineage.Lineage;
import io.cdap.wrangler.api.lineage.Many;
import io.cdap.wrangler.api.lineage.Mutation;
import io.cdap.wrangler.api.parser.ColumnName;
import io.cdap.wrangler.api.parser.Text;
import io.cdap.wrangler.api.parser.TokenType;
import io.cdap.wrangler.api.parser.UsageDefinition;

import java.util.ArrayList;
import java.util.List;

/**
 * A directive for splitting the string into multiple {@link Row}s.
 */
@Plugin(type = Directive.TYPE)
@Name(SplitToRows.NAME)
@Categories(categories = { "row"})
@Description("Splits a column into multiple rows, copies the rest of the columns.")
public class SplitToRows implements Directive, Lineage {
  public static final String NAME = "split-to-rows";
  // Column on which to apply mask.
  private String column;

  // Regex to split on.
  private String regex;

  @Override
  public UsageDefinition define() {
    UsageDefinition.Builder builder = UsageDefinition.builder(NAME);
    builder.define("column", TokenType.COLUMN_NAME);
    builder.define("regex", TokenType.TEXT);
    return builder.build();
  }

  @Override
  public void initialize(Arguments args) throws DirectiveParseException {
    column = ((ColumnName) args.value("column")).value();
    regex = ((Text) args.value("regex")).value();
  }

  @Override
  public void destroy() {
    // no-op
  }

  @Override
  public List execute(List rows, ExecutorContext context) throws DirectiveExecutionException {
    List results = new ArrayList<>();

    for (Row row : rows) {
      int idx = row.find(column);
      if (idx != -1) {
        Object object = row.getValue(idx);

        if (object == null) {
          throw new DirectiveExecutionException(
            NAME, String.format("Column '%s' has null value. It should be a non-null 'String'.", column));
        }

        if (object instanceof String) {
          String[] lines = ((String) object).split(regex);
          for (String line : lines) {
            Row r = new Row(row);
            r.setValue(idx, line);
            results.add(r);
          }
        } else {
          throw new DirectiveExecutionException(
            NAME, String.format("Column '%s' has invalid type '%s'. It should be of type 'String'.",
                                column, object.getClass().getSimpleName()));
        }
      }
    }
    return results;
  }

  @Override
  public Mutation lineage() {
    return Mutation.builder()
      .readable("Split column '%s' into multiple rows using expressions '%s'", column, regex)
      .relation(Many.columns(column), Many.columns(column))
      .build();
  }
}