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

using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Web.Mvc.Async;
using System.Web.Mvc.Properties;
using System.Web.Routing;
using System.Web.WebPages.Scope;

namespace System.Web.Mvc
{
    public abstract class ControllerBase : IController
    {
        private readonly SingleEntryGate _executeWasCalledGate = new SingleEntryGate();

        private DynamicViewDataDictionary _dynamicViewDataDictionary;
        private TempDataDictionary _tempDataDictionary;
        private bool _validateRequest = true;
        private IValueProvider _valueProvider;
        private ViewDataDictionary _viewDataDictionary;

        public ControllerContext ControllerContext { get; set; }

        [SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "This property is settable so that unit tests can provide mock implementations.")]
        public TempDataDictionary TempData
        {
            get
            {
                if (ControllerContext != null && ControllerContext.IsChildAction)
                {
                    return ControllerContext.ParentActionViewContext.TempData;
                }
                if (_tempDataDictionary == null)
                {
                    _tempDataDictionary = new TempDataDictionary();
                }
                return _tempDataDictionary;
            }
            set { _tempDataDictionary = value; }
        }

        public bool ValidateRequest
        {
            get { return _validateRequest; }
            set { _validateRequest = value; }
        }

        public IValueProvider ValueProvider
        {
            get
            {
                if (_valueProvider == null)
                {
                    _valueProvider = ValueProviderFactories.Factories.GetValueProvider(ControllerContext);
                }
                return _valueProvider;
            }
            set { _valueProvider = value; }
        }

        public dynamic ViewBag
        {
            get
            {
                if (_dynamicViewDataDictionary == null)
                {
                    _dynamicViewDataDictionary = new DynamicViewDataDictionary(() => ViewData);
                }
                return _dynamicViewDataDictionary;
            }
        }

        [SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "This property is settable so that unit tests can provide mock implementations.")]
        public ViewDataDictionary ViewData
        {
            get
            {
                if (_viewDataDictionary == null)
                {
                    _viewDataDictionary = new ViewDataDictionary();
                }
                return _viewDataDictionary;
            }
            set { _viewDataDictionary = value; }
        }

        protected virtual void Execute(RequestContext requestContext)
        {
            if (requestContext == null)
            {
                throw new ArgumentNullException("requestContext");
            }
            if (requestContext.HttpContext == null)
            {
                throw new ArgumentException(MvcResources.ControllerBase_CannotExecuteWithNullHttpContext, "requestContext");
            }

            VerifyExecuteCalledOnce();
            Initialize(requestContext);

            using (ScopeStorage.CreateTransientScope())
            {
                ExecuteCore();
            }
        }

        protected abstract void ExecuteCore();

        protected virtual void Initialize(RequestContext requestContext)
        {
            ControllerContext = new ControllerContext(requestContext, this);
        }

        internal void VerifyExecuteCalledOnce()
        {
            if (!_executeWasCalledGate.TryEnter())
            {
                string message = String.Format(CultureInfo.CurrentCulture, MvcResources.ControllerBase_CannotHandleMultipleRequests, GetType());
                throw new InvalidOperationException(message);
            }
        }

        #region IController Members

        void IController.Execute(RequestContext requestContext)
        {
            Execute(requestContext);
        }

        #endregion
    }
}
