// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Reflection;
using Microsoft.Extensions.Internal;
 
namespace Microsoft.AspNetCore.Mvc.Formatters.Xml;
 
/// <summary>
/// Provides a <see cref="IWrapperProvider"/> for interface types which implement
/// <see cref="IEnumerable{T}"/>.
/// </summary>
public class EnumerableWrapperProvider : IWrapperProvider
{
    private readonly IWrapperProvider? _wrapperProvider;
    private readonly ConstructorInfo _wrappingTypeConstructor;
 
    /// <summary>
    /// Initializes an instance of <see cref="EnumerableWrapperProvider"/>.
    /// </summary>
    /// <param name="sourceEnumerableOfT">Type of the original <see cref="IEnumerable{T}" />
    /// that is being wrapped.</param>
    /// <param name="elementWrapperProvider">The <see cref="IWrapperProvider"/> for the element type.
    /// Can be null.</param>
    public EnumerableWrapperProvider(
        Type sourceEnumerableOfT,
        IWrapperProvider? elementWrapperProvider)
    {
        ArgumentNullException.ThrowIfNull(sourceEnumerableOfT);
 
        var enumerableOfT = ClosedGenericMatcher.ExtractGenericInterface(
            sourceEnumerableOfT,
            typeof(IEnumerable<>));
        if (!sourceEnumerableOfT.IsInterface || enumerableOfT == null)
        {
            throw new ArgumentException(
                Resources.FormatEnumerableWrapperProvider_InvalidSourceEnumerableOfT(typeof(IEnumerable<>).Name),
                nameof(sourceEnumerableOfT));
        }
 
        _wrapperProvider = elementWrapperProvider;
 
        var declaredElementType = enumerableOfT.GenericTypeArguments[0];
        var wrappedElementType = elementWrapperProvider?.WrappingType ?? declaredElementType;
        WrappingType = typeof(DelegatingEnumerable<,>).MakeGenericType(wrappedElementType, declaredElementType);
 
        _wrappingTypeConstructor = WrappingType.GetConstructor(new[]
        {
                sourceEnumerableOfT,
                typeof(IWrapperProvider)
            })!;
    }
 
    /// <inheritdoc />
    public Type WrappingType
    {
        get;
    }
 
    /// <inheritdoc />
    public object? Wrap(object? original)
    {
        if (original == null)
        {
            return null;
        }
 
        return _wrappingTypeConstructor.Invoke(new[] { original, _wrapperProvider });
    }
}