/*
 * Java Genetic Algorithm Library (jenetics-8.1.0).
 * Copyright (c) 2007-2024 Franz Wilhelmstötter
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Author:
 *    Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
 */
package io.jenetics.util;

import static java.lang.String.format;
import static io.jenetics.internal.util.Hashes.hash;
import static io.jenetics.internal.util.SerialIO.readInt;
import static io.jenetics.internal.util.SerialIO.writeInt;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serial;
import java.io.Serializable;
import java.util.Optional;
import java.util.stream.IntStream;

/**
 * Integer range class.
 *
 * @implNote
 * This class is immutable and thread-safe.
 *
 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
 * @version 6.0
 * @since 3.2
 */
public final /*record*/ class IntRange implements Serializable {

        @Serial
        private static final long serialVersionUID = 2L;

        private final int _min;
        private final int _max;

        private IntRange(final int min, final int max) {
                if (min > max) {
                        throw new IllegalArgumentException(format(
                                "Min greater than max: %s > %s", min, max
                        ));
                }

                _min = min;
                _max = max;
        }

        /**
         * Return the minimum value of the integer range.
         *
         * @return the minimum value of the integer range
         */
        public int min() {
                return _min;
        }

        /**
         * Return the maximum value of the integer range.
         *
         * @return the maximum value of the integer range
         */
        public int max() {
                return _max;
        }

        /**
         * Checks whether the given {@code value} is within the range
         * {@code [min, max)}.
         *
         * @since 8.0
         *
         * @param value the value to check
         * @return {@code true} if the {@code value} is with the range
         *         {@code [min, max)}, {@code false} otherwise
         */
        public boolean contains(final int value) {
                return value >= _min && value < _max;
        }

        /**
         * Return the intersection of {@code this} range with the {@code other}.
         *
         * @since 8.0
         *
         * @param other the intersection range or {@link Optional#empty()} if there
         *        is none
         * @return the range intersection
         */
        public Optional<IntRange> intersect(final IntRange other) {
                if (_max <= other._min || _min >= other._max) {
                        return Optional.empty();
                } else {
                        return Optional.of(
                                IntRange.of(
                                        Math.max(_min, other._min),
                                        Math.min(_max, other._max)
                                )
                        );
                }
        }

        /**
         * Return the size of the {@code IntRange}: {@code max - min}.
         *
         * @since 3.9
         *
         * @return the size of the int range
         */
        public int size() {
                return _max - _min;
        }

        /**
         * Returns a sequential ordered {@code IntStream} from {@link #min()}
         * (inclusive) to {@link #max()} (exclusive) by an incremental step of
         * {@code 1}.
         * <p>
         * An equivalent sequence of increasing values can be produced sequentially
         * using a {@code for} loop as follows:
         * {@snippet lang="java":
         * for (int i = range.min(); i < range.max(); ++i) {
         *     // ...
         * }
         * }
         *
         * @since 3.4
         *
         * @return a sequential {@link IntStream} for the range of {@code int}
         *         elements
         */
        public IntStream stream() {
                return IntStream.range(_min, _max);
        }

        /**
         * Create a new {@code IntRange} object with the given {@code min} and
         * {@code max} values.
         *
         * @param min the lower bound of the integer range
         * @param max the upper bound of the integer range
         * @return a new {@code IntRange} object
         * @throws IllegalArgumentException if {@code min > max}
         */
        public static IntRange of(final int min, final int max) {
                return new IntRange(min, max);
        }

        /**
         * Return a new (half-open) range, which contains only the given value:
         * {@code [value, value + 1)}.
         *
         * @since 4.0
         *
         * @param value the value of the created (half-open) integer range
         * @return a new (half-open) range, which contains only the given value
         */
        public static IntRange of(final int value) {
                return of(value, value + 1);
        }

        @Override
        public int hashCode() {
                return hash(_min, hash(_max));
        }

        @Override
        public boolean equals(final Object obj) {
                return obj == this ||
                        obj instanceof IntRange other &&
                        _min == other._min &&
                        _max == other._max;
        }

        @Override
        public String toString() {
                return "[" + _min + ", " + _max + "]";
        }


        /* *************************************************************************
         *  Java object serialization
         * ************************************************************************/

        @Serial
        private Object writeReplace() {
                return new SerialProxy(SerialProxy.INT_RANGE, this);
        }

        @Serial
        private void readObject(final ObjectInputStream stream)
                throws InvalidObjectException
        {
                throw new InvalidObjectException("Serialization proxy required.");
        }

        void write(final DataOutput out) throws IOException {
                writeInt(_min, out);
                writeInt(_max, out);
        }

        static IntRange read(final DataInput in) throws IOException {
                return of(readInt(in), readInt(in));
        }

}