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

using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web.Mvc.Properties;

namespace System.Web.Mvc
{
    public class ReflectedControllerDescriptor : ControllerDescriptor
    {
        private readonly Type _controllerType;
        private readonly ActionMethodSelector _selector;
        private ActionDescriptor[] _canonicalActionsCache;

        public ReflectedControllerDescriptor(Type controllerType)
        {
            if (controllerType == null)
            {
                throw new ArgumentNullException("controllerType");
            }

            _controllerType = controllerType;
            _selector = new ActionMethodSelector(_controllerType);
        }

        public sealed override Type ControllerType
        {
            get { return _controllerType; }
        }

        public override ActionDescriptor FindAction(ControllerContext controllerContext, string actionName)
        {
            if (controllerContext == null)
            {
                throw new ArgumentNullException("controllerContext");
            }
            if (String.IsNullOrEmpty(actionName))
            {
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "actionName");
            }

            MethodInfo matched = _selector.FindActionMethod(controllerContext, actionName);
            if (matched == null)
            {
                return null;
            }

            return new ReflectedActionDescriptor(matched, actionName, this);
        }

        private MethodInfo[] GetAllActionMethodsFromSelector()
        {
            List<MethodInfo> allValidMethods = new List<MethodInfo>();
            allValidMethods.AddRange(_selector.AliasedMethods);
            allValidMethods.AddRange(_selector.NonAliasedMethods.SelectMany(g => g));
            return allValidMethods.ToArray();
        }

        public override ActionDescriptor[] GetCanonicalActions()
        {
            ActionDescriptor[] actions = LazilyFetchCanonicalActionsCollection();

            // need to clone array so that user modifications aren't accidentally stored
            return (ActionDescriptor[])actions.Clone();
        }

        public override object[] GetCustomAttributes(bool inherit)
        {
            return ControllerType.GetCustomAttributes(inherit);
        }

        public override object[] GetCustomAttributes(Type attributeType, bool inherit)
        {
            return ControllerType.GetCustomAttributes(attributeType, inherit);
        }

        public override IEnumerable<FilterAttribute> GetFilterAttributes(bool useCache)
        {
            if (useCache && GetType() == typeof(ReflectedControllerDescriptor))
            {
                // Do not look at cache in types derived from this type because they might incorrectly implement GetCustomAttributes
                return ReflectedAttributeCache.GetTypeFilterAttributes(ControllerType);
            }
            return base.GetFilterAttributes(useCache);
        }

        public override bool IsDefined(Type attributeType, bool inherit)
        {
            return ControllerType.IsDefined(attributeType, inherit);
        }

        private ActionDescriptor[] LazilyFetchCanonicalActionsCollection()
        {
            return DescriptorUtil.LazilyFetchOrCreateDescriptors<MethodInfo, ActionDescriptor>(
                ref _canonicalActionsCache /* cacheLocation */,
                GetAllActionMethodsFromSelector /* initializer */,
                methodInfo => ReflectedActionDescriptor.TryCreateDescriptor(methodInfo, methodInfo.Name, this) /* converter */);
        }
    }
}
