HtmlHelpers.cs

using System.Text;
using System.Web.Mvc;
using System.Web;
using Umbraco.Core.Models;
using Umbraco.Core.Security;

namespace BackOfficeExtensions
{
    public enum EditLinkPosition
    {
        TopLeft = 0,
        TopRight = 1,
        BottomRight = 2,
        BottomLeft = 3
    }

    public static class HtmlHelpers
    {
        public static IHtmlString UmbracoEditLink(this HtmlHelper helper, IPublishedContent thisPage,
            EditLinkPosition position = EditLinkPosition.TopLeft, string linkColour = "#00aea2", string editMessage = "Edit",
            int margin = 10, int zindex = 999, string umbracoEditContentUrl = "/umbraco#/content/content/edit/", 
            int fontSize = 16, string outerPosition = "fixed", string linkPosition = "absolute",
            string outerClassName = "edit-link-outer", string linkClassName = "edit-link-inner")
        {
            StringBuilder editLinkCode = new StringBuilder();
            var userTicket = new HttpContextWrapper(HttpContext.Current).GetUmbracoAuthTicket();

            if (userTicket != null)
            {
                string outerStyles = "display:block;";
                if (outerPosition == "fixed")
                {
                    switch (position)
                    {
                        case EditLinkPosition.TopLeft:
                            outerStyles += $"top:{margin}px;";
                            outerStyles += $"left:{margin}px;";
                            break;
                        case EditLinkPosition.TopRight:
                            outerStyles += $"top:{margin}px;";
                            outerStyles += $"right:{margin}px;";
                            break;
                        case EditLinkPosition.BottomRight:
                            outerStyles += $"bottom:{margin}px;";
                            outerStyles += $"right:{margin}px;";
                            break;
                        case EditLinkPosition.BottomLeft:
                            outerStyles += $"bottom:{margin}px;";
                            outerStyles += $"left:{margin}px;";
                            break;
                    }
                }

                outerStyles += $"z-index:{zindex};";
                outerStyles += $"position:{outerPosition};";

                editLinkCode.Append($"<div");
                editLinkCode.Append($" class=\"{outerClassName}\"");
                if (!string.IsNullOrEmpty(outerStyles))
                {
                    editLinkCode.Append($" style=\"{outerStyles}\"");
                }
                editLinkCode.Append($">");

                string linkStyles = $"color:{linkColour};";
                linkStyles += $"font-size:{fontSize}px;";

                editLinkCode.Append($"<a ");
                editLinkCode.Append($" class=\"{linkClassName}\"");
                if (!string.IsNullOrEmpty(linkStyles))
                {
                    editLinkCode.Append($"style={linkStyles}");
                }

                editLinkCode.Append($" target=\"_blank\"");
                editLinkCode.Append($" href =\"{umbracoEditContentUrl}{thisPage.Id}\"");
                editLinkCode.Append($">{editMessage}</a>");
                editLinkCode.Append($"</div>");
            }

            return MvcHtmlString.Create(editLinkCode.ToString());
        }
    }
}