// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.

using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;

namespace System.Web.Mvc
{
    public class ModelValidatorProviderCollection : Collection<ModelValidatorProvider>
    {
        private IResolver<IEnumerable<ModelValidatorProvider>> _serviceResolver;

        public ModelValidatorProviderCollection()
        {
            _serviceResolver = new MultiServiceResolver<ModelValidatorProvider>(() => Items);
        }

        public ModelValidatorProviderCollection(IList<ModelValidatorProvider> list)
            : base(list)
        {
            _serviceResolver = new MultiServiceResolver<ModelValidatorProvider>(() => Items);
        }

        internal ModelValidatorProviderCollection(IResolver<IEnumerable<ModelValidatorProvider>> serviceResolver, params ModelValidatorProvider[] validatorProvidors)
            : base(validatorProvidors)
        {
            _serviceResolver = serviceResolver ?? new MultiServiceResolver<ModelValidatorProvider>(() => Items);
        }

        private IEnumerable<ModelValidatorProvider> CombinedItems
        {
            get { return _serviceResolver.Current; }
        }

        protected override void InsertItem(int index, ModelValidatorProvider item)
        {
            if (item == null)
            {
                throw new ArgumentNullException("item");
            }
            base.InsertItem(index, item);
        }

        protected override void SetItem(int index, ModelValidatorProvider item)
        {
            if (item == null)
            {
                throw new ArgumentNullException("item");
            }
            base.SetItem(index, item);
        }

        public IEnumerable<ModelValidator> GetValidators(ModelMetadata metadata, ControllerContext context)
        {
            return CombinedItems.SelectMany(provider => provider.GetValidators(metadata, context));
        }
    }
}
