using System.Diagnostics;
using System.Text;
using System.Text.RegularExpressions;

namespace GitCover.WebStaticBuilder;

/// <summary>Main build orchestrator.</summary>
public static class Builder
{
    /// <returns><c>true</c> if the build completed; <c>false</c> if it was
    /// aborted due to a pre-flight check failure (missing content directory).</returns>
    public static bool Build(BuildConfig cfg, EnvironmentConfig env, string envName, bool verbose, bool dryRun)
    {
        // Pre-flight: content directory must exist — otherwise ContentLoader
        // throws an unhandled DirectoryNotFoundException. Fail gracefully with
        // an actionable message instead of a stack trace.
        if (!Directory.Exists(Directories.ContentDir))
        {
            Console.Error.WriteLine(
                $"ERROR: content directory not found: {Directories.ContentDir}");
            Console.Error.WriteLine(
                "       Specify --root <dir> or --content <dir>.");
            return false;
        }

        File.WriteAllText(Directories.BuildLogPath,
            $"=== Build Started: {DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} ===\n");
        File.AppendAllText(Directories.BuildLogPath,
            $"ENV: {envName}\nBASE_URL: {env.BaseUrl}\nCDN_ASSETS: {env.Cdn}\nROOT: {Directories.Root}\n\n");
        File.WriteAllText(Directories.RunLogPath,
            $"\n=== Run Started: {DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} ===\n");

        if (verbose)
        {
            Console.WriteLine("Build configuration:");
            Console.WriteLine($"  ENV: {envName}");
            Console.WriteLine($"  BASE_URL: {env.BaseUrl}");
            Console.WriteLine($"  CDN_ASSETS: {env.Cdn}");
            Console.WriteLine($"  Content: {Directories.ContentDir}");
            Console.WriteLine($"  Templates: {Directories.TemplateDir}");
            Console.WriteLine($"  Output: {Directories.DistDir}");
        }

        // Load UI translations (best-effort; templates fall back to keys if absent)
        I18n.Load(Directories.I18nFile);
        if (verbose && I18n.Loaded) Console.WriteLine($"  i18n: loaded {Directories.I18nFile}");

        string layout = LoadLayout();

        Directory.CreateDirectory(Directories.DistDir);
        CopyAssets(verbose);

        // Precompute, for every page, its slug per language (keyed by order|section),
        // so the language switcher can link to the equivalent page in each language
        // even when slugs differ between translations.
        var pageSlugs = new Dictionary<string, Dictionary<string, string>>();
        foreach (var l in cfg.LanguageCodes())
        {
            foreach (var p in ContentLoader.LoadContent(Directories.ContentDir, l))
            {
                var key = $"{p.Meta.Order ?? -1}|{p.Meta.Section ?? ""}";
                if (!pageSlugs.TryGetValue(key, out var m))
                    pageSlugs[key] = m = new Dictionary<string, string>();
                m[l] = p.Href;
            }
        }

        foreach (var lang in cfg.LanguageCodes())
        {
            try
            {
                var contents = ContentLoader.LoadContent(Directories.ContentDir, lang);
                if (verbose) Console.WriteLine($"Rendering {contents.Count} content files for language {lang}");
                File.AppendAllText(Directories.RunLogPath, $"Language: {lang}, Files: {contents.Count}\n");

                var sectionsHtml = BuildSectionsHtml(contents, lang);
                var navLinksHtml = BuildNavLinksHtml(contents, lang);
                var sidebarNavHtml = BuildSidebarNavHtml(contents, lang);

                var bannerPage = contents.FirstOrDefault(p => p.Meta.Order == 0);
                var bannerHtml = "";
                if (bannerPage != null)
                {
                    bannerHtml = MarkdownProcessor.RenderMarkdown(bannerPage.Content);
                    bannerHtml = MarkdownProcessor.MermaidPostprocess(bannerHtml);
                    bannerHtml = MarkdownProcessor.TablePostprocess(bannerHtml);
                }

                foreach (var page in contents)
                {
                    if (!page.Meta.Render) continue;
                    if (page.Meta.Order == 0) continue;

                    var title = page.Meta.LocalizedTitle(lang, page.Meta.Title ?? Path.GetFileNameWithoutExtension(page.Path));
                    var desc = page.Meta.LocalizedDescription(lang, "");

                    if (string.IsNullOrEmpty(title))
                        title = Path.GetFileNameWithoutExtension(page.Path);

                    var htmlContent = MarkdownProcessor.RenderMarkdown(page.Content);
                    htmlContent = MarkdownProcessor.MermaidPostprocess(htmlContent);
                    htmlContent = MarkdownProcessor.TablePostprocess(htmlContent);

                    var fullBody = page.Meta.Order == 1
                        ? bannerHtml + htmlContent
                        : htmlContent;

                    var slug = page.Href.Trim('/');
                    var canonical = string.IsNullOrEmpty(slug)
                        ? $"/{lang}/"
                        : $"/{lang}/{slug}.html";

                    var defaultTitle = cfg.Site.Title.TryGetValue(lang, out var dt) ? dt : cfg.Site.Name;
                    var defaultDesc = cfg.Site.Description.TryGetValue(lang, out var dd) ? dd : "";

                    var seoHead = SeoHelper.RenderSeoHead(lang, title, desc, $"{env.BaseUrl}{canonical}",
                        env.Cdn, defaultTitle, defaultDesc);

                    var sidebarTocHtml = BuildSidebarTocHtml(page.Content);
                    var pageNavHtml = (page.Meta.Order == 1) ? "" : BuildPageNavHtml(contents, page, lang);

                    var introHtml = string.IsNullOrEmpty(page.Meta.Intro)
                        ? "" : MarkdownProcessor.RenderMarkdown(page.Meta.Intro);
                    var positioningHtml = string.IsNullOrEmpty(page.Meta.Positioning)
                        ? "" : MarkdownProcessor.RenderMarkdown(page.Meta.Positioning);
                    var publisherHtml = string.IsNullOrEmpty(page.Meta.Publisher)
                        ? "" : MarkdownProcessor.RenderMarkdown(page.Meta.Publisher);

                    var langKey = $"{page.Meta.Order ?? -1}|{page.Meta.Section ?? ""}";
                    var langLinksHtml = BuildLangLinksHtml(
                        pageSlugs.TryGetValue(langKey, out var m) ? m : null);

                    var pageHtml = layout
                        .Replace("{{seo_head}}", seoHead).Replace("{{ seo_head }}", seoHead)
                        .Replace("{{ json_ld }}", "").Replace("{{json_ld}}", "")
                        .Replace("{{sections}}", sectionsHtml).Replace("{{ sections }}", sectionsHtml)
                        .Replace("{{nav_links}}", navLinksHtml).Replace("{{ nav_links }}", navLinksHtml)
                        .Replace("{{sidebar_nav}}", sidebarNavHtml).Replace("{{ sidebar_nav }}", sidebarNavHtml)
                        .Replace("{{sidebar_toc}}", sidebarTocHtml).Replace("{{ sidebar_toc }}", sidebarTocHtml)
                        .Replace("{{page_nav}}", pageNavHtml).Replace("{{ page_nav }}", pageNavHtml)
                        .Replace("{{lang}}", lang).Replace("{{ lang }}", lang)
                        .Replace("{{lang_links}}", langLinksHtml).Replace("{{ lang_links }}", langLinksHtml)
                        .Replace("{{glossary_href}}", GlossaryHref(lang)).Replace("{{ glossary_href }}", GlossaryHref(lang))
                        .Replace("{{glossary_label}}", GlossaryLabel(lang)).Replace("{{ glossary_label }}", GlossaryLabel(lang))
                        .Replace("{{intro}}", introHtml).Replace("{{ intro }}", introHtml)
                        .Replace("{{positioning}}", positioningHtml).Replace("{{ positioning }}", positioningHtml)
                        .Replace("{{publisher}}", publisherHtml).Replace("{{ publisher }}", publisherHtml)
                        .Replace("{{content}}", fullBody).Replace("{{ content }}", fullBody)
                        .Replace("{{body}}", fullBody).Replace("{{ body }}", fullBody);

                    pageHtml = I18n.Substitute(pageHtml, lang);

                    if (dryRun)
                    {
                        if (verbose) Console.WriteLine($"  [dry-run] Would write {lang}/{page.Href}");
                        continue;
                    }

                    var ldir = Path.Combine(Directories.DistDir, lang);
                    Directory.CreateDirectory(ldir);

                    var fileSlug = page.Href.Trim('/');
                    var outputFile = string.IsNullOrEmpty(fileSlug) ? "index.html" : $"{fileSlug}.html";
                    var outputPath = Path.Combine(ldir, outputFile);
                    File.WriteAllText(outputPath, pageHtml);

                    if (page.Meta.Order == 1)
                    {
                        var heroIndexPath = Path.Combine(ldir, "index.html");
                        File.WriteAllText(heroIndexPath, pageHtml);
                        if (verbose) Console.WriteLine($"  Written {heroIndexPath} (hero landing)");
                        File.AppendAllText(Directories.BuildLogPath, $"  Written: {heroIndexPath} (hero landing)\n");
                    }

                    if (verbose) Console.WriteLine($"  Written {outputPath}");
                    File.AppendAllText(Directories.BuildLogPath, $"  Written: {outputPath}\n");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"ERROR rendering {lang}: {ex.Message}");
                File.AppendAllText(Directories.BuildLogPath, $"ERROR rendering {lang}: {ex.Message}\n{ex.StackTrace}\n\n");
                File.AppendAllText(Directories.RunLogPath, $"ERROR rendering {lang}: {ex.Message}\n{ex.StackTrace}\n\n");
            }
        }

        BuildLegalPages(cfg, env, verbose);
        File.WriteAllText(Path.Combine(Directories.DistDir, "index.html"), BuildRootIndex(cfg, env.BaseUrl));
        if (verbose) Console.WriteLine("  Written root index.html");

        File.WriteAllText(Path.Combine(Directories.DistDir, "robots.txt"),
            $"User-agent: *\nAllow: /\nSitemap: {env.BaseUrl}/sitemap.xml");

        BuildSitemap(cfg, env.BaseUrl, verbose);

        if (cfg.Pagefind) BuildSearchIndex(verbose);
        else if (verbose) Console.WriteLine("  Pagefind disabled (config).");

        return true;
    }

    private static string LoadLayout()
    {
        var layoutPath = Path.Combine(Directories.TemplateDir, "layout.html");
        if (File.Exists(layoutPath)) return File.ReadAllText(layoutPath);
        Console.WriteLine($"WARNING: Layout file not found: {layoutPath}");
        return "<html><body>{{body}}</body></html>";
    }

    private static void CopyAssets(bool verbose)
    {
        var srcDir = Directories.AssetsDir;
        var dstDir = Path.Combine(Directories.DistDir, "assets");
        if (!Directory.Exists(srcDir))
        {
            Console.WriteLine($"WARNING: Assets directory not found: {srcDir}");
            return;
        }
        if (Directory.Exists(dstDir)) Directory.Delete(dstDir, recursive: true);
        Directory.CreateDirectory(dstDir);
        foreach (var file in Directory.GetFiles(srcDir, "*", SearchOption.AllDirectories))
        {
            var rel = Path.GetRelativePath(srcDir, file);
            var target = Path.Combine(dstDir, rel);
            Directory.CreateDirectory(Path.GetDirectoryName(target)!);
            File.Copy(file, target, overwrite: true);
        }
        if (verbose)
        {
            var count = Directory.GetFiles(dstDir, "*", SearchOption.AllDirectories).Length;
            Console.WriteLine($"  Copied {count} asset files to {dstDir}");
        }
        File.AppendAllText(Directories.BuildLogPath, $"  Assets copied to: {dstDir}\n");
    }

    /// <summary>
    /// Build the language-switch dropdown for the current page. <paramref name="langSlug"/>
    /// maps each language code to the current page's slug in that language (resolved by
    /// shared identity — order + section — so each language links to its own equivalent
    /// page). When null, all links point to the language root.
    /// </summary>
    private static string BuildLangLinksHtml(Dictionary<string, string>? langSlug)
    {
        var sb = new StringBuilder();
        foreach (var kv in Directories.Config.Languages)
        {
            var lang = kv.Key;
            var li = kv.Value;
            var label = li.Label ?? li.Name;
            var code = (li.HrefLang ?? lang).ToUpperInvariant();
            string slug = "";
            if (langSlug != null && langSlug.TryGetValue(lang, out var h)) slug = h.Trim('/');
            var href = string.IsNullOrEmpty(slug) ? $"/{lang}/" : $"/{lang}/{slug}.html";
            sb.AppendLine($"          <li><a href=\"{href}\" hreflang=\"{li.HrefLang ?? lang}\"><span>{HtmlEncode(label)}</span> <span class=\"lang-dropdown__code\">{code}</span></a></li>");
        }
        return sb.ToString().Trim();
    }

    private static string BuildNavLinksHtml(List<PageInfo> contents, string lang)
    {
        var sb = new StringBuilder();
        foreach (var page in contents)
        {
            if (!page.Meta.Navbar) continue;
            if (page.Meta.Order == 0 || page.Meta.Order == 1) continue;
            var title = page.Meta.LocalizedTitle(lang, Path.GetFileNameWithoutExtension(page.Path));
            var navLabel = page.Meta.Eyebrow ?? title;
            if (navLabel.Contains(" — "))
                navLabel = navLabel.Substring(navLabel.IndexOf(" — ") + 3);
            var slug = page.Href.Trim('/');
            var href = string.IsNullOrEmpty(slug) ? "index.html" : $"{slug}.html";
            sb.AppendLine($"    <a class=\"nav-gcbok__link\" href=\"{href}\">{HtmlEncode(navLabel)}</a>");
        }
        return sb.ToString().Trim();
    }

    private static string BuildSidebarNavHtml(List<PageInfo> contents, string lang)
    {
        var sb = new StringBuilder();
        var navPages = contents.Where(p => p.Meta.Navbar && p.Meta.Order != 0 && p.Meta.Order != 1)
                               .OrderBy(p => p.Meta.Order ?? 999).ToList();
        var heroPage = contents.FirstOrDefault(p => p.Meta.Order == 1);
        if (heroPage != null)
            sb.AppendLine($"      <li><a href=\"index.html\"><span class=\"nav-idx\">★</span> {I18n.Get(lang, "nav.home")}</a></li>");

        foreach (var page in navPages)
        {
            var navLabel = page.Meta.Eyebrow ?? page.Meta.LocalizedTitle(lang, page.Meta.Title ?? "");
            if (navLabel.Contains(" — "))
                navLabel = navLabel.Substring(navLabel.IndexOf(" — ") + 3);
            var slug = page.Href.Trim('/');
            var href = string.IsNullOrEmpty(slug) ? "index.html" : $"{slug}.html";
            var idx = page.Meta.Order?.ToString() ?? "·";
            sb.AppendLine($"      <li><a href=\"{href}\"><span class=\"nav-idx\">{idx}</span> {HtmlEncode(navLabel)}</a></li>");
        }
        return sb.ToString().Trim();
    }

    private static string BuildSidebarTocHtml(string markdownContent)
    {
        var sb = new StringBuilder();
        var lines = markdownContent.Split('\n');
        var inCodeBlock = false;
        foreach (var line in lines)
        {
            if (line.TrimStart().StartsWith("```"))
            {
                inCodeBlock = !inCodeBlock;
                continue;
            }
            if (inCodeBlock) continue;
            var trimmed = line.TrimStart();
            if (trimmed.StartsWith("## ") && !trimmed.StartsWith("### "))
            {
                var headingText = trimmed.Substring(3).Trim();
                headingText = Regex.Replace(headingText, @"\*\*(.+?)\*\*", "$1");
                headingText = Regex.Replace(headingText, @"\*(.+?)\*", "$1");
                headingText = Regex.Replace(headingText, @"`(.+?)`", "$1");
                var slug = Regex.Replace(headingText.ToLower(), @"[^a-z0-9äöüß\-]+", "-").Trim('-').TrimEnd(':');
                if (!string.IsNullOrEmpty(slug))
                    sb.AppendLine($"      <li><a href=\"#{slug}\">{HtmlEncode(headingText)}</a></li>");
            }
        }
        return sb.ToString().Trim();
    }

    private static string BuildPageNavHtml(List<PageInfo> contents, PageInfo currentPage, string lang)
    {
        var navPages = contents.Where(p => p.Meta.Navbar && p.Meta.Order != 0 && p.Meta.Order != 1)
                               .OrderBy(p => p.Meta.Order ?? 999).ToList();
        var currentIndex = navPages.FindIndex(p => p.Path == currentPage.Path);
        if (currentIndex < 0) return "";

        var sb = new StringBuilder();
        sb.AppendLine("<nav class=\"page-nav\" aria-label=\"Seitennavigation\">");
        if (currentIndex > 0)
        {
            var prev = navPages[currentIndex - 1];
            var prevLabel = (prev.Meta.Eyebrow ?? prev.Meta.LocalizedTitle(lang, prev.Meta.Title ?? ""));
            if (prevLabel.Contains(" — ")) prevLabel = prevLabel.Substring(prevLabel.IndexOf(" — ") + 3);
            sb.AppendLine($"  <a class=\"page-nav__link\" href=\"{prev.Href.Trim('/')}.html\">");
            sb.AppendLine($"    <span class=\"page-nav__label\">{I18n.Get(lang, "nav.prev")}</span>");
            sb.AppendLine($"    <span class=\"page-nav__title\">{HtmlEncode(prevLabel)}</span>");
            sb.AppendLine("  </a>");
        }
        else sb.AppendLine("  <span class=\"page-nav__link\">&nbsp;</span>");

        if (currentIndex < navPages.Count - 1)
        {
            var next = navPages[currentIndex + 1];
            var nextLabel = (next.Meta.Eyebrow ?? next.Meta.LocalizedTitle(lang, next.Meta.Title ?? ""));
            if (nextLabel.Contains(" — ")) nextLabel = nextLabel.Substring(nextLabel.IndexOf(" — ") + 3);
            sb.AppendLine($"  <a class=\"page-nav__link page-nav__link--next\" href=\"{next.Href.Trim('/')}.html\">");
            sb.AppendLine($"    <span class=\"page-nav__label\">{I18n.Get(lang, "nav.next")}</span>");
            sb.AppendLine($"    <span class=\"page-nav__title\">{HtmlEncode(nextLabel)}</span>");
            sb.AppendLine("  </a>");
        }
        else sb.AppendLine("  <span class=\"page-nav__link page-nav__link--next\">&nbsp;</span>");

        sb.AppendLine("</nav>");
        return sb.ToString().Trim();
    }

    private static string BuildSectionsHtml(List<PageInfo> contents, string lang)
    {
        var sb = new StringBuilder();
        foreach (var page in contents)
        {
            if (!page.Meta.Navbar) continue;
            var title = page.Meta.LocalizedTitle(lang, Path.GetFileNameWithoutExtension(page.Path));
            sb.AppendLine($"        <a href=\"{page.Href}\" data-lang=\"{lang}\">{HtmlEncode(title)}</a>");
        }
        return sb.ToString().Trim();
    }

    private static void BuildLegalPages(BuildConfig cfg, EnvironmentConfig env, bool verbose)
    {
        var legalDir = Directories.LegalDir;
        if (!Directory.Exists(legalDir)) return;
        var layout = LoadLayout();

        foreach (var lang in cfg.LanguageCodes())
        {
            var lld = Path.Combine(Directories.DistDir, lang);
            Directory.CreateDirectory(lld);
            var contents = ContentLoader.LoadContent(Directories.ContentDir, lang);
            var navLinksHtml = BuildNavLinksHtml(contents, lang);
            var sidebarNavHtml = BuildSidebarNavHtml(contents, lang);

            try
            {
                foreach (var lf in Directory.GetFiles(legalDir, "*.md"))
                {
                    var bn = Path.GetFileName(lf);
                    if (bn.Contains("."))
                    {
                        var match = Regex.Match(bn, @".+\.(de|en|vi)\.md$");
                        if (match.Success && match.Groups[1].Value != lang) continue;
                    }
                    var text = File.ReadAllText(lf);
                    var (meta, content) = ContentLoader.ParseFrontmatter(text);
                    var title = meta.LocalizedTitle(lang, Path.GetFileNameWithoutExtension(bn));
                    var htmlContent = MarkdownProcessor.RenderMarkdown(content);
                    htmlContent = MarkdownProcessor.MermaidPostprocess(htmlContent);
                    htmlContent = MarkdownProcessor.TablePostprocess(htmlContent);

                    var baseName = Regex.Replace(bn, @"\.(de|en|vi)\.md$", ".html").Replace(".md", ".html");
                    var legalFileName = Path.GetFileNameWithoutExtension(baseName);
                    var canonical = $"/{lang}/{legalFileName}.html";
                    var defaultTitle = cfg.Site.Title.TryGetValue(lang, out var dt) ? dt : cfg.Site.Name;
                    var defaultDesc = cfg.Site.Description.TryGetValue(lang, out var dd) ? dd : "";
                    var seoHead = SeoHelper.RenderSeoHead(lang, title, "", $"{env.BaseUrl}{canonical}",
                        env.Cdn, defaultTitle, defaultDesc);
                    var sidebarTocHtml = BuildSidebarTocHtml(content);
                    var legalSlug = $"{legalFileName}.html";
                    var legalLangSlug = cfg.LanguageCodes().ToDictionary(l => l, l => $"{l}/{legalFileName}.html");
                    var langLinksHtml = BuildLangLinksHtml(legalLangSlug);

                    var pageHtml = layout
                        .Replace("{{seo_head}}", seoHead).Replace("{{ seo_head }}", seoHead)
                        .Replace("{{ json_ld }}", "").Replace("{{json_ld}}", "")
                        .Replace("{{sections}}", "").Replace("{{ sections }}", "")
                        .Replace("{{nav_links}}", navLinksHtml).Replace("{{ nav_links }}", navLinksHtml)
                        .Replace("{{sidebar_nav}}", sidebarNavHtml).Replace("{{ sidebar_nav }}", sidebarNavHtml)
                        .Replace("{{sidebar_toc}}", sidebarTocHtml).Replace("{{ sidebar_toc }}", sidebarTocHtml)
                        .Replace("{{page_nav}}", "").Replace("{{ page_nav }}", "")
                        .Replace("{{lang}}", lang).Replace("{{ lang }}", lang)
                        .Replace("{{lang_links}}", langLinksHtml).Replace("{{ lang_links }}", langLinksHtml)
                        .Replace("{{glossary_href}}", GlossaryHref(lang)).Replace("{{ glossary_href }}", GlossaryHref(lang))
                        .Replace("{{glossary_label}}", GlossaryLabel(lang)).Replace("{{ glossary_label }}", GlossaryLabel(lang))
                        .Replace("{{intro}}", "").Replace("{{ intro }}", "")
                        .Replace("{{positioning}}", "").Replace("{{ positioning }}", "")
                        .Replace("{{publisher}}", "").Replace("{{ publisher }}", "")
                        .Replace("{{content}}", htmlContent).Replace("{{ content }}", htmlContent)
                        .Replace("{{body}}", htmlContent).Replace("{{ body }}", htmlContent);
                    pageHtml = I18n.Substitute(pageHtml, lang);

                    var outputPath = Path.Combine(lld, baseName);
                    File.WriteAllText(outputPath, pageHtml);
                    if (verbose) Console.WriteLine($"  Written {outputPath}");
                    File.AppendAllText(Directories.BuildLogPath, $"  Legal: {outputPath}\n");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"ERROR rendering legal {lang}: {ex.Message}");
                File.AppendAllText(Directories.BuildLogPath, $"ERROR rendering legal {lang}: {ex.Message}\n{ex.StackTrace}\n\n");
                File.AppendAllText(Directories.RunLogPath, $"ERROR rendering legal {lang}: {ex.Message}\n{ex.StackTrace}\n\n");
            }
        }
    }

    private static void BuildSitemap(BuildConfig cfg, string baseUrl, bool verbose)
    {
        var urls = new List<string>();
        foreach (var lang in cfg.LanguageCodes())
        {
            urls.Add($"{baseUrl}/{lang}/");
            var contents = ContentLoader.LoadContent(Directories.ContentDir, lang);
            foreach (var page in contents)
            {
                if (!page.Meta.Render) continue;
                var slug = page.Href.Trim('/');
                if (!string.IsNullOrEmpty(slug))
                    urls.Add($"{baseUrl}/{lang}/{slug}.html");
            }
        }
        var sitemap = @"<?xml version=""1.0"" encoding=""UTF-8""?>
<urlset xmlns=""http://www.sitemaps.org/schemas/sitemap/0.9"">
{0}
</urlset>";
        var urlEntries = string.Join("\n", urls.Select(u => $"  <url><loc>{u}</loc></url>"));
        File.WriteAllText(Path.Combine(Directories.DistDir, "sitemap.xml"), string.Format(sitemap, urlEntries));
        if (verbose) Console.WriteLine("  Written sitemap.xml");
    }

    private static string GlossaryHref(string lang)
    {
        if (Directories.Config.Glossary.Href.TryGetValue(lang, out var h))
            return h.EndsWith(".html") ? h : h + ".html";
        return lang == "de" ? "glossar.html" : $"{Directories.Config.GlossarySection}.html";
    }

    private static string GlossaryLabel(string lang)
    {
        if (Directories.Config.Glossary.Label.TryGetValue(lang, out var l)) return l;
        return lang == "de" ? "Glossar" : lang == "en" ? "Glossary" : "Bảng thuật ngữ";
    }

    private static void BuildSearchIndex(bool verbose)
    {
        try
        {
            var psi = new ProcessStartInfo
            {
                FileName = "npx",
                Arguments = $"pagefind --site \"{Directories.DistDir}\"",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            };
            using var proc = Process.Start(psi)
                ?? throw new InvalidOperationException("Could not start npx.");
            var sbOut = new StringBuilder();
            var sbErr = new StringBuilder();
            proc.OutputDataReceived += (_, e) => { if (e.Data != null) sbOut.AppendLine(e.Data); };
            proc.ErrorDataReceived += (_, e) => { if (e.Data != null) sbErr.AppendLine(e.Data); };
            proc.BeginOutputReadLine();
            proc.BeginErrorReadLine();
            proc.WaitForExit();
            File.AppendAllText(Directories.BuildLogPath, $"  Pagefind (exit {proc.ExitCode}): {sbOut.ToString().Trim()}\n");
            if (proc.ExitCode != 0)
                File.AppendAllText(Directories.BuildLogPath, $"  Pagefind stderr: {sbErr.ToString().Trim()}\n");
        }
        catch (Exception ex)
        {
            File.AppendAllText(Directories.BuildLogPath, $"  Pagefind skipped (search index not built): {ex.Message}\n");
        }
    }

    public static string HtmlEncode(string text)
    {
        if (string.IsNullOrEmpty(text)) return "";
        return text.Replace("&", "&amp;").Replace("<", "&lt;").Replace(">", "&gt;").Replace("\"", "&quot;");
    }

    private static string BuildRootIndex(BuildConfig cfg, string baseUrl)
    {
        var supportedArray = string.Join(",", cfg.LanguageCodes().Select(l => $"\"{l}\""));
        var defaultLang = cfg.DefaultLanguage;
        var links = string.Join(" | ", cfg.LanguageCodes().Select(l =>
        {
            var label = cfg.Languages.TryGetValue(l, out var li) ? (li.Label ?? li.Name) : l;
            return $"<a href=\"/{l}/\">{label}</a>";
        }));
        return $@"<!DOCTYPE html>
<html lang=""{defaultLang}"">
<head>
<meta charset=""UTF-8"">
<meta name=""viewport"" content=""width=device-width, initial-scale=1.0"">
<title>{HtmlEncode(cfg.Site.Name)}</title>
<script>
(function() {{
  var supported = [{supportedArray}];
  var defaultLang = ""{defaultLang}"";
  var lang = defaultLang;
  if (navigator.languages && navigator.languages.length) {{
    for (var i = 0; i < navigator.languages.length; i++) {{
      var pref = navigator.languages[i].toLowerCase().split(""-"")[0];
      if (supported.indexOf(pref) !== -1) {{ lang = pref; break; }}
    }}
  }} else if (navigator.language) {{
    var pref = navigator.language.toLowerCase().split(""-"")[0];
    if (supported.indexOf(pref) !== -1) lang = pref;
  }}
  window.location.replace(""/"" + lang + ""/"");
}})();
</script>
<meta http-equiv=""refresh"" content=""0; url=/{defaultLang}/"">
<link rel=""canonical"" href=""{baseUrl}/{defaultLang}/"">
</head>
<body>
<p>Redirecting to {links}</p>
</body>
</html>";
    }
}