// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
using Xunit;

namespace Microsoft.AspNetCore.Mvc.ViewFeatures
{
    public class MemberExpressionCacheKeyTest
    {
        [Fact]
        public void GetEnumerator_ReturnsMembers()
        {
            // Arrange
            var expected = new[]
            {
                typeof(TestModel3).GetProperty(nameof(TestModel3.Value)),
                typeof(TestModel2).GetProperty(nameof(TestModel2.TestModel3)),
                typeof(TestModel).GetProperty(nameof(TestModel.TestModel2)),
            };

            var key = GetKey(m => m.TestModel2.TestModel3.Value);

            // Act
            var actual = GetMembers(key);

            // Assert
            Assert.Equal(expected, actual);
        }

        [Fact]
        public void GetEnumerator_WithNullableType_ReturnsMembers()
        {
            // Arrange
            var expected = new[]
            {
                typeof(DateTime).GetProperty(nameof(DateTime.Ticks)),
                typeof(DateTime?).GetProperty(nameof(Nullable<DateTime>.Value)),
                typeof(TestModel).GetProperty(nameof(TestModel.NullableDateTime)),
            };

            var key = GetKey(m => m.NullableDateTime.Value.Ticks);

            // Act
            var actual = GetMembers(key);

            // Assert
            Assert.Equal(expected, actual);
        }

        [Fact]
        public void GetEnumerator_WithValueType_ReturnsMembers()
        {
            // Arrange
            var expected = new[]
            {
                typeof(DateTime).GetProperty(nameof(DateTime.Ticks)),
                typeof(TestModel).GetProperty(nameof(TestModel.DateTime)),
            };

            var key = GetKey(m => m.DateTime.Ticks);

            // Act
            var actual = GetMembers(key);

            // Assert
            Assert.Equal(expected, actual);
        }

        private static MemberExpressionCacheKey GetKey<TResult>(Expression<Func<TestModel, TResult>> expression)
        {
            var memberExpression = Assert.IsAssignableFrom<MemberExpression>(expression.Body);
            return new MemberExpressionCacheKey(typeof(TestModel), memberExpression);
        }

        private static IList<MemberInfo> GetMembers(MemberExpressionCacheKey key)
        {
            var members = new List<MemberInfo>();
            foreach (var member in key)
            {
                members.Add(member);
            }

            return members;
        }

        public class TestModel
        {
            public TestModel2 TestModel2 { get; set; }

            public DateTime DateTime { get; set; }

            public DateTime? NullableDateTime { get; set; }
        }

        public class TestModel2
        {
            public string Name { get; set; }

            public TestModel3 TestModel3 { get; set; }
        }

        public class TestModel3
        {
            public string Value { get; set; }
        }
    }
}
