/*
 * Copyright (c) 2003, PostgreSQL Global Development Group
 * See the LICENSE file in the project root for more information.
 */

package org.postgresql.jdbc;

import org.postgresql.PGStatement;
import org.postgresql.core.JavaVersion;
import org.postgresql.core.Oid;
import org.postgresql.core.Provider;
import org.postgresql.util.ByteConverter;
import org.postgresql.util.GT;
import org.postgresql.util.PSQLException;
import org.postgresql.util.PSQLState;

import java.lang.reflect.Field;
import java.sql.Date;
import java.sql.SQLException;
import java.sql.Time;
import java.sql.Timestamp;
//JCP! if mvn.project.property.postgresql.jdbc.spec >= "JDBC4.2"
import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.OffsetDateTime;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.chrono.IsoEra;
import java.time.format.DateTimeParseException;
import java.time.temporal.ChronoField;
//JCP! endif
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.SimpleTimeZone;
import java.util.TimeZone;

Misc utils for handling time and date values.
/**
 * Misc utils for handling time and date values.
 */
public class TimestampUtils {
  
Number of milliseconds in one day.
/**
   * Number of milliseconds in one day.
   */
  private static final int ONEDAY = 24 * 3600 * 1000;
  private static final char[] ZEROS = {'0', '0', '0', '0', '0', '0', '0', '0', '0'};
  private static final char[][] NUMBERS;
  private static final HashMap<String, TimeZone> GMT_ZONES = new HashMap<String, TimeZone>();
  private static final int MAX_NANOS_BEFORE_WRAP_ON_ROUND = 999999500;
  //JCP! if mvn.project.property.postgresql.jdbc.spec >= "JDBC4.2"
  private static final Duration ONE_MICROSECOND = Duration.ofNanos(1000);
  // LocalTime.MAX is 23:59:59.999_999_999, and it wraps to 24:00:00 when nanos exceed 999_999_499
  // since PostgreSQL has microsecond resolution only
  private static final LocalTime MAX_TIME = LocalTime.MAX.minus(Duration.ofMillis(500));
  private static final OffsetDateTime MAX_OFFSET_DATETIME = OffsetDateTime.MAX.minus(Duration.ofMillis(500));
  private static final LocalDateTime MAX_LOCAL_DATETIME = LocalDateTime.MAX.minus(Duration.ofMillis(500));
  //JCP! endif

  private static final Field DEFAULT_TIME_ZONE_FIELD;

  private TimeZone prevDefaultZoneFieldValue;
  private TimeZone defaultTimeZoneCache;

  static {
    // The expected maximum value is 60 (seconds), so 64 is used "just in case"
    NUMBERS = new char[64][];
    for (int i = 0; i < NUMBERS.length; i++) {
      NUMBERS[i] = ((i < 10 ? "0" : "") + Integer.toString(i)).toCharArray();
    }

    // Backend's gmt-3 means GMT+03 in Java. Here a map is created so gmt-3 can be converted to
    // java TimeZone
    for (int i = -12; i <= 14; i++) {
      TimeZone timeZone;
      String pgZoneName;
      if (i == 0) {
        timeZone = TimeZone.getTimeZone("GMT");
        pgZoneName = "GMT";
      } else {
        timeZone = TimeZone.getTimeZone("GMT" + (i <= 0 ? "+" : "-") + Math.abs(i));
        pgZoneName = "GMT" + (i >= 0 ? "+" : "-");
      }

      if (i == 0) {
        GMT_ZONES.put(pgZoneName, timeZone);
        continue;
      }
      GMT_ZONES.put(pgZoneName + Math.abs(i), timeZone);
      GMT_ZONES.put(pgZoneName + new String(NUMBERS[Math.abs(i)]), timeZone);
    }
    // Fast path to getting the default timezone.
    // Accessing the default timezone over and over creates a clone with regular API.
    // Because we don't mutate that object in our use of it, we can access the field directly.
    // This saves the creation of a clone everytime, and the memory associated to all these clones.
    Field tzField;
    try {
      tzField = null;
      // Avoid reflective access in Java 9+
      if (JavaVersion.getRuntimeVersion().compareTo(JavaVersion.v1_8) <= 0) {
        tzField = TimeZone.class.getDeclaredField("defaultTimeZone");
        tzField.setAccessible(true);
        TimeZone defaultTz = TimeZone.getDefault();
        Object tzFromField = tzField.get(null);
        if (defaultTz == null || !defaultTz.equals(tzFromField)) {
          tzField = null;
        }
      }
    } catch (Exception e) {
      tzField = null;
    }
    DEFAULT_TIME_ZONE_FIELD = tzField;
  }

  private final StringBuilder sbuf = new StringBuilder();

  // This calendar is used when user provides calendar in setX(, Calendar) method.
  // It ensures calendar is Gregorian.
  private final Calendar calendarWithUserTz = new GregorianCalendar();
  private final TimeZone utcTz = TimeZone.getTimeZone("UTC");

  private Calendar calCache;
  private int calCacheZone;

  
True if the backend uses doubles for time values. False if long is used.
/**
   * True if the backend uses doubles for time values. False if long is used.
   */
  private final boolean usesDouble;
  private final Provider<TimeZone> timeZoneProvider;

  TimestampUtils(boolean usesDouble, Provider<TimeZone> timeZoneProvider) {
    this.usesDouble = usesDouble;
    this.timeZoneProvider = timeZoneProvider;
  }

  private Calendar getCalendar(int sign, int hr, int min, int sec) {
    int rawOffset = sign * (((hr * 60 + min) * 60 + sec) * 1000);
    if (calCache != null && calCacheZone == rawOffset) {
      return calCache;
    }

    StringBuilder zoneID = new StringBuilder("GMT");
    zoneID.append(sign < 0 ? '-' : '+');
    if (hr < 10) {
      zoneID.append('0');
    }
    zoneID.append(hr);
    if (min < 10) {
      zoneID.append('0');
    }
    zoneID.append(min);
    if (sec < 10) {
      zoneID.append('0');
    }
    zoneID.append(sec);

    TimeZone syntheticTZ = new SimpleTimeZone(rawOffset, zoneID.toString());
    calCache = new GregorianCalendar(syntheticTZ);
    calCacheZone = rawOffset;
    return calCache;
  }

  private static class ParsedTimestamp {
    boolean hasDate = false;
    int era = GregorianCalendar.AD;
    int year = 1970;
    int month = 1;

    boolean hasTime = false;
    int day = 1;
    int hour = 0;
    int minute = 0;
    int second = 0;
    int nanos = 0;

    Calendar tz = null;
  }

  private static class ParsedBinaryTimestamp {
    Infinity infinity = null;
    long millis = 0;
    int nanos = 0;
  }

  enum Infinity {
    POSITIVE,
    NEGATIVE;
  }

  
Load date/time information into the provided calendar returning the fractional seconds.
/**
   * Load date/time information into the provided calendar returning the fractional seconds.
   */
  private ParsedTimestamp parseBackendTimestamp(String str) throws SQLException {
    char[] s = str.toCharArray();
    int slen = s.length;

    // This is pretty gross..
    ParsedTimestamp result = new ParsedTimestamp();

    // We try to parse these fields in order; all are optional
    // (but some combinations don't make sense, e.g. if you have
    // both date and time then they must be whitespace-separated).
    // At least one of date and time must be present.

    // leading whitespace
    // yyyy-mm-dd
    // whitespace
    // hh:mm:ss
    // whitespace
    // timezone in one of the formats: +hh, -hh, +hh:mm, -hh:mm
    // whitespace
    // if date is present, an era specifier: AD or BC
    // trailing whitespace

    try {
      int start = skipWhitespace(s, 0); // Skip leading whitespace
      int end = firstNonDigit(s, start);
      int num;
      char sep;

      // Possibly read date.
      if (charAt(s, end) == '-') {
        //
        // Date
        //
        result.hasDate = true;

        // year
        result.year = number(s, start, end);
        start = end + 1; // Skip '-'

        // month
        end = firstNonDigit(s, start);
        result.month = number(s, start, end);

        sep = charAt(s, end);
        if (sep != '-') {
          throw new NumberFormatException("Expected date to be dash-separated, got '" + sep + "'");
        }

        start = end + 1; // Skip '-'

        // day of month
        end = firstNonDigit(s, start);
        result.day = number(s, start, end);

        start = skipWhitespace(s, end); // Skip trailing whitespace
      }

      // Possibly read time.
      if (Character.isDigit(charAt(s, start))) {
        //
        // Time.
        //

        result.hasTime = true;

        // Hours

        end = firstNonDigit(s, start);
        result.hour = number(s, start, end);

        sep = charAt(s, end);
        if (sep != ':') {
          throw new NumberFormatException("Expected time to be colon-separated, got '" + sep + "'");
        }

        start = end + 1; // Skip ':'

        // minutes

        end = firstNonDigit(s, start);
        result.minute = number(s, start, end);

        sep = charAt(s, end);
        if (sep != ':') {
          throw new NumberFormatException("Expected time to be colon-separated, got '" + sep + "'");
        }

        start = end + 1; // Skip ':'

        // seconds

        end = firstNonDigit(s, start);
        result.second = number(s, start, end);
        start = end;

        // Fractional seconds.
        if (charAt(s, start) == '.') {
          end = firstNonDigit(s, start + 1); // Skip '.'
          num = number(s, start + 1, end);

          for (int numlength = (end - (start + 1)); numlength < 9; ++numlength) {
            num *= 10;
          }

          result.nanos = num;
          start = end;
        }

        start = skipWhitespace(s, start); // Skip trailing whitespace
      }

      // Possibly read timezone.
      sep = charAt(s, start);
      if (sep == '-' || sep == '+') {
        int tzsign = (sep == '-') ? -1 : 1;
        int tzhr;
        int tzmin;
        int tzsec;

        end = firstNonDigit(s, start + 1); // Skip +/-
        tzhr = number(s, start + 1, end);
        start = end;

        sep = charAt(s, start);
        if (sep == ':') {
          end = firstNonDigit(s, start + 1); // Skip ':'
          tzmin = number(s, start + 1, end);
          start = end;
        } else {
          tzmin = 0;
        }

        tzsec = 0;
        sep = charAt(s, start);
        if (sep == ':') {
          end = firstNonDigit(s, start + 1); // Skip ':'
          tzsec = number(s, start + 1, end);
          start = end;
        }

        // Setting offset does not seem to work correctly in all
        // cases.. So get a fresh calendar for a synthetic timezone
        // instead
        result.tz = getCalendar(tzsign, tzhr, tzmin, tzsec);

        start = skipWhitespace(s, start); // Skip trailing whitespace
      }

      if (result.hasDate && start < slen) {
        String eraString = new String(s, start, slen - start);
        if (eraString.startsWith("AD")) {
          result.era = GregorianCalendar.AD;
          start += 2;
        } else if (eraString.startsWith("BC")) {
          result.era = GregorianCalendar.BC;
          start += 2;
        }
      }

      if (start < slen) {
        throw new NumberFormatException(
            "Trailing junk on timestamp: '" + new String(s, start, slen - start) + "'");
      }

      if (!result.hasTime && !result.hasDate) {
        throw new NumberFormatException("Timestamp has neither date nor time");
      }

    } catch (NumberFormatException nfe) {
      throw new PSQLException(
          GT.tr("Bad value for type timestamp/date/time: {1}", str),
          PSQLState.BAD_DATETIME_FORMAT, nfe);
    }

    return result;
  }

  
Parse a string and return a timestamp representing its value.
Params:
cal – calendar to be used to parse the input string
s – The ISO formated date string to parse.
Throws:
SQLException – if there is a problem parsing s.
Returns:
null if s is null or a timestamp of the parsed string s./**
   * Parse a string and return a timestamp representing its value.
   *
   * @param cal calendar to be used to parse the input string
   * @param s The ISO formated date string to parse.
   * @return null if s is null or a timestamp of the parsed string s.
   * @throws SQLException if there is a problem parsing s.
   */
  public synchronized Timestamp toTimestamp(Calendar cal, String s) throws SQLException {
    if (s == null) {
      return null;
    }

    int slen = s.length();

    // convert postgres's infinity values to internal infinity magic value
    if (slen == 8 && s.equals("infinity")) {
      return new Timestamp(PGStatement.DATE_POSITIVE_INFINITY);
    }

    if (slen == 9 && s.equals("-infinity")) {
      return new Timestamp(PGStatement.DATE_NEGATIVE_INFINITY);
    }

    ParsedTimestamp ts = parseBackendTimestamp(s);
    Calendar useCal = ts.tz != null ? ts.tz : setupCalendar(cal);
    useCal.set(Calendar.ERA, ts.era);
    useCal.set(Calendar.YEAR, ts.year);
    useCal.set(Calendar.MONTH, ts.month - 1);
    useCal.set(Calendar.DAY_OF_MONTH, ts.day);
    useCal.set(Calendar.HOUR_OF_DAY, ts.hour);
    useCal.set(Calendar.MINUTE, ts.minute);
    useCal.set(Calendar.SECOND, ts.second);
    useCal.set(Calendar.MILLISECOND, 0);

    Timestamp result = new Timestamp(useCal.getTimeInMillis());
    result.setNanos(ts.nanos);
    return result;
  }

  //JCP! if mvn.project.property.postgresql.jdbc.spec >= "JDBC4.2"
  
Parse a string and return a LocalTime representing its value.
Params:
s – The ISO formated time string to parse.
Throws:
SQLException – if there is a problem parsing s.
Returns:
null if s is null or a LocalTime of the parsed string s./**
   * Parse a string and return a LocalTime representing its value.
   *
   * @param s The ISO formated time string to parse.
   * @return null if s is null or a LocalTime of the parsed string s.
   * @throws SQLException if there is a problem parsing s.
   */
  public LocalTime toLocalTime(String s) throws SQLException {
    if (s == null) {
      return null;
    }

    if (s.equals("24:00:00")) {
      return LocalTime.MAX;
    }

    try {
      return LocalTime.parse(s);
    } catch (DateTimeParseException nfe) {
      throw new PSQLException(
          GT.tr("Bad value for type timestamp/date/time: {1}", s),
          PSQLState.BAD_DATETIME_FORMAT, nfe);
    }

  }

  
Parse a string and return a LocalDateTime representing its value.
Params:
s – The ISO formated date string to parse.
Throws:
SQLException – if there is a problem parsing s.
Returns:
null if s is null or a LocalDateTime of the parsed string s./**
   * Parse a string and return a LocalDateTime representing its value.
   *
   * @param s The ISO formated date string to parse.
   * @return null if s is null or a LocalDateTime of the parsed string s.
   * @throws SQLException if there is a problem parsing s.
   */
  public LocalDateTime toLocalDateTime(String s) throws SQLException {
    if (s == null) {
      return null;
    }

    int slen = s.length();

    // convert postgres's infinity values to internal infinity magic value
    if (slen == 8 && s.equals("infinity")) {
      return LocalDateTime.MAX;
    }

    if (slen == 9 && s.equals("-infinity")) {
      return LocalDateTime.MIN;
    }

    ParsedTimestamp ts = parseBackendTimestamp(s);

    // intentionally ignore time zone
    // 2004-10-19 10:23:54+03:00 is 2004-10-19 10:23:54 locally
    LocalDateTime result = LocalDateTime.of(ts.year, ts.month, ts.day, ts.hour, ts.minute, ts.second, ts.nanos);
    if (ts.era == GregorianCalendar.BC) {
      return result.with(ChronoField.ERA, IsoEra.BCE.getValue());
    } else {
      return result;
    }
  }
  //JCP! endif

  public synchronized Time toTime(Calendar cal, String s) throws SQLException {
    // 1) Parse backend string
    if (s == null) {
      return null;
    }
    ParsedTimestamp ts = parseBackendTimestamp(s);
    Calendar useCal = ts.tz != null ? ts.tz : setupCalendar(cal);
    if (ts.tz == null) {
      // When no time zone provided (e.g. time or timestamp)
      // We get the year-month-day from the string, then truncate the day to 1970-01-01
      // This is used for timestamp -> time conversion
      // Note: this cannot be merged with "else" branch since
      // timestamps at which the time flips to/from DST depend on the date
      // For instance, 2000-03-26 02:00:00 is invalid timestamp in Europe/Moscow time zone
      // and the valid one is 2000-03-26 03:00:00. That is why we parse full timestamp
      // then set year to 1970 later
      useCal.set(Calendar.ERA, ts.era);
      useCal.set(Calendar.YEAR, ts.year);
      useCal.set(Calendar.MONTH, ts.month - 1);
      useCal.set(Calendar.DAY_OF_MONTH, ts.day);
    } else {
      // When time zone is given, we just pick the time part and assume date to be 1970-01-01
      // this is used for time, timez, and timestamptz parsing
      useCal.set(Calendar.ERA, GregorianCalendar.AD);
      useCal.set(Calendar.YEAR, 1970);
      useCal.set(Calendar.MONTH, Calendar.JANUARY);
      useCal.set(Calendar.DAY_OF_MONTH, 1);
    }
    useCal.set(Calendar.HOUR_OF_DAY, ts.hour);
    useCal.set(Calendar.MINUTE, ts.minute);
    useCal.set(Calendar.SECOND, ts.second);
    useCal.set(Calendar.MILLISECOND, 0);

    long timeMillis = useCal.getTimeInMillis() + ts.nanos / 1000000;
    if (ts.tz != null || (ts.year == 1970 && ts.era == GregorianCalendar.AD)) {
      // time with time zone has proper time zone, so the value can be returned as is
      return new Time(timeMillis);
    }

    // 2) Truncate date part so in given time zone the date would be formatted as 01/01/1970
    return convertToTime(timeMillis, useCal.getTimeZone());
  }

  public synchronized Date toDate(Calendar cal, String s) throws SQLException {
    // 1) Parse backend string
    Timestamp timestamp = toTimestamp(cal, s);

    if (timestamp == null) {
      return null;
    }

    // Note: infinite dates are handled in convertToDate
    // 2) Truncate date part so in given time zone the date would be formatted as 00:00
    return convertToDate(timestamp.getTime(), cal == null ? null : cal.getTimeZone());
  }

  private Calendar setupCalendar(Calendar cal) {
    TimeZone timeZone = cal == null ? null : cal.getTimeZone();
    return getSharedCalendar(timeZone);
  }

  
Get a shared calendar, applying the supplied time zone or the default time zone if null.
Params:
timeZone – time zone to be set for the calendar
Returns:
The shared calendar./**
   * Get a shared calendar, applying the supplied time zone or the default time zone if null.
   *
   * @param timeZone time zone to be set for the calendar
   * @return The shared calendar.
   */
  public Calendar getSharedCalendar(TimeZone timeZone) {
    if (timeZone == null) {
      timeZone = getDefaultTz();
    }
    Calendar tmp = calendarWithUserTz;
    tmp.setTimeZone(timeZone);
    return tmp;
  }

  
Returns true when microsecond part of the time should be increased
when rounding to microseconds
Params:
nanos – nanosecond part of the time
Returns:
true when microsecond part of the time should be increased when rounding to microseconds/**
   * Returns true when microsecond part of the time should be increased
   * when rounding to microseconds
   * @param nanos nanosecond part of the time
   * @return true when microsecond part of the time should be increased when rounding to microseconds
   */
  private static boolean nanosExceed499(int nanos) {
    return nanos % 1000 > 499;
  }

  public synchronized String toString(Calendar cal, Timestamp x) {
    return toString(cal, x, true);
  }

  public synchronized String toString(Calendar cal, Timestamp x,
      boolean withTimeZone) {
    if (x.getTime() == PGStatement.DATE_POSITIVE_INFINITY) {
      return "infinity";
    } else if (x.getTime() == PGStatement.DATE_NEGATIVE_INFINITY) {
      return "-infinity";
    }

    cal = setupCalendar(cal);
    long timeMillis = x.getTime();

    // Round to microseconds
    int nanos = x.getNanos();
    if (nanos >= MAX_NANOS_BEFORE_WRAP_ON_ROUND) {
      nanos = 0;
      timeMillis++;
    } else if (nanosExceed499(nanos)) {
      // PostgreSQL does not support nanosecond resolution yet, and appendTime will just ignore
      // 0..999 part of the nanoseconds, however we subtract nanos % 1000 to make the value
      // a little bit saner for debugging reasons
      nanos += 1000 - nanos % 1000;
    }
    cal.setTimeInMillis(timeMillis);

    sbuf.setLength(0);

    appendDate(sbuf, cal);
    sbuf.append(' ');
    appendTime(sbuf, cal, nanos);
    if (withTimeZone) {
      appendTimeZone(sbuf, cal);
    }
    appendEra(sbuf, cal);

    return sbuf.toString();
  }

  public synchronized String toString(Calendar cal, Date x) {
    return toString(cal, x, true);
  }

  public synchronized String toString(Calendar cal, Date x,
      boolean withTimeZone) {
    if (x.getTime() == PGStatement.DATE_POSITIVE_INFINITY) {
      return "infinity";
    } else if (x.getTime() == PGStatement.DATE_NEGATIVE_INFINITY) {
      return "-infinity";
    }

    cal = setupCalendar(cal);
    cal.setTime(x);

    sbuf.setLength(0);

    appendDate(sbuf, cal);
    appendEra(sbuf, cal);
    if (withTimeZone) {
      sbuf.append(' ');
      appendTimeZone(sbuf, cal);
    }

    return sbuf.toString();
  }

  public synchronized String toString(Calendar cal, Time x) {
    return toString(cal, x, true);
  }

  public synchronized String toString(Calendar cal, Time x,
      boolean withTimeZone) {
    cal = setupCalendar(cal);
    cal.setTime(x);

    sbuf.setLength(0);

    appendTime(sbuf, cal, cal.get(Calendar.MILLISECOND) * 1000000);

    // The 'time' parser for <= 7.3 doesn't like timezones.
    if (withTimeZone) {
      appendTimeZone(sbuf, cal);
    }

    return sbuf.toString();
  }

  private static void appendDate(StringBuilder sb, Calendar cal) {
    int year = cal.get(Calendar.YEAR);
    int month = cal.get(Calendar.MONTH) + 1;
    int day = cal.get(Calendar.DAY_OF_MONTH);
    appendDate(sb, year, month, day);
  }

  private static void appendDate(StringBuilder sb, int year, int month, int day) {
    // always use at least four digits for the year so very
    // early years, like 2, don't get misinterpreted
    //
    int prevLength = sb.length();
    sb.append(year);
    int leadingZerosForYear = 4 - (sb.length() - prevLength);
    if (leadingZerosForYear > 0) {
      sb.insert(prevLength, ZEROS, 0, leadingZerosForYear);
    }

    sb.append('-');
    sb.append(NUMBERS[month]);
    sb.append('-');
    sb.append(NUMBERS[day]);
  }

  private static void appendTime(StringBuilder sb, Calendar cal, int nanos) {
    int hours = cal.get(Calendar.HOUR_OF_DAY);
    int minutes = cal.get(Calendar.MINUTE);
    int seconds = cal.get(Calendar.SECOND);
    appendTime(sb, hours, minutes, seconds, nanos);
  }

  
Appends time part to the StringBuilder in PostgreSQL-compatible format. The function truncates {@param nanos} to microseconds. The value is expected to be rounded beforehand. 
Params:
sb – destination
hours – hours
minutes – minutes
seconds – seconds
nanos – nanoseconds/**
   * Appends time part to the {@code StringBuilder} in PostgreSQL-compatible format.
   * The function truncates {@param nanos} to microseconds. The value is expected to be rounded
   * beforehand.
   * @param sb destination
   * @param hours hours
   * @param minutes minutes
   * @param seconds seconds
   * @param nanos nanoseconds
   */
  private static void appendTime(StringBuilder sb, int hours, int minutes, int seconds, int nanos) {
    sb.append(NUMBERS[hours]);

    sb.append(':');
    sb.append(NUMBERS[minutes]);

    sb.append(':');
    sb.append(NUMBERS[seconds]);

    // Add nanoseconds.
    // This won't work for server versions < 7.2 which only want
    // a two digit fractional second, but we don't need to support 7.1
    // anymore and getting the version number here is difficult.
    //
    if (nanos < 1000) {
      return;
    }
    sb.append('.');
    int len = sb.length();
    sb.append(nanos / 1000); // append microseconds
    int needZeros = 6 - (sb.length() - len);
    if (needZeros > 0) {
      sb.insert(len, ZEROS, 0, needZeros);
    }

    int end = sb.length() - 1;
    while (sb.charAt(end) == '0') {
      sb.deleteCharAt(end);
      end--;
    }
  }

  private void appendTimeZone(StringBuilder sb, java.util.Calendar cal) {
    int offset = (cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET)) / 1000;

    appendTimeZone(sb, offset);
  }

  private void appendTimeZone(StringBuilder sb, int offset) {
    int absoff = Math.abs(offset);
    int hours = absoff / 60 / 60;
    int mins = (absoff - hours * 60 * 60) / 60;
    int secs = absoff - hours * 60 * 60 - mins * 60;

    sb.append((offset >= 0) ? "+" : "-");

    sb.append(NUMBERS[hours]);

    if (mins == 0 && secs == 0) {
      return;
    }
    sb.append(':');

    sb.append(NUMBERS[mins]);

    if (secs != 0) {
      sb.append(':');
      sb.append(NUMBERS[secs]);
    }
  }

  private static void appendEra(StringBuilder sb, Calendar cal) {
    if (cal.get(Calendar.ERA) == GregorianCalendar.BC) {
      sb.append(" BC");
    }
  }

  //JCP! if mvn.project.property.postgresql.jdbc.spec >= "JDBC4.2"
  public synchronized String toString(LocalDate localDate) {
    if (LocalDate.MAX.equals(localDate)) {
      return "infinity";
    } else if (LocalDate.MIN.equals(localDate)) {
      return "-infinity";
    }

    sbuf.setLength(0);

    appendDate(sbuf, localDate);
    appendEra(sbuf, localDate);

    return sbuf.toString();
  }

  public synchronized String toString(LocalTime localTime) {

    sbuf.setLength(0);

    if (localTime.isAfter(MAX_TIME)) {
      return "24:00:00";
    }

    int nano = localTime.getNano();
    if (nanosExceed499(nano)) {
      // Technically speaking this is not a proper rounding, however
      // it relies on the fact that appendTime just truncates 000..999 nanosecond part
      localTime = localTime.plus(ONE_MICROSECOND);
    }
    appendTime(sbuf, localTime);

    return sbuf.toString();
  }

  public synchronized String toString(OffsetDateTime offsetDateTime) {
    if (offsetDateTime.isAfter(MAX_OFFSET_DATETIME)) {
      return "infinity";
    } else if (OffsetDateTime.MIN.equals(offsetDateTime)) {
      return "-infinity";
    }

    sbuf.setLength(0);

    int nano = offsetDateTime.getNano();
    if (nanosExceed499(nano)) {
      // Technically speaking this is not a proper rounding, however
      // it relies on the fact that appendTime just truncates 000..999 nanosecond part
      offsetDateTime = offsetDateTime.plus(ONE_MICROSECOND);
    }
    LocalDateTime localDateTime = offsetDateTime.toLocalDateTime();
    LocalDate localDate = localDateTime.toLocalDate();
    appendDate(sbuf, localDate);
    sbuf.append(' ');
    appendTime(sbuf, localDateTime.toLocalTime());
    appendTimeZone(sbuf, offsetDateTime.getOffset());
    appendEra(sbuf, localDate);

    return sbuf.toString();
  }

  
Formats LocalDateTime to be sent to the backend, thus it adds time zone. Do not use this method in ResultSet.getString(int) 
Params:
localDateTime – The local date to format as a String
Returns:
The formatted local date/**
   * Formats {@link LocalDateTime} to be sent to the backend, thus it adds time zone.
   * Do not use this method in {@link java.sql.ResultSet#getString(int)}
   * @param localDateTime The local date to format as a String
   * @return The formatted local date
   */
  public synchronized String toString(LocalDateTime localDateTime) {
    if (localDateTime.isAfter(MAX_LOCAL_DATETIME)) {
      return "infinity";
    } else if (LocalDateTime.MIN.equals(localDateTime)) {
      return "-infinity";
    }

    // LocalDateTime is always passed with time zone so backend can decide between timestamp and timestamptz
    ZonedDateTime zonedDateTime = localDateTime.atZone(getDefaultTz().toZoneId());
    return toString(zonedDateTime.toOffsetDateTime());
  }

  private static void appendDate(StringBuilder sb, LocalDate localDate) {
    int year = localDate.get(ChronoField.YEAR_OF_ERA);
    int month = localDate.getMonthValue();
    int day = localDate.getDayOfMonth();
    appendDate(sb, year, month, day);
  }

  private static void appendTime(StringBuilder sb, LocalTime localTime) {
    int hours = localTime.getHour();
    int minutes = localTime.getMinute();
    int seconds = localTime.getSecond();
    int nanos = localTime.getNano();
    appendTime(sb, hours, minutes, seconds, nanos);
  }

  private void appendTimeZone(StringBuilder sb, ZoneOffset offset) {
    int offsetSeconds = offset.getTotalSeconds();

    appendTimeZone(sb, offsetSeconds);
  }

  private static void appendEra(StringBuilder sb, LocalDate localDate) {
    if (localDate.get(ChronoField.ERA) == IsoEra.BCE.getValue()) {
      sb.append(" BC");
    }
  }
  //JCP! endif

  private static int skipWhitespace(char[] s, int start) {
    int slen = s.length;
    for (int i = start; i < slen; i++) {
      if (!Character.isSpace(s[i])) {
        return i;
      }
    }
    return slen;
  }

  private static int firstNonDigit(char[] s, int start) {
    int slen = s.length;
    for (int i = start; i < slen; i++) {
      if (!Character.isDigit(s[i])) {
        return i;
      }
    }
    return slen;
  }

  private static int number(char[] s, int start, int end) {
    if (start >= end) {
      throw new NumberFormatException();
    }
    int n = 0;
    for (int i = start; i < end; i++) {
      n = 10 * n + (s[i] - '0');
    }
    return n;
  }

  private static char charAt(char[] s, int pos) {
    if (pos >= 0 && pos < s.length) {
      return s[pos];
    }
    return '\0';
  }

  
Returns the SQL Date object matching the given bytes with Oid.DATE. 
Params:
tz – The timezone used.
bytes – The binary encoded date value.
Throws:
PSQLException – If binary format could not be parsed.
Returns:
The parsed date object./**
   * Returns the SQL Date object matching the given bytes with {@link Oid#DATE}.
   *
   * @param tz The timezone used.
   * @param bytes The binary encoded date value.
   * @return The parsed date object.
   * @throws PSQLException If binary format could not be parsed.
   */
  public Date toDateBin(TimeZone tz, byte[] bytes) throws PSQLException {
    if (bytes.length != 4) {
      throw new PSQLException(GT.tr("Unsupported binary encoding of {0}.", "date"),
          PSQLState.BAD_DATETIME_FORMAT);
    }
    int days = ByteConverter.int4(bytes, 0);
    if (tz == null) {
      tz = getDefaultTz();
    }
    long secs = toJavaSecs(days * 86400L);
    long millis = secs * 1000L;

    if (millis <= PGStatement.DATE_NEGATIVE_SMALLER_INFINITY) {
      millis = PGStatement.DATE_NEGATIVE_INFINITY;
    } else if (millis >= PGStatement.DATE_POSITIVE_SMALLER_INFINITY) {
      millis = PGStatement.DATE_POSITIVE_INFINITY;
    } else {
      // Here be dragons: backend did not provide us the timezone, so we guess the actual point in
      // time

      millis = guessTimestamp(millis, tz);
    }
    return new Date(millis);
  }

  private TimeZone getDefaultTz() {
    // Fast path to getting the default timezone.
    if (DEFAULT_TIME_ZONE_FIELD != null) {
      try {
        TimeZone defaultTimeZone = (TimeZone) DEFAULT_TIME_ZONE_FIELD.get(null);
        if (defaultTimeZone == prevDefaultZoneFieldValue) {
          return defaultTimeZoneCache;
        }
        prevDefaultZoneFieldValue = defaultTimeZone;
      } catch (Exception e) {
        // If this were to fail, fallback on slow method.
      }
    }
    TimeZone tz = TimeZone.getDefault();
    defaultTimeZoneCache = tz;
    return tz;
  }

  public boolean hasFastDefaultTimeZone() {
    return DEFAULT_TIME_ZONE_FIELD != null;
  }

  
Returns the SQL Time object matching the given bytes with Oid.TIME or Oid.TIMETZ. 
Params:
tz – The timezone used when received data is Oid.TIME, ignored if data already contains Oid.TIMETZ.
bytes – The binary encoded time value.
Throws:
PSQLException – If binary format could not be parsed.
Returns:
The parsed time object./**
   * Returns the SQL Time object matching the given bytes with {@link Oid#TIME} or
   * {@link Oid#TIMETZ}.
   *
   * @param tz The timezone used when received data is {@link Oid#TIME}, ignored if data already
   *        contains {@link Oid#TIMETZ}.
   * @param bytes The binary encoded time value.
   * @return The parsed time object.
   * @throws PSQLException If binary format could not be parsed.
   */
  public Time toTimeBin(TimeZone tz, byte[] bytes) throws PSQLException {
    if ((bytes.length != 8 && bytes.length != 12)) {
      throw new PSQLException(GT.tr("Unsupported binary encoding of {0}.", "time"),
          PSQLState.BAD_DATETIME_FORMAT);
    }

    long millis;
    int timeOffset;

    if (usesDouble) {
      double time = ByteConverter.float8(bytes, 0);

      millis = (long) (time * 1000);
    } else {
      long time = ByteConverter.int8(bytes, 0);

      millis = time / 1000;
    }

    if (bytes.length == 12) {
      timeOffset = ByteConverter.int4(bytes, 8);
      timeOffset *= -1000;
      millis -= timeOffset;
      return new Time(millis);
    }

    if (tz == null) {
      tz = getDefaultTz();
    }

    // Here be dragons: backend did not provide us the timezone, so we guess the actual point in
    // time
    millis = guessTimestamp(millis, tz);

    return convertToTime(millis, tz); // Ensure date part is 1970-01-01
  }

  //JCP! if mvn.project.property.postgresql.jdbc.spec >= "JDBC4.2"
  
Returns the SQL Time object matching the given bytes with Oid.TIME. 
Params:
bytes – The binary encoded time value.
Throws:
PSQLException – If binary format could not be parsed.
Returns:
The parsed time object./**
   * Returns the SQL Time object matching the given bytes with {@link Oid#TIME}.
   *
   * @param bytes The binary encoded time value.
   * @return The parsed time object.
   * @throws PSQLException If binary format could not be parsed.
   */
  public LocalTime toLocalTimeBin(byte[] bytes) throws PSQLException {
    if (bytes.length != 8) {
      throw new PSQLException(GT.tr("Unsupported binary encoding of {0}.", "time"),
          PSQLState.BAD_DATETIME_FORMAT);
    }

    long micros;

    if (usesDouble) {
      double seconds = ByteConverter.float8(bytes, 0);

      micros = (long) (seconds * 1000000d);
    } else {
      micros = ByteConverter.int8(bytes, 0);
    }


    return LocalTime.ofNanoOfDay(micros * 1000);
  }
  //JCP! endif

  
Returns the SQL Timestamp object matching the given bytes with Oid.TIMESTAMP or Oid.TIMESTAMPTZ. 
Params:
tz – The timezone used when received data is Oid.TIMESTAMP, ignored if data already contains Oid.TIMESTAMPTZ.
bytes – The binary encoded timestamp value.
timestamptz – True if the binary is in GMT.
Throws:
PSQLException – If binary format could not be parsed.
Returns:
The parsed timestamp object./**
   * Returns the SQL Timestamp object matching the given bytes with {@link Oid#TIMESTAMP} or
   * {@link Oid#TIMESTAMPTZ}.
   *
   * @param tz The timezone used when received data is {@link Oid#TIMESTAMP}, ignored if data
   *        already contains {@link Oid#TIMESTAMPTZ}.
   * @param bytes The binary encoded timestamp value.
   * @param timestamptz True if the binary is in GMT.
   * @return The parsed timestamp object.
   * @throws PSQLException If binary format could not be parsed.
   */
  public Timestamp toTimestampBin(TimeZone tz, byte[] bytes, boolean timestamptz)
      throws PSQLException {

    ParsedBinaryTimestamp parsedTimestamp = this.toParsedTimestampBin(tz, bytes, timestamptz);
    if (parsedTimestamp.infinity == Infinity.POSITIVE) {
      return new Timestamp(PGStatement.DATE_POSITIVE_INFINITY);
    } else if (parsedTimestamp.infinity == Infinity.NEGATIVE) {
      return new Timestamp(PGStatement.DATE_NEGATIVE_INFINITY);
    }

    Timestamp ts = new Timestamp(parsedTimestamp.millis);
    ts.setNanos(parsedTimestamp.nanos);
    return ts;
  }

  private ParsedBinaryTimestamp toParsedTimestampBin(TimeZone tz, byte[] bytes, boolean timestamptz)
          throws PSQLException {

    if (bytes.length != 8) {
      throw new PSQLException(GT.tr("Unsupported binary encoding of {0}.", "timestamp"),
              PSQLState.BAD_DATETIME_FORMAT);
    }

    long secs;
    int nanos;

    if (usesDouble) {
      double time = ByteConverter.float8(bytes, 0);
      if (time == Double.POSITIVE_INFINITY) {
        ParsedBinaryTimestamp ts = new ParsedBinaryTimestamp();
        ts.infinity = Infinity.POSITIVE;
        return ts;
      } else if (time == Double.NEGATIVE_INFINITY) {
        ParsedBinaryTimestamp ts = new ParsedBinaryTimestamp();
        ts.infinity = Infinity.NEGATIVE;
        return ts;
      }

      secs = (long) time;
      nanos = (int) ((time - secs) * 1000000);
    } else {
      long time = ByteConverter.int8(bytes, 0);

      // compatibility with text based receiving, not strictly necessary
      // and can actually be confusing because there are timestamps
      // that are larger than infinite
      if (time == Long.MAX_VALUE) {
        ParsedBinaryTimestamp ts = new ParsedBinaryTimestamp();
        ts.infinity = Infinity.POSITIVE;
        return ts;
      } else if (time == Long.MIN_VALUE) {
        ParsedBinaryTimestamp ts = new ParsedBinaryTimestamp();
        ts.infinity = Infinity.NEGATIVE;
        return ts;
      }

      secs = time / 1000000;
      nanos = (int) (time - secs * 1000000);
    }
    if (nanos < 0) {
      secs--;
      nanos += 1000000;
    }
    nanos *= 1000;

    secs = toJavaSecs(secs);
    long millis = secs * 1000L;
    if (!timestamptz) {
      // Here be dragons: backend did not provide us the timezone, so we guess the actual point in
      // time
      millis = guessTimestamp(millis, tz);
    }

    ParsedBinaryTimestamp ts = new ParsedBinaryTimestamp();
    ts.millis = millis;
    ts.nanos = nanos;
    return ts;
  }

  //JCP! if mvn.project.property.postgresql.jdbc.spec >= "JDBC4.2"
  
Returns the local date time object matching the given bytes with Oid.TIMESTAMP or Oid.TIMESTAMPTZ. 
Params:
tz – time zone to use
bytes – The binary encoded local date time value.
Throws:
PSQLException – If binary format could not be parsed.
Returns:
The parsed local date time object./**
   * Returns the local date time object matching the given bytes with {@link Oid#TIMESTAMP} or
   * {@link Oid#TIMESTAMPTZ}.
   *
   * @param tz time zone to use
   * @param bytes The binary encoded local date time value.
   * @return The parsed local date time object.
   * @throws PSQLException If binary format could not be parsed.
   */
  public LocalDateTime toLocalDateTimeBin(TimeZone tz, byte[] bytes) throws PSQLException {

    ParsedBinaryTimestamp parsedTimestamp = this.toParsedTimestampBin(tz, bytes, true);
    if (parsedTimestamp.infinity == Infinity.POSITIVE) {
      return LocalDateTime.MAX;
    } else if (parsedTimestamp.infinity == Infinity.NEGATIVE) {
      return LocalDateTime.MIN;
    }

    return LocalDateTime.ofEpochSecond(parsedTimestamp.millis / 1000L, parsedTimestamp.nanos, ZoneOffset.UTC);
  }
  //JCP! endif

  
Given a UTC timestamp millis finds another point in time that is rendered in given time zone tz exactly as "millis in UTC".
For instance, given 7 Jan 16:00 UTC and tz=GMT+02:00 it returns 7 Jan 14:00 UTC == 7 Jan 16:00 GMT+02:00 Note that is not trivial for timestamps near DST change. For such cases, we rely on Calendar to figure out the proper timestamp.
Params:
millis – source timestamp
tz – desired time zone
Returns:
timestamp that would be rendered in tz like millis in UTC/**
   * <p>Given a UTC timestamp {@code millis} finds another point in time that is rendered in given time
   * zone {@code tz} exactly as "millis in UTC".</p>
   *
   * <p>For instance, given 7 Jan 16:00 UTC and tz=GMT+02:00 it returns 7 Jan 14:00 UTC == 7 Jan 16:00
   * GMT+02:00 Note that is not trivial for timestamps near DST change. For such cases, we rely on
   * {@link Calendar} to figure out the proper timestamp.</p>
   *
   * @param millis source timestamp
   * @param tz desired time zone
   * @return timestamp that would be rendered in {@code tz} like {@code millis} in UTC
   */
  private long guessTimestamp(long millis, TimeZone tz) {
    if (tz == null) {
      // If client did not provide us with time zone, we use system default time zone
      tz = getDefaultTz();
    }
    // The story here:
    // Backend provided us with something like '2015-10-04 13:40' and it did NOT provide us with a
    // time zone.
    // On top of that, user asked us to treat the timestamp as if it were in GMT+02:00.
    //
    // The code below creates such a timestamp that is rendered as '2015-10-04 13:40 GMT+02:00'
    // In other words, its UTC value should be 11:40 UTC == 13:40 GMT+02:00.
    // It is not sufficient to just subtract offset as you might cross DST change as you subtract.
    //
    // For instance, on 2000-03-26 02:00:00 Moscow went to DST, thus local time became 03:00:00
    // Suppose we deal with 2000-03-26 02:00:01
    // If you subtract offset from the timestamp, the time will be "a hour behind" since
    // "just a couple of hours ago the OFFSET was different"
    //
    // To make a long story short: we have UTC timestamp that looks like "2000-03-26 02:00:01" when
    // rendered in UTC tz.
    // We want to know another timestamp that will look like "2000-03-26 02:00:01" in Europe/Moscow
    // time zone.

    if (isSimpleTimeZone(tz.getID())) {
      // For well-known non-DST time zones, just subtract offset
      return millis - tz.getRawOffset();
    }
    // For all the other time zones, enjoy debugging Calendar API
    // Here we do a straight-forward implementation that splits original timestamp into pieces and
    // composes it back.
    // Note: cal.setTimeZone alone is not sufficient as it would alter hour (it will try to keep the
    // same time instant value)
    Calendar cal = calendarWithUserTz;
    cal.setTimeZone(utcTz);
    cal.setTimeInMillis(millis);
    int era = cal.get(Calendar.ERA);
    int year = cal.get(Calendar.YEAR);
    int month = cal.get(Calendar.MONTH);
    int day = cal.get(Calendar.DAY_OF_MONTH);
    int hour = cal.get(Calendar.HOUR_OF_DAY);
    int min = cal.get(Calendar.MINUTE);
    int sec = cal.get(Calendar.SECOND);
    int ms = cal.get(Calendar.MILLISECOND);
    cal.setTimeZone(tz);
    cal.set(Calendar.ERA, era);
    cal.set(Calendar.YEAR, year);
    cal.set(Calendar.MONTH, month);
    cal.set(Calendar.DAY_OF_MONTH, day);
    cal.set(Calendar.HOUR_OF_DAY, hour);
    cal.set(Calendar.MINUTE, min);
    cal.set(Calendar.SECOND, sec);
    cal.set(Calendar.MILLISECOND, ms);
    return cal.getTimeInMillis();
  }

  private static boolean isSimpleTimeZone(String id) {
    return id.startsWith("GMT") || id.startsWith("UTC");
  }

  
Extracts the date part from a timestamp.
Params:
millis – The timestamp from which to extract the date.
tz – The time zone of the date.
Returns:
The extracted date./**
   * Extracts the date part from a timestamp.
   *
   * @param millis The timestamp from which to extract the date.
   * @param tz The time zone of the date.
   * @return The extracted date.
   */
  public Date convertToDate(long millis, TimeZone tz) {

    // no adjustments for the inifity hack values
    if (millis <= PGStatement.DATE_NEGATIVE_INFINITY
        || millis >= PGStatement.DATE_POSITIVE_INFINITY) {
      return new Date(millis);
    }
    if (tz == null) {
      tz = getDefaultTz();
    }
    if (isSimpleTimeZone(tz.getID())) {
      // Truncate to 00:00 of the day.
      // Suppose the input date is 7 Jan 15:40 GMT+02:00 (that is 13:40 UTC)
      // We want it to become 7 Jan 00:00 GMT+02:00
      // 1) Make sure millis becomes 15:40 in UTC, so add offset
      int offset = tz.getRawOffset();
      millis += offset;
      // 2) Truncate hours, minutes, etc. Day is always 86400 seconds, no matter what leap seconds
      // are
      millis = floorDiv(millis, ONEDAY) * ONEDAY;
      // 2) Now millis is 7 Jan 00:00 UTC, however we need that in GMT+02:00, so subtract some
      // offset
      millis -= offset;
      // Now we have brand-new 7 Jan 00:00 GMT+02:00
      return new Date(millis);
    }

    Calendar cal = calendarWithUserTz;
    cal.setTimeZone(tz);
    cal.setTimeInMillis(millis);
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);

    return new Date(cal.getTimeInMillis());
  }

  
Extracts the time part from a timestamp. This method ensures the date part of output timestamp
looks like 1970-01-01 in given timezone.
Params:
millis – The timestamp from which to extract the time.
tz – timezone to use.
Returns:
The extracted time./**
   * Extracts the time part from a timestamp. This method ensures the date part of output timestamp
   * looks like 1970-01-01 in given timezone.
   *
   * @param millis The timestamp from which to extract the time.
   * @param tz timezone to use.
   * @return The extracted time.
   */
  public Time convertToTime(long millis, TimeZone tz) {
    if (tz == null) {
      tz = getDefaultTz();
    }
    if (isSimpleTimeZone(tz.getID())) {
      // Leave just time part of the day.
      // Suppose the input date is 2015 7 Jan 15:40 GMT+02:00 (that is 13:40 UTC)
      // We want it to become 1970 1 Jan 15:40 GMT+02:00
      // 1) Make sure millis becomes 15:40 in UTC, so add offset
      int offset = tz.getRawOffset();
      millis += offset;
      // 2) Truncate year, month, day. Day is always 86400 seconds, no matter what leap seconds are
      millis = floorMod(millis, ONEDAY);
      // 2) Now millis is 1970 1 Jan 15:40 UTC, however we need that in GMT+02:00, so subtract some
      // offset
      millis -= offset;
      // Now we have brand-new 1970 1 Jan 15:40 GMT+02:00
      return new Time(millis);
    }
    Calendar cal = calendarWithUserTz;
    cal.setTimeZone(tz);
    cal.setTimeInMillis(millis);
    cal.set(Calendar.ERA, GregorianCalendar.AD);
    cal.set(Calendar.YEAR, 1970);
    cal.set(Calendar.MONTH, 0);
    cal.set(Calendar.DAY_OF_MONTH, 1);

    return new Time(cal.getTimeInMillis());
  }

  
Returns the given time value as String matching what the current postgresql server would send
in text mode.
Params:
time – time value
withTimeZone – whether timezone should be added
Returns:
given time value as String/**
   * Returns the given time value as String matching what the current postgresql server would send
   * in text mode.
   *
   * @param time time value
   * @param withTimeZone whether timezone should be added
   * @return given time value as String
   */
  public String timeToString(java.util.Date time, boolean withTimeZone) {
    Calendar cal = null;
    if (withTimeZone) {
      cal = calendarWithUserTz;
      cal.setTimeZone(timeZoneProvider.get());
    }
    if (time instanceof Timestamp) {
      return toString(cal, (Timestamp) time, withTimeZone);
    }
    if (time instanceof Time) {
      return toString(cal, (Time) time, withTimeZone);
    }
    return toString(cal, (Date) time, withTimeZone);
  }

  
Converts the given postgresql seconds to java seconds. Reverse engineered by inserting varying dates to postgresql and tuning the formula until the java dates matched. See toPgSecs for the reverse operation. 
Params:
secs – Postgresql seconds.
Returns:
Java seconds./**
   * Converts the given postgresql seconds to java seconds. Reverse engineered by inserting varying
   * dates to postgresql and tuning the formula until the java dates matched. See {@link #toPgSecs}
   * for the reverse operation.
   *
   * @param secs Postgresql seconds.
   * @return Java seconds.
   */
  private static long toJavaSecs(long secs) {
    // postgres epoc to java epoc
    secs += 946684800L;

    // Julian/Gregorian calendar cutoff point
    if (secs < -12219292800L) { // October 4, 1582 -> October 15, 1582
      secs += 86400 * 10;
      if (secs < -14825808000L) { // 1500-02-28 -> 1500-03-01
        int extraLeaps = (int) ((secs + 14825808000L) / 3155760000L);
        extraLeaps--;
        extraLeaps -= extraLeaps / 4;
        secs += extraLeaps * 86400L;
      }
    }
    return secs;
  }

  
Converts the given java seconds to postgresql seconds. See toJavaSecs for the reverse operation. The conversion is valid for any year 100 BC onwards. 
Params:
secs – Postgresql seconds.
Returns:
Java seconds./**
   * Converts the given java seconds to postgresql seconds. See {@link #toJavaSecs} for the reverse
   * operation. The conversion is valid for any year 100 BC onwards.
   *
   * @param secs Postgresql seconds.
   * @return Java seconds.
   */
  private static long toPgSecs(long secs) {
    // java epoc to postgres epoc
    secs -= 946684800L;

    // Julian/Greagorian calendar cutoff point
    if (secs < -13165977600L) { // October 15, 1582 -> October 4, 1582
      secs -= 86400 * 10;
      if (secs < -15773356800L) { // 1500-03-01 -> 1500-02-28
        int years = (int) ((secs + 15773356800L) / -3155823050L);
        years++;
        years -= years / 4;
        secs += years * 86400L;
      }
    }

    return secs;
  }

  
Converts the SQL Date to binary representation for Oid.DATE. 
Params:
tz – The timezone used.
bytes – The binary encoded date value.
value – value
Throws:
PSQLException – If binary format could not be parsed./**
   * Converts the SQL Date to binary representation for {@link Oid#DATE}.
   *
   * @param tz The timezone used.
   * @param bytes The binary encoded date value.
   * @param value value
   * @throws PSQLException If binary format could not be parsed.
   */
  public void toBinDate(TimeZone tz, byte[] bytes, Date value) throws PSQLException {
    long millis = value.getTime();

    if (tz == null) {
      tz = getDefaultTz();
    }
    // It "getOffset" is UNTESTED
    // See org.postgresql.jdbc.AbstractJdbc2Statement.setDate(int, java.sql.Date,
    // java.util.Calendar)
    // The problem is we typically do not know for sure what is the exact required date/timestamp
    // type
    // Thus pgjdbc sticks to text transfer.
    millis += tz.getOffset(millis);

    long secs = toPgSecs(millis / 1000);
    ByteConverter.int4(bytes, 0, (int) (secs / 86400));
  }

  
Converts backend's TimeZone parameter to java format.
Notable difference: backend's gmt-3 is GMT+03 in Java.
Params:
timeZone – time zone to use
Returns:
java TimeZone/**
   * Converts backend's TimeZone parameter to java format.
   * Notable difference: backend's gmt-3 is GMT+03 in Java.
   *
   * @param timeZone time zone to use
   * @return java TimeZone
   */
  public static TimeZone parseBackendTimeZone(String timeZone) {
    if (timeZone.startsWith("GMT")) {
      TimeZone tz = GMT_ZONES.get(timeZone);
      if (tz != null) {
        return tz;
      }
    }
    return TimeZone.getTimeZone(timeZone);
  }

  private static long floorDiv(long x, long y) {
    long r = x / y;
    // if the signs are different and modulo not zero, round down
    if ((x ^ y) < 0 && (r * y != x)) {
      r--;
    }
    return r;
  }

  private static long floorMod(long x, long y) {
    return x - floorDiv(x, y) * y;
  }
}