package org.hl7.fhir.r4.model;

/*
  Copyright (c) 2011+, HL7, Inc.
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without modification, 
  are permitted provided that the following conditions are met:
    
   * Redistributions of source code must retain the above copyright notice, this 
     list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright notice, 
     this list of conditions and the following disclaimer in the documentation 
     and/or other materials provided with the distribution.
   * Neither the name of HL7 nor the names of its contributors may be used to 
     endorse or promote products derived from this software without specific 
     prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
  POSSIBILITY OF SUCH DAMAGE.
  
 */

import static org.apache.commons.lang3.StringUtils.isBlank;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Map;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentHashMap;

import javax.annotation.Nullable;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.apache.commons.lang3.time.DateUtils;
import org.hl7.fhir.utilities.DateTimeUtil;
import org.hl7.fhir.utilities.Utilities;

import ca.uhn.fhir.model.api.TemporalPrecisionEnum;
import ca.uhn.fhir.parser.DataFormatException;

public abstract class BaseDateTimeType extends PrimitiveType<Date> {

  static final long NANOS_PER_MILLIS = 1000000L;

  static final long NANOS_PER_SECOND = 1000000000L;
  private static final Map<String, TimeZone> timezoneCache = new ConcurrentHashMap<>();
  private static final long serialVersionUID = 1L;

  private String myFractionalSeconds;
  private TemporalPrecisionEnum myPrecision = null;
  private TimeZone myTimeZone;
  private boolean myTimeZoneZulu = false;

  /**
   * Constructor
   */
  public BaseDateTimeType() {
    // nothing
  }

  /**
   * Constructor
   *
   * @throws IllegalArgumentException If the specified precision is not allowed
   *                                  for this type
   */
  public BaseDateTimeType(Date theDate, TemporalPrecisionEnum thePrecision) {
    setValue(theDate, thePrecision);
    validatePrecisionAndThrowIllegalArgumentException();
  }

  /**
   * Constructor
   */
  public BaseDateTimeType(Date theDate, TemporalPrecisionEnum thePrecision, TimeZone theTimeZone) {
    this(theDate, thePrecision);
    setTimeZone(theTimeZone);
    validatePrecisionAndThrowIllegalArgumentException();
  }

  /**
   * Constructor
   *
   * @throws IllegalArgumentException If the specified precision is not allowed
   *                                  for this type
   */
  public BaseDateTimeType(String theString) {
    setValueAsString(theString);
    validatePrecisionAndThrowIllegalArgumentException();
  }

  private void validatePrecisionAndThrowIllegalArgumentException() {
    if (!isPrecisionAllowed(getPrecision())) {
      throw new IllegalArgumentException("Invalid date/time string (datatype " + getClass().getSimpleName()
          + " does not support " + getPrecision() + " precision): " + getValueAsString());
    }
  }

  /**
   * Adds the given amount to the field specified by theField
   *
   * @param theField The field, uses constants from {@link Calendar} such as
   *                 {@link Calendar#YEAR}
   * @param theValue The number to add (or subtract for a negative number)
   */
  public void add(int theField, int theValue) {
    switch (theField) {
    case Calendar.YEAR:
      setValue(DateUtils.addYears(getValue(), theValue), getPrecision());
      break;
    case Calendar.MONTH:
      setValue(DateUtils.addMonths(getValue(), theValue), getPrecision());
      break;
    case Calendar.DATE:
      setValue(DateUtils.addDays(getValue(), theValue), getPrecision());
      break;
    case Calendar.HOUR:
      setValue(DateUtils.addHours(getValue(), theValue), getPrecision());
      break;
    case Calendar.MINUTE:
      setValue(DateUtils.addMinutes(getValue(), theValue), getPrecision());
      break;
    case Calendar.SECOND:
      setValue(DateUtils.addSeconds(getValue(), theValue), getPrecision());
      break;
    case Calendar.MILLISECOND:
      setValue(DateUtils.addMilliseconds(getValue(), theValue), getPrecision());
      break;
    default:
      throw new DataFormatException("Unknown field constant: " + theField);
    }
  }

  /**
   * Returns <code>true</code> if the given object represents a date/time before
   * <code>this</code> object
   *
   * @throws NullPointerException If <code>this.getValue()</code> or
   *                              <code>theDateTimeType.getValue()</code> return
   *                              <code>null</code>
   */
  public boolean after(DateTimeType theDateTimeType) {
    validateBeforeOrAfter(theDateTimeType);
    return getValue().after(theDateTimeType.getValue());
  }

  /**
   * Returns <code>true</code> if the given object represents a date/time before
   * <code>this</code> object
   *
   * @throws NullPointerException If <code>this.getValue()</code> or
   *                              <code>theDateTimeType.getValue()</code> return
   *                              <code>null</code>
   */
  public boolean before(DateTimeType theDateTimeType) {
    validateBeforeOrAfter(theDateTimeType);
    return getValue().before(theDateTimeType.getValue());
  }

  private void clearTimeZone() {
    myTimeZone = null;
    myTimeZoneZulu = false;
  }

  /**
   * @param thePrecision
   * @return the String value of this instance with the specified precision.
   */
  public String getValueAsString(TemporalPrecisionEnum thePrecision) {
    return encode(getValue(), thePrecision);
  }

  @Override
  protected String encode(Date theValue) {
    return encode(theValue, myPrecision);
  }

  @Nullable
  private String encode(Date theValue, TemporalPrecisionEnum thePrecision) {
    if (theValue == null) {
      return null;
    } else {
      GregorianCalendar cal;
      if (myTimeZoneZulu) {
        cal = new GregorianCalendar(getTimeZone("GMT"));
      } else if (myTimeZone != null) {
        cal = new GregorianCalendar(myTimeZone);
      } else {
        cal = new GregorianCalendar();
      }
      cal.setTime(theValue);

      StringBuilder b = new StringBuilder();
      leftPadWithZeros(cal.get(Calendar.YEAR), 4, b);

      if (thePrecision.ordinal() > TemporalPrecisionEnum.YEAR.ordinal()) {
        b.append('-');
        leftPadWithZeros(cal.get(Calendar.MONTH) + 1, 2, b);
        if (thePrecision.ordinal() > TemporalPrecisionEnum.MONTH.ordinal()) {
          b.append('-');
          leftPadWithZeros(cal.get(Calendar.DATE), 2, b);
          if (thePrecision.ordinal() > TemporalPrecisionEnum.DAY.ordinal()) {
            b.append('T');
            leftPadWithZeros(cal.get(Calendar.HOUR_OF_DAY), 2, b);
            b.append(':');
            leftPadWithZeros(cal.get(Calendar.MINUTE), 2, b);
            if (thePrecision.ordinal() > TemporalPrecisionEnum.MINUTE.ordinal()) {
              b.append(':');
              leftPadWithZeros(cal.get(Calendar.SECOND), 2, b);
              if (thePrecision.ordinal() > TemporalPrecisionEnum.SECOND.ordinal()) {
                b.append('.');
                b.append(myFractionalSeconds);
                for (int i = myFractionalSeconds.length(); i < 3; i++) {
                  b.append('0');
                }
              }
            }

            if (myTimeZoneZulu) {
              b.append('Z');
            } else if (myTimeZone != null) {
              int offset = myTimeZone.getOffset(theValue.getTime());
              if (offset >= 0) {
                b.append('+');
              } else {
                b.append('-');
                offset = Math.abs(offset);
              }

              int hoursOffset = (int) (offset / DateUtils.MILLIS_PER_HOUR);
              leftPadWithZeros(hoursOffset, 2, b);
              b.append(':');
              int minutesOffset = (int) (offset % DateUtils.MILLIS_PER_HOUR);
              minutesOffset = (int) (minutesOffset / DateUtils.MILLIS_PER_MINUTE);
              leftPadWithZeros(minutesOffset, 2, b);
            }
          }
        }
      }
      return b.toString();
    }
  }

  /**
   * Returns the month with 1-index, e.g. 1=the first day of the month
   */
  public Integer getDay() {
    return getFieldValue(Calendar.DAY_OF_MONTH);
  }

  /**
   * Returns the default precision for the given datatype
   */
  protected abstract TemporalPrecisionEnum getDefaultPrecisionForDatatype();

  private Integer getFieldValue(int theField) {
    if (getValue() == null) {
      return null;
    }
    Calendar cal = getValueAsCalendar();
    return cal.get(theField);
  }

  /**
   * Returns the hour of the day in a 24h clock, e.g. 13=1pm
   */
  public Integer getHour() {
    return getFieldValue(Calendar.HOUR_OF_DAY);
  }

  /**
   * Returns the milliseconds within the current second.
   * <p>
   * Note that this method returns the same value as {@link #getNanos()} but with
   * less precision.
   * </p>
   */
  public Integer getMillis() {
    return getFieldValue(Calendar.MILLISECOND);
  }

  /**
   * Returns the minute of the hour in the range 0-59
   */
  public Integer getMinute() {
    return getFieldValue(Calendar.MINUTE);
  }

  /**
   * Returns the month with 0-index, e.g. 0=January
   */
  public Integer getMonth() {
    return getFieldValue(Calendar.MONTH);
  }

  public float getSecondsMilli() {
    int sec = getSecond();
    int milli = getMillis();
    String s = Integer.toString(sec) + "." + Utilities.padLeft(Integer.toString(milli), '0', 3);
    return Float.parseFloat(s);
  }

  /**
   * Returns the nanoseconds within the current second
   * <p>
   * Note that this method returns the same value as {@link #getMillis()} but with
   * more precision.
   * </p>
   */
  public Long getNanos() {
    if (isBlank(myFractionalSeconds)) {
      return null;
    }
    String retVal = StringUtils.rightPad(myFractionalSeconds, 9, '0');
    retVal = retVal.substring(0, 9);
    return Long.parseLong(retVal);
  }

  private int getOffsetIndex(String theValueString) {
    int plusIndex = theValueString.indexOf('+', 16);
    int minusIndex = theValueString.indexOf('-', 16);
    int zIndex = theValueString.indexOf('Z', 16);
    int retVal = Math.max(Math.max(plusIndex, minusIndex), zIndex);
    if (retVal == -1) {
      return -1;
    }
    if ((retVal - 2) != (plusIndex + minusIndex + zIndex)) {
      throwBadDateFormat(theValueString);
    }
    return retVal;
  }

  /**
   * Gets the precision for this datatype (using the default for the given type if
   * not set)
   *
   * @see #setPrecision(TemporalPrecisionEnum)
   */
  public TemporalPrecisionEnum getPrecision() {
    if (myPrecision == null) {
      return getDefaultPrecisionForDatatype();
    }
    return myPrecision;
  }

  /**
   * Returns the second of the minute in the range 0-59
   */
  public Integer getSecond() {
    return getFieldValue(Calendar.SECOND);
  }

  /**
   * Returns the TimeZone associated with this dateTime's value. May return
   * <code>null</code> if no timezone was supplied.
   */
  public TimeZone getTimeZone() {
    if (myTimeZoneZulu) {
      return getTimeZone("GMT");
    }
    return myTimeZone;
  }

  /**
   * Returns the value of this object as a {@link GregorianCalendar}
   */
  public GregorianCalendar getValueAsCalendar() {
    if (getValue() == null) {
      return null;
    }
    GregorianCalendar cal;
    if (getTimeZone() != null) {
      cal = new GregorianCalendar(getTimeZone());
    } else {
      cal = new GregorianCalendar();
    }
    cal.setTime(getValue());
    return cal;
  }

  /**
   * Returns the year, e.g. 2015
   */
  public Integer getYear() {
    return getFieldValue(Calendar.YEAR);
  }

  /**
   * To be implemented by subclasses to indicate whether the given precision is
   * allowed by this type
   */
  abstract boolean isPrecisionAllowed(TemporalPrecisionEnum thePrecision);

  /**
   * Returns true if the timezone is set to GMT-0:00 (Z)
   */
  public boolean isTimeZoneZulu() {
    return myTimeZoneZulu;
  }

  /**
   * Returns <code>true</code> if this object represents a date that is today's
   * date
   *
   * @throws NullPointerException if {@link #getValue()} returns <code>null</code>
   */
  public boolean isToday() {
    Validate.notNull(getValue(), getClass().getSimpleName() + " contains null value");
    return DateUtils.isSameDay(new Date(), getValue());
  }

  private void leftPadWithZeros(int theInteger, int theLength, StringBuilder theTarget) {
    String string = Integer.toString(theInteger);
    for (int i = string.length(); i < theLength; i++) {
      theTarget.append('0');
    }
    theTarget.append(string);
  }

  @Override
  protected Date parse(String theValue) throws DataFormatException {
    Calendar cal = new GregorianCalendar(0, 0, 0);
    cal.setTimeZone(TimeZone.getDefault());
    String value = theValue;
    boolean fractionalSecondsSet = false;

    if (value.length() > 0 && (value.charAt(0) == ' ' || value.charAt(value.length() - 1) == ' ')) {
      value = value.trim();
    }

    int length = value.length();
    if (length == 0) {
      return null;
    }

    if (length < 4) {
      throwBadDateFormat(value);
    }

    TemporalPrecisionEnum precision = null;
    cal.set(Calendar.YEAR, parseInt(value, value.substring(0, 4), 0, 9999));
    precision = TemporalPrecisionEnum.YEAR;
    if (length > 4) {
      validateCharAtIndexIs(value, 4, '-');
      validateLengthIsAtLeast(value, 7);
      int monthVal = parseInt(value, value.substring(5, 7), 1, 12) - 1;
      cal.set(Calendar.MONTH, monthVal);
      precision = TemporalPrecisionEnum.MONTH;
      if (length > 7) {
        validateCharAtIndexIs(value, 7, '-');
        validateLengthIsAtLeast(value, 10);
        cal.set(Calendar.DATE, 1); // for some reason getActualMaximum works incorrectly if date isn't set
        int actualMaximum = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
        cal.set(Calendar.DAY_OF_MONTH, parseInt(value, value.substring(8, 10), 1, actualMaximum));
        precision = TemporalPrecisionEnum.DAY;
        if (length > 10) {
          validateLengthIsAtLeast(value, 17);
          validateCharAtIndexIs(value, 10, 'T'); // yyyy-mm-ddThh:mm:ss
          int offsetIdx = getOffsetIndex(value);
          String time;
          if (offsetIdx == -1) {
            // throwBadDateFormat(theValue);
            // No offset - should this be an error?
            time = value.substring(11);
          } else {
            time = value.substring(11, offsetIdx);
            String offsetString = value.substring(offsetIdx);
            setTimeZone(value, offsetString);
            cal.setTimeZone(getTimeZone());
          }
          int timeLength = time.length();

          validateCharAtIndexIs(value, 13, ':');
          cal.set(Calendar.HOUR_OF_DAY, parseInt(value, value.substring(11, 13), 0, 23));
          cal.set(Calendar.MINUTE, parseInt(value, value.substring(14, 16), 0, 59));
          precision = TemporalPrecisionEnum.MINUTE;
          if (timeLength > 5) {
            validateLengthIsAtLeast(value, 19);
            validateCharAtIndexIs(value, 16, ':'); // yyyy-mm-ddThh:mm:ss
            cal.set(Calendar.SECOND, parseInt(value, value.substring(17, 19), 0, 60)); // note: this allows leap seconds
            precision = TemporalPrecisionEnum.SECOND;
            if (timeLength > 8) {
              validateCharAtIndexIs(value, 19, '.'); // yyyy-mm-ddThh:mm:ss.SSSS
              validateLengthIsAtLeast(value, 20);
              int endIndex = getOffsetIndex(value);
              if (endIndex == -1) {
                endIndex = value.length();
              }
              int millis;
              String millisString;
              if (endIndex > 23) {
                myFractionalSeconds = value.substring(20, endIndex);
                fractionalSecondsSet = true;
                endIndex = 23;
                millisString = value.substring(20, endIndex);
                millis = parseInt(value, millisString, 0, 999);
              } else {
                millisString = value.substring(20, endIndex);
                millis = parseInt(value, millisString, 0, 999);
                myFractionalSeconds = millisString;
                fractionalSecondsSet = true;
              }
              if (millisString.length() == 1) {
                millis = millis * 100;
              } else if (millisString.length() == 2) {
                millis = millis * 10;
              }
              cal.set(Calendar.MILLISECOND, millis);
              precision = TemporalPrecisionEnum.MILLI;
            }
          }
        }
      } else {
        cal.set(Calendar.DATE, 1);
      }
    } else {
      cal.set(Calendar.DATE, 1);
    }

    if (fractionalSecondsSet == false) {
      myFractionalSeconds = "";
    }

    myPrecision = precision;
    return cal.getTime();

  }

  private int parseInt(String theValue, String theSubstring, int theLowerBound, int theUpperBound) {
    int retVal = 0;
    try {
      retVal = Integer.parseInt(theSubstring);
    } catch (NumberFormatException e) {
      throwBadDateFormat(theValue);
    }

    if (retVal < theLowerBound || retVal > theUpperBound) {
      throwBadDateFormat(theValue);
    }

    return retVal;
  }

  /**
   * Sets the month with 1-index, e.g. 1=the first day of the month
   */
  public BaseDateTimeType setDay(int theDay) {
    setFieldValue(Calendar.DAY_OF_MONTH, theDay, null, 0, 31);
    return this;
  }

  private void setFieldValue(int theField, int theValue, String theFractionalSeconds, int theMinimum, int theMaximum) {
    validateValueInRange(theValue, theMinimum, theMaximum);
    Calendar cal;
    if (getValue() == null) {
      cal = new GregorianCalendar();
    } else {
      cal = getValueAsCalendar();
    }
    if (theField != -1) {
      cal.set(theField, theValue);
    }
    if (theFractionalSeconds != null) {
      myFractionalSeconds = theFractionalSeconds;
    } else if (theField == Calendar.MILLISECOND) {
      myFractionalSeconds = StringUtils.leftPad(Integer.toString(theValue), 3, '0');
    }
    super.setValue(cal.getTime());
  }

  /**
   * Sets the hour of the day in a 24h clock, e.g. 13=1pm
   */
  public BaseDateTimeType setHour(int theHour) {
    setFieldValue(Calendar.HOUR_OF_DAY, theHour, null, 0, 23);
    return this;
  }

  /**
   * Sets the milliseconds within the current second.
   * <p>
   * Note that this method sets the same value as {@link #setNanos(long)} but with
   * less precision.
   * </p>
   */
  public BaseDateTimeType setMillis(int theMillis) {
    setFieldValue(Calendar.MILLISECOND, theMillis, null, 0, 999);
    return this;
  }

  /**
   * Sets the minute of the hour in the range 0-59
   */
  public BaseDateTimeType setMinute(int theMinute) {
    setFieldValue(Calendar.MINUTE, theMinute, null, 0, 59);
    return this;
  }

  /**
   * Sets the month with 0-index, e.g. 0=January
   */
  public BaseDateTimeType setMonth(int theMonth) {
    setFieldValue(Calendar.MONTH, theMonth, null, 0, 11);
    return this;
  }

  /**
   * Sets the nanoseconds within the current second
   * <p>
   * Note that this method sets the same value as {@link #setMillis(int)} but with
   * more precision.
   * </p>
   */
  public BaseDateTimeType setNanos(long theNanos) {
    validateValueInRange(theNanos, 0, NANOS_PER_SECOND - 1);
    String fractionalSeconds = StringUtils.leftPad(Long.toString(theNanos), 9, '0');

    // Strip trailing 0s
    for (int i = fractionalSeconds.length(); i > 0; i--) {
      if (fractionalSeconds.charAt(i - 1) != '0') {
        fractionalSeconds = fractionalSeconds.substring(0, i);
        break;
      }
    }
    int millis = (int) (theNanos / NANOS_PER_MILLIS);
    setFieldValue(Calendar.MILLISECOND, millis, fractionalSeconds, 0, 999);
    return this;
  }

  /**
   * Sets the precision for this datatype
   *
   * @throws DataFormatException
   */
  public void setPrecision(TemporalPrecisionEnum thePrecision) throws DataFormatException {
    if (thePrecision == null) {
      throw new NullPointerException("Precision may not be null");
    }
    myPrecision = thePrecision;
    updateStringValue();
  }

  /**
   * Sets the second of the minute in the range 0-59
   */
  public BaseDateTimeType setSecond(int theSecond) {
    setFieldValue(Calendar.SECOND, theSecond, null, 0, 59);
    return this;
  }

  private BaseDateTimeType setTimeZone(String theWholeValue, String theValue) {

    if (isBlank(theValue)) {
      throwBadDateFormat(theWholeValue);
    } else if (theValue.charAt(0) == 'Z') {
      myTimeZone = null;
      myTimeZoneZulu = true;
    } else if (theValue.length() != 6) {
      throwBadDateFormat(theWholeValue, "Timezone offset must be in the form \"Z\", \"-HH:mm\", or \"+HH:mm\"");
    } else if (theValue.charAt(3) != ':' || !(theValue.charAt(0) == '+' || theValue.charAt(0) == '-')) {
      throwBadDateFormat(theWholeValue, "Timezone offset must be in the form \"Z\", \"-HH:mm\", or \"+HH:mm\"");
    } else {
      parseInt(theWholeValue, theValue.substring(1, 3), 0, 23);
      parseInt(theWholeValue, theValue.substring(4, 6), 0, 59);
      myTimeZoneZulu = false;
      myTimeZone = getTimeZone("GMT" + theValue);
    }

    return this;
  }

  public BaseDateTimeType setTimeZone(TimeZone theTimeZone) {
    myTimeZone = theTimeZone;
    myTimeZoneZulu = false;
    updateStringValue();
    return this;
  }

  public BaseDateTimeType setTimeZoneZulu(boolean theTimeZoneZulu) {
    myTimeZoneZulu = theTimeZoneZulu;
    myTimeZone = null;
    updateStringValue();
    return this;
  }

  /**
   * Sets the value for this type using the given Java Date object as the time,
   * and using the default precision for this datatype (unless the precision is
   * already set), as well as the local timezone as determined by the local
   * operating system. Both of these properties may be modified in subsequent
   * calls if neccesary.
   */
  @Override
  public BaseDateTimeType setValue(Date theValue) {
    setValue(theValue, getPrecision());
    return this;
  }

  /**
   * Sets the value for this type using the given Java Date object as the time,
   * and using the specified precision, as well as the local timezone as
   * determined by the local operating system. Both of these properties may be
   * modified in subsequent calls if neccesary.
   *
   * @param theValue     The date value
   * @param thePrecision The precision
   * @throws DataFormatException
   */
  public void setValue(Date theValue, TemporalPrecisionEnum thePrecision) throws DataFormatException {
    if (getTimeZone() == null) {
      setTimeZone(TimeZone.getDefault());
    }
    myPrecision = thePrecision;
    myFractionalSeconds = "";
    if (theValue != null) {
      long millis = theValue.getTime() % 1000;
      if (millis < 0) {
        // This is for times before 1970 (see bug #444)
        millis = 1000 + millis;
      }
      String fractionalSeconds = Integer.toString((int) millis);
      myFractionalSeconds = StringUtils.leftPad(fractionalSeconds, 3, '0');
    }
    super.setValue(theValue);
  }

  @Override
  public void setValueAsString(String theString) throws DataFormatException {
    clearTimeZone();
    super.setValueAsString(theString);
  }

  protected void setValueAsV3String(String theV3String) {
    if (StringUtils.isBlank(theV3String)) {
      setValue(null);
    } else {
      StringBuilder b = new StringBuilder();
      String timeZone = null;
      for (int i = 0; i < theV3String.length(); i++) {
        char nextChar = theV3String.charAt(i);
        if (nextChar == '+' || nextChar == '-' || nextChar == 'Z') {
          timeZone = (theV3String.substring(i));
          break;
        }

        // assertEquals("2013-02-02T20:13:03-05:00",
        // DateAndTime.parseV3("20130202201303-0500").toString());
        if (i == 4 || i == 6) {
          b.append('-');
        } else if (i == 8) {
          b.append('T');
        } else if (i == 10 || i == 12) {
          b.append(':');
        }

        b.append(nextChar);
      }

      if (b.length() == 13)
        b.append(":00"); // schema rule, must have minutes
      if (b.length() == 16)
        b.append(":00"); // schema rule, must have seconds
      if (timeZone != null && b.length() > 10) {
        if (timeZone.length() == 5) {
          b.append(timeZone.substring(0, 3));
          b.append(':');
          b.append(timeZone.substring(3));
        } else {
          b.append(timeZone);
        }
      }

      setValueAsString(b.toString());
    }
  }

  /**
   * Sets the year, e.g. 2015
   */
  public BaseDateTimeType setYear(int theYear) {
    setFieldValue(Calendar.YEAR, theYear, null, 0, 9999);
    return this;
  }

  private void throwBadDateFormat(String theValue) {
    throw new DataFormatException("Invalid date/time format: \"" + theValue + "\"");
  }

  private void throwBadDateFormat(String theValue, String theMesssage) {
    throw new DataFormatException("Invalid date/time format: \"" + theValue + "\": " + theMesssage);
  }

  /**
   * Returns a view of this date/time as a Calendar object. Note that the returned
   * Calendar object is entirely independent from <code>this</code> object.
   * Changes to the calendar will not affect <code>this</code>.
   */
  public Calendar toCalendar() {
    Calendar retVal = Calendar.getInstance();
    retVal.setTime(getValue());
    retVal.setTimeZone(getTimeZone());
    return retVal;
  }

  /**
   * Returns a human readable version of this date/time using the system local
   * format.
   * <p>
   * <b>Note on time zones:</b> This method renders the value using the time zone
   * that is contained within the value. For example, if this date object contains
   * the value "2012-01-05T12:00:00-08:00", the human display will be rendered as
   * "12:00:00" even if the application is being executed on a system in a
   * different time zone. If this behaviour is not what you want, use
   * {@link #toHumanDisplayLocalTimezone()} instead.
   * </p>
   */
  public String toHumanDisplay() {
    return DateTimeUtil.toHumanDisplay(getTimeZone(), getPrecision(), getValue(), getValueAsString());
  }

  /**
   * Returns a human readable version of this date/time using the system local
   * format, converted to the local timezone if neccesary.
   *
   * @see #toHumanDisplay() for a method which does not convert the time to the
   *      local timezone before rendering it.
   */
  public String toHumanDisplayLocalTimezone() {
    return DateTimeUtil.toHumanDisplayLocalTimezone(getPrecision(), getValue(), getValueAsString());
  }

  private void validateBeforeOrAfter(DateTimeType theDateTimeType) {
    if (getValue() == null) {
      throw new NullPointerException("This BaseDateTimeType does not contain a value (getValue() returns null)");
    }
    if (theDateTimeType == null) {
      throw new NullPointerException("theDateTimeType must not be null");
    }
    if (theDateTimeType.getValue() == null) {
      throw new NullPointerException(
          "The given BaseDateTimeType does not contain a value (theDateTimeType.getValue() returns null)");
    }
  }

  private void validateCharAtIndexIs(String theValue, int theIndex, char theChar) {
    if (theValue.charAt(theIndex) != theChar) {
      throwBadDateFormat(theValue,
          "Expected character '" + theChar + "' at index " + theIndex + " but found " + theValue.charAt(theIndex));
    }
  }

  private void validateLengthIsAtLeast(String theValue, int theLength) {
    if (theValue.length() < theLength) {
      throwBadDateFormat(theValue);
    }
  }

  private void validateValueInRange(long theValue, long theMinimum, long theMaximum) {
    if (theValue < theMinimum || theValue > theMaximum) {
      throw new IllegalArgumentException(
          "Value " + theValue + " is not between allowable range: " + theMinimum + " - " + theMaximum);
    }
  }

  @Override
  public boolean isDateTime() {
    return true;
  }

  @Override
  public BaseDateTimeType dateTimeValue() {
    return this;
  }

  public boolean hasTime() {
    return (myPrecision == TemporalPrecisionEnum.MINUTE || myPrecision == TemporalPrecisionEnum.SECOND
        || myPrecision == TemporalPrecisionEnum.MILLI);
  }

  /**
   * This method implements a datetime equality check using the rules as defined
   * by FHIRPath.
   *
   * This method returns:
   * <ul>
   * <li>true if the given datetimes represent the exact same instant with the
   * same precision (irrespective of the timezone)</li>
   * <li>true if the given datetimes represent the exact same instant but one
   * includes milliseconds of <code>.[0]+</code> while the other includes only
   * SECONDS precision (irrespecitve of the timezone)</li>
   * <li>true if the given datetimes represent the exact same
   * year/year-month/year-month-date (if both operands have the same
   * precision)</li>
   * <li>false if both datetimes have equal precision of MINUTE or greater, one
   * has no timezone specified but the other does, and could not represent the
   * same instant in any timezone</li>
   * <li>null if both datetimes have equal precision of MINUTE or greater, one has
   * no timezone specified but the other does, and could potentially represent the
   * same instant in any timezone</li>
   * <li>false if the given datetimes have the same precision but do not represent
   * the same instant (irrespective of timezone)</li>
   * <li>null otherwise (since these datetimes are not comparable)</li>
   * </ul>
   */
  public Boolean equalsUsingFhirPathRules(BaseDateTimeType theOther) {
    if (hasTimezone() != theOther.hasTimezone()) {
      if (!couldBeTheSameTime(this, theOther)) {
        return false;
      } else {
        return null;
      }
    } else {
      BaseDateTimeType left = (BaseDateTimeType) this.copy();
      BaseDateTimeType right = (BaseDateTimeType) theOther.copy();
      if (left.hasTimezone() && left.getPrecision().ordinal() > TemporalPrecisionEnum.DAY.ordinal()) {
        left.setTimeZoneZulu(true);
      }
      if (right.hasTimezone() && right.getPrecision().ordinal() > TemporalPrecisionEnum.DAY.ordinal()) {
        right.setTimeZoneZulu(true);
      }
      Integer i = compareTimes(left, right, null);
      return i == null ? null : i == 0;
    }
  }

  private boolean couldBeTheSameTime(BaseDateTimeType theArg1, BaseDateTimeType theArg2) {
    long lowLeft = theArg1.getValue().getTime();
    long highLeft = theArg1.getHighEdge().getValue().getTime();
    if (!theArg1.hasTimezone()) {
      lowLeft = lowLeft - (14 * DateUtils.MILLIS_PER_HOUR);
      highLeft = highLeft + (14 * DateUtils.MILLIS_PER_HOUR);
    }
    long lowRight = theArg2.getValue().getTime();
    long highRight = theArg2.getHighEdge().getValue().getTime();
    if (!theArg2.hasTimezone()) {
      lowRight = lowRight - (14 * DateUtils.MILLIS_PER_HOUR);
      highRight = highRight + (14 * DateUtils.MILLIS_PER_HOUR);
    }
    if (highRight < lowLeft) {
      return false;
    }
    if (highLeft < lowRight) {
      return false;
    }
    return true;
  }

  private BaseDateTimeType getHighEdge() {
    BaseDateTimeType result = (BaseDateTimeType) copy();
    switch (getPrecision()) {
    case DAY:
      result.add(Calendar.DATE, 1);
      break;
    case MILLI:
      break;
    case MINUTE:
      result.add(Calendar.MINUTE, 1);
      break;
    case MONTH:
      result.add(Calendar.MONTH, 1);
      break;
    case SECOND:
      result.add(Calendar.SECOND, 1);
      break;
    case YEAR:
      result.add(Calendar.YEAR, 1);
      break;
    default:
      break;
    }
    return result;
  }

  boolean hasTimezoneIfRequired() {
    return getPrecision().ordinal() <= TemporalPrecisionEnum.DAY.ordinal() || getTimeZone() != null;
  }

  boolean hasTimezone() {
    return getTimeZone() != null;
  }

  public static Integer compareTimes(BaseDateTimeType left, BaseDateTimeType right, Integer def) {
    if (left.getYear() < right.getYear()) {
      return -1;
    } else if (left.getYear() > right.getYear()) {
      return 1;
    } else if (left.getPrecision() == TemporalPrecisionEnum.YEAR
        && right.getPrecision() == TemporalPrecisionEnum.YEAR) {
      return 0;
    } else if (left.getPrecision() == TemporalPrecisionEnum.YEAR
        || right.getPrecision() == TemporalPrecisionEnum.YEAR) {
      return def;
    }

    if (left.getMonth() < right.getMonth()) {
      return -1;
    } else if (left.getMonth() > right.getMonth()) {
      return 1;
    } else if (left.getPrecision() == TemporalPrecisionEnum.MONTH
        && right.getPrecision() == TemporalPrecisionEnum.MONTH) {
      return 0;
    } else if (left.getPrecision() == TemporalPrecisionEnum.MONTH
        || right.getPrecision() == TemporalPrecisionEnum.MONTH) {
      return def;
    }

    if (left.getDay() < right.getDay()) {
      return -1;
    } else if (left.getDay() > right.getDay()) {
      return 1;
    } else if (left.getPrecision() == TemporalPrecisionEnum.DAY && right.getPrecision() == TemporalPrecisionEnum.DAY) {
      return 0;
    } else if (left.getPrecision() == TemporalPrecisionEnum.DAY || right.getPrecision() == TemporalPrecisionEnum.DAY) {
      return def;
    }

    if (left.getHour() < right.getHour()) {
      return -1;
    } else if (left.getHour() > right.getHour()) {
      return 1;
      // hour is not a valid precision
//      } else if (dateLeft.getPrecision() == TemporalPrecisionEnum.YEAR && dateRight.getPrecision() == TemporalPrecisionEnum.YEAR) {
//        return 0;
//      } else if (dateLeft.getPrecision() == TemporalPrecisionEnum.HOUR || dateRight.getPrecision() == TemporalPrecisionEnum.HOUR) {
//        return null;
    }

    if (left.getMinute() < right.getMinute()) {
      return -1;
    } else if (left.getMinute() > right.getMinute()) {
      return 1;
    } else if (left.getPrecision() == TemporalPrecisionEnum.MINUTE
        && right.getPrecision() == TemporalPrecisionEnum.MINUTE) {
      return 0;
    } else if (left.getPrecision() == TemporalPrecisionEnum.MINUTE
        || right.getPrecision() == TemporalPrecisionEnum.MINUTE) {
      return def;
    }

    if (left.getSecond() < right.getSecond()) {
      return -1;
    } else if (left.getSecond() > right.getSecond()) {
      return 1;
    } else if (left.getPrecision() == TemporalPrecisionEnum.SECOND
        && right.getPrecision() == TemporalPrecisionEnum.SECOND) {
      return 0;
    }

    if (left.getSecondsMilli() < right.getSecondsMilli()) {
      return -1;
    } else if (left.getSecondsMilli() > right.getSecondsMilli()) {
      return 1;
    } else {
      return 0;
    }
  }

  @Override
  public String fpValue() {
    return "@" + primitiveValue();
  }

  private TimeZone getTimeZone(String offset) {
    return timezoneCache.computeIfAbsent(offset, TimeZone::getTimeZone);
  }

}