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

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

namespace System.Web.Mvc
{
    public sealed class GlobalFilterCollection : IEnumerable<Filter>, IFilterProvider
    {
        private List<Filter> _filters = new List<Filter>();

        public int Count
        {
            get { return _filters.Count; }
        }

        public void Add(object filter)
        {
            AddInternal(filter, order: null);
        }

        public void Add(object filter, int order)
        {
            AddInternal(filter, order);
        }

        private void AddInternal(object filter, int? order)
        {
            ValidateFilterInstance(filter);
            _filters.Add(new Filter(filter, FilterScope.Global, order));
        }

        public void Clear()
        {
            _filters.Clear();
        }

        public bool Contains(object filter)
        {
            return _filters.Any(f => f.Instance == filter);
        }

        public IEnumerator<Filter> GetEnumerator()
        {
            return _filters.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return _filters.GetEnumerator();
        }

        IEnumerable<Filter> IFilterProvider.GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
        {
            return this;
        }

        public void Remove(object filter)
        {
            _filters.RemoveAll(f => f.Instance == filter);
        }

        private static void ValidateFilterInstance(object instance)
        {
            if (instance != null &&
                !(instance is IActionFilter || instance is IAuthorizationFilter || instance is IExceptionFilter || instance is IResultFilter))
            {
                throw new InvalidOperationException(Properties.MvcResources.GlobalFilterCollection_UnsupportedFilterInstance);
            }
        }
    }
}
