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/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos

 *

 * All rights reserved.

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 * modification, are permitted provided that the following conditions are met:

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package java.time.temporal;

import java.time.DateTimeException;

/**

 * Framework-level interface defining read-write access to a temporal object,

 * such as a date, time, offset or some combination of these.

 * <p>

 * This is the base interface type for date, time and offset objects that

 * are complete enough to be manipulated using plus and minus.

 * It is implemented by those classes that can provide and manipulate information

 * as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}.

 * See {@link TemporalAccessor} for the read-only version of this interface.

 * <p>

 * Most date and time information can be represented as a number.

 * These are modeled using {@code TemporalField} with the number held using

 * a {@code long} to handle large values. Year, month and day-of-month are

 * simple examples of fields, but they also include instant and offsets.

 * See {@link ChronoField} for the standard set of fields.

 * <p>

 * Two pieces of date/time information cannot be represented by numbers,

 * the {@linkplain java.time.chrono.Chronology chronology} and the

 * {@linkplain java.time.ZoneId time-zone}.

 * These can be accessed via {@link #query(TemporalQuery) queries} using

 * the static methods defined on {@link TemporalQuery}.

 * <p>

 * This interface is a framework-level interface that should not be widely

 * used in application code. Instead, applications should create and pass

 * around instances of concrete types, such as {@code LocalDate}.

 * There are many reasons for this, part of which is that implementations

 * of this interface may be in calendar systems other than ISO.

 * See {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues.

 *

 * <h3>When to implement</h3>

 * <p>

 * A class should implement this interface if it meets three criteria:

 * <ul>

 * <li>it provides access to date/time/offset information, as per {@code TemporalAccessor}

 * <li>the set of fields are contiguous from the largest to the smallest

 * <li>the set of fields are complete, such that no other field is needed to define the

 *  valid range of values for the fields that are represented

 * </ul>

 * <p>

 * Four examples make this clear:

 * <ul>

 * <li>{@code LocalDate} implements this interface as it represents a set of fields

 *  that are contiguous from days to forever and require no external information to determine

 *  the validity of each date. It is therefore able to implement plus/minus correctly.

 * <li>{@code LocalTime} implements this interface as it represents a set of fields

 *  that are contiguous from nanos to within days and require no external information to determine

 *  validity. It is able to implement plus/minus correctly, by wrapping around the day.

 * <li>{@code MonthDay}, the combination of month-of-year and day-of-month, does not implement

 *  this interface.  While the combination is contiguous, from days to months within years,

 *  the combination does not have sufficient information to define the valid range of values

 *  for day-of-month.  As such, it is unable to implement plus/minus correctly.

 * <li>The combination day-of-week and day-of-month ("Friday the 13th") should not implement

 *  this interface. It does not represent a contiguous set of fields, as days to weeks overlaps

 *  days to months.

 * </ul>

 *

 * @implSpec

 * This interface places no restrictions on the mutability of implementations,

 * however immutability is strongly recommended.

 * All implementations must be {@link Comparable}.

 *

 * @since 1.8

 */

public interface Temporal extends TemporalAccessor {

    /**

     * Checks if the specified unit is supported.

     * <p>

     * This checks if the specified unit can be added to, or subtracted from, this date-time.

     * If false, then calling the {@link #plus(long, TemporalUnit)} and

     * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.

     *

     * @implSpec

     * Implementations must check and handle all units defined in {@link ChronoUnit}.

     * If the unit is supported, then true must be returned, otherwise false must be returned.

     * <p>

     * If the field is not a {@code ChronoUnit}, then the result of this method

     * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}

     * passing {@code this} as the argument.

     * <p>

     * Implementations must ensure that no observable state is altered when this

     * read-only method is invoked.

     *

     * @param unit  the unit to check, null returns false

     * @return true if the unit can be added/subtracted, false if not

     */

    boolean isSupported(TemporalUnit unit);

    /**

     * Returns an adjusted object of the same type as this object with the adjustment made.

     * <p>

     * This adjusts this date-time according to the rules of the specified adjuster.

     * A simple adjuster might simply set the one of the fields, such as the year field.

     * A more complex adjuster might set the date to the last day of the month.

     * These include finding the "last day of the month" and "next Wednesday".

     * The adjuster is responsible for handling special cases, such as the varying

     * lengths of month and leap years.

     * <p>

     * Some example code indicating how and why this method is used:

     * <pre>

     *  date = date.with(Month.JULY);        // most key classes implement TemporalAdjuster

     *  date = date.with(lastDayOfMonth());  // static import from Adjusters

     *  date = date.with(next(WEDNESDAY));   // static import from Adjusters and DayOfWeek

     * </pre>

     *

     * @implSpec

     * <p>

     * Implementations must not alter either this object or the specified temporal object.

     * Instead, an adjusted copy of the original must be returned.

     * This provides equivalent, safe behavior for immutable and mutable implementations.

     * <p>

     * The default implementation must behave equivalent to this code:

     * <pre>

     *  return adjuster.adjustInto(this);

     * </pre>

     *

     * @param adjuster  the adjuster to use, not null

     * @return an object of the same type with the specified adjustment made, not null

     * @throws DateTimeException if unable to make the adjustment

     * @throws ArithmeticException if numeric overflow occurs

     */

    default Temporal with(TemporalAdjuster adjuster) {

        return adjuster.adjustInto(this);

    }

    /**

     * Returns an object of the same type as this object with the specified field altered.

     * <p>

     * This returns a new object based on this one with the value for the specified field changed.

     * For example, on a {@code LocalDate}, this could be used to set the year, month or day-of-month.

     * The returned object will have the same observable type as this object.

     * <p>

     * In some cases, changing a field is not fully defined. For example, if the target object is

     * a date representing the 31st January, then changing the month to February would be unclear.

     * In cases like this, the field is responsible for resolving the result. Typically it will choose

     * the previous valid date, which would be the last valid day of February in this example.

     *

     * @implSpec

     * Implementations must check and handle all fields defined in {@link ChronoField}.

     * If the field is supported, then the adjustment must be performed.

     * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.

     * <p>

     * If the field is not a {@code ChronoField}, then the result of this method

     * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}

     * passing {@code this} as the first argument.

     * <p>

     * Implementations must not alter this object.

     * Instead, an adjusted copy of the original must be returned.

     * This provides equivalent, safe behavior for immutable and mutable implementations.

     *

     * @param field  the field to set in the result, not null

     * @param newValue  the new value of the field in the result

     * @return an object of the same type with the specified field set, not null

     * @throws DateTimeException if the field cannot be set

     * @throws UnsupportedTemporalTypeException if the field is not supported

     * @throws ArithmeticException if numeric overflow occurs

     */

    Temporal with(TemporalField field, long newValue);

    //-----------------------------------------------------------------------

    /**

     * Returns an object of the same type as this object with an amount added.

     * <p>

     * This adjusts this temporal, adding according to the rules of the specified amount.

     * The amount is typically a {@link java.time.Period} but may be any other type implementing

     * the {@link TemporalAmount} interface, such as {@link java.time.Duration}.

     * <p>

     * Some example code indicating how and why this method is used:

     * <pre>

     *  date = date.plus(period);                // add a Period instance

     *  date = date.plus(duration);              // add a Duration instance

     *  date = date.plus(workingDays(6));        // example user-written workingDays method

     * </pre>

     * <p>

     * Note that calling {@code plus} followed by {@code minus} is not guaranteed to

     * return the same date-time.

     *

     * @implSpec

     * <p>

     * Implementations must not alter either this object or the specified temporal object.

     * Instead, an adjusted copy of the original must be returned.

     * This provides equivalent, safe behavior for immutable and mutable implementations.

     * <p>

     * The default implementation must behave equivalent to this code:

     * <pre>

     *  return amount.addTo(this);

     * </pre>

     *

     * @param amount  the amount to add, not null

     * @return an object of the same type with the specified adjustment made, not null

     * @throws DateTimeException if the addition cannot be made

     * @throws ArithmeticException if numeric overflow occurs

     */

    default Temporal plus(TemporalAmount amount) {

        return amount.addTo(this);

    }

    /**

     * Returns an object of the same type as this object with the specified period added.

     * <p>

     * This method returns a new object based on this one with the specified period added.

     * For example, on a {@code LocalDate}, this could be used to add a number of years, months or days.

     * The returned object will have the same observable type as this object.

     * <p>

     * In some cases, changing a field is not fully defined. For example, if the target object is

     * a date representing the 31st January, then adding one month would be unclear.

     * In cases like this, the field is responsible for resolving the result. Typically it will choose

     * the previous valid date, which would be the last valid day of February in this example.

     *

     * @implSpec

     * Implementations must check and handle all units defined in {@link ChronoUnit}.

     * If the unit is supported, then the addition must be performed.

     * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.

     * <p>

     * If the unit is not a {@code ChronoUnit}, then the result of this method

     * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}

     * passing {@code this} as the first argument.

     * <p>

     * Implementations must not alter this object.

     * Instead, an adjusted copy of the original must be returned.

     * This provides equivalent, safe behavior for immutable and mutable implementations.

     *

     * @param amountToAdd  the amount of the specified unit to add, may be negative

     * @return an object of the same type with the specified period added, not null

     * @throws DateTimeException if the unit cannot be added

     * @throws UnsupportedTemporalTypeException if the unit is not supported

     * @throws ArithmeticException if numeric overflow occurs

     */

    Temporal plus(long amountToAdd, TemporalUnit unit);

    //-----------------------------------------------------------------------

    /**

     * Returns an object of the same type as this object with an amount subtracted.

     * <p>

     * This adjusts this temporal, subtracting according to the rules of the specified amount.

     * The amount is typically a {@link java.time.Period} but may be any other type implementing

     * the {@link TemporalAmount} interface, such as {@link java.time.Duration}.

     * <p>

     * Some example code indicating how and why this method is used:

     * <pre>

     *  date = date.minus(period);               // subtract a Period instance

     *  date = date.minus(duration);             // subtract a Duration instance

     *  date = date.minus(workingDays(6));       // example user-written workingDays method

     * </pre>

     * <p>

     * Note that calling {@code plus} followed by {@code minus} is not guaranteed to

     * return the same date-time.

     *

     * @implSpec

     * <p>

     * Implementations must not alter either this object or the specified temporal object.

     * Instead, an adjusted copy of the original must be returned.

     * This provides equivalent, safe behavior for immutable and mutable implementations.

     * <p>

     * The default implementation must behave equivalent to this code:

     * <pre>

     *  return amount.subtractFrom(this);

     * </pre>

     *

     * @param amount  the amount to subtract, not null

     * @return an object of the same type with the specified adjustment made, not null

     * @throws DateTimeException if the subtraction cannot be made

     * @throws ArithmeticException if numeric overflow occurs

     */

    default Temporal minus(TemporalAmount amount) {

        return amount.subtractFrom(this);

    }

    /**

     * Returns an object of the same type as this object with the specified period subtracted.

     * <p>

     * This method returns a new object based on this one with the specified period subtracted.

     * For example, on a {@code LocalDate}, this could be used to subtract a number of years, months or days.

     * The returned object will have the same observable type as this object.

     * <p>

     * In some cases, changing a field is not fully defined. For example, if the target object is

     * a date representing the 31st March, then subtracting one month would be unclear.

     * In cases like this, the field is responsible for resolving the result. Typically it will choose

     * the previous valid date, which would be the last valid day of February in this example.

     *

     * @implSpec

     * Implementations must behave in a manor equivalent to the default method behavior.

     * <p>

     * Implementations must not alter this object.

     * Instead, an adjusted copy of the original must be returned.

     * This provides equivalent, safe behavior for immutable and mutable implementations.

     * <p>

     * The default implementation must behave equivalent to this code:

     * <pre>

     *  return (amountToSubtract == Long.MIN_VALUE ?

     *      plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));

     * </pre>

     *

     * @param amountToSubtract  the amount of the specified unit to subtract, may be negative

     * @return an object of the same type with the specified period subtracted, not null

     * @throws DateTimeException if the unit cannot be subtracted

     * @throws UnsupportedTemporalTypeException if the unit is not supported

     * @throws ArithmeticException if numeric overflow occurs

     */

    default Temporal minus(long amountToSubtract, TemporalUnit unit) {

        return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));

    }

    //-----------------------------------------------------------------------

    /**

     * Calculates the amount of time until another temporal in terms of the specified unit.

     * <p>

     * This calculates the amount of time between two temporal objects

     * in terms of a single {@code TemporalUnit}.

     * The start and end points are {@code this} and the specified temporal.

     * The end point is converted to be of the same type as the start point if different.

     * The result will be negative if the end is before the start.

     * calculated using {@code startTime.until(endTime, HOURS)}.

     * <p>

     * The calculation returns a whole number, representing the number of

     * complete units between the two temporals.

     * will only be one hour as it is one minute short of two hours.

     * <p>

     * There are two equivalent ways of using this method.

     * The first is to invoke this method directly.

     * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:

     * <pre>

     *   // these two lines are equivalent

     *   temporal = start.until(end, unit);

     *   temporal = unit.between(start, end);

     * </pre>

     * The choice should be made based on which makes the code more readable.

     * <p>

     * For example, this method allows the number of days between two dates to

     * be calculated:

     * <pre>

     *  long daysBetween = start.until(end, DAYS);

     *  // or alternatively

     *  long daysBetween = DAYS.between(start, end);

     * </pre>

     *

     * @implSpec

     * Implementations must begin by checking to ensure that the input temporal

     * object is of the same observable type as the implementation.

     * They must then perform the calculation for all instances of {@link ChronoUnit}.

     * An {@code UnsupportedTemporalTypeException} must be thrown for {@code ChronoUnit}

     * instances that are unsupported.

     * <p>

     * If the unit is not a {@code ChronoUnit}, then the result of this method

     * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}

     * passing {@code this} as the first argument and the converted input temporal as

     * the second argument.

     * <p>

     * In summary, implementations must behave in a manner equivalent to this pseudo-code:

     * <pre>

     *  // convert the end temporal to the same type as this class

     *  if (unit instanceof ChronoUnit) {

     *    // if unit is supported, then calculate and return result

     *    // else throw UnsupportedTemporalTypeException for unsupported units

     *  }

     *  return unit.between(this, convertedEndTemporal);

     * </pre>

     * <p>

     * Note that the unit's {@code between} method must only be invoked if the

     * two temporal objects have exactly the same type evaluated by {@code getClass()}.

     * <p>

     * Implementations must ensure that no observable state is altered when this

     * read-only method is invoked.

     *

     * @param endExclusive  the end temporal, exclusive, converted to be of the

     *  same type as this object, not null

     * @param unit  the unit to measure the amount in, not null

     * @return the amount of time between this temporal object and the specified one

     *  in terms of the unit; positive if the specified object is later than this one,

     *  negative if it is earlier than this one

     * @throws DateTimeException if the amount cannot be calculated, or the end

     *  temporal cannot be converted to the same type as this temporal

     * @throws UnsupportedTemporalTypeException if the unit is not supported

     * @throws ArithmeticException if numeric overflow occurs

     */

    long until(Temporal endExclusive, TemporalUnit unit);

}