// 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;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
using Xunit;

namespace Microsoft.AspNetCore.Mvc.Internal
{
    public class DefaultCollectionValidationStrategyTest
    {
        [Fact]
        public void EnumerateElements()
        {
            // Arrange
            var model = new List<int>() { 2, 3, 5 };

            var metadata = TestModelMetadataProvider.CreateDefaultProvider().GetMetadataForType(typeof(List<int>));
            var strategy = DefaultCollectionValidationStrategy.Instance;

            // Act
            var enumerator = strategy.GetChildren(metadata, "prefix", model);

            // Assert
            Assert.Collection(
                BufferEntries(enumerator).OrderBy(e => e.Key),
                e => 
                {
                    Assert.Equal("prefix[0]", e.Key);
                    Assert.Equal(2, e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                },
                e =>
                {
                    Assert.Equal("prefix[1]", e.Key);
                    Assert.Equal(3, e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                },
                e =>
                {
                    Assert.Equal("prefix[2]", e.Key);
                    Assert.Equal(5, e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                });
        }

        [Fact]
        public void EnumerateElements_Dictionary()
        {
            // Arrange
            var model = new Dictionary<int, string>()
            {
                { 2, "two" },
                { 3, "three" },
                { 5, "five" },
            };

            var metadata = TestModelMetadataProvider.CreateDefaultProvider().GetMetadataForType(typeof(List<int>));
            var strategy = DefaultCollectionValidationStrategy.Instance;

            // Act
            var enumerator = strategy.GetChildren(metadata, "prefix", model);

            // Assert
            Assert.Collection(
                BufferEntries(enumerator).OrderBy(e => e.Key),
                e =>
                {
                    Assert.Equal("prefix[0]", e.Key);
                    Assert.Equal(new KeyValuePair<int, string>(2, "two"), e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                },
                e =>
                {
                    Assert.Equal("prefix[1]", e.Key);
                    Assert.Equal(new KeyValuePair<int, string>(3, "three"), e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                },
                e =>
                {
                    Assert.Equal("prefix[2]", e.Key);
                    Assert.Equal(new KeyValuePair<int, string>(5, "five"), e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                });
        }

        [Fact]
        public void EnumerateElements_TwoEnumerableImplemenations()
        {
            // Arrange
            var model = new TwiceEnumerable(new int[] { 2, 3, 5 });

            var metadata = TestModelMetadataProvider.CreateDefaultProvider().GetMetadataForType(typeof(TwiceEnumerable));
            var strategy = DefaultCollectionValidationStrategy.Instance;

            // Act
            var enumerator = strategy.GetChildren(metadata, "prefix", model);

            // Assert
            Assert.Collection(
                BufferEntries(enumerator).OrderBy(e => e.Key),
                e =>
                {
                    Assert.Equal("prefix[0]", e.Key);
                    Assert.Equal(2, e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                },
                e =>
                {
                    Assert.Equal("prefix[1]", e.Key);
                    Assert.Equal(3, e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                },
                e =>
                {
                    Assert.Equal("prefix[2]", e.Key);
                    Assert.Equal(5, e.Model);
                    Assert.Same(metadata.ElementMetadata, e.Metadata);
                });
        }

        // 'int' is chosen by validation because it's declared on the more derived type.
        private class TwiceEnumerable : List<string>, IEnumerable<int>
        {
            private readonly IEnumerable<int> _enumerable;

            public TwiceEnumerable(IEnumerable<int> enumerable)
            {
                _enumerable = enumerable;
            }

            IEnumerator<int> IEnumerable<int>.GetEnumerator()
            {
                return _enumerable.GetEnumerator();
            }

            IEnumerator IEnumerable.GetEnumerator()
            {
                throw new InvalidOperationException();
            }
        }

        private List<ValidationEntry> BufferEntries(IEnumerator<ValidationEntry> enumerator)
        {
            var entries = new List<ValidationEntry>();
            while (enumerator.MoveNext())
            {
                entries.Add(enumerator.Current);
            }

            return entries;
        }
    }
}