Add GravatarTagHelper

src/EventHub.Web.Theme/Helpers/TagHelpers/GravatarTagHelper.cs

@@ -0,0 +1,206 @@
+using System;
+using System.ComponentModel;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+
+namespace EventHub.Web.Theme.Helpers.TagHelpers
+{
+    /// <inheritdoc />
+    /// <summary>
+    ///  Returns a Globally Recognised Avatar https://en.gravatar.com
+    /// </summary>
+    [HtmlTargetElement("img", Attributes = "gravatar-email")]
+    public class GravatarTagHelper : TagHelper
+    {
+        private readonly IHttpContextAccessor _contextAccessor;
+
+        public GravatarTagHelper(IHttpContextAccessor contextAccessor)
+        {
+            _contextAccessor = contextAccessor;
+        }
+
+        /// <summary>
+        /// Email Address for the Gravatar
+        /// </summary>
+        [HtmlAttributeName("gravatar-email")]
+        public string Email { get; set; }
+
+        /// <summary>
+        /// Gravatar content rating (note that Gravatars are self-rated)
+        /// </summary>
+        [HtmlAttributeName("gravatar-rating")]
+        public GravatarRating Rating { get; set; } = GravatarRating.GeneralAudiences;
+
+        /// <summary>
+        /// Size in pixels (default: 80)
+        /// </summary>
+        [HtmlAttributeName("gravatar-size")]
+        public int Size { get; set; } = 80;
+
+        /// <summary>
+        /// URL to a custom default image (e.g: 'Url.Content("~/images/no-grvatar.png")' )
+        /// </summary>
+        [HtmlAttributeName("default-image-url")]
+        public string DefaultImageUrl { get; set; } = "";
+
+        /// <summary>
+        /// Prefer the default image over the users own Gravatar
+        /// </summary>
+        [HtmlAttributeName("force-default-image")]
+        public bool ForceDefaultImage { get; set; }
+
+        /// <summary>
+        /// Default image if user hasn't created a Gravatar
+        /// </summary>
+        [HtmlAttributeName("default-image")]
+        public GravatarDefaultImage DefaultImage { get; set; } = GravatarDefaultImage.Default;
+
+        /// <summary>
+        /// Always do secure (https) requests
+        /// </summary>
+        [HtmlAttributeName("force-secure-request")]
+        public bool ForceSecureRequest { get; set; } = true;
+
+
+        public override void Process(TagHelperContext context, TagHelperOutput output)
+        {
+            var emailAddress = Email == null ? string.Empty : Email.Trim().ToLower();
+
+            var url = string.Format("{0}://{1}.gravatar.com/avatar/{2}?s={3}{4}{5}{6}",
+                GetUrlScheme(),
+                GetUrlPrefix(),
+                GetMd5Hash(emailAddress),
+                Size,
+                GetDefaultImageParameter(),
+                GetForceDefaultImageParameter(),
+                GetRatingParameter()
+            );
+
+            output.Attributes.SetAttribute("src", url);
+        }
+
+        private string GetUrlScheme()
+        {
+            return ForceSecureRequest || _contextAccessor.HttpContext.Request.IsHttps
+                ? "https"
+                : "http";
+        }
+
+        private string GetUrlPrefix()
+        {
+            return ForceSecureRequest || _contextAccessor.HttpContext.Request.IsHttps ? "secure" : "www";
+        }
+
+        private string GetDefaultImageParameter()
+        {
+            return "&d=" + (!string.IsNullOrEmpty(DefaultImageUrl)
+                ? System.Net.WebUtility.UrlEncode(DefaultImageUrl)
+                : GetEnumDescription(DefaultImage));
+        }
+
+        private string GetForceDefaultImageParameter()
+        {
+            return ForceDefaultImage ? "&f=y" : "";
+        }
+
+        private string GetRatingParameter()
+        {
+            return "&r=" + GetEnumDescription(Rating);
+        }
+
+        /// <summary>
+        /// Generates an MD5 hash of the given string
+        /// </summary>
+        /// <remarks>Source: http://msdn.microsoft.com/en-us/library/system.security.cryptography.md5.aspx </remarks>
+        private static string GetMd5Hash(string input)
+        {
+            // Convert the input string to a byte array and compute the hash.
+            var data = MD5.Create().ComputeHash(Encoding.UTF8.GetBytes(input));
+
+            // Create a new Stringbuilder to collect the bytes
+            // and create a string.
+            var sBuilder = new StringBuilder();
+
+            // Loop through each byte of the hashed data
+            // and format each one as a hexadecimal string.
+            foreach (var t in data)
+            {
+                sBuilder.Append(t.ToString("x2"));
+            }
+
+            // Return the hexadecimal string.
+            return sBuilder.ToString();
+        }
+
+        /// <summary>
+        /// Returns the value of a Description for a given Enum value
+        /// </summary>
+        /// <remarks>Source: http://blogs.msdn.com/b/abhinaba/archive/2005/10/21/483337.aspx </remarks>
+        /// <param name="en"></param>
+        /// <returns></returns>
+        private static string GetEnumDescription(Enum en)
+        {
+            var type = en.GetType();
+            var memInfo = type.GetMember(en.ToString());
+
+            if (memInfo == null || memInfo.Length <= 0)
+            {
+                return en.ToString();
+            }
+
+            var attrs = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
+
+            if (attrs != null && attrs.Any())
+            {
+                return ((DescriptionAttribute) attrs.First()).Description;
+            }
+
+            return en.ToString();
+        }
+
+        public enum GravatarDefaultImage
+        {
+            /// <summary>Default Gravatar logo</summary>
+            [Description("")] Default,
+
+            /// <summary>404 - do not load any image if none is associated with the email hash, instead return an HTTP 404 (File Not Found) response</summary>
+            [Description("404")] Http404,
+
+            /// <summary>Mystery-Man - a simple, cartoon-style silhouetted outline of a person (does not vary by email hash)</summary>
+            [Description("mm")] MysteryMan,
+
+            /// <summary>Identicon - a geometric pattern based on an email hash</summary>
+            [Description("identicon")] Identicon,
+
+            /// <summary>MonsterId - a generated 'monster' with different colors, faces, etc</summary>
+            [Description("monsterid")] MonsterId,
+
+            /// <summary>Wavatar - generated faces with differing features and backgrounds</summary>
+            [Description("wavatar")] Wavatar,
+
+            /// <summary>Retro - awesome generated, 8-bit arcade-style pixelated faces</summary>
+            [Description("retro")] Retro
+        }
+
+        /// <summary>
+        /// Gravatar allows users to self-rate their images so that they can indicate if an image is appropriate for a certain audience. By default, only 'G' rated images are displayed unless you indicate that you would like to see higher ratings
+        /// </summary>
+        public enum GravatarRating
+        {
+            /// <summary>Suitable for display on all websites with any audience type</summary>
+            [Description("g")] GeneralAudiences,
+
+            /// <summary>May contain rude gestures, provocatively dressed individuals, the lesser swear words, or mild violence</summary>
+            [Description("pg")] ParentalGuidance,
+
+            /// <summary>May contain such things as harsh profanity, intense violence, nudity, or hard drug use</summary>
+            [Description("r")] Restricted,
+
+            /// <summary>May contain hardcore sexual imagery or extremely disturbing violence</summary>
+            [Description("x")] OnlyMature
+        }
+    }
+}

src/EventHub.Web.Theme/Themes/EventHub/_ViewImports.cshtml

@@ -1,4 +1,5 @@
 @using System.Globalization
 @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
 @addTagHelper *, Volo.Abp.AspNetCore.Mvc.UI.Bootstrap
-@addTagHelper *, Volo.Abp.AspNetCore.Mvc.UI.Bundling
+@addTagHelper *, Volo.Abp.AspNetCore.Mvc.UI.Bundling
+@addTagHelper *, EventHub.Web.Theme