From a54f783ff3193195bde18f2d16dc4cfd195199ab Mon Sep 17 00:00:00 2001
From: Kevin F <Freymaurer@gmx.de>
Date: Mon, 20 Jun 2022 16:10:47 +0200
Subject: [PATCH] add nfdi-code parsing

---
 src/Nfdi4Plants.Fornax/Loaders.fs             |  2 +
 .../MarkdigExtensions/nfdi-code.fs            | 86 +++++++++++++++++++
 .../Nfdi4Plants.Fornax.fsproj                 |  1 +
 3 files changed, 89 insertions(+)
 create mode 100644 src/Nfdi4Plants.Fornax/MarkdigExtensions/nfdi-code.fs

diff --git a/src/Nfdi4Plants.Fornax/Loaders.fs b/src/Nfdi4Plants.Fornax/Loaders.fs
index 29fb405..ad88757 100644
--- a/src/Nfdi4Plants.Fornax/Loaders.fs
+++ b/src/Nfdi4Plants.Fornax/Loaders.fs
@@ -2,6 +2,7 @@ namespace Fornax.Nfdi4Plants
 
 module Pipelines =
     open Markdig
+    open Fornax.Nfdi4Plants.MarkdigExtensions.NfdiCode
     open Fornax.Nfdi4Plants.MarkdigExtensions.NfdiHeader
     open Fornax.Nfdi4Plants.MarkdigExtensions.NfdiSidebarElementHeader
 
@@ -10,6 +11,7 @@ module Pipelines =
             .UseAdvancedExtensions()
             .UseEmojiAndSmiley()
             .UseNFDIHeader()
+            .UseNFDICodeBlock()
             .Build()
 
     let sidebarMarkdownPipeline =
diff --git a/src/Nfdi4Plants.Fornax/MarkdigExtensions/nfdi-code.fs b/src/Nfdi4Plants.Fornax/MarkdigExtensions/nfdi-code.fs
new file mode 100644
index 0000000..8a02102
--- /dev/null
+++ b/src/Nfdi4Plants.Fornax/MarkdigExtensions/nfdi-code.fs
@@ -0,0 +1,86 @@
+namespace Fornax.Nfdi4Plants.MarkdigExtensions
+
+open System.Text
+open Markdig.Parsers;
+open Markdig.Renderers;
+open Markdig.Renderers.Html;
+open Markdig.Syntax;
+open Markdig
+
+module NfdiCode =
+
+    open System
+
+        // https://github.com/ilich/Markdig.Prism/blob/main/src/Markdig.Prism/PrismCodeBlockRenderer.cs
+    type NFDICodeBlockRenderer() =
+        inherit HtmlObjectRenderer<CodeBlock>()
+
+        let extractSourcecode (node: LeafBlock) = 
+            let code = new StringBuilder()
+            let lines = node.Lines.Lines
+            let totalLines = lines.Length
+            let rec appendLines (counter: int) (c: StringBuilder) =
+                if counter >= totalLines then
+                    c
+                else
+                    let line = lines[counter]
+                    let slice = line.Slice
+                    if isNull slice.Text then
+                        appendLines (counter + 1) c
+                    else
+                        let lineText = slice.Text.Substring(slice.Start, slice.Length);
+                        if counter > 0 then 
+                            appendLines (counter+1) (c.AppendLine().Append(lineText))
+                        else
+                            appendLines (counter+1) (c.Append(lineText))
+            appendLines 0 code
+            |> fun x -> x.ToString()
+
+        override this.Write(renderer : HtmlRenderer , cb : CodeBlock ) =
+
+            if cb :? FencedCodeBlock && cb.Parser :? FencedCodeBlockParser then
+                let fcb = cb :?> FencedCodeBlock
+                let parser = cb.Parser :?> FencedCodeBlockParser
+                let languageCode = fcb.Info.Replace(parser.InfoPrefix, "").Trim()
+                let code = extractSourcecode(cb)
+                if languageCode = "" then
+                    renderer
+                        .Write("<nfdi-code>")
+                        .Write(code)
+                        .Write("</nfdi-code>")
+                    |> ignore
+                else
+                    let attributes = new HtmlAttributes()
+                    attributes.AddClass($"language-{languageCode}")
+                    
+                    renderer
+                        .Write("<nfdi-code")
+                        .WriteAttributes(attributes)
+                        .Write(">")
+                        .Write(code)
+                        .Write("</nfdi-code>")
+                    |> ignore
+            else
+                // let codeBlockRenderer = new CodeBlockRenderer()
+                renderer.Write(cb) |> ignore
+
+    /// An extension for Markdig that highlights syntax in fenced code blocks
+    type NFDICodeExtension() =
+
+        interface IMarkdownExtension with
+
+            member __.Setup(_) = ()
+
+            member __.Setup(_, renderer) = 
+                renderer.ObjectRenderers.ReplaceOrAdd<CodeBlockRenderer>(new NFDICodeBlockRenderer()) |> ignore
+
+    open System.Runtime.CompilerServices
+
+    [<Extension>]
+    type MarkdownPipelineBuilderExtensions() =
+        [<Extension>]
+        // <summary>Highlight code in fenced code blocks</summary>
+        // <param name="pipeline">The Markdig <see cref="MarkdownPipelineBuilder"/> to add the extension to</param>
+        static member UseNFDICodeBlock(pipeline : MarkdownPipelineBuilder) =
+            pipeline.Extensions.Add(NFDICodeExtension())
+            pipeline
\ No newline at end of file
diff --git a/src/Nfdi4Plants.Fornax/Nfdi4Plants.Fornax.fsproj b/src/Nfdi4Plants.Fornax/Nfdi4Plants.Fornax.fsproj
index f9243d7..2e9b97b 100644
--- a/src/Nfdi4Plants.Fornax/Nfdi4Plants.Fornax.fsproj
+++ b/src/Nfdi4Plants.Fornax/Nfdi4Plants.Fornax.fsproj
@@ -18,6 +18,7 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="MarkdigExtensions/nfdi-code.fs" />
     <Compile Include="MarkdigExtensions/nfdi-header.fs" />
     <Compile Include="MarkdigExtensions/nfdi-sidebar-element-header.fs" />
     <Compile Include="Loaders.fs" />