// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.

namespace System.Data.Entity.Config
{
    using System.Collections.Concurrent;
    using System.Linq;
    using Moq;
    using Xunit;

    public class CompositeResolverTests : TestBase
    {
        [Fact]
        public void Get_returns_result_of_first_resolver_if_result_is_non_null()
        {
            var mockFirstResolver = new Mock<IDbDependencyResolver>();
            var mockSecondResolver = new Mock<IDbDependencyResolver>();

            var karl = new Mock<IPilkington>().Object;
            mockFirstResolver.Setup(m => m.GetService(typeof(IPilkington), "Karl")).Returns(karl);

            Assert.Same(
                karl,
                new CompositeResolver<IDbDependencyResolver, IDbDependencyResolver>(
                    mockFirstResolver.Object, mockSecondResolver.Object).GetService<IPilkington>("Karl"));

            mockFirstResolver.Verify(m => m.GetService(typeof(IPilkington), "Karl"), Times.Once());
            mockSecondResolver.Verify(m => m.GetService(It.IsAny<Type>(), It.IsAny<string>()), Times.Never());
        }

        [Fact]
        public void Get_returns_result_of_second_resolver_if_result_of_first_is_null()
        {
            var mockFirstResolver = new Mock<IDbDependencyResolver>();
            var mockSecondResolver = new Mock<IDbDependencyResolver>();

            var karl = new Mock<IPilkington>().Object;
            mockSecondResolver.Setup(m => m.GetService(typeof(IPilkington), "Karl")).Returns(karl);

            Assert.Same(
                karl,
                new CompositeResolver<IDbDependencyResolver, IDbDependencyResolver>(
                    mockFirstResolver.Object, mockSecondResolver.Object).GetService<IPilkington>("Karl"));

            mockFirstResolver.Verify(m => m.GetService(typeof(IPilkington), "Karl"), Times.Once());
            mockSecondResolver.Verify(m => m.GetService(typeof(IPilkington), "Karl"), Times.Once());
        }

        [Fact]
        public void Get_returns_null_if_both_resolvers_return_null()
        {
            var mockFirstResolver = new Mock<IDbDependencyResolver>();
            var mockSecondResolver = new Mock<IDbDependencyResolver>();

            Assert.Null(
                new CompositeResolver<IDbDependencyResolver, IDbDependencyResolver>(
                    mockFirstResolver.Object, mockSecondResolver.Object).GetService<IPilkington>("Karl"));

            mockFirstResolver.Verify(m => m.GetService(typeof(IPilkington), "Karl"), Times.Once());
            mockSecondResolver.Verify(m => m.GetService(typeof(IPilkington), "Karl"), Times.Once());
        }

        public interface IPilkington
        {
        }

        /// <summary>
        ///     This test makes calls from multiple threads such that we have at least some chance of finding threading
        ///     issues. As with any test of this type just because the test passes does not mean that the code is
        ///     correct. On the other hand if this test ever fails (EVEN ONCE) then we know there is a problem to
        ///     be investigated. DON'T just re-run and think things are okay if the test then passes.
        /// </summary>
        [Fact]
        public void GetService_can_be_accessed_from_multiple_threads_concurrently()
        {
            for (var i = 0; i < 30; i++)
            {
                var bag = new ConcurrentBag<IPilkington>();
                var karl1 = new Mock<IPilkington>().Object;
                var resolver = new CompositeResolver<IDbDependencyResolver, IDbDependencyResolver>(
                    new SingletonDependencyResolver<IPilkington>(karl1),
                    new SingletonDependencyResolver<IPilkington>(new Mock<IPilkington>().Object));

                ExecuteInParallel(() => bag.Add(resolver.GetService<IPilkington>()));

                Assert.Equal(20, bag.Count);
                Assert.True(bag.All(c => karl1 == c));
            }
        }
    }
}