/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.collection.diffset;

import org.eclipse.collections.api.set.primitive.LongSet;
import org.eclipse.collections.impl.factory.primitive.LongSets;

/**
 * Read only variant of specialised primitive longs collection that with given a sequence of add
 * and removal operations, tracks which elements need to actually be added and removed at minimum from some
 * target collection such that the result is equivalent to just
 * executing the sequence of additions and removals in order.
 */
public interface LongDiffSets {
    LongDiffSets EMPTY = new LongDiffSets() {
        @Override
        public boolean isAdded(long element) {
            return false;
        }

        @Override
        public boolean isRemoved(long element) {
            return false;
        }

        @Override
        public LongSet getAdded() {
            return LongSets.immutable.empty();
        }

        @Override
        public LongSet getRemoved() {
            return LongSets.immutable.empty();
        }

        @Override
        public LongSet getRemovedFromAdded() {
            return LongSets.immutable.empty();
        }

        @Override
        public boolean isEmpty() {
            return true;
        }

        @Override
        public int delta() {
            return 0;
        }
    };

    /**
     * Check if provided element added in this collection
     * @param element element to check
     * @return true if added, false otherwise
     */
    boolean isAdded(long element);

    /**
     * Check if provided element is removed in this collection
     * @param element element to check
     * @return true if removed, false otherwise
     */
    boolean isRemoved(long element);

    /**
     * All elements that added into this collection
     * @return all added elements
     */
    LongSet getAdded();

    /**
     * All elements that are removed according to underlying collection
     * @return all removed elements
     */
    LongSet getRemoved();

    /**
     * @return all elements that were added into and then removed from this collection.
     */
    LongSet getRemovedFromAdded();

    /**
     * Check if underlying diff set is empty
     * @return true if there is no added and removed elements, false otherwise
     */
    boolean isEmpty();

    /**
     * Difference between number of added and removed elements
     * @return difference between number of added and removed elements
     */
    int delta();
}
