using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

using Coverlet.Core.Samples.Tests;
using Coverlet.Tests.Xunit.Extensions;
using Xunit;

namespace Coverlet.Core.Tests
{
    public partial class CoverageTests
    {
        [Fact]
        public void AsyncForeach()
        {
            string path = Path.GetTempFileName();
            try
            {
                FunctionExecutor.Run(async (string[] pathSerialize) =>
                {
                    CoveragePrepareResult coveragePrepareResult = await TestInstrumentationHelper.Run<AsyncForeach>(instance =>
                    {
                        int res = ((ValueTask<int>)instance.SumWithATwist(AsyncEnumerable.Range(1, 5))).GetAwaiter().GetResult();
                        res += ((ValueTask<int>)instance.Sum(AsyncEnumerable.Range(1, 3))).GetAwaiter().GetResult();
                        res += ((ValueTask<int>)instance.SumEmpty()).GetAwaiter().GetResult();

                        return Task.CompletedTask;
                    }, persistPrepareResultToFile: pathSerialize[0]);
                    return 0;
                }, new string[] { path });

                TestInstrumentationHelper.GetCoverageResult(path)
                .Document("Instrumentation.AsyncForeach.cs")
                .AssertLinesCovered(BuildConfiguration.Debug,
                                    // SumWithATwist(IAsyncEnumerable<int>)
                                    // Apparently due to entering and exiting the async state machine, line 17
                                    // (the top of an "await foreach" loop) is reached three times *plus* twice
                                    // per loop iteration.  So, in this case, with five loop iterations, we end
                                    // up with 3 + 5 * 2 = 13 hits.
                                    (14, 1), (15, 1), (17, 13), (18, 5), (19, 5), (20, 5), (21, 5), (22, 5),
                                    (24, 0), (25, 0), (26, 0), (27, 5), (29, 1), (30, 1),
                                    // Sum(IAsyncEnumerable<int>)
                                    (34, 1), (35, 1), (37, 9), (38, 3), (39, 3), (40, 3), (42, 1), (43, 1),
                                    // SumEmpty()
                                    (47, 1), (48, 1), (50, 3), (51, 0), (52, 0), (53, 0), (55, 1), (56, 1)
                                    )
                .AssertBranchesCovered(BuildConfiguration.Debug,
                                       // SumWithATwist(IAsyncEnumerable<int>)
                                       (17, 2, 1), (17, 3, 5), (19, 0, 5), (19, 1, 0),
                                       // Sum(IAsyncEnumerable<int>)
                                       (37, 0, 1), (37, 1, 3),
                                       // SumEmpty()
                                       // If we never entered the loop, that's a branch not taken, which is
                                       // what we want to see.
                                       (50, 0, 1), (50, 1, 0)
                                       )
                .ExpectedTotalNumberOfBranches(BuildConfiguration.Debug, 4);
            }
            finally
            {
                File.Delete(path);
            }
        }
    }
}