// 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 System.Linq;
using System.Linq.Expressions;
 
namespace Microsoft.AspNetCore.Mvc.ModelBinding;
 
/// <summary>
/// Default implementation for <see cref="IPropertyFilterProvider"/>.
/// Provides a expression based way to provide include properties.
/// </summary>
/// <typeparam name="TModel">The target model Type.</typeparam>
public class DefaultPropertyFilterProvider<TModel> : IPropertyFilterProvider
    where TModel : class
{
    private static readonly Func<ModelMetadata, bool> _default = (m) => true;
 
    /// <summary>
    /// The prefix which is used while generating the property filter.
    /// </summary>
    public virtual string Prefix => string.Empty;
 
    /// <summary>
    /// Expressions which can be used to generate property filter which can filter model
    /// properties.
    /// </summary>
    public virtual IEnumerable<Expression<Func<TModel, object?>>>? PropertyIncludeExpressions => null;
 
    /// <inheritdoc />
    public virtual Func<ModelMetadata, bool> PropertyFilter
    {
        get
        {
            if (PropertyIncludeExpressions == null)
            {
                return _default;
            }
 
            // We do not cache by default.
            return DefaultPropertyFilterProvider<TModel>.GetPropertyFilterFromExpression(PropertyIncludeExpressions);
        }
    }
 
    private static Func<ModelMetadata, bool> GetPropertyFilterFromExpression(
        IEnumerable<Expression<Func<TModel, object?>>> includeExpressions)
    {
        var expression = ModelBindingHelper.GetPropertyFilterExpression(includeExpressions.ToArray());
        return expression.Compile();
    }
}