namespace System.Web.Mvc {
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Diagnostics.CodeAnalysis;
    using System.Globalization;
    using System.Linq;
    using System.Reflection;
    using System.Web.Mvc.Resources;

    public abstract class ActionDescriptor : ICustomAttributeProvider, IUniquelyIdentifiable {

        private readonly static ActionMethodDispatcherCache _staticDispatcherCache = new ActionMethodDispatcherCache();
        private ActionMethodDispatcherCache _instanceDispatcherCache;
        private readonly Lazy<string> _uniqueId;

        private static readonly ActionSelector[] _emptySelectors = new ActionSelector[0];

        protected ActionDescriptor() {
            _uniqueId = new Lazy<string>(CreateUniqueId);
        }

        public abstract string ActionName {
            get;
        }

        public abstract ControllerDescriptor ControllerDescriptor {
            get;
        }

        internal ActionMethodDispatcherCache DispatcherCache {
            get {
                if (_instanceDispatcherCache == null) {
                    _instanceDispatcherCache = _staticDispatcherCache;
                }
                return _instanceDispatcherCache;
            }
            set {
                _instanceDispatcherCache = value;
            }
        }

        [SuppressMessage("Microsoft.Security", "CA2119:SealMethodsThatSatisfyPrivateInterfaces", Justification = "This is overridden elsewhere in System.Web.Mvc")]
        public virtual string UniqueId {
            get {
                return _uniqueId.Value;
            }
        }

        private string CreateUniqueId() {
            return DescriptorUtil.CreateUniqueId(GetType(), ControllerDescriptor, ActionName);
        }

        public abstract object Execute(ControllerContext controllerContext, IDictionary<string, object> parameters);

        internal static object ExtractParameterFromDictionary(ParameterInfo parameterInfo, IDictionary<string, object> parameters, MethodInfo methodInfo) {
            object value;

            if (!parameters.TryGetValue(parameterInfo.Name, out value)) {
                // the key should always be present, even if the parameter value is null
                string message = String.Format(CultureInfo.CurrentCulture, MvcResources.ReflectedActionDescriptor_ParameterNotInDictionary,
                    parameterInfo.Name, parameterInfo.ParameterType, methodInfo, methodInfo.DeclaringType);
                throw new ArgumentException(message, "parameters");
            }

            if (value == null && !TypeHelpers.TypeAllowsNullValue(parameterInfo.ParameterType)) {
                // tried to pass a null value for a non-nullable parameter type
                string message = String.Format(CultureInfo.CurrentCulture, MvcResources.ReflectedActionDescriptor_ParameterCannotBeNull,
                    parameterInfo.Name, parameterInfo.ParameterType, methodInfo, methodInfo.DeclaringType);
                throw new ArgumentException(message, "parameters");
            }

            if (value != null && !parameterInfo.ParameterType.IsInstanceOfType(value)) {
                // value was supplied but is not of the proper type
                string message = String.Format(CultureInfo.CurrentCulture, MvcResources.ReflectedActionDescriptor_ParameterValueHasWrongType,
                    parameterInfo.Name, methodInfo, methodInfo.DeclaringType, value.GetType(), parameterInfo.ParameterType);
                throw new ArgumentException(message, "parameters");
            }

            return value;
        }

        internal static object ExtractParameterOrDefaultFromDictionary(ParameterInfo parameterInfo, IDictionary<string, object> parameters) {
            Type parameterType = parameterInfo.ParameterType;

            object value;
            parameters.TryGetValue(parameterInfo.Name, out value);

            // if wrong type, replace with default instance
            if (parameterType.IsInstanceOfType(value)) {
                return value;
            }
            else {
                object defaultValue;
                if (ParameterInfoUtil.TryGetDefaultValue(parameterInfo, out defaultValue)) {
                    return defaultValue;
                }
                else {
                    return TypeHelpers.GetDefaultValue(parameterType);
                }
            }
        }

        public virtual object[] GetCustomAttributes(bool inherit) {
            return GetCustomAttributes(typeof(object), inherit);
        }

        public virtual object[] GetCustomAttributes(Type attributeType, bool inherit) {
            if (attributeType == null) {
                throw new ArgumentNullException("attributeType");
            }

            return (object[])Array.CreateInstance(attributeType, 0);
        }

        internal virtual IEnumerable<FilterAttribute> GetFilterAttributes(bool useCache) {
            return GetCustomAttributes(typeof(FilterAttribute), inherit: true).Cast<FilterAttribute>();
        }

        [EditorBrowsable(EditorBrowsableState.Never)]
        [Obsolete("Please call System.Web.Mvc.FilterProviders.Providers.GetFilters() now.", true)]
        public virtual FilterInfo GetFilters() {
            return new FilterInfo();
        }

        public abstract ParameterDescriptor[] GetParameters();

        [SuppressMessage("Microsoft.Design", "CA1024:UsePropertiesWhereAppropriate", Justification = "This method may perform non-trivial work.")]
        public virtual ICollection<ActionSelector> GetSelectors() {
            return _emptySelectors;
        }

        public virtual bool IsDefined(Type attributeType, bool inherit) {
            if (attributeType == null) {
                throw new ArgumentNullException("attributeType");
            }

            return false;
        }

        internal static string VerifyActionMethodIsCallable(MethodInfo methodInfo) {
            // we can't call static methods
            if (methodInfo.IsStatic) {
                return String.Format(CultureInfo.CurrentCulture,
                                     MvcResources.ReflectedActionDescriptor_CannotCallStaticMethod,
                                     methodInfo,
                                     methodInfo.ReflectedType.FullName);
            }

            // we can't call instance methods where the 'this' parameter is a type other than ControllerBase
            if (!typeof(ControllerBase).IsAssignableFrom(methodInfo.ReflectedType)) {
                return String.Format(CultureInfo.CurrentCulture, MvcResources.ReflectedActionDescriptor_CannotCallInstanceMethodOnNonControllerType,
                    methodInfo, methodInfo.ReflectedType.FullName);
            }

            // we can't call methods with open generic type parameters
            if (methodInfo.ContainsGenericParameters) {
                return String.Format(CultureInfo.CurrentCulture, MvcResources.ReflectedActionDescriptor_CannotCallOpenGenericMethods,
                    methodInfo, methodInfo.ReflectedType.FullName);
            }

            // we can't call methods with ref/out parameters
            ParameterInfo[] parameterInfos = methodInfo.GetParameters();
            foreach (ParameterInfo parameterInfo in parameterInfos) {
                if (parameterInfo.IsOut || parameterInfo.ParameterType.IsByRef) {
                    return String.Format(CultureInfo.CurrentCulture, MvcResources.ReflectedActionDescriptor_CannotCallMethodsWithOutOrRefParameters,
                        methodInfo, methodInfo.ReflectedType.FullName, parameterInfo);
                }
            }

            // we can call this method
            return null;
        }
    }
}