Switch code, scripts and docs to English; drop plan.md references

Elternbeirat.Web/Services/PageService.cs

@@ -0,0 +1,86 @@
+using Markdig;
+using Markdig.Extensions.Yaml;
+using Markdig.Syntax;
+
+namespace Elternbeirat.Web.Services;
+
+/// <summary>
+/// Reads the static content pages from <c>Content/pages/*.md</c>, renders them
+/// to HTML once at startup and keeps them in memory. Registered as a singleton
+/// because the content lives in the image and does not change at runtime.
+/// </summary>
+public sealed class PageService
+{
+    private readonly IReadOnlyDictionary<string, Page> _pagesBySlug;
+
+    /// <summary>
+    /// Reads every Markdown page from the <c>Content/pages</c> directory below
+    /// the application root and caches it.
+    /// </summary>
+    public PageService(IWebHostEnvironment environment)
+    {
+        var pipeline = new MarkdownPipelineBuilder()
+            .UseYamlFrontMatter()
+            .Build();
+
+        var directory = Path.Combine(environment.ContentRootPath, "Content", "pages");
+        var pages = new Dictionary<string, Page>(StringComparer.OrdinalIgnoreCase);
+
+        if (Directory.Exists(directory))
+        {
+            foreach (var path in Directory.EnumerateFiles(directory, "*.md"))
+            {
+                var page = Read(path, pipeline);
+                pages[page.Slug] = page;
+            }
+        }
+
+        _pagesBySlug = pages;
+    }
+
+    /// <summary>
+    /// Returns the page for the given slug, or <c>null</c> if there is none.
+    /// The lookup is case-insensitive.
+    /// </summary>
+    public Page? Find(string slug) =>
+        _pagesBySlug.GetValueOrDefault(slug);
+
+    private static Page Read(string path, MarkdownPipeline pipeline)
+    {
+        var slug = Path.GetFileNameWithoutExtension(path);
+        var source = File.ReadAllText(path);
+
+        var document = Markdown.Parse(source, pipeline);
+        var title = ReadTitle(document, source) ?? slug;
+        var html = Markdown.ToHtml(source, pipeline);
+
+        return new Page { Slug = slug, Title = title, ContentHtml = html };
+    }
+
+    /// <summary>
+    /// Pulls the <c>titel:</c> value out of the YAML front matter. Kept
+    /// deliberately simple (a single <c>key: value</c> line) — YamlDotNet will
+    /// take over once we need structured metadata. The key stays German because
+    /// the Markdown files are edited by German-speaking editors.
+    /// </summary>
+    private static string? ReadTitle(MarkdownDocument document, string source)
+    {
+        var block = document.Descendants<YamlFrontMatterBlock>().FirstOrDefault();
+        if (block is null)
+        {
+            return null;
+        }
+
+        var frontMatter = source.Substring(block.Span.Start, block.Span.Length);
+        foreach (var line in frontMatter.Split('\n'))
+        {
+            var trimmed = line.Trim();
+            if (trimmed.StartsWith("titel:", StringComparison.OrdinalIgnoreCase))
+            {
+                return trimmed["titel:".Length..].Trim().Trim('"');
+            }
+        }
+
+        return null;
+    }
+}