// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Security.Principal;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNet.Http;
using Microsoft.AspNet.Mvc.Core;
using Microsoft.AspNet.Mvc.ModelBinding;
using Microsoft.AspNet.Mvc.Rendering;

namespace Microsoft.AspNet.Mvc
{
    public class Controller : IActionFilter, IAsyncActionFilter
    {
        private DynamicViewData _viewBag;

        public HttpContext Context
        {
            get
            {
                if (ActionContext == null)
                {
                    return null;
                }

                return ActionContext.HttpContext;
            }
        }

        public ModelStateDictionary ModelState
        {
            get
            {
                if (ViewData == null)
                {
                    return null;
                }

                return ViewData.ModelState;
            }
        }

        [Activate]
        public ActionContext ActionContext { get; set; }

        [Activate]
        public IUrlHelper Url { get; set; }

        [Activate]
        public IActionBindingContextProvider BindingContextProvider { get; set; }

        public IPrincipal User
        {
            get
            {
                if (Context == null)
                {
                    return null;
                }

                return Context.User;
            }
        }

        [Activate]
        public ViewDataDictionary ViewData { get; set; }

        public dynamic ViewBag
        {
            get
            {
                if (_viewBag == null)
                {
                    _viewBag = new DynamicViewData(() => ViewData);
                }

                return _viewBag;
            }
        }

        /// <summary>
        /// Creates a <see cref="ViewResult"/> object that renders a view to the response.
        /// </summary>
        /// <returns>The created <see cref="ViewResult"/> object for the response.</returns>
        [NonAction]
        public virtual ViewResult View()
        {
            return View(viewName: null);
        }

        /// <summary>
        /// Creates a <see cref="ViewResult"/> object by specifying a <paramref name="viewName"/>.
        /// </summary>
        /// <param name="viewName">The name of the view that is rendered to the response.</param>
        /// <returns>The created <see cref="ViewResult"/> object for the response.</returns>
        [NonAction]
        public virtual ViewResult View(string viewName)
        {
            return View(viewName, model: null);
        }

        /// <summary>
        /// Creates a <see cref="ViewResult"/> object by specifying a <paramref name="model"/>
        /// to be rendered by the view.
        /// </summary>
        /// <param name="model">The model that is rendered by the view.</param>
        /// <returns>The created <see cref="ViewResult"/> object for the response.</returns>
        [NonAction]
        public virtual ViewResult View(object model)
        {
            return View(viewName: null, model: model);
        }

        /// <summary>
        /// Creates a <see cref="ViewResult"/> object by specifying a <paramref name="viewName"/>
        /// and the <paramref name="model"/> to be rendered by the view.
        /// </summary>
        /// <param name="viewName">The name of the view that is rendered to the response.</param>
        /// <param name="model">The model that is rendered by the view.</param>
        /// <returns>The created <see cref="ViewResult"/> object for the response.</returns>
        [NonAction]
        public virtual ViewResult View(string viewName, object model)
        {
            // Do not override ViewData.Model unless passed a non-null value.
            if (model != null)
            {
                ViewData.Model = model;
            }

            return new ViewResult()
            {
                ViewName = viewName,
                ViewData = ViewData,
            };
        }

        /// <summary>
        /// Creates a <see cref="ContentResult"/> object by specifying a <paramref name="content"/> string.
        /// </summary>
        /// <param name="content">The content to write to the response.</param>
        /// <returns>The created <see cref="ContentResult"/> object for the response.</returns>
        [NonAction]
        public virtual ContentResult Content(string content)
        {
            return Content(content, contentType: null);
        }

        /// <summary>
        /// Creates a <see cref="ContentResult"/> object by specifying a <paramref name="content"/> string
        /// and a content type.
        /// </summary>
        /// <param name="content">The content to write to the response.</param>
        /// <param name="contentType">The content type (MIME type).</param>
        /// <returns>The created <see cref="ContentResult"/> object for the response.</returns>
        [NonAction]
        public virtual ContentResult Content(string content, string contentType)
        {
            return Content(content, contentType, contentEncoding: null);
        }

        /// <summary>
        /// Creates a <see cref="ContentResult"/> object by specifying a <paramref name="content"/> string,
        /// a <paramref name="contentType"/>, and <paramref name="contentEncoding"/>.
        /// </summary>
        /// <param name="content">The content to write to the response.</param>
        /// <param name="contentType">The content type (MIME type).</param>
        /// <param name="contentEncoding">The content encoding.</param>
        /// <returns>The created <see cref="ContentResult"/> object for the response.</returns>
        [NonAction]
        public virtual ContentResult Content(string content, string contentType, Encoding contentEncoding)
        {
            var result = new ContentResult
            {
                Content = content,
            };

            if (contentType != null)
            {
                result.ContentType = contentType;
            }

            if (contentEncoding != null)
            {
                result.ContentEncoding = contentEncoding;
            }

            return result;
        }

        /// <summary>
        /// Creates a <see cref="JsonResult"/> object that serializes the specified <paramref name="data"/> object
        /// to JSON.
        /// </summary>
        /// <param name="data">The object to serialize.</param>
        /// <returns>The created <see cref="JsonResult"/> that serializes the specified <paramref name="data"/>
        /// to JSON format for the response.</returns>
        [NonAction]
        public virtual JsonResult Json(object data)
        {
            return new JsonResult(data);
        }

        /// <summary>
        /// Creates a <see cref="RedirectResult"/> object that redirects to the specified <paramref name="url"/>.
        /// </summary>
        /// <param name="url">The URL to redirect to.</param>
        /// <returns>The created <see cref="RedirectResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectResult Redirect(string url)
        {
            if (string.IsNullOrEmpty(url))
            {
                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, "url");
            }

            return new RedirectResult(url);
        }

        /// <summary>
        /// Creates a <see cref="RedirectResult"/> object with <see cref="RedirectResult.Permanent"/> set to true
        /// using the specified <paramref name="url"/>.
        /// </summary>
        /// <param name="url">The URL to redirect to.</param>
        /// <returns>The created <see cref="RedirectResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectResult RedirectPermanent(string url)
        {
            if (string.IsNullOrEmpty(url))
            {
                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, "url");
            }

            return new RedirectResult(url, permanent: true);
        }

        /// <summary>
        /// Redirects to the specified action using the <paramref name="actionName"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToAction(string actionName)
        {
            return RedirectToAction(actionName, routeValues: null);
        }

        /// <summary>
        /// Redirects to the specified action using the <paramref name="actionName"/>
        /// and <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToAction(string actionName, object routeValues)
        {
            return RedirectToAction(actionName, controllerName: null, routeValues: routeValues);
        }

        /// <summary>
        /// Redirects to the specified action using the <paramref name="actionName"/>
        /// and the <paramref name="controllerName"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <param name="controllerName">The name of the controller.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToAction(string actionName, string controllerName)
        {
            return RedirectToAction(actionName, controllerName, routeValues: null);
        }

        /// <summary>
        /// Redirects to the specified action using the specified <paramref name="actionName"/>,
        /// <paramref name="controllerName"/>, and <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <param name="controllerName">The name of the controller.</param>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToAction(string actionName, string controllerName,
                                        object routeValues)
        {
            return new RedirectToActionResult(Url, actionName, controllerName,
                                                TypeHelper.ObjectToDictionary(routeValues));
        }

        /// <summary>
        /// Redirects to the specified action with <see cref="RedirectToActionResult.Permanent"/> set to true
        /// using the specified <paramref name="actionName"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToActionPermanent(string actionName)
        {
            return RedirectToActionPermanent(actionName, routeValues: null);
        }

        /// <summary>
        /// Redirects to the specified action with <see cref="RedirectToActionResult.Permanent"/> set to true
        /// using the specified <paramref name="actionName"/> and <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToActionPermanent(string actionName, object routeValues)
        {
            return RedirectToActionPermanent(actionName, controllerName: null, routeValues: routeValues);
        }

        /// <summary>
        /// Redirects to the specified action with <see cref="RedirectToActionResult.Permanent"/> set to true
        /// using the specified <paramref name="actionName"/> and <paramref name="controllerName"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <param name="controllerName">The name of the controller.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToActionPermanent(string actionName, string controllerName)
        {
            return RedirectToActionPermanent(actionName, controllerName, routeValues: null);
        }

        /// <summary>
        /// Redirects to the specified action with <see cref="RedirectToActionResult.Permanent"/> set to true
        /// using the specified <paramref name="actionName"/>, <paramref name="controllerName"/>,
        /// and <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="actionName">The name of the action.</param>
        /// <param name="controllerName">The name of the controller.</param>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToActionResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToActionResult RedirectToActionPermanent(string actionName, string controllerName,
                                        object routeValues)
        {
            return new RedirectToActionResult(Url, actionName, controllerName,
                                                TypeHelper.ObjectToDictionary(routeValues), permanent: true);
        }

        /// <summary>
        /// Redirects to the specified route using the specified <paramref name="routeName"/>.
        /// </summary>
        /// <param name="routeName">The name of the route.</param>
        /// <returns>The created <see cref="RedirectToRouteResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToRouteResult RedirectToRoute(string routeName)
        {
            return RedirectToRoute(routeName, routeValues: null);
        }

        /// <summary>
        /// Redirects to the specified route using the specified <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToRouteResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToRouteResult RedirectToRoute(object routeValues)
        {
            return RedirectToRoute(routeName: null, routeValues: routeValues);
        }

        /// <summary>
        /// Redirects to the specified route using the specified <paramref name="routeName"/>
        /// and <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="routeName">The name of the route.</param>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToRouteResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToRouteResult RedirectToRoute(string routeName, object routeValues)
        {
            return new RedirectToRouteResult(Url, routeName, routeValues);
        }

        /// <summary>
        /// Redirects to the specified route with <see cref="RedirectToRouteResult.Permanent"/> set to true
        /// using the specified <paramref name="routeName"/>.
        /// </summary>
        /// <param name="routeName">The name of the route.</param>
        /// <returns>The created <see cref="RedirectToRouteResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToRouteResult RedirectToRoutePermanent(string routeName)
        {
            return RedirectToRoutePermanent(routeName, routeValues: null);
        }

        /// <summary>
        /// Redirects to the specified route with <see cref="RedirectToRouteResult.Permanent"/> set to true
        /// using the specified <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToRouteResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToRouteResult RedirectToRoutePermanent(object routeValues)
        {
            return RedirectToRoutePermanent(routeName: null, routeValues: routeValues);
        }

        /// <summary>
        /// Redirects to the specified route with <see cref="RedirectToRouteResult.Permanent"/> set to true
        /// using the specified <paramref name="routeName"/> and <paramref name="routeValues"/>.
        /// </summary>
        /// <param name="routeName">The name of the route.</param>
        /// <param name="routeValues">The parameters for a route.</param>
        /// <returns>The created <see cref="RedirectToRouteResult"/> for the response.</returns>
        [NonAction]
        public virtual RedirectToRouteResult RedirectToRoutePermanent(string routeName, object routeValues)
        {
            return new RedirectToRouteResult(Url, routeName, routeValues, permanent: true);
        }

        /// <summary>
        /// Creates an <see cref="HttpNotFoundResult"/> that produces a Not Found (404) response.
        /// </summary>
        /// <returns>The created <see cref="HttpNotFoundResult"/> for the response.</returns>
        [NonAction]
        public virtual HttpNotFoundResult HttpNotFound()
        {
            return new HttpNotFoundResult();
        }

        /// <summary>
        /// Called before the action method is invoked.
        /// </summary>
        /// <param name="context">The action executing context.</param>
        [NonAction]
        public virtual void OnActionExecuting([NotNull] ActionExecutingContext context)
        {
        }

        /// <summary>
        /// Called after the action method is invoked.
        /// </summary>
        /// <param name="context">The action executed context.</param>
        [NonAction]
        public virtual void OnActionExecuted([NotNull] ActionExecutedContext context)
        {
        }

        /// <summary>
        /// Called before the action method is invoked.
        /// </summary>
        /// <param name="context">The action executing context.</param>
        /// <param name="next">The <see cref="ActionExecutionDelegate"/> to execute. Invoke this delegate in the body
        /// of <see cref="OnActionExecutionAsync" /> to continue execution of the action.</param>
        /// <returns>A <see cref="Task"/> instance.</returns>
        [NonAction]
        public virtual async Task OnActionExecutionAsync(
            [NotNull] ActionExecutingContext context,
            [NotNull] ActionExecutionDelegate next)
        {
            OnActionExecuting(context);
            if (context.Result == null)
            {
                OnActionExecuted(await next());
            }
        }

        /// <summary>
        /// Updates the specified model instance using values from the controller's current value provider.
        /// </summary>
        /// <typeparam name="TModel">The type of the model object.</typeparam>
        /// <param name="model">The model instance to update.</param>
        /// <returns>true if the update is successful; otherwise, false.</returns>
        [NonAction]
        public virtual Task<bool> TryUpdateModelAsync<TModel>([NotNull] TModel model)
            where TModel : class
        {
            return TryUpdateModelAsync(model, prefix: typeof(TModel).Name);
        }

        /// <summary>
        /// Updates the specified model instance using values from the controller's current value provider
        /// and a prefix.
        /// </summary>
        /// <typeparam name="TModel">The type of the model object.</typeparam>
        /// <param name="model">The model instance to update.</param>
        /// <param name="prefix">The prefix to use when looking up values in the value provider.</param>
        /// <returns>true if the update is successful; otherwise, false.</returns>
        [NonAction]
        public virtual async Task<bool> TryUpdateModelAsync<TModel>([NotNull] TModel model,
                                                                    [NotNull] string prefix)
            where TModel : class
        {
            if (BindingContextProvider == null)
            {
                var message = Resources.FormatPropertyOfTypeCannotBeNull("BindingContextProvider", GetType().FullName);
                throw new InvalidOperationException(message);
            }

            var bindingContext = await BindingContextProvider.GetActionBindingContextAsync(ActionContext);
            return await TryUpdateModelAsync(model, prefix, bindingContext.ValueProvider);
        }

        /// <summary>
        /// Updates the specified model instance using the value provider and a prefix.
        /// </summary>
        /// <typeparam name="TModel">The type of the model object.</typeparam>
        /// <param name="model">The model instance to update.</param>
        /// <param name="prefix">The prefix to use when looking up values in the value provider.</param>
        /// <param name="valueProvider">The value provider used for looking up values.</param>
        /// <returns>true if the update is successful; otherwise, false.</returns>
        [NonAction]
        public virtual async Task<bool> TryUpdateModelAsync<TModel>([NotNull] TModel model,
                                                                    [NotNull] string prefix,
                                                                    [NotNull] IValueProvider valueProvider)
            where TModel : class
        {
            if (BindingContextProvider == null)
            {
                var message = Resources.FormatPropertyOfTypeCannotBeNull("BindingContextProvider", GetType().FullName);
                throw new InvalidOperationException(message);
            }

            var bindingContext = await BindingContextProvider.GetActionBindingContextAsync(ActionContext);
            return await ModelBindingHelper.TryUpdateModelAsync(model,
                                                                prefix,
                                                                ActionContext.HttpContext,
                                                                ModelState,
                                                                bindingContext.MetadataProvider,
                                                                bindingContext.ModelBinder,
                                                                valueProvider,
                                                                bindingContext.ValidatorProviders);
        }
    }
}