// 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.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
using System.Security;
using System.Web.Http.Metadata;
using System.Web.Http.Properties;
using System.Web.Http.Validation.Validators;

namespace System.Web.Http.Validation.Providers
{
    /// <summary>
    /// An implementation of <see cref="ModelValidatorProvider"/> which provides validators that throw exceptions when the model is invalid.
    /// </summary>
    public class InvalidModelValidatorProvider : AssociatedValidatorProvider
    {
        protected override IEnumerable<ModelValidator> GetValidators(ModelMetadata metadata, IEnumerable<ModelValidatorProvider> validatorProviders, IEnumerable<Attribute> attributes)
        {
            if (metadata.ContainerType == null || String.IsNullOrEmpty(metadata.PropertyName))
            {
                // Validate that the type's fields and nonpublic properties don't have any validation attributes on them
                // Validation only runs against public properties
                Type type = metadata.ModelType;
                PropertyInfo[] nonPublicProperties = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Instance);
                foreach (PropertyInfo nonPublicProperty in nonPublicProperties)
                {
                    if (nonPublicProperty.GetCustomAttributes(typeof(ValidationAttribute), inherit: true).Length > 0)
                    {
                        yield return new ErrorModelValidator(validatorProviders, Error.Format(SRResources.ValidationAttributeOnNonPublicProperty, nonPublicProperty.Name, type));
                    }
                }

                FieldInfo[] allFields = metadata.ModelType.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
                foreach (FieldInfo field in allFields)
                {
                    if (field.GetCustomAttributes(typeof(ValidationAttribute), inherit: true).Length > 0)
                    {
                        yield return new ErrorModelValidator(validatorProviders, Error.Format(SRResources.ValidationAttributeOnField, field.Name, type));
                    }
                }
            }
            else
            {
                // Validate that value-typed properties marked as [Required] are also marked as [DataMember(IsRequired=true)]
                // Certain formatters may not recognize a member as required if it's marked as [Required] but not [DataMember(IsRequired=true)]
                // This is not a problem for reference types because [Required] will still cause a model error to be raised after a null value is deserialized
                if (metadata.ModelType.IsValueType && attributes.Any(attribute => attribute is RequiredAttribute))
                {
                    if (!DataMemberModelValidatorProvider.IsRequiredDataMember(metadata.ContainerType, attributes))
                    {
                        yield return new ErrorModelValidator(validatorProviders, Error.Format(SRResources.MissingDataMemberIsRequired, metadata.PropertyName, metadata.ContainerType));
                    }
                }
            }
        }
    }
}