logofclient/Wiki/MarkdownRenderer.cs

using System.Collections.Generic;
using Avalonia.Controls;
using Avalonia.Media;
using Markdig;
using Markdig.Syntax;
using Markdig.Syntax.Inlines;
using System.Text;

namespace Logof_Client.Wiki;

public static class MarkdownRenderer
{
    public static Control Render(string markdown)
    {
        var panel = new StackPanel { Spacing = 6 };
        if (string.IsNullOrWhiteSpace(markdown)) return panel;

        var doc = Markdown.Parse(markdown);

        foreach (var block in doc)
        {
            switch (block)
            {
                case HeadingBlock hb:
                {
                    var text = GetInlineText(hb.Inline);
                    var tb = new TextBlock
                    {
                        Text = text,
                        FontWeight = FontWeight.Bold,
                        Margin = new Avalonia.Thickness(0, hb.Level == 1 ? 6 : 2, 0, 2)
                    };
                    tb.FontSize = hb.Level switch { 1 => 22, 2 => 18, 3 => 16, _ => 14 };
                    panel.Children.Add(tb);
                    break;
                }

                case ParagraphBlock pb:
                {
                    var text = GetInlineText(pb.Inline);
                    var tb = new TextBlock { Text = text, TextWrapping = Avalonia.Media.TextWrapping.Wrap };
                    panel.Children.Add(tb);
                    break;
                }

                case FencedCodeBlock cb:
                {
                    var sb = new StringBuilder();
                    foreach (var line in cb.Lines.Lines)
                    {
                        sb.Append(line.ToString());
                    }
                    var codeBox = new TextBox
                    {
                        Text = sb.ToString(),
                        FontFamily = "Consolas, monospace",
                        IsReadOnly = true,
                        AcceptsReturn = true
                    };
                    panel.Children.Add(codeBox);
                    break;
                }

                case ListBlock lb:
                {
                    var sp = new StackPanel { Spacing = 2 };
                    var number = 1;
                    foreach (var item in lb)
                    {
                        if (item is ListItemBlock lib)
                        {
                            var itemText = new StringBuilder();
                            foreach (var sub in lib)
                            {
                                if (sub is ParagraphBlock pp)
                                    itemText.Append(GetInlineText(pp.Inline));
                            }
                            var tb = new TextBlock { Text = (lb.IsOrdered ? (number++ + ". ") : "• ") + itemText.ToString() };
                            sp.Children.Add(tb);
                        }
                    }
                    panel.Children.Add(sp);
                    break;
                }

                default:
                {
                    // fallback: raw text
                    panel.Children.Add(new TextBlock { Text = block.ToString() });
                    break;
                }
            }
        }

        return panel;
    }

    private static string GetInlineText(ContainerInline? container)
    {
        if (container == null) return string.Empty;
        var sb = new StringBuilder();
        foreach (var inline in container)
        {
            switch (inline)
            {
                case LiteralInline li:
                    sb.Append(li.Content.ToString());
                    break;
                case EmphasisInline ei:
                    sb.Append(GetInlineText(ei));
                    break;
                case CodeInline ci:
                    sb.Append(ci.Content);
                    break;
                case LinkInline li:
                    sb.Append(GetInlineText(li));
                    break;
                case LineBreakInline:
                    sb.Append("\n");
                    break;
                default:
                    sb.Append(inline.ToString());
                    break;
            }
        }

        return sb.ToString();
    }
}