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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) 2011-2012, 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.

 *

 *  * Redistributions in binary form must reproduce the above copyright notice,

 *    this list of conditions and the following disclaimer in the documentation

 *    and/or other materials provided with the distribution.

 *

 *  * Neither the name of JSR-310 nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

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 */

package java.time.format;

import static java.time.temporal.ChronoField.EPOCH_DAY;

import static java.time.temporal.ChronoField.INSTANT_SECONDS;

import static java.time.temporal.ChronoField.OFFSET_SECONDS;

import java.time.DateTimeException;

import java.time.Instant;

import java.time.ZoneId;

import java.time.ZoneOffset;

import java.time.chrono.ChronoLocalDate;

import java.time.chrono.Chronology;

import java.time.chrono.IsoChronology;

import java.time.temporal.ChronoField;

import java.time.temporal.TemporalAccessor;

import java.time.temporal.TemporalField;

import java.time.temporal.TemporalQuery;

import java.time.temporal.ValueRange;

import java.util.Locale;

import java.util.Objects;

/**

 * Context object used during date and time printing.

 * <p>

 * This class provides a single wrapper to items used in the format.

 *

 * This class is a mutable context intended for use from a single thread.

 * Usage of the class is thread-safe within standard printing as the framework creates

 * a new instance of the class for each format and printing is single-threaded.

 *

 * @since 1.8

 */

final class DateTimePrintContext {

    /**

     * The temporal being output.

     */

    private TemporalAccessor temporal;

    /**

     * The formatter, not null.

     */

    private DateTimeFormatter formatter;

    /**

     * Whether the current formatter is optional.

     */

    private int optional;

    /**

     * Creates a new instance of the context.

     *

     * @param temporal  the temporal object being output, not null

     * @param formatter  the formatter controlling the format, not null

     */

    DateTimePrintContext(TemporalAccessor temporal, DateTimeFormatter formatter) {

        super();

        this.temporal = adjust(temporal, formatter);

        this.formatter = formatter;

    }

    private static TemporalAccessor adjust(final TemporalAccessor temporal, DateTimeFormatter formatter) {

        // normal case first (early return is an optimization)

        Chronology overrideChrono = formatter.getChronology();

        ZoneId overrideZone = formatter.getZone();

        if (overrideChrono == null && overrideZone == null) {

            return temporal;

        }

        // ensure minimal change (early return is an optimization)

        Chronology temporalChrono = temporal.query(TemporalQuery.chronology());

        ZoneId temporalZone = temporal.query(TemporalQuery.zoneId());

        if (Objects.equals(overrideChrono, temporalChrono)) {

            overrideChrono = null;

        }

        if (Objects.equals(overrideZone, temporalZone)) {

            overrideZone = null;

        }

        if (overrideChrono == null && overrideZone == null) {

            return temporal;

        }

        // make adjustment

        final Chronology effectiveChrono = (overrideChrono != null ? overrideChrono : temporalChrono);

        if (overrideZone != null) {

            // if have zone and instant, calculation is simple, defaulting chrono if necessary

            if (temporal.isSupported(INSTANT_SECONDS)) {

                Chronology chrono = (effectiveChrono != null ? effectiveChrono : IsoChronology.INSTANCE);

                return chrono.zonedDateTime(Instant.from(temporal), overrideZone);

            }

            // block changing zone on OffsetTime, and similar problem cases

            if (overrideZone.normalized() instanceof ZoneOffset && temporal.isSupported(OFFSET_SECONDS) &&

                    temporal.get(OFFSET_SECONDS) != overrideZone.getRules().getOffset(Instant.EPOCH).getTotalSeconds()) {

                throw new DateTimeException("Unable to apply override zone '" + overrideZone +

                        "' because the temporal object being formatted has a different offset but" +

                        " does not represent an instant: " + temporal);

            }

        }

        final ZoneId effectiveZone = (overrideZone != null ? overrideZone : temporalZone);

        final ChronoLocalDate<?> effectiveDate;

        if (overrideChrono != null) {

            if (temporal.isSupported(EPOCH_DAY)) {

                effectiveDate = effectiveChrono.date(temporal);

            } else {

                // check for date fields other than epoch-day, ignoring case of converting null to ISO

                if (!(overrideChrono == IsoChronology.INSTANCE && temporalChrono == null)) {

                    for (ChronoField f : ChronoField.values()) {

                        if (f.isDateBased() && temporal.isSupported(f)) {

                            throw new DateTimeException("Unable to apply override chronology '" + overrideChrono +

                                    "' because the temporal object being formatted contains date fields but" +

                                    " does not represent a whole date: " + temporal);

                        }

                    }

                }

                effectiveDate = null;

            }

        } else {

            effectiveDate = null;

        }

        // combine available data

        // this is a non-standard temporal that is almost a pure delegate

        // this better handles map-like underlying temporal instances

        return new TemporalAccessor() {

            @Override

            public boolean isSupported(TemporalField field) {

                if (effectiveDate != null && field.isDateBased()) {

                    return effectiveDate.isSupported(field);

                }

                return temporal.isSupported(field);

            }

            @Override

            public ValueRange range(TemporalField field) {

                if (effectiveDate != null && field.isDateBased()) {

                    return effectiveDate.range(field);

                }

                return temporal.range(field);

            }

            @Override

            public long getLong(TemporalField field) {

                if (effectiveDate != null && field.isDateBased()) {

                    return effectiveDate.getLong(field);

                }

                return temporal.getLong(field);

            }

            @SuppressWarnings("unchecked")

            @Override

            public <R> R query(TemporalQuery<R> query) {

                if (query == TemporalQuery.chronology()) {

                    return (R) effectiveChrono;

                }

                if (query == TemporalQuery.zoneId()) {

                    return (R) effectiveZone;

                }

                if (query == TemporalQuery.precision()) {

                    return temporal.query(query);

                }

                return query.queryFrom(this);

            }

        };

    }

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

    /**

     * Gets the temporal object being output.

     *

     * @return the temporal object, not null

     */

    TemporalAccessor getTemporal() {

        return temporal;

    }

    /**

     * Gets the locale.

     * <p>

     * This locale is used to control localization in the format output except

     *

     * @return the locale, not null

     */

    Locale getLocale() {

        return formatter.getLocale();

    }

    /**

     * <p>

     *

     */

    }

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

    /**

     * Starts the printing of an optional segment of the input.

     */

    void startOptional() {

        this.optional++;

    }

    /**

     * Ends the printing of an optional segment of the input.

     */

    void endOptional() {

        this.optional--;

    }

    /**

     * Gets a value using a query.

     *

     * @param query  the query to use, not null

     * @return the result, null if not found and optional is true

     * @throws DateTimeException if the type is not available and the section is not optional

     */

    <R> R getValue(TemporalQuery<R> query) {

        R result = temporal.query(query);

        if (result == null && optional == 0) {

            throw new DateTimeException("Unable to extract value: " + temporal.getClass());

        }

        return result;

    }

    /**

     * Gets the value of the specified field.

     * <p>

     * This will return the value for the specified field.

     *

     * @param field  the field to find, not null

     * @return the value, null if not found and optional is true

     * @throws DateTimeException if the field is not available and the section is not optional

     */

    Long getValue(TemporalField field) {

        try {

            return temporal.getLong(field);

        } catch (DateTimeException ex) {

            if (optional > 0) {

                return null;

            }

            throw ex;

        }

    }

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

    /**

     * Returns a string version of the context for debugging.

     *

     * @return a string representation of the context, not null

     */

    @Override

    public String toString() {

        return temporal.toString();

    }

}