/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      https://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.
 */

package org.springframework.util.comparator;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * A comparator that chains a sequence of one or more Comparators.
 *
 * <p>A compound comparator calls each Comparator in sequence until a single
 * Comparator returns a non-zero result, or the comparators are exhausted and
 * zero is returned.
 *
 * <p>This facilitates in-memory sorting similar to multi-column sorting in SQL.
 * The order of any single Comparator in the list can also be reversed.
 *
 * @author Keith Donald
 * @author Juergen Hoeller
 * @since 1.2.2
 * @param <T> the type of objects that may be compared by this comparator
 * @deprecated as of Spring Framework 5.0, in favor of the standard JDK 8
 * {@link Comparator#thenComparing(Comparator)}
 */
@Deprecated
@SuppressWarnings({"serial", "rawtypes"})
public class CompoundComparator<T> implements Comparator<T>, Serializable {

        private final List<InvertibleComparator> comparators;


        /**
         * Construct a CompoundComparator with initially no Comparators. Clients
         * must add at least one Comparator before calling the compare method or an
         * IllegalStateException is thrown.
         */
        public CompoundComparator() {
                this.comparators = new ArrayList<>();
        }

        /**
         * Construct a CompoundComparator from the Comparators in the provided array.
         * <p>All Comparators will default to ascending sort order,
         * unless they are InvertibleComparators.
         * @param comparators the comparators to build into a compound comparator
         * @see InvertibleComparator
         */
        @SuppressWarnings("unchecked")
        public CompoundComparator(Comparator... comparators) {
                Assert.notNull(comparators, "Comparators must not be null");
                this.comparators = new ArrayList<>(comparators.length);
                for (Comparator comparator : comparators) {
                        addComparator(comparator);
                }
        }


        /**
         * Add a Comparator to the end of the chain.
         * <p>The Comparator will default to ascending sort order,
         * unless it is a InvertibleComparator.
         * @param comparator the Comparator to add to the end of the chain
         * @see InvertibleComparator
         */
        @SuppressWarnings("unchecked")
        public void addComparator(Comparator<? extends T> comparator) {
                if (comparator instanceof InvertibleComparator) {
                        this.comparators.add((InvertibleComparator) comparator);
                }
                else {
                        this.comparators.add(new InvertibleComparator(comparator));
                }
        }

        /**
         * Add a Comparator to the end of the chain using the provided sort order.
         * @param comparator the Comparator to add to the end of the chain
         * @param ascending the sort order: ascending (true) or descending (false)
         */
        @SuppressWarnings("unchecked")
        public void addComparator(Comparator<? extends T> comparator, boolean ascending) {
                this.comparators.add(new InvertibleComparator(comparator, ascending));
        }

        /**
         * Replace the Comparator at the given index.
         * <p>The Comparator will default to ascending sort order,
         * unless it is a InvertibleComparator.
         * @param index the index of the Comparator to replace
         * @param comparator the Comparator to place at the given index
         * @see InvertibleComparator
         */
        @SuppressWarnings("unchecked")
        public void setComparator(int index, Comparator<? extends T> comparator) {
                if (comparator instanceof InvertibleComparator) {
                        this.comparators.set(index, (InvertibleComparator) comparator);
                }
                else {
                        this.comparators.set(index, new InvertibleComparator(comparator));
                }
        }

        /**
         * Replace the Comparator at the given index using the given sort order.
         * @param index the index of the Comparator to replace
         * @param comparator the Comparator to place at the given index
         * @param ascending the sort order: ascending (true) or descending (false)
         */
        public void setComparator(int index, Comparator<T> comparator, boolean ascending) {
                this.comparators.set(index, new InvertibleComparator<>(comparator, ascending));
        }

        /**
         * Invert the sort order of each sort definition contained by this compound
         * comparator.
         */
        public void invertOrder() {
                for (InvertibleComparator comparator : this.comparators) {
                        comparator.invertOrder();
                }
        }

        /**
         * Invert the sort order of the sort definition at the specified index.
         * @param index the index of the comparator to invert
         */
        public void invertOrder(int index) {
                this.comparators.get(index).invertOrder();
        }

        /**
         * Change the sort order at the given index to ascending.
         * @param index the index of the comparator to change
         */
        public void setAscendingOrder(int index) {
                this.comparators.get(index).setAscending(true);
        }

        /**
         * Change the sort order at the given index to descending sort.
         * @param index the index of the comparator to change
         */
        public void setDescendingOrder(int index) {
                this.comparators.get(index).setAscending(false);
        }

        /**
         * Returns the number of aggregated comparators.
         */
        public int getComparatorCount() {
                return this.comparators.size();
        }


        @Override
        @SuppressWarnings("unchecked")
        public int compare(T o1, T o2) {
                Assert.state(!this.comparators.isEmpty(),
                                "No sort definitions have been added to this CompoundComparator to compare");
                for (InvertibleComparator comparator : this.comparators) {
                        int result = comparator.compare(o1, o2);
                        if (result != 0) {
                                return result;
                        }
                }
                return 0;
        }


        @Override
        @SuppressWarnings("unchecked")
        public boolean equals(@Nullable Object other) {
                return (this == other || (other instanceof CompoundComparator &&
                                this.comparators.equals(((CompoundComparator<T>) other).comparators)));
        }

        @Override
        public int hashCode() {
                return this.comparators.hashCode();
        }

        @Override
        public String toString() {
                return "CompoundComparator: " + this.comparators;
        }

}