HttpContextExtentions

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Caching;
using System.Web.Mvc;

namespace Core.Web {

    public static class HttpContextExtentions {

        public static T GetOrAdd<T>(this HttpContext context,object key,Func<T> notFoundFunc = null) {

            if(key == null)
                throw new ArgumentNullException("object key");

            T result = (T)context.Items[key];

            if(result == null) {
                if(notFoundFunc != null) {
                    result = notFoundFunc();
                    context.Items.Add(key,result);
                    return result;
                }
                return default(T);
            }
            return result;
        }
    }
    public static class HtmlHelperExtentions {
        public static IDictionary<string,object> GetClassAttribute(this HtmlHelper html,string className,IDictionary<string,object> additionalAttributes = null) {

            IDictionary<string,object> dict = null;
            if(additionalAttributes != null)
                dict = new Dictionary<string,object>(additionalAttributes);
            else
                dict = new Dictionary<string,object>();

            object previousClassName = null;
            if(dict.TryGetValue("class",out previousClassName)) {
                dict["class"] = previousClassName.ToStringEmpty() + " " + className;
            }
            else {
                dict.Add("class",className);
            }

            return dict;
        }
        public static MvcHtmlString WrapEmailAnchor(this HtmlHelper html,string innerHtml,string nameAndId = null,string title = null) {
            TagBuilder anchor = new TagBuilder("a");
            anchor.GenerateId(nameAndId);
            anchor.MergeAttribute("href","mailto:{0}".FormatString(innerHtml));
            anchor.MergeAttribute("title",title);
            anchor.InnerHtml = innerHtml;
            return MvcHtmlString.Create(anchor.ToString());
        }
    }
}