using Lucene.Net.Util;

namespace Lucene.Net.Facet
{
    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You 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.
     */

    /// <summary>
    /// Keeps highest results, first by largest <see cref="float"/> value,
    /// then tie break by smallest ord.
    /// <para/>
    /// NOTE: This was TopOrdAndFloatQueue in Lucene
    /// </summary>
    public class TopOrdAndSingleQueue : PriorityQueue<TopOrdAndSingleQueue.OrdAndValue>
    {
        /// <summary>
        /// Holds a single entry.
        /// </summary>
        public sealed class OrdAndValue
        {
            /// <summary>
            /// Ordinal of the entry. </summary>
            public int Ord { get; set; }

            /// <summary>
            /// Value associated with the ordinal. </summary>
            public float Value { get; set; }

            /// <summary>
            /// Default constructor.
            /// </summary>
            public OrdAndValue()
            {
            }
        }

        /// <summary>
        /// Sole constructor.
        /// </summary>
        public TopOrdAndSingleQueue(int topN) : base(topN, false)
        {
        }

        protected internal override bool LessThan(OrdAndValue a, OrdAndValue b)
        {
            if (a.Value < b.Value)
            {
                return true;
            }
            else if (a.Value > b.Value)
            {
                return false;
            }
            else
            {
                return a.Ord > b.Ord;
            }
        }
    }
}