DTBuilder.java

// Copyright (C) 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.ical.util;

import com.google.ical.values.DateTimeValue;
import com.google.ical.values.DateTimeValueImpl;
import com.google.ical.values.DateValue;
import com.google.ical.values.DateValueImpl;
import com.google.ical.util.TimeUtils;
import com.google.ical.values.TimeValue;

/**
 * a mutable buffer that can be used to build {@link DateValue}s and
 * {@link DateTimeValue}s.
 *
 * @author mikesamuel+svn@gmail.com (Mike Samuel)
 */
public class DTBuilder {

  /** in AD.  0 -> 1BC. */
  public int year;
  /** one indexed. */
  public int month;
  /** one indexed */
  public int day;
  /** zero indexed in 24 hour time. */
  public int hour;
  /** zero indexed */
  public int minute;
  /** zero indexed */
  public int second;

  public DTBuilder(int year, int month, int day,
                   int hour, int minute, int second) {
    this.year = year;
    this.month = month;
    this.day = day;
    this.hour = hour;
    this.minute = minute;
    this.second = second;
  }

  public DTBuilder(int year, int month, int day) {
    this.year = year;
    this.month = month;
    this.day = day;
  }

  public DTBuilder(DateValue dv) {
    this.year = dv.year();
    this.month = dv.month();
    this.day = dv.day();
    if (dv instanceof TimeValue) {
      TimeValue tv = (TimeValue) dv;
      this.hour = tv.hour();
      this.minute = tv.minute();
      this.second = tv.second();
    }
  }

  /**
   * produces a normalized date time, using zero for the time fields if none
   * were provided.
   * @return not null
   */
  public DateTimeValue toDateTime() {
    normalize();
    return new DateTimeValueImpl(year, month, day, hour, minute, second);
  }

  /**
   * produces a normalized date.
   * @return not null
   */
  public DateValue toDate() {
    normalize();
    return new DateValueImpl(year, month, day);
  }

  /**
   * behavior undefined unless normalized.
   * If you're not sure whether it's appropriate to use this method, use
   * <code>toDateValue().compareTo(dv)</code> instead.
   */
  public int compareTo(DateValue dv) {
    long dvComparable =
      (((((long) dv.year()) << 4) + dv.month()) << 5) + dv.day();
    long dtbComparable =
      ((((long) year << 4) + month << 5)) + day;
    if (dv instanceof TimeValue) {
      TimeValue tv = (TimeValue) dv;
      dvComparable = (((((dvComparable << 5) + tv.hour()) << 6) + tv.minute())
                      << 6) + tv.second();
      dtbComparable = (((((dtbComparable << 5) + hour) << 6) + minute)
                       << 6) + second;
    }
    long delta = dtbComparable - dvComparable;
    return delta < 0 ? -1 : delta == 0 ? 0 : 1;
  }

  /**
   * makes sure that the fields are in the proper ranges, by e.g. converting
   * 32 January to 1 February, or month 0 to December of the year before.
   */
  public void normalize() {
    this.normalizeTime();
    this.normalizeDate();
  }

  @Override
  public String toString() {
    return year + "-" + month + "-" + day + " " + hour + ":" + minute + ":"
      + second;
  }

  @Override
  public boolean equals(Object o) {
    if (!(o instanceof DTBuilder)) { return false; }
    DTBuilder that = (DTBuilder) o;
    return this.year == that.year
       && this.month == that.month
         && this.day == that.day
        && this.hour == that.hour
      && this.minute == that.minute
      && this.second == that.second;
  }

  @Override
  public int hashCode() {
    return
      ((((((((year << 4) + month << 5) + day) << 5) + hour) << 6) + minute)
       << 6) + second;
  }

  private void normalizeTime() {
    int addMinutes = ((second < 0) ? (second - 59) : second) / 60;
    second -= addMinutes * 60;
    minute += addMinutes;
    int addHours = ((minute < 0) ? (minute - 59) : minute) / 60;
    minute -= addHours * 60;
    hour += addHours;
    int addDays = ((hour < 0) ? (hour - 23) : hour) / 24;
    hour -= addDays * 24;
    day += addDays;
  }
  private void normalizeDate() {
    while (day <= 0) {
      int days = TimeUtils.yearLength(month > 2 ? year : year - 1);
      day += days;
      --year;
    }
    if (month <= 0) {
      int years = month / 12 - 1;
      year += years;
      month -= 12 * years;
    } else if (month > 12) {
      int years = (month - 1) / 12;
      year += years;
      month -= 12 * years;
    }
    while (true) {
      if (month == 1) {
        int yearLength = TimeUtils.yearLength(year);
        if (day > yearLength) {
          ++year;
          day -= yearLength;
        }
      }
      int monthLength = TimeUtils.monthLength(year, month);
      if (day > monthLength) {
        day -= monthLength;
        if (++month > 12) {
          month -= 12;
          ++year;
        }
      } else {
        break;
      }
    }
  }

}