001/*
002 *  Copyright 2001-2006 Stephen Colebourne
003 *
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package org.joda.time;
017
018import org.joda.time.base.BaseSingleFieldPeriod;
019import org.joda.time.field.FieldUtils;
020import org.joda.time.format.ISOPeriodFormat;
021import org.joda.time.format.PeriodFormatter;
022
023/**
024 * An immutable time period representing a number of weeks.
025 * <p>
026 * <code>Weeks</code> is an immutable period that can only store weeks.
027 * It does not store years, months or hours for example. As such it is a
028 * type-safe way of representing a number of weeks in an application.
029 * <p>
030 * The number of weeks is set in the constructor, and may be queried using
031 * <code>getWeeks()</code>. Basic mathematical operations are provided -
032 * <code>plus()</code>, <code>minus()</code>, <code>multipliedBy()</code> and
033 * <code>dividedBy()</code>.
034 * <p>
035 * <code>Weeks</code> is thread-safe and immutable.
036 *
037 * @author Stephen Colebourne
038 * @since 1.4
039 */
040public final class Weeks extends BaseSingleFieldPeriod {
041
042    /** Constant representing zero weeks. */
043    public static final Weeks ZERO = new Weeks(0);
044    /** Constant representing one week. */
045    public static final Weeks ONE = new Weeks(1);
046    /** Constant representing two weeks. */
047    public static final Weeks TWO = new Weeks(2);
048    /** Constant representing three weeks. */
049    public static final Weeks THREE = new Weeks(3);
050    /** Constant representing the maximum number of weeks that can be stored in this object. */
051    public static final Weeks MAX_VALUE = new Weeks(Integer.MAX_VALUE);
052    /** Constant representing the minimum number of weeks that can be stored in this object. */
053    public static final Weeks MIN_VALUE = new Weeks(Integer.MIN_VALUE);
054
055    /** The paser to use for this class. */
056    private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.weeks());
057    /** Serialization version. */
058    private static final long serialVersionUID = 87525275727380866L;
059
060    //-----------------------------------------------------------------------
061    /**
062     * Obtains an instance of <code>Weeks</code> that may be cached.
063     * <code>Weeks</code> is immutable, so instances can be cached and shared.
064     * This factory method provides access to shared instances.
065     *
066     * @param weeks  the number of weeks to obtain an instance for
067     * @return the instance of Weeks
068     */
069    public static Weeks weeks(int weeks) {
070        switch (weeks) {
071            case 0:
072                return ZERO;
073            case 1:
074                return ONE;
075            case 2:
076                return TWO;
077            case 3:
078                return THREE;
079            case Integer.MAX_VALUE:
080                return MAX_VALUE;
081            case Integer.MIN_VALUE:
082                return MIN_VALUE;
083            default:
084                return new Weeks(weeks);
085        }
086    }
087
088    //-----------------------------------------------------------------------
089    /**
090     * Creates a <code>Weeks</code> representing the number of whole weeks
091     * between the two specified datetimes.
092     *
093     * @param start  the start instant, must not be null
094     * @param end  the end instant, must not be null
095     * @return the period in weeks
096     * @throws IllegalArgumentException if the instants are null or invalid
097     */
098    public static Weeks weeksBetween(ReadableInstant start, ReadableInstant end) {
099        int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.weeks());
100        return Weeks.weeks(amount);
101    }
102
103    /**
104     * Creates a <code>Weeks</code> representing the number of whole weeks
105     * between the two specified partial datetimes.
106     * <p>
107     * The two partials must contain the same fields, for example you can specify
108     * two <code>LocalDate</code> objects.
109     *
110     * @param start  the start partial date, must not be null
111     * @param end  the end partial date, must not be null
112     * @return the period in weeks
113     * @throws IllegalArgumentException if the partials are null or invalid
114     */
115    public static Weeks weeksBetween(ReadablePartial start, ReadablePartial end) {
116        if (start instanceof LocalDate && end instanceof LocalDate)   {
117            Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
118            int weeks = chrono.weeks().getDifference(
119                    ((LocalDate) end).getLocalMillis(), ((LocalDate) start).getLocalMillis());
120            return Weeks.weeks(weeks);
121        }
122        int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
123        return Weeks.weeks(amount);
124    }
125
126    /**
127     * Creates a <code>Weeks</code> representing the number of whole weeks
128     * in the specified interval.
129     *
130     * @param interval  the interval to extract weeks from, null returns zero
131     * @return the period in weeks
132     * @throws IllegalArgumentException if the partials are null or invalid
133     */
134    public static Weeks weeksIn(ReadableInterval interval) {
135        if (interval == null)   {
136            return Weeks.ZERO;
137        }
138        int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.weeks());
139        return Weeks.weeks(amount);
140    }
141
142    /**
143     * Creates a new <code>Weeks</code> representing the number of complete
144     * standard length weeks in the specified period.
145     * <p>
146     * This factory method converts all fields from the period to hours using standardised
147     * durations for each field. Only those fields which have a precise duration in
148     * the ISO UTC chronology can be converted.
149     * <ul>
150     * <li>One week consists of 7 days.
151     * <li>One day consists of 24 hours.
152     * <li>One hour consists of 60 minutes.
153     * <li>One minute consists of 60 weeks.
154     * <li>One second consists of 1000 milliseconds.
155     * </ul>
156     * Months and Years are imprecise and periods containing these values cannot be converted.
157     *
158     * @param period  the period to get the number of hours from, null returns zero
159     * @return the period in weeks
160     * @throws IllegalArgumentException if the period contains imprecise duration values
161     */
162    public static Weeks standardWeeksIn(ReadablePeriod period) {
163        int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_WEEK);
164        return Weeks.weeks(amount);
165    }
166
167    /**
168     * Creates a new <code>Weeks</code> by parsing a string in the ISO8601 format 'PnW'.
169     * <p>
170     * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the
171     * weeks component may be non-zero. If any other component is non-zero, an exception
172     * will be thrown.
173     *
174     * @param periodStr  the period string, null returns zero
175     * @return the period in weeks
176     * @throws IllegalArgumentException if the string format is invalid
177     */
178    public static Weeks parseWeeks(String periodStr) {
179        if (periodStr == null) {
180            return Weeks.ZERO;
181        }
182        Period p = PARSER.parsePeriod(periodStr);
183        return Weeks.weeks(p.getWeeks());
184    }
185
186    //-----------------------------------------------------------------------
187    /**
188     * Creates a new instance representing a number of weeks.
189     * You should consider using the factory method {@link #weeks(int)}
190     * instead of the constructor.
191     *
192     * @param weeks  the number of weeks to represent
193     */
194    private Weeks(int weeks) {
195        super(weeks);
196    }
197
198    /**
199     * Resolves singletons.
200     * 
201     * @return the singleton instance
202     */
203    private Object readResolve() {
204        return Weeks.weeks(getValue());
205    }
206
207    //-----------------------------------------------------------------------
208    /**
209     * Gets the duration field type, which is <code>weeks</code>.
210     *
211     * @return the period type
212     */
213    public DurationFieldType getFieldType() {
214        return DurationFieldType.weeks();
215    }
216
217    /**
218     * Gets the period type, which is <code>weeks</code>.
219     *
220     * @return the period type
221     */
222    public PeriodType getPeriodType() {
223        return PeriodType.weeks();
224    }
225
226    //-----------------------------------------------------------------------
227    /**
228     * Converts this period in weeks to a period in days assuming a
229     * 7 day week.
230     * <p>
231     * This method allows you to convert between different types of period.
232     * However to achieve this it makes the assumption that all weeks are
233     * 7 days long.
234     * This may not be true for some unusual chronologies. However, it is included
235     * as it is a useful operation for many applications and business rules.
236     * 
237     * @return a period representing the number of days for this number of weeks
238     * @throws ArithmeticException if the number of days is too large to be represented
239     */
240    public Days toStandardDays() {
241        return Days.days(FieldUtils.safeMultiply(getValue(), DateTimeConstants.DAYS_PER_WEEK));
242    }
243
244    /**
245     * Converts this period in weeks to a period in hours assuming a
246     * 7 day week and 24 hour day.
247     * <p>
248     * This method allows you to convert between different types of period.
249     * However to achieve this it makes the assumption that all weeks are
250     * 7 days long and all days are 24 hours long.
251     * This is not true when daylight savings is considered and may also not
252     * be true for some unusual chronologies. However, it is included
253     * as it is a useful operation for many applications and business rules.
254     * 
255     * @return a period representing the number of hours for this number of weeks
256     * @throws ArithmeticException if the number of hours is too large to be represented
257     */
258    public Hours toStandardHours() {
259        return Hours.hours(FieldUtils.safeMultiply(getValue(), DateTimeConstants.HOURS_PER_WEEK));
260    }
261
262    /**
263     * Converts this period in weeks to a period in minutes assuming a
264     * 7 day week, 24 hour day and 60 minute hour.
265     * <p>
266     * This method allows you to convert between different types of period.
267     * However to achieve this it makes the assumption that all weeks are
268     * 7 days long, all days are 24 hours long and all hours are 60 minutes long.
269     * This is not true when daylight savings is considered and may also not
270     * be true for some unusual chronologies. However, it is included
271     * as it is a useful operation for many applications and business rules.
272     * 
273     * @return a period representing the number of minutes for this number of weeks
274     * @throws ArithmeticException if the number of minutes is too large to be represented
275     */
276    public Minutes toStandardMinutes() {
277        return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_WEEK));
278    }
279
280    /**
281     * Converts this period in weeks to a period in seconds assuming a
282     * 7 day week, 24 hour day, 60 minute hour and 60 second minute.
283     * <p>
284     * This method allows you to convert between different types of period.
285     * However to achieve this it makes the assumption that all weeks are
286     * 7 days long, all days are 24 hours long, all hours are 60 minutes long
287     * and all minutes are 60 seconds long.
288     * This is not true when daylight savings is considered and may also not
289     * be true for some unusual chronologies. However, it is included
290     * as it is a useful operation for many applications and business rules.
291     * 
292     * @return a period representing the number of seconds for this number of weeks
293     * @throws ArithmeticException if the number of seconds is too large to be represented
294     */
295    public Seconds toStandardSeconds() {
296        return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_WEEK));
297    }
298
299    //-----------------------------------------------------------------------
300    /**
301     * Converts this period in weeks to a duration in milliweeks assuming a
302     * 7 day week, 24 hour day, 60 minute hour and 60 second minute.
303     * <p>
304     * This method allows you to convert from a period to a duration.
305     * However to achieve this it makes the assumption that all weeks are
306     * 7 days long, all days are 24 hours long, all hours are 60 minutes long
307     * and all minutes are 60 seconds long.
308     * This is not true when daylight savings time is considered, and may also
309     * not be true for some unusual chronologies. However, it is included as it
310     * is a useful operation for many applications and business rules.
311     * 
312     * @return a duration equivalent to this number of weeks
313     */
314    public Duration toStandardDuration() {
315        long weeks = getValue();  // assign to a long
316        return new Duration(weeks * DateTimeConstants.MILLIS_PER_WEEK);
317    }
318
319    //-----------------------------------------------------------------------
320    /**
321     * Gets the number of weeks that this period represents.
322     *
323     * @return the number of weeks in the period
324     */
325    public int getWeeks() {
326        return getValue();
327    }
328
329    //-----------------------------------------------------------------------
330    /**
331     * Returns a new instance with the specified number of weeks added.
332     * <p>
333     * This instance is immutable and unaffected by this method call.
334     *
335     * @param weeks  the amount of weeks to add, may be negative
336     * @return the new period plus the specified number of weeks
337     * @throws ArithmeticException if the result overflows an int
338     */
339    public Weeks plus(int weeks) {
340        if (weeks == 0) {
341            return this;
342        }
343        return Weeks.weeks(FieldUtils.safeAdd(getValue(), weeks));
344    }
345
346    /**
347     * Returns a new instance with the specified number of weeks added.
348     * <p>
349     * This instance is immutable and unaffected by this method call.
350     *
351     * @param weeks  the amount of weeks to add, may be negative, null means zero
352     * @return the new period plus the specified number of weeks
353     * @throws ArithmeticException if the result overflows an int
354     */
355    public Weeks plus(Weeks weeks) {
356        if (weeks == null) {
357            return this;
358        }
359        return plus(weeks.getValue());
360    }
361
362    //-----------------------------------------------------------------------
363    /**
364     * Returns a new instance with the specified number of weeks taken away.
365     * <p>
366     * This instance is immutable and unaffected by this method call.
367     *
368     * @param weeks  the amount of weeks to take away, may be negative
369     * @return the new period minus the specified number of weeks
370     * @throws ArithmeticException if the result overflows an int
371     */
372    public Weeks minus(int weeks) {
373        return plus(FieldUtils.safeNegate(weeks));
374    }
375
376    /**
377     * Returns a new instance with the specified number of weeks taken away.
378     * <p>
379     * This instance is immutable and unaffected by this method call.
380     *
381     * @param weeks  the amount of weeks to take away, may be negative, null means zero
382     * @return the new period minus the specified number of weeks
383     * @throws ArithmeticException if the result overflows an int
384     */
385    public Weeks minus(Weeks weeks) {
386        if (weeks == null) {
387            return this;
388        }
389        return minus(weeks.getValue());
390    }
391
392    //-----------------------------------------------------------------------
393    /**
394     * Returns a new instance with the weeks multiplied by the specified scalar.
395     * <p>
396     * This instance is immutable and unaffected by this method call.
397     *
398     * @param scalar  the amount to multiply by, may be negative
399     * @return the new period multiplied by the specified scalar
400     * @throws ArithmeticException if the result overflows an int
401     */
402    public Weeks multipliedBy(int scalar) {
403        return Weeks.weeks(FieldUtils.safeMultiply(getValue(), scalar));
404    }
405
406    /**
407     * Returns a new instance with the weeks divided by the specified divisor.
408     * The calculation uses integer division, thus 3 divided by 2 is 1.
409     * <p>
410     * This instance is immutable and unaffected by this method call.
411     *
412     * @param divisor  the amount to divide by, may be negative
413     * @return the new period divided by the specified divisor
414     * @throws ArithmeticException if the divisor is zero
415     */
416    public Weeks dividedBy(int divisor) {
417        if (divisor == 1) {
418            return this;
419        }
420        return Weeks.weeks(getValue() / divisor);
421    }
422
423    //-----------------------------------------------------------------------
424    /**
425     * Returns a new instance with the weeks value negated.
426     *
427     * @return the new period with a negated value
428     * @throws ArithmeticException if the result overflows an int
429     */
430    public Weeks negated() {
431        return Weeks.weeks(FieldUtils.safeNegate(getValue()));
432    }
433
434    //-----------------------------------------------------------------------
435    /**
436     * Is this weeks instance greater than the specified number of weeks.
437     *
438     * @param other  the other period, null means zero
439     * @return true if this weeks instance is greater than the specified one
440     */
441    public boolean isGreaterThan(Weeks other) {
442        if (other == null) {
443            return getValue() > 0;
444        }
445        return getValue() > other.getValue();
446    }
447
448    /**
449     * Is this weeks instance less than the specified number of weeks.
450     *
451     * @param other  the other period, null means zero
452     * @return true if this weeks instance is less than the specified one
453     */
454    public boolean isLessThan(Weeks other) {
455        if (other == null) {
456            return getValue() < 0;
457        }
458        return getValue() < other.getValue();
459    }
460
461    //-----------------------------------------------------------------------
462    /**
463     * Gets this instance as a String in the ISO8601 duration format.
464     * <p>
465     * For example, "P4W" represents 4 weeks.
466     *
467     * @return the value as an ISO8601 string
468     */
469    public String toString() {
470        return "P" + String.valueOf(getValue()) + "W";
471    }
472
473}