using J2N.Threading.Atomic;
using Lucene.Net.Analysis;
using Lucene.Net.Documents;
using Lucene.Net.Index.Extensions;
using Lucene.Net.Store;
using Lucene.Net.Support.Threading;
using Lucene.Net.Util;
using RandomizedTesting.Generators;
using System;
using Test = NUnit.Framework.TestAttribute;

namespace Lucene.Net.Index
{
    /*
     * 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>
    /// Base test case for <see cref="Index.MergePolicy"/>.
    /// </summary>
    public abstract class BaseMergePolicyTestCase : LuceneTestCase
    {
        /// <summary>
        /// Create a new <see cref="Index.MergePolicy"/> instance. </summary>
        new protected abstract MergePolicy NewMergePolicy(); // LUCENENET specific - renamed from MergePolicy() to be consistent

        [Test]
        public virtual void TestForceMergeNotNeeded()
        {
            using Directory dir = NewDirectory();
            AtomicBoolean mayMerge = new AtomicBoolean(true);
            MergeScheduler mergeScheduler = new SerialMergeSchedulerAnonymousClass(mayMerge);
            using IndexWriter writer = new IndexWriter(dir, NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random)).SetMergeScheduler(mergeScheduler).SetMergePolicy(NewMergePolicy()));
            writer.Config.MergePolicy.NoCFSRatio = Random.NextBoolean() ? 0 : 1;
            int numSegments = TestUtil.NextInt32(Random, 2, 20);
            for (int i = 0; i < numSegments; ++i)
            {
                int numDocs = TestUtil.NextInt32(Random, 1, 5);
                for (int j = 0; j < numDocs; ++j)
                {
                    writer.AddDocument(new Document());
                }
                writer.GetReader().Dispose();
            }
            for (int i = 5; i >= 0; --i)
            {
                int segmentCount = writer.SegmentCount;
                int maxNumSegments = i == 0 ? 1 : TestUtil.NextInt32(Random, 1, 10);
                mayMerge.Value = (segmentCount > maxNumSegments);
                writer.ForceMerge(maxNumSegments);
            }
        }

        private sealed class SerialMergeSchedulerAnonymousClass : SerialMergeScheduler
        {
            private readonly AtomicBoolean mayMerge;

            public SerialMergeSchedulerAnonymousClass(AtomicBoolean mayMerge)
            {
                this.mayMerge = mayMerge;
            }

            public override void Merge(IndexWriter writer, MergeTrigger trigger, bool newMergesFound)
            {
                UninterruptableMonitor.Enter(this);
                try
                {
                    if (!mayMerge.Value && writer.GetNextMerge() != null)
                    {
                        throw AssertionError.Create();
                    }
                    base.Merge(writer, trigger, newMergesFound);
                }
                finally
                {
                    UninterruptableMonitor.Exit(this);
                }
            }
        }
    }
}