using System;
using System.Diagnostics;

namespace Lucene.Net.Search
{
    using System.Collections.Generic;

    /*
         * 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.
         */

    using IndexReader = Lucene.Net.Index.IndexReader;
    using Term = Lucene.Net.Index.Term;

    /// <summary>
    /// Assertion-enabled query. </summary>
    public class AssertingQuery : Query
    {
        private readonly Random Random;
        private readonly Query @in;

        /// <summary>
        /// Sole constructor.
        /// </summary>
        public AssertingQuery(Random random, Query @in)
        {
            Debug.Assert(@in != null);
            this.Random = random;
            this.@in = @in;
        }

        /// <summary>
        /// Wrap a query if necessary. </summary>
        public static Query Wrap(Random random, Query query)
        {
            var aq = query as AssertingQuery;
            return aq ?? new AssertingQuery(random, query);
        }

        public override Weight CreateWeight(IndexSearcher searcher)
        {
            return AssertingWeight.Wrap(new Random(Random.Next()), @in.CreateWeight(searcher));
        }

        public override void ExtractTerms(ISet<Term> terms)
        {
            @in.ExtractTerms(terms);
        }

        public override string ToString(string field)
        {
            return @in.ToString(field);
        }

        public override bool Equals(object obj)
        {
            var that = obj as AssertingQuery;
            if (that == null)
            {
                return false;
            }
            return this.@in.Equals(that.@in);
        }

        public override int GetHashCode()
        {
            return -@in.GetHashCode();
        }

        public override object Clone()
        {
            return Wrap(new Random(Random.Next()), (Query)@in.Clone());
        }

        public override Query Rewrite(IndexReader reader)
        {
            Query rewritten = @in.Rewrite(reader);
            if (rewritten == @in)
            {
                return this;
            }
            else
            {
                return Wrap(new Random(Random.Next()), rewritten);
            }
        }

        public override float Boost
        {
            get
            {
                return @in.Boost;
            }
            set
            {
                if (@in != null)
                    @in.Boost = value;
            }
        }
    }
}