/*
 * Units of Measurement API
 * Copyright (c) 2014-2023, Jean-Marie Dautelle, Werner Keil, Otavio Santana.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. Neither the name of JSR-385 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 LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package javax.measure.format;

import java.io.IOException;
import java.text.ParsePosition;

import javax.measure.Unit;

/**
 * Formats instances of {@link Unit} to a {@link String} or {@link Appendable} and parses a {@link CharSequence} to a {@link Unit}.
 *
 * <dl>
 * <dt><span class="strong"><a id="synchronization">Synchronization</a></span></dt>
 * </dl>
 * <p>
 * Instances of this class are not required to be thread-safe. It is recommended to use separate format instances for each thread. If multiple threads
 * access a format concurrently, it must be synchronized externally.
 * </p>
 *
 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
 * @author <a href="mailto:werner@uom.technology">Werner Keil</a>
 *
 * @version 2.2, May 20, 2023
 * @since 1.0
 *
 * @see Unit
 */
public interface UnitFormat {
    /**
     * Formats the specified {@link Unit}.
     *
     * @param unit
     *            the {@link Unit} to format, not {@code null}
     * @param appendable
     *            the appendable destination.
     * @return the appendable destination passed in with formatted text appended.
     * @throws IOException
     *             if an error occurs while writing to the destination.
     */
    Appendable format(Unit<?> unit, Appendable appendable) throws IOException;

    /**
     * Formats the specified {@link Unit}.
     *
     * @param unit
     *            the {@link Unit} to format, not {@code null}
     * @return the string representation using the settings of this {@link UnitFormat}.
     */
    String format(Unit<?> unit);

    /**
     * Attaches a system-wide label to the specified {@link Unit}.
     * <p>
     * This method overrides the previous unit's label (e.g. label from unit database or unit system) as units may only have one label. Depending on the
     * {@link UnitFormat} implementation, this call may be ignored if the particular unit already has a label.
     * </p>
     * If a {@link UnitFormat} implementation is explicitly <b>immutable</b>, similar to e.g. the result of <code>Collections.unmodifiableList()</code>,
     * then an {@linkplain UnsupportedOperationException} may be thrown upon this call.
     * <p>
     * Since <code>UnitFormat</code> implementations often apply the Singleton pattern, <b>system-wide</b> means, the label applies to every instance of
     * <code>UnitFormatA</code> implementing <code>UnitFormat</code> in this case, but not every instance of <code>UnitFormatB</code> or <code>UnitFormatC</code> both
     * also implementing <code>UnitFormat</code>. If a <code>UnitFormat</code> #isLocaleSensitive() it is up to the implementation, whether the label is
     * ignored, applied in a local-neutral manner (in addition to its local-sensitive information) or locale-specific.
     * </p>
     *
     * @param unit
     *            the unit being labeled.
     * @param label
     *            the new label for this unit.
     * @throws IllegalArgumentException
     *             if the label is not a valid identifier. This may include characters not supported by a particular {@link UnitFormat} implementation
     *             (e.g. only <b>ASCII</b> characters for certain devices)
     * @throws UnsupportedOperationException
     *             if the <code>label</code> operation is not supported by this {@link UnitFormat}
     */
    void label(Unit<?> unit, String label);

    /**
     * Returns <code>true</code> if this {@link UnitFormat} depends on a <code>Locale</code> to perform its tasks.
     * <p>
     * In environments that do not support a <code>Locale</code>, e.g. Java ME, this usually returns <code>false</code>.
     * </p>
     *
     * @return Whether this format depends on a locale.
     */
    default boolean isLocaleSensitive() {
        return false;
    }

    /**
     * Parses a portion of the specified <code>CharSequence</code> from the specified position to produce a {@link Unit}.
     * If parsing succeeds, then the index of the <code>pos</code> argument is updated to the index after the last character used.
     *
     * @param csq
     *            the <code>CharSequence</code> to parse.
     * @param pos
     *            a ParsePosition object holding the current parsing index and error parsing index information as described above.
     * @return the unit parsed from the specified character sub-sequence.
     * @throws MeasurementParseException
     *             if any problem occurs while parsing the specified character sequence (e.g. illegal syntax).
     * @since 2.0
     */
    Unit<?> parse(CharSequence csq, ParsePosition pos) throws MeasurementParseException;

    /**
     * Parses the text into an instance of {@link Unit}.
     * <p>
     * The parse must complete normally and parse the entire text. If the parse completes without reading the entire length of the text, an exception
     * is thrown. If any other problem occurs during parsing, an exception is thrown.
     * </p>
     *
     * @param csq
     *            the {@code CharSequence} to parse.
     * @return the unit parsed from the specified character sequence.
     * @throws MeasurementParseException
     *             if any problem occurs while parsing the specified character sequence (e.g. illegal syntax).
     * @throws UnsupportedOperationException
     *             if the {@link UnitFormat} is unable to parse.
     * @since 2.0
     */
    Unit<?> parse(CharSequence csq) throws MeasurementParseException;
}