001/*
002 *  Copyright 2001-2010 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.convert.FromString;
019import org.joda.convert.ToString;
020import org.joda.time.base.BaseSingleFieldPeriod;
021import org.joda.time.field.FieldUtils;
022import org.joda.time.format.ISOPeriodFormat;
023import org.joda.time.format.PeriodFormatter;
024
025/**
026 * An immutable time period representing a number of weeks.
027 * <p>
028 * <code>Weeks</code> is an immutable period that can only store weeks.
029 * It does not store years, months or hours for example. As such it is a
030 * type-safe way of representing a number of weeks in an application.
031 * <p>
032 * The number of weeks is set in the constructor, and may be queried using
033 * <code>getWeeks()</code>. Basic mathematical operations are provided -
034 * <code>plus()</code>, <code>minus()</code>, <code>multipliedBy()</code> and
035 * <code>dividedBy()</code>.
036 * <p>
037 * <code>Weeks</code> is thread-safe and immutable.
038 *
039 * @author Stephen Colebourne
040 * @since 1.4
041 */
042public final class Weeks extends BaseSingleFieldPeriod {
043
044    /** Constant representing zero weeks. */
045    public static final Weeks ZERO = new Weeks(0);
046    /** Constant representing one week. */
047    public static final Weeks ONE = new Weeks(1);
048    /** Constant representing two weeks. */
049    public static final Weeks TWO = new Weeks(2);
050    /** Constant representing three weeks. */
051    public static final Weeks THREE = new Weeks(3);
052    /** Constant representing the maximum number of weeks that can be stored in this object. */
053    public static final Weeks MAX_VALUE = new Weeks(Integer.MAX_VALUE);
054    /** Constant representing the minimum number of weeks that can be stored in this object. */
055    public static final Weeks MIN_VALUE = new Weeks(Integer.MIN_VALUE);
056
057    /** The paser to use for this class. */
058    private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.weeks());
059    /** Serialization version. */
060    private static final long serialVersionUID = 87525275727380866L;
061
062    //-----------------------------------------------------------------------
063    /**
064     * Obtains an instance of <code>Weeks</code> that may be cached.
065     * <code>Weeks</code> is immutable, so instances can be cached and shared.
066     * This factory method provides access to shared instances.
067     *
068     * @param weeks  the number of weeks to obtain an instance for
069     * @return the instance of Weeks
070     */
071    public static Weeks weeks(int weeks) {
072        switch (weeks) {
073            case 0:
074                return ZERO;
075            case 1:
076                return ONE;
077            case 2:
078                return TWO;
079            case 3:
080                return THREE;
081            case Integer.MAX_VALUE:
082                return MAX_VALUE;
083            case Integer.MIN_VALUE:
084                return MIN_VALUE;
085            default:
086                return new Weeks(weeks);
087        }
088    }
089
090    //-----------------------------------------------------------------------
091    /**
092     * Creates a <code>Weeks</code> representing the number of whole weeks
093     * between the two specified datetimes.
094     *
095     * @param start  the start instant, must not be null
096     * @param end  the end instant, must not be null
097     * @return the period in weeks
098     * @throws IllegalArgumentException if the instants are null or invalid
099     */
100    public static Weeks weeksBetween(ReadableInstant start, ReadableInstant end) {
101        int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.weeks());
102        return Weeks.weeks(amount);
103    }
104
105    /**
106     * Creates a <code>Weeks</code> representing the number of whole weeks
107     * between the two specified partial datetimes.
108     * <p>
109     * The two partials must contain the same fields, for example you can specify
110     * two <code>LocalDate</code> objects.
111     *
112     * @param start  the start partial date, must not be null
113     * @param end  the end partial date, must not be null
114     * @return the period in weeks
115     * @throws IllegalArgumentException if the partials are null or invalid
116     */
117    public static Weeks weeksBetween(ReadablePartial start, ReadablePartial end) {
118        if (start instanceof LocalDate && end instanceof LocalDate)   {
119            Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
120            int weeks = chrono.weeks().getDifference(
121                    ((LocalDate) end).getLocalMillis(), ((LocalDate) start).getLocalMillis());
122            return Weeks.weeks(weeks);
123        }
124        int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
125        return Weeks.weeks(amount);
126    }
127
128    /**
129     * Creates a <code>Weeks</code> representing the number of whole weeks
130     * in the specified interval.
131     *
132     * @param interval  the interval to extract weeks from, null returns zero
133     * @return the period in weeks
134     * @throws IllegalArgumentException if the partials are null or invalid
135     */
136    public static Weeks weeksIn(ReadableInterval interval) {
137        if (interval == null)   {
138            return Weeks.ZERO;
139        }
140        int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.weeks());
141        return Weeks.weeks(amount);
142    }
143
144    /**
145     * Creates a new <code>Weeks</code> representing the number of complete
146     * standard length weeks in the specified period.
147     * <p>
148     * This factory method converts all fields from the period to hours using standardised
149     * durations for each field. Only those fields which have a precise duration in
150     * the ISO UTC chronology can be converted.
151     * <ul>
152     * <li>One week consists of 7 days.
153     * <li>One day consists of 24 hours.
154     * <li>One hour consists of 60 minutes.
155     * <li>One minute consists of 60 weeks.
156     * <li>One second consists of 1000 milliseconds.
157     * </ul>
158     * Months and Years are imprecise and periods containing these values cannot be converted.
159     *
160     * @param period  the period to get the number of hours from, null returns zero
161     * @return the period in weeks
162     * @throws IllegalArgumentException if the period contains imprecise duration values
163     */
164    public static Weeks standardWeeksIn(ReadablePeriod period) {
165        int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_WEEK);
166        return Weeks.weeks(amount);
167    }
168
169    /**
170     * Creates a new <code>Weeks</code> by parsing a string in the ISO8601 format 'PnW'.
171     * <p>
172     * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the
173     * weeks component may be non-zero. If any other component is non-zero, an exception
174     * will be thrown.
175     *
176     * @param periodStr  the period string, null returns zero
177     * @return the period in weeks
178     * @throws IllegalArgumentException if the string format is invalid
179     */
180    @FromString
181    public static Weeks parseWeeks(String periodStr) {
182        if (periodStr == null) {
183            return Weeks.ZERO;
184        }
185        Period p = PARSER.parsePeriod(periodStr);
186        return Weeks.weeks(p.getWeeks());
187    }
188
189    //-----------------------------------------------------------------------
190    /**
191     * Creates a new instance representing a number of weeks.
192     * You should consider using the factory method {@link #weeks(int)}
193     * instead of the constructor.
194     *
195     * @param weeks  the number of weeks to represent
196     */
197    private Weeks(int weeks) {
198        super(weeks);
199    }
200
201    /**
202     * Resolves singletons.
203     * 
204     * @return the singleton instance
205     */
206    private Object readResolve() {
207        return Weeks.weeks(getValue());
208    }
209
210    //-----------------------------------------------------------------------
211    /**
212     * Gets the duration field type, which is <code>weeks</code>.
213     *
214     * @return the period type
215     */
216    public DurationFieldType getFieldType() {
217        return DurationFieldType.weeks();
218    }
219
220    /**
221     * Gets the period type, which is <code>weeks</code>.
222     *
223     * @return the period type
224     */
225    public PeriodType getPeriodType() {
226        return PeriodType.weeks();
227    }
228
229    //-----------------------------------------------------------------------
230    /**
231     * Converts this period in weeks to a period in days assuming a
232     * 7 day week.
233     * <p>
234     * This method allows you to convert between different types of period.
235     * However to achieve this it makes the assumption that all weeks are
236     * 7 days long.
237     * This may not be true for some unusual chronologies. However, it is included
238     * as it is a useful operation for many applications and business rules.
239     * 
240     * @return a period representing the number of days for this number of weeks
241     * @throws ArithmeticException if the number of days is too large to be represented
242     */
243    public Days toStandardDays() {
244        return Days.days(FieldUtils.safeMultiply(getValue(), DateTimeConstants.DAYS_PER_WEEK));
245    }
246
247    /**
248     * Converts this period in weeks to a period in hours assuming a
249     * 7 day week and 24 hour day.
250     * <p>
251     * This method allows you to convert between different types of period.
252     * However to achieve this it makes the assumption that all weeks are
253     * 7 days long and all days are 24 hours long.
254     * This is not true when daylight savings is considered and may also not
255     * be true for some unusual chronologies. However, it is included
256     * as it is a useful operation for many applications and business rules.
257     * 
258     * @return a period representing the number of hours for this number of weeks
259     * @throws ArithmeticException if the number of hours is too large to be represented
260     */
261    public Hours toStandardHours() {
262        return Hours.hours(FieldUtils.safeMultiply(getValue(), DateTimeConstants.HOURS_PER_WEEK));
263    }
264
265    /**
266     * Converts this period in weeks to a period in minutes assuming a
267     * 7 day week, 24 hour day and 60 minute hour.
268     * <p>
269     * This method allows you to convert between different types of period.
270     * However to achieve this it makes the assumption that all weeks are
271     * 7 days long, all days are 24 hours long and all hours are 60 minutes long.
272     * This is not true when daylight savings is considered and may also not
273     * be true for some unusual chronologies. However, it is included
274     * as it is a useful operation for many applications and business rules.
275     * 
276     * @return a period representing the number of minutes for this number of weeks
277     * @throws ArithmeticException if the number of minutes is too large to be represented
278     */
279    public Minutes toStandardMinutes() {
280        return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_WEEK));
281    }
282
283    /**
284     * Converts this period in weeks to a period in seconds assuming a
285     * 7 day week, 24 hour day, 60 minute hour and 60 second minute.
286     * <p>
287     * This method allows you to convert between different types of period.
288     * However to achieve this it makes the assumption that all weeks are
289     * 7 days long, all days are 24 hours long, all hours are 60 minutes long
290     * and all minutes are 60 seconds long.
291     * This is not true when daylight savings is considered and may also not
292     * be true for some unusual chronologies. However, it is included
293     * as it is a useful operation for many applications and business rules.
294     * 
295     * @return a period representing the number of seconds for this number of weeks
296     * @throws ArithmeticException if the number of seconds is too large to be represented
297     */
298    public Seconds toStandardSeconds() {
299        return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_WEEK));
300    }
301
302    //-----------------------------------------------------------------------
303    /**
304     * Converts this period in weeks to a duration in milliweeks assuming a
305     * 7 day week, 24 hour day, 60 minute hour and 60 second minute.
306     * <p>
307     * This method allows you to convert from a period to a duration.
308     * However to achieve this it makes the assumption that all weeks are
309     * 7 days long, all days are 24 hours long, all hours are 60 minutes long
310     * and all minutes are 60 seconds long.
311     * This is not true when daylight savings time is considered, and may also
312     * not be true for some unusual chronologies. However, it is included as it
313     * is a useful operation for many applications and business rules.
314     * 
315     * @return a duration equivalent to this number of weeks
316     */
317    public Duration toStandardDuration() {
318        long weeks = getValue();  // assign to a long
319        return new Duration(weeks * DateTimeConstants.MILLIS_PER_WEEK);
320    }
321
322    //-----------------------------------------------------------------------
323    /**
324     * Gets the number of weeks that this period represents.
325     *
326     * @return the number of weeks in the period
327     */
328    public int getWeeks() {
329        return getValue();
330    }
331
332    //-----------------------------------------------------------------------
333    /**
334     * Returns a new instance with the specified number of weeks added.
335     * <p>
336     * This instance is immutable and unaffected by this method call.
337     *
338     * @param weeks  the amount of weeks to add, may be negative
339     * @return the new period plus the specified number of weeks
340     * @throws ArithmeticException if the result overflows an int
341     */
342    public Weeks plus(int weeks) {
343        if (weeks == 0) {
344            return this;
345        }
346        return Weeks.weeks(FieldUtils.safeAdd(getValue(), weeks));
347    }
348
349    /**
350     * Returns a new instance with the specified number of weeks added.
351     * <p>
352     * This instance is immutable and unaffected by this method call.
353     *
354     * @param weeks  the amount of weeks to add, may be negative, null means zero
355     * @return the new period plus the specified number of weeks
356     * @throws ArithmeticException if the result overflows an int
357     */
358    public Weeks plus(Weeks weeks) {
359        if (weeks == null) {
360            return this;
361        }
362        return plus(weeks.getValue());
363    }
364
365    //-----------------------------------------------------------------------
366    /**
367     * Returns a new instance with the specified number of weeks taken away.
368     * <p>
369     * This instance is immutable and unaffected by this method call.
370     *
371     * @param weeks  the amount of weeks to take away, may be negative
372     * @return the new period minus the specified number of weeks
373     * @throws ArithmeticException if the result overflows an int
374     */
375    public Weeks minus(int weeks) {
376        return plus(FieldUtils.safeNegate(weeks));
377    }
378
379    /**
380     * Returns a new instance with the specified number of weeks taken away.
381     * <p>
382     * This instance is immutable and unaffected by this method call.
383     *
384     * @param weeks  the amount of weeks to take away, may be negative, null means zero
385     * @return the new period minus the specified number of weeks
386     * @throws ArithmeticException if the result overflows an int
387     */
388    public Weeks minus(Weeks weeks) {
389        if (weeks == null) {
390            return this;
391        }
392        return minus(weeks.getValue());
393    }
394
395    //-----------------------------------------------------------------------
396    /**
397     * Returns a new instance with the weeks multiplied by the specified scalar.
398     * <p>
399     * This instance is immutable and unaffected by this method call.
400     *
401     * @param scalar  the amount to multiply by, may be negative
402     * @return the new period multiplied by the specified scalar
403     * @throws ArithmeticException if the result overflows an int
404     */
405    public Weeks multipliedBy(int scalar) {
406        return Weeks.weeks(FieldUtils.safeMultiply(getValue(), scalar));
407    }
408
409    /**
410     * Returns a new instance with the weeks divided by the specified divisor.
411     * The calculation uses integer division, thus 3 divided by 2 is 1.
412     * <p>
413     * This instance is immutable and unaffected by this method call.
414     *
415     * @param divisor  the amount to divide by, may be negative
416     * @return the new period divided by the specified divisor
417     * @throws ArithmeticException if the divisor is zero
418     */
419    public Weeks dividedBy(int divisor) {
420        if (divisor == 1) {
421            return this;
422        }
423        return Weeks.weeks(getValue() / divisor);
424    }
425
426    //-----------------------------------------------------------------------
427    /**
428     * Returns a new instance with the weeks value negated.
429     *
430     * @return the new period with a negated value
431     * @throws ArithmeticException if the result overflows an int
432     */
433    public Weeks negated() {
434        return Weeks.weeks(FieldUtils.safeNegate(getValue()));
435    }
436
437    //-----------------------------------------------------------------------
438    /**
439     * Is this weeks instance greater than the specified number of weeks.
440     *
441     * @param other  the other period, null means zero
442     * @return true if this weeks instance is greater than the specified one
443     */
444    public boolean isGreaterThan(Weeks other) {
445        if (other == null) {
446            return getValue() > 0;
447        }
448        return getValue() > other.getValue();
449    }
450
451    /**
452     * Is this weeks instance less than the specified number of weeks.
453     *
454     * @param other  the other period, null means zero
455     * @return true if this weeks instance is less than the specified one
456     */
457    public boolean isLessThan(Weeks other) {
458        if (other == null) {
459            return getValue() < 0;
460        }
461        return getValue() < other.getValue();
462    }
463
464    //-----------------------------------------------------------------------
465    /**
466     * Gets this instance as a String in the ISO8601 duration format.
467     * <p>
468     * For example, "P4W" represents 4 weeks.
469     *
470     * @return the value as an ISO8601 string
471     */
472    @ToString
473    public String toString() {
474        return "P" + String.valueOf(getValue()) + "W";
475    }
476
477}