Add support for headers in markdown

DiscordChatExporter.Core/Exporting/HtmlMarkdownVisitor.cs

@@ -91,6 +91,25 @@ internal partial class HtmlMarkdownVisitor : MarkdownVisitor
         return result;
     }
 
+    protected override async ValueTask<MarkdownNode> VisitHeaderAsync(
+        HeaderNode header,
+        CancellationToken cancellationToken = default)
+    {
+        _buffer.Append(
+            // lang=html
+            $"<h{header.Level}>"
+        );
+
+        var result = await base.VisitHeaderAsync(header, cancellationToken);
+
+        _buffer.Append(
+            // lang=html
+            $"</h{header.Level}>"
+        );
+
+        return result;
+    }
+
     protected override async ValueTask<MarkdownNode> VisitInlineCodeBlockAsync(
         InlineCodeBlockNode inlineCodeBlock,
         CancellationToken cancellationToken = default)

DiscordChatExporter.Core/Exporting/PreambleTemplate.cshtml

@@ -758,6 +758,37 @@
             overflow-wrap: break-word;
         }
 
+        .chatlog__markdown h1 {
+            margin-block: 0;
+            margin-top: 1rem;
+            margin-bottom: 0.5rem;
+            color: @Themed("#f2f3f5", "#060607");
+            font-size: 1.5rem;
+            line-height: 1;
+        }
+
+        .chatlog__markdown h2 {
+            margin-block: 0;
+            margin-top: 1rem;
+            margin-bottom: 0.5rem;
+            color: @Themed("#f2f3f5", "#060607");
+            font-size: 1.25rem;
+            line-height: 1;
+        }
+
+        .chatlog__markdown h3 {
+            margin-block: 0;
+            margin-top: 1rem;
+            margin-bottom: 0.5rem;
+            color: @Themed("#f2f3f5", "#060607");
+            font-size: 1rem;
+            line-height: 1;
+        }
+
+        .chatlog__markdown h1:first-child, h2:first-child, h3:first-child {
+            margin-top: 0.5rem;
+        }
+
         .chatlog__markdown-preserve {
             white-space: pre-wrap;
         }

DiscordChatExporter.Core/Markdown/HeaderNode.cs

@@ -0,0 +1,8 @@
+using System.Collections.Generic;
+
+namespace DiscordChatExporter.Core.Markdown;
+
+internal record HeaderNode(
+    int Level,
+    IReadOnlyList<MarkdownNode> Children
+) : MarkdownNode, IContainerNode;

DiscordChatExporter.Core/Markdown/Parsing/MarkdownParser.cs

@@ -81,15 +81,15 @@ internal static partial class MarkdownParser
     private static readonly IMatcher<MarkdownNode> SingleLineQuoteNodeMatcher = new RegexMatcher<MarkdownNode>(
         // Capture any character until the end of the line.
         // Opening 'greater than' character must be followed by whitespace.
-        // Text content is optional.
-        new Regex(@"^>\s(.*\n?)", DefaultRegexOptions),
+        // Consume the newline character so that it's not included in the content.
+        new Regex(@"^>\s(.+\n?)", DefaultRegexOptions),
         (s, m) => new FormattingNode(FormattingKind.Quote, Parse(s.Relocate(m.Groups[1])))
     );
 
     private static readonly IMatcher<MarkdownNode> RepeatedSingleLineQuoteNodeMatcher = new RegexMatcher<MarkdownNode>(
         // Repeatedly capture any character until the end of the line.
-        // This one is tricky as it ends up producing multiple separate captures which need to be joined.
-        new Regex(@"(?:^>\s(.*\n?)){2,}", DefaultRegexOptions),
+        // Consume the newline character so that it's not included in the content.
+        new Regex(@"(?:^>\s(.+\n?)){2,}", DefaultRegexOptions),
         (_, m) => new FormattingNode(
             FormattingKind.Quote,
             Parse(
@@ -106,6 +106,16 @@ internal static partial class MarkdownParser
         (s, m) => new FormattingNode(FormattingKind.Quote, Parse(s.Relocate(m.Groups[1])))
     );
 
+    /* Headers */
+
+    private static readonly IMatcher<MarkdownNode> HeaderNodeMatcher = new RegexMatcher<MarkdownNode>(
+        // Capture any character until the end of the line.
+        // Opening 'hash' character(s) must be followed by whitespace.
+        // Consume the newline character so that it's not included in the content.
+        new Regex(@"^(\#{1,3})\s(.+\n?)", DefaultRegexOptions),
+        (s, m) => new HeaderNode(m.Groups[1].Length, Parse(s.Relocate(m.Groups[2])))
+    );
+
     /* Code blocks */
 
     private static readonly IMatcher<MarkdownNode> InlineCodeBlockNodeMatcher = new RegexMatcher<MarkdownNode>(
@@ -330,6 +340,9 @@ internal static partial class MarkdownParser
         RepeatedSingleLineQuoteNodeMatcher,
         SingleLineQuoteNodeMatcher,
 
+        // Headers
+        HeaderNodeMatcher,
+
         // Code blocks
         MultiLineCodeBlockNodeMatcher,
         InlineCodeBlockNodeMatcher,

DiscordChatExporter.Core/Markdown/Parsing/MarkdownVisitor.cs

@@ -20,6 +20,14 @@ internal abstract class MarkdownVisitor
         return formatting;
     }
 
+    protected virtual async ValueTask<MarkdownNode> VisitHeaderAsync(
+        HeaderNode header,
+        CancellationToken cancellationToken = default)
+    {
+        await VisitAsync(header.Children, cancellationToken);
+        return header;
+    }
+
     protected virtual ValueTask<MarkdownNode> VisitInlineCodeBlockAsync(
         InlineCodeBlockNode inlineCodeBlock,
         CancellationToken cancellationToken = default) =>
@@ -63,6 +71,9 @@ internal abstract class MarkdownVisitor
             FormattingNode formatting =>
                 await VisitFormattingAsync(formatting, cancellationToken),
 
+            HeaderNode header =>
+                await VisitHeaderAsync(header, cancellationToken),
+
             InlineCodeBlockNode inlineCodeBlock =>
                 await VisitInlineCodeBlockAsync(inlineCodeBlock, cancellationToken),