time/chrono/CopticDate.java

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/*
 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
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 *  * Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
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 *
 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
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package tck.java.time.chrono;

import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_MONTH;
import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_YEAR;
import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_MONTH;
import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_YEAR;
import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoField.YEAR_OF_ERA;

import java.io.Serializable;

import java.time.DateTimeException;
import java.time.LocalDate;
import java.time.Period;
import java.time.Year;
import java.time.chrono.ChronoLocalDate;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalUnit;
import java.time.temporal.ValueRange;
import java.time.temporal.UnsupportedTemporalTypeException;

/**
 * A date in the Coptic calendar system.
 * <p>
 * This implements {@code ChronoLocalDate} for the {@link CopticChronology Coptic calendar}.
 *
 * <h4>Implementation notes</h4>
 * This class is immutable and thread-safe.
 */
public final class CopticDate
        implements ChronoLocalDate, Serializable {

    /**
     * Serialization version.
     */
    private static final long serialVersionUID = -7920528871688876868L;
    /**
     * The difference between the Coptic and Coptic epoch day count.
     */
    private static final int EPOCH_DAY_DIFFERENCE = 574971 + 40587;

    /**
     * The proleptic year.
     */
    private final int prolepticYear;
    /**
     * The month.
     */
    private final short month;
    /**
     * The day.
     */
    private final short day;

    //-----------------------------------------------------------------------
    /**
     * Creates an instance.
     *
     * @param epochDay  the epoch day to convert based on 1970-01-01 (ISO)
     * @return the Coptic date, not null
     * @throws DateTimeException if the date is invalid
     */
    static CopticDate ofEpochDay(long epochDay) {
        epochDay += EPOCH_DAY_DIFFERENCE;
        int prolepticYear = (int) (((epochDay * 4) + 1463) / 1461);
        int startYearEpochDay = (prolepticYear - 1) * 365 + (prolepticYear / 4);
        int doy0 = (int) (epochDay - startYearEpochDay);
        int month = doy0 / 30 + 1;
        int dom = doy0 % 30 + 1;
        return new CopticDate(prolepticYear, month, dom);
    }

    private static CopticDate resolvePreviousValid(int prolepticYear, int month, int day) {
        if (month == 13 && day > 5) {
            day = CopticChronology.INSTANCE.isLeapYear(prolepticYear) ? 6 : 5;
        }
        return new CopticDate(prolepticYear, month, day);
    }

    //-----------------------------------------------------------------------
    /**
     * Creates an instance.
     *
     * @param prolepticYear  the Coptic proleptic-year
     * @param month  the Coptic month, from 1 to 13
     * @param dayOfMonth  the Coptic day-of-month, from 1 to 30
     * @throws DateTimeException if the date is invalid
     */
    CopticDate(int prolepticYear, int month, int dayOfMonth) {
        CopticChronology.MOY_RANGE.checkValidValue(month, MONTH_OF_YEAR);
        ValueRange range;
        if (month == 13) {
            range = CopticChronology.INSTANCE.isLeapYear(prolepticYear) ? CopticChronology.DOM_RANGE_LEAP : CopticChronology.DOM_RANGE_NONLEAP;
        } else {
            range = CopticChronology.DOM_RANGE;
        }
        range.checkValidValue(dayOfMonth, DAY_OF_MONTH);

        this.prolepticYear = prolepticYear;
        this.month = (short) month;
        this.day = (short) dayOfMonth;
    }

    /**
     * Validates the object.
     *
     * @return the resolved date, not null
     */
    private Object readResolve() {
        // TODO: validate
        return this;
    }

    //-----------------------------------------------------------------------
    @Override
    public CopticChronology getChronology() {
        return CopticChronology.INSTANCE;
    }

    //-----------------------------------------------------------------------
    @Override
    public int lengthOfMonth() {
        switch (month) {
            case 13:
                return (isLeapYear() ? 6 : 5);
            default:
                return 30;
        }
    }

    @Override
    public ValueRange range(TemporalField field) {
        if (field instanceof ChronoField) {
            if (isSupported(field)) {
                ChronoField f = (ChronoField) field;
                switch (f) {
                    case DAY_OF_MONTH: return ValueRange.of(1, lengthOfMonth());
                    case DAY_OF_YEAR: return ValueRange.of(1, lengthOfYear());
                    case ALIGNED_WEEK_OF_MONTH: return ValueRange.of(1, month == 13 ? 1 : 5);
                    case YEAR:
                    case YEAR_OF_ERA: return (prolepticYear <= 0 ?
                            ValueRange.of(1, Year.MAX_VALUE + 1) : ValueRange.of(1, Year.MAX_VALUE));  // TODO
                }
                return getChronology().range(f);
            }
            throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        }
        return field.rangeRefinedBy(this);
    }

    @Override
    public long getLong(TemporalField field) {
        if (field instanceof ChronoField) {
            switch ((ChronoField) field) {
                case DAY_OF_WEEK: return Math.floorMod(toEpochDay() + 3, 7) + 1;
                case ALIGNED_DAY_OF_WEEK_IN_MONTH: return ((day - 1) % 7) + 1;
                case ALIGNED_DAY_OF_WEEK_IN_YEAR: return ((get(ChronoField.DAY_OF_YEAR) - 1) % 7) + 1;
                case DAY_OF_MONTH: return day;
                case DAY_OF_YEAR: return (month - 1) * 30 + day;
                case EPOCH_DAY: return toEpochDay();
                case ALIGNED_WEEK_OF_MONTH: return ((day - 1) / 7) + 1;
                case ALIGNED_WEEK_OF_YEAR: return ((get(ChronoField.DAY_OF_YEAR) - 1) / 7) + 1;
                case MONTH_OF_YEAR: return month;
                case YEAR_OF_ERA: return (prolepticYear >= 1 ? prolepticYear : 1 - prolepticYear);
                case YEAR: return prolepticYear;
                case ERA: return (prolepticYear >= 1 ? 1 : 0);
            }
            throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        }
        return field.getFrom(this);
    }

    @Override
    public CopticDate with(TemporalField field, long newValue) {
        if (field instanceof ChronoField) {
            ChronoField f = (ChronoField) field;
            f.checkValidValue(newValue);        // TODO: validate value
            int nvalue = (int) newValue;
            switch (f) {
                case DAY_OF_WEEK: return plusDays(newValue - get(ChronoField.DAY_OF_WEEK));
                case ALIGNED_DAY_OF_WEEK_IN_MONTH: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_MONTH));
                case ALIGNED_DAY_OF_WEEK_IN_YEAR: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_YEAR));
                case DAY_OF_MONTH: return resolvePreviousValid(prolepticYear, month, nvalue);
                case DAY_OF_YEAR: return resolvePreviousValid(prolepticYear, ((nvalue - 1) / 30) + 1, ((nvalue - 1) % 30) + 1);
                case EPOCH_DAY: return ofEpochDay(nvalue);
                case ALIGNED_WEEK_OF_MONTH: return plusDays((newValue - getLong(ALIGNED_WEEK_OF_MONTH)) * 7);
                case ALIGNED_WEEK_OF_YEAR: return plusDays((newValue - getLong(ALIGNED_WEEK_OF_YEAR)) * 7);
                case MONTH_OF_YEAR: return resolvePreviousValid(prolepticYear, nvalue, day);
                case YEAR_OF_ERA: return resolvePreviousValid(prolepticYear >= 1 ? nvalue : 1 - nvalue, month, day);
                case YEAR: return resolvePreviousValid(nvalue, month, day);
                case ERA: return resolvePreviousValid(1 - prolepticYear, month, day);
            }
            throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        }
        return field.adjustInto(this, newValue);
    }

    //-----------------------------------------------------------------------
    @Override
    public CopticDate plus(long amountToAdd, TemporalUnit unit) {
        if (unit instanceof ChronoUnit) {
            ChronoUnit f = (ChronoUnit) unit;
            switch (f) {
                case DAYS: return plusDays(amountToAdd);
                case WEEKS: return plusDays(Math.multiplyExact(amountToAdd, 7));
                case MONTHS: return plusMonths(amountToAdd);
                case YEARS: return plusYears(amountToAdd);
                case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
                case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
                case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
            }
            throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
        }
        return unit.addTo(this, amountToAdd);
    }

    //-----------------------------------------------------------------------
    private CopticDate plusYears(long years) {
        return plusMonths(Math.multiplyExact(years, 13));
    }

    private CopticDate plusMonths(long months) {
        if (months == 0) {
            return this;
        }
        long curEm = prolepticYear * 13L + (month - 1);
        long calcEm = Math.addExact(curEm, months);
        int newYear = Math.toIntExact(Math.floorDiv(calcEm, 13));
        int newMonth = (int)Math.floorMod(calcEm, 13) + 1;
        return resolvePreviousValid(newYear, newMonth, day);
    }

    private CopticDate plusDays(long days) {
        if (days == 0) {
            return this;
        }
        return CopticDate.ofEpochDay(Math.addExact(toEpochDay(), days));
    }

    @Override
    public long until(Temporal endExclusive, TemporalUnit unit) {
        CopticDate end = getChronology().date(endExclusive);
        if (unit instanceof ChronoUnit) {
            return LocalDate.from(this).until(end, unit);  // TODO: this is wrong
        }
        return unit.between(this, end);
    }

    @Override
    public Period until(ChronoLocalDate endDate) {
        // TODO: untested
        CopticDate end = getChronology().date(endDate);
        long totalMonths = (end.prolepticYear - this.prolepticYear) * 13 + (end.month - this.month);  // safe
        int days = end.day - this.day;
        if (totalMonths > 0 && days < 0) {
            totalMonths--;
            CopticDate calcDate = this.plusMonths(totalMonths);
            days = (int) (end.toEpochDay() - calcDate.toEpochDay());  // safe
        } else if (totalMonths < 0 && days > 0) {
            totalMonths++;
            days -= end.lengthOfMonth();
        }
        long years = totalMonths / 13;  // safe
        int months = (int) (totalMonths % 13);  // safe
        return Period.of(Math.toIntExact(years), months, days);
    }

    //-----------------------------------------------------------------------
    @Override
    public long toEpochDay() {
        long year = (long) prolepticYear;
        long copticEpochDay = ((year - 1) * 365) + Math.floorDiv(year, 4) + (get(ChronoField.DAY_OF_YEAR) - 1);
        return copticEpochDay - EPOCH_DAY_DIFFERENCE;
    }

    @Override
    public String toString() {
        // getLong() reduces chances of exceptions in toString()
        long yoe = getLong(YEAR_OF_ERA);
        long moy = getLong(MONTH_OF_YEAR);
        long dom = getLong(DAY_OF_MONTH);
        StringBuilder buf = new StringBuilder(30);
        buf.append(getChronology().toString())
                .append(" ")
                .append(getEra())
                .append(" ")
                .append(yoe)
                .append(moy < 10 ? "-0" : "-").append(moy)
                .append(dom < 10 ? "-0" : "-").append(dom);
        return buf.toString();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof CopticDate) {
            CopticDate cd = (CopticDate)obj;
            if (this.prolepticYear == cd.prolepticYear &&
                    this.month == cd.month &&
                    this.day == cd.day) {
                return true;
            }
        }
        return false;
    }

    @Override
    public int hashCode() {
        long epDay = toEpochDay();
        return getChronology().hashCode() ^ ((int) (epDay ^ (epDay >>> 32)));
    }

}