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/*
 * 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 tech.tablesaw.io.csv;

import com.univocity.parsers.csv.CsvWriterSettings;
import javax.annotation.concurrent.Immutable;
import tech.tablesaw.api.Table;
import tech.tablesaw.io.DataWriter;
import tech.tablesaw.io.Destination;
import tech.tablesaw.io.WriterRegistry;

/** Class that writes tables and individual columns to CSV files */
@Immutable
public final class CsvWriter implements DataWriter {

  private static final CsvWriter INSTANCE = new CsvWriter();
  private static final String nullValue = "";

  static {
    register(Table.defaultWriterRegistry);
  }

  public static void register(WriterRegistry registry) {
    registry.registerExtension("csv", INSTANCE);
    registry.registerOptions(CsvWriteOptions.class, INSTANCE);
  }

  public void write(Table table, CsvWriteOptions options) {
    CsvWriterSettings settings = createSettings(options);

    com.univocity.parsers.csv.CsvWriter csvWriter = null;
    // Creates a writer with the above settings;
    try {
      csvWriter =
          new com.univocity.parsers.csv.CsvWriter(options.destination().createWriter(), settings);

      if (options.header()) {
        String[] header = new String[table.columnCount()];
        for (int c = 0; c < table.columnCount(); c++) {
          header[c] = table.column(c).name();
        }
        csvWriter.writeHeaders(header);
      }
      for (int r = 0; r < table.rowCount(); r++) {
        String[] entries = new String[table.columnCount()];
        for (int c = 0; c < table.columnCount(); c++) {
          table.get(r, c);
          entries[c] = table.getUnformatted(r, c);
        }
        csvWriter.writeRow(entries);
      }
    } finally {
      if (csvWriter != null) {
        csvWriter.flush();
        csvWriter.close();
      }
    }
  }

  protected static CsvWriterSettings createSettings(CsvWriteOptions options) {
    CsvWriterSettings settings = new CsvWriterSettings();
    // Sets the character sequence to write for the values that are null.
    settings.setNullValue(nullValue);
    if (options.separator() != null) {
      settings.getFormat().setDelimiter(options.separator());
    }
    if (options.quoteChar() != null) {
      settings.getFormat().setQuote(options.quoteChar());
    }
    if (options.escapeChar() != null) {
      settings.getFormat().setQuoteEscape(options.escapeChar());
    }
    if (options.lineEnd() != null) {
      settings.getFormat().setLineSeparator(options.lineEnd());
    }
    settings.setIgnoreLeadingWhitespaces(options.ignoreLeadingWhitespaces());
    settings.setIgnoreTrailingWhitespaces(options.ignoreTrailingWhitespaces());
    // writes empty lines as well.
    settings.setSkipEmptyLines(false);
    settings.setQuoteAllFields(options.quoteAllFields());
    return settings;
  }

  @Override
  public void write(Table table, Destination dest) {
    write(table, CsvWriteOptions.builder(dest).build());
  }
}