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/*
 * Copyright © 2017 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 co.cask.wrangler.steps.writer;

import co.cask.wrangler.api.AbstractStep;
import co.cask.wrangler.api.PipelineContext;
import co.cask.wrangler.api.Record;
import co.cask.wrangler.api.StepException;
import co.cask.wrangler.api.Usage;
import com.google.gson.Gson;

import java.util.List;
import java.util.Objects;

/**
 * A step to write the record fields as JSON.
 */
@Usage(
  directive = "to-string",
  usage = "to-string ",
  description = "Changes the column value to a string."
)
// TODO: add to usageRegistory and TextDirectives
public class ToString extends AbstractStep {
  private final String column;

  public ToString(int lineno, String directive, String column) {
    super(lineno, directive);
    this.column = column;
  }

  /**
   * Executes a wrangle step on single {@link Record} and return an array of wrangled {@link Record}.
   *
   * @param records  Input {@link Record} to be wrangled by this step.
   * @param context {@link PipelineContext} passed to each step.
   * @return Wrangled {@link Record}.
   */
  @Override
  public List execute(List records, PipelineContext context) throws StepException {
    for (Record record : records) {
      int idx = record.find(column);
      if (idx == -1) {
        // TODO:
        throw new StepException("");
      }
      Object value = record.getValue(idx);
      // how is null handled? is that what we want?
      record.addOrSet(column, Objects.toString(value));
    }
    return records;
  }
}