luni/src/main/java/libcore/icu/DateIntervalFormat.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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 libcore.icu;

import android.compat.annotation.UnsupportedAppUsage;
import android.icu.util.Calendar;
import android.icu.util.ULocale;

import java.text.FieldPosition;
import java.util.TimeZone;

import static libcore.icu.DateUtilsBridge.FORMAT_UTC;

/**
 * This class is only kept for @UnsupportedAppUsage, and should not used by libcore/frameworks.
 *
 * @hide
 */
public final class DateIntervalFormat {

  private DateIntervalFormat() {
  }

  @UnsupportedAppUsage
  public static String formatDateRange(long startMs, long endMs, int flags, String olsonId) {
    if ((flags & FORMAT_UTC) != 0) {
      olsonId = "UTC";
    }
    // We create a java.util.TimeZone here to use libcore's data and libcore's olson ID / pseudo-tz
    // logic.
    TimeZone tz = (olsonId != null) ? TimeZone.getTimeZone(olsonId) : TimeZone.getDefault();
    android.icu.util.TimeZone icuTimeZone = DateUtilsBridge.icuTimeZone(tz);
    ULocale icuLocale = ULocale.getDefault();
    return formatDateRange(icuLocale, icuTimeZone, startMs, endMs, flags);
  }

  // This is our slightly more sensible internal API. (A better replacement would take a
  // skeleton instead of int flags.)
  public static String formatDateRange(ULocale icuLocale, android.icu.util.TimeZone icuTimeZone,
      long startMs, long endMs, int flags) {
    Calendar startCalendar = DateUtilsBridge.createIcuCalendar(icuTimeZone, icuLocale, startMs);
    Calendar endCalendar;
    if (startMs == endMs) {
      endCalendar = startCalendar;
    } else {
      endCalendar = DateUtilsBridge.createIcuCalendar(icuTimeZone, icuLocale, endMs);
    }

    // Special handling when the range ends at midnight:
    // - If we're not showing times, and the range is non-empty, we fudge the end date so we don't
    //   count the day that's about to start.
    // - If we are showing times, and the range ends at exactly 00:00 of the day following its start
    //   (which can be thought of as 24:00 the same day), we fudge the end date so we don't show the
    //    dates --- unless the start is anything displayed as 00:00, in which case we include both
    //    dates to disambiguate.
    // This is not the behavior of icu4j's DateIntervalFormat, but it's the required behavior
    // of Android's DateUtils.formatDateRange.
    if (isExactlyMidnight(endCalendar)) {
      boolean showTime =
          (flags & DateUtilsBridge.FORMAT_SHOW_TIME) == DateUtilsBridge.FORMAT_SHOW_TIME;
      boolean endsDayAfterStart = DateUtilsBridge.dayDistance(startCalendar, endCalendar) == 1;
      if ((!showTime && startMs != endMs)
          || (endsDayAfterStart
                  && !DateUtilsBridge.isDisplayMidnightUsingSkeleton(startCalendar))) {
        endCalendar.add(Calendar.DAY_OF_MONTH, -1);
      }
    }

    String skeleton = DateUtilsBridge.toSkeleton(startCalendar, endCalendar, flags);
    android.icu.text.DateIntervalFormat formatter =
            android.icu.text.DateIntervalFormat.getInstance(skeleton, icuLocale);
    formatter.setTimeZone(icuTimeZone);
    return formatter.format(startCalendar, endCalendar, new StringBuffer(),
        new FieldPosition(0)).toString();
  }

  private static boolean isExactlyMidnight(Calendar c) {
    return c.get(Calendar.HOUR_OF_DAY) == 0 &&
        c.get(Calendar.MINUTE) == 0 &&
        c.get(Calendar.SECOND) == 0 &&
        c.get(Calendar.MILLISECOND) == 0;
  }
}