/*
 * Units of Measurement Reference Implementation
 * Copyright (c) 2005-2021, 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, Indriya nor the names of their 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 tech.units.indriya.unit;

import javax.measure.Dimension;
import javax.measure.Quantity;
import javax.measure.Unit;
import javax.measure.UnitConverter;

import tech.units.indriya.AbstractUnit;

import java.util.Map;
import java.util.Objects;

/**
 * <p>
 * This class represents units used in expressions to distinguish between
 * quantities of a different nature but of the same dimensions.
 * </p>
 * 
 * <p>
 * Examples of alternate units:
 * </p>
 *
 * <code>
 *     {@literal Unit<Angle>} RADIAN = AlternateUnit.of(ONE, "rad").asType(Angle.class);<br>
 *     {@literal Unit<Force>} NEWTON = AlternateUnit.of(METRE.multiply(KILOGRAM).divide(SECOND.pow(2)), "N").asType(Force.class);<br>
 *     {@literal Unit<Pressure>} PASCAL = AlternateUnit.of(NEWTON.divide(METRE.pow(2), "Pa").asType(Pressure.class);<br>
 * </code>
 *
 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
 * @author <a href="mailto:werner@units.tech">Werner Keil</a>
 * @version 2.0, February 08, 2020
 * @since 1.0
 */
public final class AlternateUnit<Q extends Quantity<Q>> extends AbstractUnit<Q> {

        /**
         * 
         */
        private static final long serialVersionUID = 4696690756456282705L;

        /**
         * Holds the parent unit (a system unit).
         */
        private final Unit<?> parentUnit;

        /**
         * Creates an alternate unit for the specified system unit identified by the
         * specified name and symbol.
         *
         * @param parentUnit the system unit from which this alternate unit is derived.
         * @param symbol     the symbol for this alternate unit.
         * @throws IllegalArgumentException if the specified parent unit is not an
         *                                  {@link AbstractUnit#isSystemUnit() system
         *                                  unit}
         */
        @SuppressWarnings("rawtypes")
        public AlternateUnit(Unit<?> parentUnit, String symbol) {
                super(symbol);
                if (!(parentUnit instanceof AbstractUnit))
                        throw new IllegalArgumentException("The parent unit: " + parentUnit + " is not an AbstractUnit");
                if (!((AbstractUnit) parentUnit).isSystemUnit())
                        throw new IllegalArgumentException("The parent unit: " + parentUnit + " is not an unscaled SI unit");
                this.parentUnit = parentUnit instanceof AlternateUnit ? ((AlternateUnit) parentUnit).getParentUnit()
                                : parentUnit;
        }

        /**
         * Creates an alternate unit for the specified system unit identified by the
         * specified name and symbol.
         *
         * @param parentUnit the system unit from which this alternate unit is derived.
         * @param symbol     the symbol for this alternate unit.
         * @param name       the name for this alternate unit.
         * @throws IllegalArgumentException if the specified parent unit is not an
         *                                  {@link AbstractUnit#isSystemUnit() system
         *                                  unit}
         * @since 2.0
         */
        AlternateUnit(Unit<?> parentUnit, String symbol, String name) {
                this(parentUnit, symbol);
                this.name = name;
        }

        /**
         * Returns the parent unit of this alternate unit, always a system unit and
         * never an alternate unit.
         *
         * @return the parent unit.
         */
        public Unit<?> getParentUnit() {
                return parentUnit;
        }

        @Override
        public Dimension getDimension() {
                return parentUnit.getDimension();
        }

        @SuppressWarnings("rawtypes")
        @Override
        public UnitConverter getSystemConverter() {
                return ((AbstractUnit) parentUnit).getSystemConverter();
        }

        @Override
        public Unit<Q> toSystemUnit() {
                return this; // Alternate units are SI units.
        }

        @Override
        public Map<? extends Unit<?>, Integer> getBaseUnits() {
                return parentUnit.getBaseUnits();
        }

        @Override
        public int hashCode() {
                return Objects.hash(parentUnit, getSymbol());
        }

        @SuppressWarnings("rawtypes")
        @Override
        public boolean equals(Object obj) {
                if (this == obj) {
                        return true;
                }
                if (obj instanceof AlternateUnit) {
                        AlternateUnit that = (AlternateUnit) obj;
                        return Objects.equals(parentUnit, that.parentUnit) && Objects.equals(getSymbol(), that.getSymbol());
                }
                return false;
        }

        /**
     * Creates an alternate unit for the specified system unit identified by the specified name and symbol.
     *
     * @param parent
     *            the system unit from which this alternate unit is derived.
     * @param symbol
     *            the symbol for this alternate unit.
     * @throws IllegalArgumentException
     *             if the specified parent unit is not an unscaled standard {@link AbstractUnit#isSystemUnit() system unit}.
     * @throws MeasurementException
     *           if the specified symbol is not valid or is already associated to a different unit.
     */
    public static <Q extends Quantity<Q>> AlternateUnit<Q> of(Unit<?> parent, String symbol) {
        return new AlternateUnit<>(parent, symbol);
    }

        /**
     * Creates an alternate unit for the specified system unit identified by the specified name and symbol.
     *
     * @param parent
     *            the system unit from which this alternate unit is derived.
     * @param symbol
     *            the symbol for this alternate unit.
     * @param name       the name for this alternate unit.
     * @throws IllegalArgumentException
     *             if the specified parent unit is not an unscaled standard {@link AbstractUnit#isSystemUnit() system unit}.
     * @throws MeasurementException
     *           if the specified symbol is not valid or is already associated to a different unit.
     * @since 2.0
     */
    public static <Q extends Quantity<Q>> AlternateUnit<Q> of(Unit<?> parent, String symbol, String name) {
        return new AlternateUnit<>(parent, symbol, name);
    }
}