Add frontmatter parser for markdown content type

Should the action read and delete frontmatter in a markdown file. Frontmatter should start with --- and end with ---. Should be on the top of the page. When parsing frontmatter, only markdown is supported and settings will be overwritten if specified in the frontmatter.

Signed-off-by: Brend Smits <[email protected]>

Action/.env-example

@@ -9,4 +9,5 @@ License=all-rights-reserved
 PublicationId=123456789
 PublicationName=Philips Tech Blog
 NotifyFollowers=true
-File=
+File=
+ParseFrontmatter=false

Action/PostMediumGitHubAction.csproj

@@ -11,7 +11,9 @@
 	<ItemGroup>
 		<PackageReference Include="CommandLineParser" Version="2.8.0" />
 		<PackageReference Include="DotNetEnv" Version="2.2.0" />
+		<PackageReference Include="Markdig" Version="0.26.0" />
 		<PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.11.1" />
+		<PackageReference Include="YamlDotNet" Version="11.2.1" />
 	</ItemGroup>
 
 </Project>

Action/Properties/launchSettings.json

@@ -1,6 +1,6 @@
 {
   "profiles": {
-    "PostMediumGitHubAction2": {
+    "PostMediumGitHubAction": {
       "commandName": "Project"
     },
     "Docker": {

Action/Services/ConfigureService.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Net.Http;
 using System.Net.Http.Headers;
 using CommandLine;
@@ -7,6 +8,9 @@ namespace PostMediumGitHubAction.Services
 {
     internal class ConfigureService
     {
+        public ConfigureService()
+        {
+        }
         public ConfigureService(string[] args)
         {
             ConfigureApplication(args);
@@ -31,6 +35,7 @@ private void ConfigureApplication(string[] args)
             Program.Settings.PublicationName =
                 Environment.GetEnvironmentVariable(nameof(Program.Settings.PublicationName));
             Program.Settings.PublishStatus = Environment.GetEnvironmentVariable(nameof(Program.Settings.PublishStatus));
+            Program.Settings.ParseFrontmatter = Convert.ToBoolean(Environment.GetEnvironmentVariable(nameof(Program.Settings.ParseFrontmatter)));
             Program.Settings.Tags = Environment.GetEnvironmentVariable(nameof(Program.Settings.Tags))?.Split(',');
             Program.Settings.Title = Environment.GetEnvironmentVariable(nameof(Program.Settings.Title));
 
@@ -53,6 +58,42 @@ private void ConfigureApplication(string[] args)
             Program.Settings.ContentFormat = Program.Settings.ContentFormat?.ToLower();
         }
 
+        /// <summary>
+        /// Override Program Settings with values from parameter if they are not null.
+        /// </summary>
+        /// <param name="settingsToReplace">Settings to replace Program settings with</param>
+        public void OverrideSettings(Settings settingsToReplace)
+        {
+            if (settingsToReplace.CanonicalUrl != null)
+            {
+                Program.Settings.CanonicalUrl = settingsToReplace.CanonicalUrl;
+            }
+
+            if (settingsToReplace.ContentFormat != null)
+            {
+                Program.Settings.ContentFormat = settingsToReplace.ContentFormat;
+            }
+
+            if (settingsToReplace.Tags.Any())
+            {
+                Program.Settings.Tags = settingsToReplace.Tags;
+            }
+
+            if (settingsToReplace.License != null)
+            {
+                Program.Settings.License = settingsToReplace.License;
+            }
+
+            if (settingsToReplace.PublishStatus != null)
+            {
+                Program.Settings.PublishStatus = settingsToReplace.PublishStatus;
+            }
+
+            if (settingsToReplace.Title != null)
+            {
+                Program.Settings.Title = settingsToReplace.Title;
+            }
+        }
         /// <summary>
         ///     Checks if settings are filled in correctly.
         /// </summary>

Action/Services/MediumService.cs

@@ -5,12 +5,19 @@
 using System.Text;
 using System.Text.Json;
 using System.Threading.Tasks;
+using Markdig;
+using Markdig.Extensions.Yaml;
+using Markdig.Renderers;
+using Markdig.Syntax;
 using PostMediumGitHubAction.Domain;
+using YamlDotNet.Serialization;
+using YamlDotNet.Serialization.NamingConventions;
 
 namespace PostMediumGitHubAction.Services
 {
     public class MediumService
     {
+        private ConfigureService _configureService = new ConfigureService();
         public async Task SubmitNewContentAsync()
         {
             User user = await GetCurrentMediumUserAsync();
@@ -20,11 +27,56 @@ public async Task SubmitNewContentAsync()
 
             if (!string.IsNullOrEmpty(Program.Settings.File))
                 Program.Settings.Content = await ReadFileFromPath(Program.Settings.File);
+            if (Program.Settings.ContentFormat == "markdown" && Program.Settings.ParseFrontmatter)
+            {
+                await ParseFrontmatter(Program.Settings.Content);
+            }
 
             MediumCreatedPost post = await CreateNewPostUnderPublicationAsync(pub.Id);
             SetWorkflowOutputs(post);
         }
 
+        /// <summary>
+        /// Parse markdown content and look for frontmatter.
+        /// Convert the markdown into HTML to remove the frontmatter.
+        /// </summary>
+        /// <param name="content">Content in markdown</param>
+        /// <returns></returns>
+        private async Task ParseFrontmatter(string content)
+        {
+            MarkdownPipeline pipeline = new MarkdownPipelineBuilder()
+                .UseYamlFrontMatter()
+                .Build();
+
+            StringWriter writer = new StringWriter();
+            HtmlRenderer renderer = new HtmlRenderer(writer);
+            pipeline.Setup(renderer);
+
+            MarkdownDocument document = Markdown.Parse(content, pipeline);
+
+            // extract the front matter from markdown document
+            YamlFrontMatterBlock yamlBlock = document.Descendants<YamlFrontMatterBlock>().FirstOrDefault();
+
+            if (yamlBlock != null)
+            {
+                string yaml = yamlBlock.Lines.ToString();
+
+                // deserialize the yaml block into a custom type
+                IDeserializer deserializer = new DeserializerBuilder()
+                    .WithNamingConvention(PascalCaseNamingConvention.Instance)
+                    .Build();
+
+                Settings metadata = deserializer.Deserialize<Settings>(yaml);
+                _configureService.OverrideSettings(metadata);
+                // finally we can render the markdown content as html if necessary
+                renderer.Render(document);
+                await writer.FlushAsync();
+                string html = writer.ToString();
+                Program.Settings.Content = html;
+                Program.Settings.ContentFormat = "html";
+            }
+        }
+
         /// <summary>
         ///     Retrieves current authenticated user
         /// </summary>
@@ -79,7 +131,7 @@ public async Task<MediumCreatedPost> CreateNewPostUnderPublicationAsync(string p
                 Content = Program.Settings.Content,
                 ContentFormat = Program.Settings.ContentFormat,
                 PublishStatus = Program.Settings.PublishStatus,
-                Tags = (string[])Program.Settings.Tags,
+                Tags = Program.Settings.Tags as string[],
                 Title = Program.Settings.Title
             };
             HttpResponseMessage response = await Program.Client.PostAsync($"publications/{publicationId}/posts",

Action/Settings.cs

@@ -58,5 +58,9 @@ public class Settings
             HelpText =
                 "The token that should be used to authenticate in the API. Token can be retrieved at https://medium.com/me/settings under \"Integration Token\"")]
         public string IntegrationToken { get; set; }
+
+        [Option('m', "parse-frontmatter", Required = false,
+            HelpText = "Should the action read and delete frontmatter in a markdown file. Frontmatter should start with --- and end with ---. Should be on the top of the page. When parsing frontmatter, only markdown is supported and settings will be overwritten if specified in the frontmatter.")]
+        public bool ParseFrontmatter { get; set; } = false;
     }
 }

README.md

@@ -26,22 +26,22 @@
 <p align="right">(<a href="#top">back to top</a>)</p>
 
 ## State
-> Functional, but work in progress. Use at your own risk.
+> Functional
 
 ## Usage
 
 The easiest way to use this action is to add the following into your workflow file. Additional configuration might be necessary to fit your usecase.
 
 1. Add the following part in your workflow file:
 
-   ```yaml
+   ```
    jobs:
      post-to-medium:
        name: Post to Medium
        runs-on: ubuntu-latest
        steps:
          - name: Create Medium Post
-           uses: philips-software/post-to-medium-action@v0.2
+           uses: philips-software/post-to-medium-action@v0.3
            with:
              integration_token: "${{ secrets.INTEGRATION_TOKEN }}"
              content: "content here"
@@ -69,6 +69,7 @@ The easiest way to use this action is to add the following into your workflow fi
 | canonical_url | The canonical URL of the post. If canonicalUrl was not specified in the creation of the post, this field will not be present. | `false` |  |
 | tags | The post’s tags. Provide a comma separated string without spaces. | `true` |  |
 | title | The post's title. | `true` |  |
+| parse_frontmatter | Should the action read and delete frontmatter in a markdown file. Frontmatter should start with --- and end with ---. Should be on the top of the page. When parsing frontmatter, only markdown is supported and settings will be overwritten if specified in the frontmatter. | `true` | false |
 
 
 ## Outputs

action.yaml

@@ -47,6 +47,10 @@ inputs:
     description: "The post's title."
     required: true
     default: ""
+  parse_frontmatter:
+    description: "Should the action read and delete frontmatter in a markdown file. Frontmatter should start with --- and end with ---. Should be on the top of the page. When parsing frontmatter, only markdown is supported and settings will be overwritten if specified in the frontmatter."
+    required: false
+    default: "false"
 
 outputs:
   id:
@@ -98,6 +102,8 @@ runs:
     - ${{ inputs.content }}
     - '--file'
     - ${{ inputs.file }}
+    - '--parse-frontmatter'
+    - ${{ inputs.parse_frontmatter }}
 
 
 branding: