using Lucene.Net.Analysis;
using Lucene.Net.Codecs;
using Lucene.Net.Documents;
using Lucene.Net.Index.Extensions;
using Lucene.Net.Store;
using Lucene.Net.TestFramework;
using Lucene.Net.Util;
using System;
using System.Collections.Generic;
using JCG = J2N.Collections.Generic;

#if TESTFRAMEWORK_MSTEST
using Test = Microsoft.VisualStudio.TestTools.UnitTesting.TestMethodAttribute;
#elif TESTFRAMEWORK_NUNIT
using Test = NUnit.Framework.TestAttribute;
#elif TESTFRAMEWORK_XUNIT
using Test = Lucene.Net.TestFramework.SkippableFactAttribute;
#endif

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>
    /// Common tests to all index formats.
    /// </summary>
    public abstract class BaseIndexFileFormatTestCase : LuceneTestCase
#if TESTFRAMEWORK_XUNIT
        , Xunit.IClassFixture<BeforeAfterClass>
    {
        // LUCENENET specific - this class was internal in Java, but we can't mark it that way
        // because it has public subclasses. So we are creating an internal constructor instead.
        internal BaseIndexFileFormatTestCase(BeforeAfterClass beforeAfter)
            : base(beforeAfter)
        {
        }
#else
    {

        // LUCENENET specific - this class was internal in Java, but we can't mark it that way
        // because it has public subclasses. So we are creating an internal constructor instead.
        internal BaseIndexFileFormatTestCase() { }
#endif
        // LUCENENET specific - optimized empty array creation
        internal static readonly byte[] EMPTY_BYTES =
#if FEATURE_ARRAYEMPTY
            Array.Empty<byte>();
#else
            new byte[0];
#endif


        /// <summary>
        /// Returns the codec to run tests against </summary>
        protected abstract Codec GetCodec();

        private Codec savedCodec;

        //[SetUp]
        public override void SetUp()
        {
            base.SetUp();
            // set the default codec, so adding test cases to this isn't fragile
            savedCodec = Codec.Default;
            Codec.Default = GetCodec();
        }

        //[TearDown]
        public override void TearDown()
        {
            Codec.Default = savedCodec; // restore
            base.TearDown();
        }

        /// <summary>
        /// Add random fields to the provided document. </summary>
        protected abstract void AddRandomFields(Document doc);

        private IDictionary<string, long> BytesUsedByExtension(Directory d)
        {
            IDictionary<string, long> bytesUsedByExtension = new JCG.Dictionary<string, long>();
            foreach (string file in d.ListAll())
            {
                string ext = IndexFileNames.GetExtension(file);
                long previousLength = bytesUsedByExtension.TryGetValue(ext, out long length) ? length : 0;
                bytesUsedByExtension[ext] = previousLength + d.FileLength(file);
            }
            foreach (string item in ExcludedExtensionsFromByteCounts)
            {
                bytesUsedByExtension.Remove(item);
            }
            return bytesUsedByExtension;
        }

        /// <summary>
        /// Return the list of extensions that should be excluded from byte counts when
        /// comparing indices that store the same content.
        /// </summary>
        protected virtual ICollection<string> ExcludedExtensionsFromByteCounts
        {
            get
            {
                return new string[] {
                    // segment infos store various pieces of information that don't solely depend
                    // on the content of the index in the diagnostics (such as a timestamp) so we
                    // exclude this file from the bytes counts
                        "si",
                    // lock files are 0 bytes (one directory in the test could be RAMDir, the other FSDir)
                        "lock"
                };
            }
        }

        /// <summary>
        /// The purpose of this test is to make sure that bulk merge doesn't accumulate useless data over runs.
        /// </summary>
        [Test]
        public virtual void TestMergeStability()
        {
            using (Directory dir = NewDirectory())
            {
                // do not use newMergePolicy that might return a MockMergePolicy that ignores the no-CFS ratio
                MergePolicy mp = NewTieredMergePolicy();
                mp.NoCFSRatio = 0;
                var cfg = (new IndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random))).SetUseCompoundFile(false).SetMergePolicy(mp);
                using (var w = new RandomIndexWriter(Random, dir, cfg))
                {
                    var numDocs = AtLeast(500);
                    for (var i = 0; i < numDocs; ++i)
                    {
                        var d = new Document();
                        AddRandomFields(d);
                        w.AddDocument(d);
                    }
                    w.ForceMerge(1);
                    w.Commit();
                }
                using (IndexReader reader = DirectoryReader.Open(dir))
                {
                    using (Directory dir2 = NewDirectory())
                    {
                        mp = NewTieredMergePolicy();
                        mp.NoCFSRatio = 0;
                        cfg = (new IndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random))).SetUseCompoundFile(false).SetMergePolicy(mp);

                        using (var w = new RandomIndexWriter(Random, dir2, cfg))
                        {
                            w.AddIndexes(reader);
                            w.Commit();
                        }

                        // LUCENENET: We need to explicitly call Equals() and use HashMap in order to ensure our
                        // equality check is done correctly. Calling Assert.AreEqual doesn't guarantee this is done.
                        Assert.True(BytesUsedByExtension(dir).Equals(BytesUsedByExtension(dir2)));

                    } // dir2.Dispose();
                } // reader.Dispose();
            } // dir.Dispose();
            
        }
    }
}