// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable enable
 
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
 
namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders;
 
/// <summary>
/// An <see cref="IModelBinderProvider"/> for complex types.
/// </summary>
public class ComplexObjectModelBinderProvider : IModelBinderProvider
{
    /// <inheritdoc />
    public IModelBinder? GetBinder(ModelBinderProviderContext context)
    {
        ArgumentNullException.ThrowIfNull(context);
 
        var metadata = context.Metadata;
        if (metadata.IsComplexType && !metadata.IsCollectionType)
        {
            var loggerFactory = context.Services.GetRequiredService<ILoggerFactory>();
            var logger = loggerFactory.CreateLogger(typeof(ComplexObjectModelBinder));
            var parameterBinders = GetParameterBinders(context);
 
            var propertyBinders = new Dictionary<ModelMetadata, IModelBinder>();
            for (var i = 0; i < context.Metadata.Properties.Count; i++)
            {
                var property = context.Metadata.Properties[i];
                propertyBinders.Add(property, context.CreateBinder(property));
            }
 
            return new ComplexObjectModelBinder(propertyBinders, parameterBinders, logger);
        }
 
        return null;
    }
 
    private static IReadOnlyList<IModelBinder> GetParameterBinders(ModelBinderProviderContext context)
    {
        var boundConstructor = context.Metadata.BoundConstructor;
        if (boundConstructor is null)
        {
            return Array.Empty<IModelBinder>();
        }
 
        var parameterBinders = boundConstructor.BoundConstructorParameters!.Count == 0 ?
            Array.Empty<IModelBinder>() :
            new IModelBinder[boundConstructor.BoundConstructorParameters.Count];
 
        for (var i = 0; i < parameterBinders.Length; i++)
        {
            parameterBinders[i] = context.CreateBinder(boundConstructor.BoundConstructorParameters[i]);
        }
 
        return parameterBinders;
    }
}