Ombi/Ombi.UI/Helpers/ContravariantBindingResolver.cs

#region Copyright
// /************************************************************************
//    Copyright (c) 2016 Jamie Rees
//    File: ContravariantBindingResolver.cs
//    Created By: Jamie Rees
//   
//    Permission is hereby granted, free of charge, to any person obtaining
//    a copy of this software and associated documentation files (the
//    "Software"), to deal in the Software without restriction, including
//    without limitation the rights to use, copy, modify, merge, publish,
//    distribute, sublicense, and/or sell copies of the Software, and to
//    permit persons to whom the Software is furnished to do so, subject to
//    the following conditions:
//   
//    The above copyright notice and this permission notice shall be
//    included in all copies or substantial portions of the Software.
//   
//    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
//    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
//    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
//    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
//    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
//    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//  ************************************************************************/
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Ninject.Components;
using Ninject.Infrastructure;
using Ninject.Planning.Bindings;
using Ninject.Planning.Bindings.Resolvers;

namespace Ombi.UI.Helpers
{
    public class ContravariantBindingResolver : NinjectComponent, IBindingResolver
    {
        /// <summary>
        /// Returns any bindings from the specified collection that match the specified service.
        /// </summary>
        public IEnumerable<IBinding> Resolve(Multimap<Type, IBinding> bindings, Type service)
        {
            if (service.IsGenericType)
            {
                var genericType = service.GetGenericTypeDefinition();
                var genericArguments = genericType.GetGenericArguments();
                if (!genericArguments.Any())
                {
                    return Enumerable.Empty<IBinding>();
                }
                if (genericArguments.Length == 1 && genericArguments.Single().GenericParameterAttributes.HasFlag(GenericParameterAttributes.Contravariant))
                {
                    var argument = service.GetGenericArguments().FirstOrDefault();
                    if (argument == null)
                    {
                        return Enumerable.Empty<IBinding>();
                    }

                    var matches =
                        bindings.Where(
                            kvp =>
                            {
                                var assignableFrom = kvp.Key.GetGenericArguments().FirstOrDefault();
                                
                                return kvp.Key.IsGenericType && kvp.Key.GetGenericTypeDefinition() == genericType &&
                                       kvp.Key.GetGenericArguments().FirstOrDefault() != argument
                                       && assignableFrom.IsAssignableFrom(argument);


                            }).SelectMany(kvp => kvp.Value); 
                    return matches;
                }
            }

            return Enumerable.Empty<IBinding>();
        }
    }
}