code format

Yavsc/Helpers/Tags/MarkDownTagHelper.cs

@@ -0,0 +1,133 @@
+
+
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using MarkdownDeep;
+using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Razor.TagHelpers;
+
+namespace Yavsc.Helpers
+{
+    [HtmlTargetElement("div", Attributes = MarkdownContentAttributeName)]
+    [HtmlTargetElement("h1", Attributes = MarkdownContentAttributeName)]
+    [HtmlTargetElement("h2", Attributes = MarkdownContentAttributeName)]
+    [HtmlTargetElement("h3", Attributes = MarkdownContentAttributeName)]
+    [HtmlTargetElement("p", Attributes = "ismarkdown")]
+    [HtmlTargetElement("div", Attributes = "ismarkdown")]
+    [HtmlTargetElement("h1", Attributes = "ismarkdown")]
+    [HtmlTargetElement("h2", Attributes = "ismarkdown")]
+    [HtmlTargetElement("h3", Attributes = "ismarkdown")]
+    [HtmlTargetElement("markdown")]
+    [OutputElementHint("p")]
+    public class MarkdownTagHelper : TagHelper
+    {
+        private const string MarkdownContentAttributeName = "markdown";
+        private const string MarkdownMarkAttributeName = "ismarkdown";
+		[HtmlAttributeName("site")]
+        public SiteSettings Site { get; set; }
+        [HtmlAttributeName("base")]
+        public string Base { get; set; }
+
+        [HtmlAttributeName(MarkdownContentAttributeName)]
+        public string MarkdownContent { get; set; }
+
+        static Regex rxExtractLanguage = new Regex("^({{(.+)}}[\r\n])", RegexOptions.Compiled);
+        private static string FormatCodePrettyPrint(MarkdownDeep.Markdown m, string code)
+        {
+            // Try to extract the language from the first line
+            var match = rxExtractLanguage.Match(code);
+            string language = null;
+
+            if (match.Success)
+            {
+                // Save the language
+                var g = (Group)match.Groups[2];
+                language = g.ToString();
+
+                // Remove the first line
+                code = code.Substring(match.Groups[1].Length);
+            }
+
+            // If not specified, look for a link definition called "default_syntax" and
+            // grab the language from its title
+            if (language == null)
+            {
+                var d = m.GetLinkDefinition("default_syntax");
+                if (d != null)
+                    language = d.title;
+            }
+
+            // Common replacements
+            if (language == "C#")
+                language = "csharp";
+            if (language == "C++")
+                language = "cpp";
+
+            // Wrap code in pre/code tags and add PrettyPrint attributes if necessary
+            if (string.IsNullOrEmpty(language))
+                return string.Format("<pre><code>{0}</code></pre>\n", code);
+            else
+                return string.Format("<pre class=\"prettyprint lang-{0}\"><code>{1}</code></pre>\n",
+                    language.ToLowerInvariant(), code);
+        }
+
+
+        /// <summary>
+        /// Transforms a string of Markdown into HTML.
+        /// </summary>
+        /// <param name="text">The Markdown that should be transformed.</param>
+        /// <param name="urlBaseLocation">The url Base Location.</param>
+        /// <returns>The HTML representation of the supplied Markdown.</returns>
+        public string Markdown(string text, string urlBaseLocation = "")
+        {
+            // Transform the supplied text (Markdown) into HTML.
+            var markdownTransformer = GetMarkdownTransformer();
+            markdownTransformer.UrlBaseLocation = urlBaseLocation;
+            string html = markdownTransformer.Transform(text);
+            // Wrap the html in an MvcHtmlString otherwise it'll be HtmlEncoded and displayed to the user as HTML :(
+            return html;
+        }
+
+        internal Markdown GetMarkdownTransformer()
+        {
+            var markdownTransformer = new Markdown();
+            markdownTransformer.ExtraMode = true;
+            markdownTransformer.NoFollowLinks = true;
+            markdownTransformer.SafeMode = false;
+            markdownTransformer.FormatCodeBlock = FormatCodePrettyPrint;
+            markdownTransformer.ExtractHeadBlocks = true;
+            markdownTransformer.UserBreaks = true;
+            return markdownTransformer;
+        }
+
+        public ModelExpression Content { get; set; }
+        
+        public async override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
+        {
+            if (output.TagName == "markdown")
+            {
+                output.TagName = null;
+            }
+            output.Attributes.RemoveAll("markdown");
+
+            var content = await GetContent(output);
+            var markdown = content;
+
+            var htbase = Base;
+            
+
+            var html = Markdown(markdown, htbase);
+
+            output.Content.SetHtmlContent(html ?? "");
+        }
+        private async Task<string> GetContent(TagHelperOutput output)
+        {
+            if (MarkdownContent != null)
+                return MarkdownContent;
+            if (Content != null)
+                return Content.Model?.ToString();
+            return (await output.GetChildContentAsync(false)).GetContent();
+        }
+    }
+
+}