/*
 * Units of Measurement Reference Implementation
 * Copyright (c) 2005-2023, 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, 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.function;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.function.DoubleSupplier;

import javax.measure.Prefix;
import javax.measure.UnitConverter;

import tech.units.indriya.spi.NumberSystem;
import tech.uom.lib.common.function.Converter;
import tech.uom.lib.common.function.FactorSupplier;
import tech.uom.lib.common.function.ValueSupplier;

/**
 * <p>
 * This class represents a converter multiplying numeric values by a constant
 * scaling factor represented by the {@link Number} type.
 * </p>
 * 
 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
 * @author <a href="mailto:werner@units.tech">Werner Keil</a>
 * @author Andi Huber
 * @version 2.7, October 8, 2020
 * @since 1.0
 */
public interface MultiplyConverter extends UnitConverter, Converter<Number, Number>, 
 ValueSupplier<Number>, FactorSupplier<Number>, DoubleSupplier, Comparable<UnitConverter> {

        // -- FACTORIES

        public static MultiplyConverter ofRational(RationalNumber factor) {
                if (factor.equals(RationalNumber.ONE)) {
                        return identity();
                }
                return RationalConverter.of(factor);
        }

        /**
         * Creates a MultiplyConverter with the specified rational factor made up of
         * {@code dividend} and {@code divisor}
         * 
         * @param dividend
         * @param divisor
         */
        public static MultiplyConverter ofRational(long dividend, long divisor) {
                RationalNumber rational = RationalNumber.of(dividend, divisor);
                return ofRational(rational);
        }

        /**
         * Creates a MultiplyConverter with the specified rational factor made up of
         * {@code dividend} and {@code divisor}
         * 
         * @param dividend
         * @param divisor
         */
        public static MultiplyConverter ofRational(BigInteger dividend, BigInteger divisor) {
                RationalNumber rational = RationalNumber.of(dividend, divisor);
                return ofRational(rational);
        }

        /**
         * Creates a MultiplyConverter with the specified constant factor.
         * 
         * @param factor
         * @return
         */
        public static MultiplyConverter of(Number factor) {

                NumberSystem ns = Calculus.currentNumberSystem();

                if (ns.isOne(factor)) {
                        return identity();
                }

                Number narrowedFactor = ns.narrow(factor);

                if (narrowedFactor instanceof RationalNumber) {
                        return ofRational((RationalNumber) narrowedFactor);
                }

                if (ns.isInteger(narrowedFactor)) {
                        if (narrowedFactor instanceof BigInteger) {
                                return ofRational(RationalNumber.ofInteger((BigInteger) narrowedFactor));
                        }

                        // TODO[220] yet only implemented for the default number system,
                        // any other implementation might behave differently;
                        // could fall back to long, but instead fail early
                        if (!(ns instanceof DefaultNumberSystem)) {
                                throw new UnsupportedOperationException("not yet supported");
                        }

                        return ofRational(RationalNumber.ofInteger(narrowedFactor.longValue()));
                }

                if (narrowedFactor instanceof Double || narrowedFactor instanceof Float) {
                        return of(narrowedFactor.doubleValue());
                }

                if (narrowedFactor instanceof BigDecimal) {
                        BigDecimal decimal = (BigDecimal) narrowedFactor;
                        RationalNumber rational = RationalNumber.of(decimal);
                        return ofRational(rational);
                }

                // TODO[220] any other case not supported yet, could fall back to double, but
                // instead fail early
                throw new UnsupportedOperationException("not yet supported");
        }

        /**
         * Creates a MultiplyConverter with the specified constant factor.
         * 
         * @param factor the double factor.
         * @return a new MultiplyConverter.
         */
        public static MultiplyConverter of(double factor) {
                if (factor == 1.d) {
                        return identity();
                }
                RationalNumber rational = RationalNumber.of(factor);
                return ofRational(rational);
        }

        /**
         * Creates a MultiplyConverter with the specified Prefix.
         * 
         * @param prefix the prefix for the factor.
         * @return a new MultiplyConverter.
         */
        public static MultiplyConverter ofPrefix(Prefix prefix) {
                if (prefix == null) {
                        return identity();
                }

            // this is an optimization for the special case of exponent == 1, where we simply use
                // Prefix.getValue() as the factor 
        if (prefix.getExponent() == 1) {
            return of(prefix.getValue());
        }
                
                // as the spec allows for Prefix.getValue() to also return non integer numbers, 
                // we do have to account for these (rare) cases 
                NumberSystem ns = Calculus.currentNumberSystem();
                if(!ns.isInteger(prefix.getValue())) {
                    Number factor = ns.power(prefix.getValue(), prefix.getExponent());
                    return of(factor);    
                }
                
                return PowerOfIntConverter.of(prefix);
                
        }

        /**
         * Creates a MultiplyConverter with the specified exponent of Pi.
         * 
         * @param exponent the exponent for the factor π^exponent.
         * @return a new MultiplyConverter.
         */
        public static MultiplyConverter ofPiExponent(int exponent) {
                if (exponent == 0) {
                        return identity();
                }
                return PowerOfPiConverter.of(exponent);
        }
        
        /**
         * Creates a MultiplyConverter with the specified base and exponent.
         * @param base the base.
         * @param exponent the exponent.
         * @return a new MultiplyConverter.
         */
        public static MultiplyConverter ofExponent(int base, int exponent) {
                if (exponent == 0) {
                        return identity();
                }
                return PowerOfIntConverter.of(base, exponent);
        }
        
        /**
         * Creates a MultiplyConverter with base 10 and an exponent.
         * @param exponent the exponent for the factor 10^exponent.
         */
        public static MultiplyConverter ofTenExponent(int exponent) {
                if (exponent == 0) {
                        return identity();
                }
                return PowerOfIntConverter.of(10, exponent);
        }

        /**
         * Returns a MultiplyConverter that acts as a 'pass-through'.
         * 
         */
        public static MultiplyConverter identity() {
                return IdentityMultiplyConverter.INSTANCE;
        }

        // -- DEFAULTS

        @Override
        default boolean isLinear() {
                return true;
        }

        /**
         * Returns the scale factor of this converter.
         * 
         * @return the scale factor.
         */
        default Number getFactor() {
                return getValue();
        }
}