/*
 * QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
 * Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
 *
 * Licensed 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 System;
using System.IO;
using NUnit.Framework;
using QuantConnect.Data;
using QuantConnect.Data.Auxiliary;
using QuantConnect.Data.Market;
using QuantConnect.Interfaces;
using QuantConnect.Lean.Engine.DataFeeds;
using QuantConnect.Util;

namespace QuantConnect.Tests.Engine.DataFeeds
{
    [TestFixture]
    public class SubscriptionDataReaderTests
    {
        // this is the core of this unit test:
        // the stream will have two data points one of which does not correspond to the tradable date,
        // and it shouldn't be emitted because we have a new source for the next tradable date
        [TestCase(@"25980000,1679600,1679700,1679600,1679700,200
                99900000,1679400,1679400,1679200,1679200,600", false, Resolution.Minute)]
        // this test case has two data point which should be emitted because they correspond to the same tradable date
        [TestCase(@"25980000,1679600,1679700,1679600,1679700,200
                30980000,1679400,1679400,1679200,1679200,600", true, Resolution.Minute)]
        // even if the second data point is another tradable date we emit it because daily resolution
        // always uses the same source
        [TestCase(@"20191209 00:00,956900,959700,947200,958100,3647000
                20191211 00:00,956900,959700,947200,958100,3647000", true, Resolution.Daily)]
        public void DoesNotEmitDataBeyondTradableDate(string data, bool shouldEmitSecondDataPoint, Resolution dataResolution)
        {
            var start = new DateTime(2019, 12, 9);
            var end = new DateTime(2019, 12, 12);

            var mapFileProvider = new LocalDiskMapFileProvider();
            var mapFileResolver = new MapFileResolver(mapFileProvider.Get(Market.USA));

            var dataReader = new SubscriptionDataReader(
                new SubscriptionDataConfig(typeof(TradeBar),
                    Symbols.SPY,
                    dataResolution,
                    TimeZones.NewYork,
                    TimeZones.NewYork,
                    false,
                    false,
                    false),
                start,
                end,
                mapFileResolver,
                new LocalDiskFactorFileProvider(mapFileProvider),
                LinqExtensions.Range(start, end, time => time + TimeSpan.FromDays(1)),
                false,
                new TestDataCacheProvider
                { Data = data }
                );

            Assert.IsTrue(dataReader.MoveNext());
            Assert.AreEqual(shouldEmitSecondDataPoint, dataReader.MoveNext());

        }

        private class TestDataCacheProvider : IDataCacheProvider
        {
            private bool _alreadyEmitted;

            public string Data { get; set; }
            public void Dispose()
            {
            }

            public bool IsDataEphemeral => true;
            public Stream Fetch(string key)
            {
                if (_alreadyEmitted)
                {
                    return null;
                }
                _alreadyEmitted = true;

                var stream = new MemoryStream();
                var writer = new StreamWriter(stream);
                writer.Write(Data);
                writer.Flush();
                stream.Position = 0;
                return stream;
            }
            public void Store(string key, byte[] data)
            {
            }
        }
    }
}