Make a copy of DateIntervalFormat from libcore

/*

 * 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 android.text.format;

import android.compat.annotation.UnsupportedAppUsage;

import android.icu.util.Calendar;

import android.icu.util.ULocale;

import java.text.FieldPosition;

import java.util.TimeZone;

import libcore.util.BasicLruCache;

import static libcore.icu.DateUtilsBridge.FORMAT_UTC;

/**

 * Exposes icu4j's DateIntervalFormat.

 *

 * @hide

 */

@libcore.api.CorePlatformApi

public final class DateIntervalFormat {

  private static final BasicLruCache<String, android.icu.text.DateIntervalFormat> CACHED_FORMATTERS

      = new BasicLruCache<>(8);

  private DateIntervalFormat() {

  }

  // This is public DateUtils API in frameworks/base.

  @UnsupportedAppUsage

  @libcore.api.CorePlatformApi

  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 truly sane 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);

    synchronized (CACHED_FORMATTERS) {

      android.icu.text.DateIntervalFormat formatter =

          getFormatter(skeleton, icuLocale, icuTimeZone);

      return formatter.format(startCalendar, endCalendar, new StringBuffer(),

          new FieldPosition(0)).toString();

    }

  }

  private static android.icu.text.DateIntervalFormat getFormatter(String skeleton, ULocale locale,

      android.icu.util.TimeZone icuTimeZone) {

    String key = skeleton + "\t" + locale + "\t" + icuTimeZone;

    android.icu.text.DateIntervalFormat formatter = CACHED_FORMATTERS.get(key);

    if (formatter != null) {

      return formatter;

    }

    formatter = android.icu.text.DateIntervalFormat.getInstance(skeleton, locale);

    formatter.setTimeZone(icuTimeZone);

    CACHED_FORMATTERS.put(key, formatter);

    return formatter;

  }

  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;

  }

}