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package tech.tablesaw.columns.times;

import com.google.common.base.Strings;
import com.google.common.collect.Lists;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.DateTimeParseException;
import java.util.Locale;
import tech.tablesaw.api.ColumnType;
import tech.tablesaw.columns.AbstractColumnParser;
import tech.tablesaw.io.ReadOptions;

public class TimeParser extends AbstractColumnParser {

  private static final DateTimeFormatter timef1 = DateTimeFormatter.ofPattern("HH:mm:ss.SSS");
  private static final DateTimeFormatter timef2 = DateTimeFormatter.ofPattern("hh:mm:ss a");
  private static final DateTimeFormatter timef3 = DateTimeFormatter.ofPattern("h:mm:ss a");
  private static final DateTimeFormatter timef4 = DateTimeFormatter.ISO_LOCAL_TIME;
  private static final DateTimeFormatter timef5 = DateTimeFormatter.ofPattern("hh:mm a");
  private static final DateTimeFormatter timef6 = DateTimeFormatter.ofPattern("h:mm a");

  // only for parsing:
  private static final DateTimeFormatter timef7 = DateTimeFormatter.ofPattern("HHmm");

  // A formatter that handles time formats defined above used for type detection.
  // It is more conservative than the converter
  private static final DateTimeFormatter TIME_DETECTION_FORMATTER =
      new DateTimeFormatterBuilder()
          .appendOptional(timef5)
          .appendOptional(timef2)
          .appendOptional(timef3)
          .appendOptional(timef1)
          .appendOptional(timef4)
          .appendOptional(timef6)
          .toFormatter();

  // A formatter that handles time formats defined above
  /**
   * A formatter for parsing. Useful when the user has specified that a numeric-like column is
   * really supposed to be a time See timef7 definition
   */
  private static final DateTimeFormatter TIME_CONVERSION_FORMATTER =
      new DateTimeFormatterBuilder()
          .appendOptional(timef5)
          .appendOptional(timef2)
          .appendOptional(timef3)
          .appendOptional(timef1)
          .appendOptional(timef4)
          .appendOptional(timef6)
          .appendOptional(timef7)
          .toFormatter();

  private static final DateTimeFormatter DEFAULT_FORMATTER = TIME_DETECTION_FORMATTER;

  private Locale locale = Locale.getDefault();

  private DateTimeFormatter formatter = DEFAULT_FORMATTER;
  private DateTimeFormatter parserFormatter = TIME_CONVERSION_FORMATTER;

  public TimeParser(ColumnType columnType) {
    super(columnType);
  }

  public TimeParser(ColumnType columnType, ReadOptions readOptions) {
    super(columnType);
    DateTimeFormatter readCsvFormatter = readOptions.timeFormatter();
    if (readCsvFormatter != null) {
      formatter = readCsvFormatter;
      parserFormatter = readCsvFormatter;
    }
    if (readOptions.locale() != null) {
      locale = readOptions.locale();
    }
    if (readOptions.missingValueIndicator() != null) {
      missingValueStrings = Lists.newArrayList(readOptions.missingValueIndicator());
    }
  }

  @Override
  public boolean canParse(String s) {
    if (isMissing(s)) {
      return true;
    }
    try {
      LocalTime.parse(s, formatter.withLocale(locale));
      return true;
    } catch (DateTimeParseException e) {
      // it's all part of the plan
      return false;
    }
  }

  @Override
  public LocalTime parse(String value) {
    if (isMissing(value)) {
      return null;
    }
    String paddedValue = Strings.padStart(value, 4, '0');
    return LocalTime.parse(paddedValue, parserFormatter);
  }
}