using System.Globalization;
using System.Text.RegularExpressions;
using HtmlAgilityPack;

namespace wp2ghost
{
    // =============================================================================
    // HtmlGhostConverter — WordPress HTML zu Ghost-kompatibles HTML konvertieren
    // =============================================================================
    public static class HtmlGhostConverter
    {
        private static readonly Dictionary<string, string?> WpClassMap = new(StringComparer.OrdinalIgnoreCase)
        {
            // Block-Elemente → Ghost-Äquivalent oder null (Klasse entfernen)
            { "wp-block-paragraph",       null },
            { "wp-block-heading",         null },
            { "wp-block-list",            null },
            { "wp-block-quote",           null },
            { "wp-block-code",            null },
            { "wp-block-separator",       null },
            { "wp-block-group",           null },
            { "wp-block-columns",         null },
            { "wp-block-column",          null },
            { "wp-block-freeform",        null },
            { "wp-block-verse",           null },
            { "wp-block-preformatted",    null },

            // Ghost-Kompatible Klassen
            { "wp-block-image",           "kg-card kg-image-card" },
            { "wp-block-gallery",         "kg-card kg-gallery-card" },
            { "wp-block-pullquote",       "kg-card kg-pullquote" },
            { "wp-block-embed",           "kg-card kg-embed-card" },
            { "wp-block-embed-wrapper",   "kg-card kg-embed-card" },
            { "wp-block-video",           "kg-card kg-embed-card" },
            { "wp-block-audio",           "kg-card kg-embed-card" },
            { "wp-block-cover",           "kg-card kg-header-card" },
            { "wp-block-media-text",      "kg-card kg-width-wide" },
            { "wp-block-table",           "kg-card kg-table-card" },
            { "wp-block-button",          "kg-card kg-button-card" },
            { "wp-block-buttons",         "kg-card kg-button-card" },
            { "wp-block-file",            "kg-card kg-file-card" },

            // Sub-Elemente
            { "wp-block-button__link",    "gh-btn" },
            { "wp-block-button__link__inline", "gh-btn" },
            { "wp-element-button",        "gh-btn" },
            { "has-text-align-center",    "kg-width-wide" },
            { "has-text-align-left",      "" },
            { "has-text-align-right",     "" },
            { "is-style-wide",            "kg-width-wide" },
            { "is-style-full",            "kg-width-wide" },
            { "is-style-large",           "kg-width-wide" },

            // Theme-spezifisch
            { "wp-block-post-title",      null },
            { "wp-block-post-content",    null },
            { "wp-block-site-title",      null },
            { "wp-block-site-tagline",    null },
            { "wp-block-query",           null },
            { "wp-block-comments",        null },
            { "wp-block-comment-template", null },
            { "wp-block-template-part",   null },

            // CoBlocks
            { "wp-block-coblocks-gallery-stacked", "kg-card kg-gallery-card" },
            { "wp-block-coblocks-gallery-collage", "kg-card kg-gallery-card" },
            { "wp-block-coblocks-gallery-masonry", "kg-card kg-gallery-card" },
            { "wp-block-coblocks-gallery-thumbnails", "kg-card kg-gallery-card" },
            { "wp-block-coblocks-alert",  "kg-card kg-alert-card" },
            { "wp-block-coblocks-accordion", "kg-card kg-accordion-card" },
            { "wp-block-coblocks-accordion-item", "kg-accordion-item" },
            { "wp-block-coblocks-row",    "kg-width-wide" },
            { "wp-block-coblocks-column", "" },
            { "wp-block-coblocks-click-to-tweet", "kg-card kg-click-to-tweet" },
            { "wp-block-coblocks-social-profiles", "kg-card kg-social-link" },

            // Jetpack
            { "wp-block-jetpack-tiled-gallery", "kg-card kg-gallery-card" },
            { "wp-block-jetpack-slideshow", "kg-card kg-gallery-card" },
            { "wp-block-jetpack-story",   "kg-card kg-gallery-card" },
        };

        // Ghost-Galerien fassen maximal 9 Bilder (3 pro Zeile) — größere WordPress-Galerien
        // werden in mehrere aufeinanderfolgende Ghost-Galerien aufgeteilt.
        private const int MaxGalleryImages = 9;
        private const int GalleryImagesPerRow = 3;

        // Liefert die echten Maße eines bereits heruntergeladenen Bildes (per src-URL)
        private static Func<string, (int Width, int Height)?>? _imageSizeResolver;
        private static int _ghostGalleryCount;
        private static int _skippedGalleryImages;
        private static int _captionedGalleryImages;

        public static string Convert(string html, Func<string, (int Width, int Height)?>? imageSizeResolver = null)
        {
            if (string.IsNullOrWhiteSpace(html)) return string.Empty;

            _imageSizeResolver = imageSizeResolver;
            _ghostGalleryCount = 0;
            _skippedGalleryImages = 0;
            _captionedGalleryImages = 0;

            var htmlDoc = new HtmlDocument();
            htmlDoc.LoadHtml(html);

            RemoveJunkCaptions(htmlDoc);

            int brokenImages = RemoveBrokenImages(htmlDoc);
            if (brokenImages > 0)
                Console.WriteLine($"   [Warnung] {brokenImages} Bild(er) mit blob:-Quelle entfernt (schon in WordPress defekt)");

            int totalGalleries = 0;
            totalGalleries += ConvertClassicGalleries(htmlDoc);

            // Gutenberg Gallery
            totalGalleries += ConvertImageGalleries(htmlDoc,
                "//figure[contains(@class, 'wp-block-gallery')] | " +
                "//div[contains(@class, 'wp-block-gallery')] | " +
                "//ul[contains(@class, 'wp-block-gallery')]");

            // Jetpack Tiled Gallery
            totalGalleries += ConvertImageGalleries(htmlDoc,
                "//div[contains(@class, 'wp-block-jetpack-tiled-gallery')] | " +
                "//figure[contains(@class, 'wp-block-jetpack-tiled-gallery')]");

            // CoBlocks Gallery
            totalGalleries += ConvertImageGalleries(htmlDoc,
                "//figure[contains(@class, 'wp-block-coblocks-gallery-masonry')] | " +
                "//figure[contains(@class, 'wp-block-coblocks-gallery-stacked')] | " +
                "//figure[contains(@class, 'wp-block-coblocks-gallery-collage')] | " +
                "//figure[contains(@class, 'wp-block-coblocks-gallery-thumbnails')]");

            if (totalGalleries > 0)
            {
                string split = _ghostGalleryCount > totalGalleries ? $" → {_ghostGalleryCount} Ghost-Galerien (max. {MaxGalleryImages} Bilder)" : "";
                Console.WriteLine($"   [Gallery] {totalGalleries} Galerie(n) konvertiert{split}");
            }
            if (_captionedGalleryImages > 0)
                Console.WriteLine($"   [Gallery] {_captionedGalleryImages} Galerie-Bild(er) mit Unterschrift als Einzelbild ausgegeben");
            if (_skippedGalleryImages > 0)
                Console.WriteLine($"   [Warnung] {_skippedGalleryImages} Galerie-Bild(er) ohne gültige Bildquelle (data:) ausgelassen");

            ConvertSingleImages(htmlDoc);
            ConvertFigures(htmlDoc);
            ConvertWpClasses(htmlDoc);
            AddTargetBlankToExternalLinks(htmlDoc);

            _imageSizeResolver = null;
            return htmlDoc.DocumentNode.OuterHtml;
        }

        // =========================================================================
        // Bilder mit blob:-Quelle entfernen: der Upload ist in WordPress nie
        // abgeschlossen worden, es gibt keine Datei, die übernommen werden könnte.
        // =========================================================================
        private static int RemoveBrokenImages(HtmlDocument htmlDoc)
        {
            var imgs = htmlDoc.DocumentNode.SelectNodes("//img[starts-with(@src, 'blob:')]");
            if (imgs == null) return 0;

            int count = 0;
            foreach (var img in imgs.ToList())
            {
                if (!string.IsNullOrEmpty(GetBestImageUrl(img)) && !GetBestImageUrl(img).StartsWith("blob:"))
                    continue; // data-orig-file/srcset liefern noch eine echte Quelle

                // Umschließende Einzelbild-Figure mit entfernen, wenn sie nur dieses Bild enthält
                var figure = img.Ancestors("figure").FirstOrDefault();
                HtmlNode toRemove = figure != null && figure.SelectNodes(".//img")?.Count == 1 ? figure : img;
                toRemove.Remove();
                count++;
            }
            return count;
        }

        // =========================================================================
        // Platzhalter-Unterschriften entfernen, die die Kamera/Handy-App automatisch
        // einträgt ("default") — sie gelten für kein Bild.
        // =========================================================================
        private static void RemoveJunkCaptions(HtmlDocument htmlDoc)
        {
            var captions = htmlDoc.DocumentNode.SelectNodes("//figcaption");
            if (captions == null) return;

            foreach (var caption in captions.ToList())
            {
                string text = HtmlEntity.DeEntitize(caption.InnerText).Trim();
                if (text.Equals("default", StringComparison.OrdinalIgnoreCase))
                    caption.Remove();
            }
        }

        private static string? GetCaptionHtml(HtmlNode? figcaption)
        {
            if (figcaption == null || string.IsNullOrWhiteSpace(HtmlEntity.DeEntitize(figcaption.InnerText)))
                return null;
            return figcaption.InnerHtml.Trim();
        }

        // =========================================================================
        // Gallery-Typ 1: WordPress Classic Gallery
        // HTML: <div class='gallery gallery-columns-3'>
        //         <figure class='gallery-item'>
        //           <div class='gallery-icon portrait'>
        //             <a href='...'><img src='thumb' data-orig-file='full.jpg' /></a>
        //           </div>
        //         </figure>
        //       </div>
        // =========================================================================
        private static int ConvertClassicGalleries(HtmlDocument htmlDoc)
        {
            var galleryNodes = htmlDoc.DocumentNode.SelectNodes(
                "//div[contains(@class, 'gallery') and not(contains(@class, 'wp-block'))]"
            );
            if (galleryNodes == null) return 0;

            int count = 0;
            foreach (var gallery in galleryNodes.ToList())
            {
                var items = gallery.SelectNodes(".//figure[contains(@class, 'gallery-item')]");
                if (items == null || items.Count == 0) continue;

                var images = new List<(HtmlNode Wrapper, string? Caption)>();
                foreach (var item in items)
                {
                    var img = item.SelectSingleNode(".//img");
                    if (img == null) continue;

                    var wrapper = TryBuildGalleryImage(htmlDoc, img);
                    if (wrapper != null)
                        images.Add((wrapper, GetCaptionHtml(item.SelectSingleNode(".//figcaption"))));
                }

                if (images.Count == 0) continue;

                ReplaceWithGhostGalleries(htmlDoc, gallery, images);
                count++;
            }
            return count;
        }

        // =========================================================================
        // Gallery-Typ 2-4: Gutenberg, Jetpack Tiled, CoBlocks — alle <img> des Blocks
        // =========================================================================
        private static int ConvertImageGalleries(HtmlDocument htmlDoc, string xpath)
        {
            var galleryNodes = htmlDoc.DocumentNode.SelectNodes(xpath);
            if (galleryNodes == null) return 0;

            int count = 0;
            foreach (var gallery in galleryNodes.ToList())
            {
                var imgs = gallery.SelectNodes(".//img");
                if (imgs == null || imgs.Count == 0) continue;

                var images = new List<(HtmlNode Wrapper, string? Caption)>();
                foreach (var img in imgs)
                {
                    var wrapper = TryBuildGalleryImage(htmlDoc, img);
                    if (wrapper == null) continue;

                    // Unterschrift des einzelnen Bildes: figcaption seiner eigenen Figure (nicht der Galerie)
                    var imageFigure = img.Ancestors().TakeWhile(a => a != gallery).FirstOrDefault(a => a.Name == "figure");
                    images.Add((wrapper, GetCaptionHtml(imageFigure?.SelectSingleNode(".//figcaption"))));
                }

                if (images.Count == 0) continue;

                ReplaceWithGhostGalleries(htmlDoc, gallery, images);
                count++;
            }
            return count;
        }

        // =========================================================================
        // Galerie-Helfer: Aufteilen, Unterschriften, Wide-Klasse, Bild-Wrapper, Zeilen
        // =========================================================================

        /// <summary>
        /// Ersetzt eine WordPress-Galerie durch Ghost-Karten in der ursprünglichen Bildreihenfolge.
        /// Eine Ghost-Galerie hat nur EINE Unterschrift für alle Bilder; damit jede Unterschrift
        /// bei ihrem Bild bleibt, wird ein Bild mit Unterschrift als eigenes Einzelbild ausgegeben
        /// und die Bilder davor/danach bilden jeweils eigene Galerien (max. 9 Bilder).
        /// </summary>
        private static void ReplaceWithGhostGalleries(HtmlDocument htmlDoc, HtmlNode gallery, List<(HtmlNode Wrapper, string? Caption)> images)
        {
            var parent = gallery.ParentNode;
            if (parent == null) return;

            string? galleryCaption = TakeGalleryCaption(gallery);
            HtmlNode? lastGallery = null;
            var run = new List<HtmlNode>();

            void FlushRun()
            {
                if (run.Count == 1)
                {
                    parent.InsertBefore(BuildImageCard(htmlDoc, run[0], null), gallery);
                }
                else
                {
                    foreach (var chunk in SplitGallery(run))
                    {
                        var ghostGallery = htmlDoc.CreateElement("figure");
                        SetClasses(ghostGallery, "kg-card kg-gallery-card");
                        AddWideClass(ghostGallery, gallery);

                        var container = htmlDoc.CreateElement("div");
                        container.AddClass("kg-gallery-container");
                        AppendGalleryRows(htmlDoc, container, chunk, GalleryImagesPerRow);
                        ghostGallery.AppendChild(container);

                        parent.InsertBefore(ghostGallery, gallery);
                        lastGallery = ghostGallery;
                        _ghostGalleryCount++;
                    }
                }
                run.Clear();
            }

            foreach (var (wrapper, caption) in images)
            {
                if (caption == null)
                {
                    run.Add(wrapper);
                    continue;
                }

                FlushRun();
                parent.InsertBefore(BuildImageCard(htmlDoc, wrapper, caption), gallery);
                _captionedGalleryImages++;
            }
            FlushRun();

            // Unterschrift der ganzen Galerie: an die letzte Teil-Galerie, sonst als Absatz dahinter
            if (galleryCaption != null)
            {
                if (lastGallery != null)
                {
                    var newCaption = htmlDoc.CreateElement("figcaption");
                    newCaption.InnerHtml = galleryCaption;
                    lastGallery.AppendChild(newCaption);
                    lastGallery.AddClass("kg-card-hascaption");
                }
                else
                {
                    var paragraph = htmlDoc.CreateElement("p");
                    paragraph.InnerHtml = galleryCaption;
                    parent.InsertBefore(paragraph, gallery);
                }
            }

            parent.RemoveChild(gallery);
        }

        // Unterschrift der ganzen Galerie: direktes figcaption-Kind (Gutenberg) oder ein
        // figcaption unmittelbar HINTER der Galerie (CoBlocks: class="blocks-gallery-caption").
        private static string? TakeGalleryCaption(HtmlNode gallery)
        {
            var captionNode = gallery.SelectSingleNode("./figcaption");
            if (captionNode == null)
            {
                var next = gallery.NextSibling;
                while (next != null && next.NodeType != HtmlNodeType.Element && string.IsNullOrWhiteSpace(next.InnerText))
                    next = next.NextSibling;
                if (next != null && next.Name == "figcaption")
                    captionNode = next;
            }
            if (captionNode == null) return null;

            string? caption = GetCaptionHtml(captionNode);
            captionNode.Remove();
            return caption;
        }

        private static HtmlNode BuildImageCard(HtmlDocument htmlDoc, HtmlNode galleryImageWrapper, string? captionHtml)
        {
            var figure = htmlDoc.CreateElement("figure");
            SetClasses(figure, "kg-card kg-image-card");

            var img = galleryImageWrapper.SelectSingleNode("./img")!;
            img.Remove();
            figure.AppendChild(img);

            if (!string.IsNullOrEmpty(captionHtml))
            {
                var caption = htmlDoc.CreateElement("figcaption");
                caption.InnerHtml = captionHtml;
                figure.AppendChild(caption);
                figure.AddClass("kg-card-hascaption");
            }
            return figure;
        }

        private static List<List<HtmlNode>> SplitGallery(List<HtmlNode> wrappers)
        {
            var chunks = new List<List<HtmlNode>>();
            for (int i = 0; i < wrappers.Count;)
            {
                int remaining = wrappers.Count - i;
                int take = Math.Min(MaxGalleryImages, remaining);
                // Kein einzelnes Bild als letzte Galerie übrig lassen (10 → 8 + 2)
                if (remaining - take == 1) take--;
                chunks.Add(wrappers.GetRange(i, take));
                i += take;
            }
            return chunks;
        }

        private static void AddWideClass(HtmlNode ghostGallery, HtmlNode originalGallery)
        {
            string origClass = originalGallery.GetAttributeValue("class", "");
            if (origClass.Contains("is-style-wide") || origClass.Contains("alignwide"))
                ghostGallery.AddClass("kg-width-wide");
        }

        private static HtmlNode? TryBuildGalleryImage(HtmlDocument htmlDoc, HtmlNode img)
        {
            string src = GetBestImageUrl(img);
            if (string.IsNullOrEmpty(src)) return null;

            // data:-Bilder (Platzhalter) lassen sich nicht als Galerie-Bild exportieren
            if (src.StartsWith("data:", StringComparison.OrdinalIgnoreCase))
            {
                _skippedGalleryImages++;
                return null;
            }

            return BuildGalleryImage(htmlDoc, img, src);
        }

        private static HtmlNode BuildGalleryImage(HtmlDocument htmlDoc, HtmlNode originalImg, string src)
        {
            var imgWrapper = htmlDoc.CreateElement("div");
            imgWrapper.AddClass("kg-gallery-image");

            var newImg = htmlDoc.CreateElement("img");
            newImg.SetAttributeValue("src", src);

            // Ghost verwirft Galerie-Bilder ohne Breite/Höhe → möglichst die echten Maße der Datei verwenden
            double w = 0, h = 0;

            var realSize = _imageSizeResolver?.Invoke(src);
            if (realSize.HasValue)
            {
                w = realSize.Value.Width;
                h = realSize.Value.Height;
            }

            if (w <= 0 || h <= 0)
            {
                string origSize = originalImg.GetAttributeValue("data-orig-size", "");
                var parts = origSize.Split(',');
                if (parts.Length == 2 &&
                    double.TryParse(parts[0].Trim(), NumberStyles.Float, CultureInfo.InvariantCulture, out double ow) &&
                    double.TryParse(parts[1].Trim(), NumberStyles.Float, CultureInfo.InvariantCulture, out double oh))
                {
                    w = ow;
                    h = oh;
                }
            }

            if (w <= 0 || h <= 0)
            {
                if (double.TryParse(originalImg.GetAttributeValue("width", ""), NumberStyles.Float, CultureInfo.InvariantCulture, out double aw) &&
                    double.TryParse(originalImg.GetAttributeValue("height", ""), NumberStyles.Float, CultureInfo.InvariantCulture, out double ah))
                {
                    w = aw;
                    h = ah;
                }
            }

            // Maße unbekannt (z.B. extern eingebundenes Bild): 3:2 annehmen, statt das Bild zu verlieren
            if (w <= 0 || h <= 0)
            {
                w = 1200;
                h = 800;
            }

            newImg.SetAttributeValue("width", ((int)w).ToString(CultureInfo.InvariantCulture));
            newImg.SetAttributeValue("height", ((int)h).ToString(CultureInfo.InvariantCulture));
            string ratio = (w / h).ToString("G6", CultureInfo.InvariantCulture);
            imgWrapper.SetAttributeValue("style", $"flex: {ratio} 1 0%;");

            newImg.SetAttributeValue("loading", "lazy");
            newImg.SetAttributeValue("alt", originalImg.GetAttributeValue("alt", ""));

            imgWrapper.AppendChild(newImg);
            return imgWrapper;
        }

        private static void AppendGalleryRows(HtmlDocument htmlDoc, HtmlNode container, List<HtmlNode> wrappers, int columns)
        {
            for (int i = 0; i < wrappers.Count; i += columns)
            {
                var row = htmlDoc.CreateElement("div");
                row.AddClass("kg-gallery-row");

                int end = Math.Min(i + columns, wrappers.Count);
                for (int j = i; j < end; j++)
                    row.AppendChild(wrappers[j]);

                container.AppendChild(row);
            }
        }


        // =========================================================================
        // Helper: Beste Bild-URL aus img-Element holen
        // Priorität: data-orig-file → data-large-file → srcset (letzter/Widest) → src
        // =========================================================================
        private static string GetBestImageUrl(HtmlNode img)
        {
            // 1. data-orig-file (Vollbild)
            string src = img.GetAttributeValue("data-orig-file", "");
            if (!string.IsNullOrEmpty(src)) return src;

            // 2. data-large-file
            src = img.GetAttributeValue("data-large-file", "");
            if (!string.IsNullOrEmpty(src)) return src;

            // 3. srcset (größte Variante nehmen)
            string srcset = img.GetAttributeValue("srcset", "");
            if (!string.IsNullOrEmpty(srcset))
            {
                src = GetLargestFromSrcset(srcset);
                if (!string.IsNullOrEmpty(src)) return src;
            }

            // 4. src (Fallback)
            return img.GetAttributeValue("src", "");
        }

        private static string GetLargestFromSrcset(string srcset)
        {
            string bestUrl = "";
            int bestWidth = 0;

            foreach (string part in srcset.Split(',', StringSplitOptions.RemoveEmptyEntries))
            {
                string trimmed = part.Trim();
                string[] tokens = trimmed.Split(' ', StringSplitOptions.RemoveEmptyEntries);
                if (tokens.Length < 2) continue;

                string url = tokens[0];
                string descriptor = tokens[1];

                if (int.TryParse(descriptor.Replace("w", ""), out int width) && width > bestWidth)
                {
                    bestWidth = width;
                    bestUrl = url;
                }
            }

            return bestUrl;
        }

        // =========================================================================
        // Einzelbilder (nicht in Galerien)
        // =========================================================================
        private static void ConvertSingleImages(HtmlDocument htmlDoc)
        {
            var singleImgNodes = htmlDoc.DocumentNode.SelectNodes("//img");
            if (singleImgNodes == null) return;

            foreach (var img in singleImgNodes.ToList())
            {
                if (img.Ancestors("figure").Any(a => HasClass(a, "kg-gallery-card")))
                    continue;

                string src = GetBestImageUrl(img);
                if (string.IsNullOrEmpty(src)) continue;

                // Beste Variante als src setzen; srcset/sizes verweisen auf WordPress-Größenvarianten
                img.SetAttributeValue("src", src);
                img.Attributes.Remove("srcset");
                img.Attributes.Remove("sizes");

                var parentFigure = img.Ancestors("figure").FirstOrDefault();
                if (parentFigure != null)
                {
                    bool hasCaption = GetCaptionHtml(parentFigure.SelectSingleNode("./figcaption")) != null;
                    SetClasses(parentFigure, hasCaption ? "kg-card kg-image-card kg-card-hascaption" : "kg-card kg-image-card");
                    img.AddClass("kg-image");
                }
                else
                {
                    var wrapper = htmlDoc.CreateElement("figure");
                    SetClasses(wrapper, "kg-card kg-image-card");
                    img.AddClass("kg-image");

                    var imgParent = img.ParentNode;
                    if (imgParent != null)
                    {
                        imgParent.InsertBefore(wrapper, img);
                        imgParent.RemoveChild(img);
                        wrapper.AppendChild(img);
                    }
                }
            }
        }

        // =========================================================================
        // Figure ohne kg-card → kg-width-wide
        // =========================================================================
        private static void ConvertFigures(HtmlDocument htmlDoc)
        {
            var figures = htmlDoc.DocumentNode.SelectNodes("//figure");
            if (figures == null) return;

            foreach (var figure in figures.ToList())
            {
                if (HasClass(figure, "kg-card")) continue;
                SetClasses(figure, "kg-width-wide kg-card-width-wide");
            }
        }

        // =========================================================================
        // WP-Klassen mappen
        // =========================================================================
        private static void ConvertWpClasses(HtmlDocument htmlDoc)
        {
            var allNodes = htmlDoc.DocumentNode.SelectNodes("//*[contains(@class, 'wp-block')]");
            if (allNodes == null) return;

            foreach (var node in allNodes.ToList())
            {
                string classes = node.GetAttributeValue("class", "");
                if (string.IsNullOrEmpty(classes)) continue;

                var classList = classes.Split(' ', StringSplitOptions.RemoveEmptyEntries).ToList();
                var newClasses = new List<string>();
                bool changed = false;

                foreach (string cls in classList)
                {
                    if (WpClassMap.TryGetValue(cls, out string? ghostClass))
                    {
                        changed = true;
                        if (ghostClass != null && ghostClass.Length > 0)
                            newClasses.AddRange(ghostClass.Split(' '));
                    }
                    else
                    {
                        newClasses.Add(cls);
                    }
                }

                if (changed)
                {
                    string finalClasses = string.Join(" ", newClasses.Where(c => c.Length > 0).Distinct());
                    if (finalClasses.Length > 0)
                        node.SetAttributeValue("class", finalClasses);
                    else
                        node.Attributes.Remove("class");
                }
            }

            // Separator
            var separators = htmlDoc.DocumentNode.SelectNodes("//div[contains(@class, 'wp-block-separator')]");
            if (separators != null)
            {
                foreach (var sep in separators.ToList())
                {
                    var hr = htmlDoc.CreateElement("hr");
                    foreach (var attr in sep.Attributes)
                        hr.SetAttributeValue(attr.Name, attr.Value);
                    sep.ParentNode?.ReplaceChild(hr, sep);
                }
            }
        }

        // =========================================================================
        // Externe Links mit target="_blank" versehen
        // =========================================================================
        private static void AddTargetBlankToExternalLinks(HtmlDocument htmlDoc)
        {
            var anchors = htmlDoc.DocumentNode.SelectNodes("//a[@href]");
            if (anchors == null) return;

            foreach (var anchor in anchors.ToList())
            {
                string href = anchor.GetAttributeValue("href", "").Trim();
                if (string.IsNullOrEmpty(href)) continue;

                // Nur absolute externe URLs (http/https)
                if (href.StartsWith("http://") || href.StartsWith("https://"))
                {
                    anchor.SetAttributeValue("target", "_blank");
                    anchor.SetAttributeValue("rel", "noopener noreferrer");
                }
            }
        }

        private static bool HasClass(HtmlNode node, string className)
        {
            string classes = node.GetAttributeValue("class", "");
            return classes.Split(' ', StringSplitOptions.RemoveEmptyEntries)
                          .Any(c => c.Equals(className, StringComparison.OrdinalIgnoreCase));
        }

        private static void SetClasses(HtmlNode node, string classes)
        {
            node.SetAttributeValue("class", classes);
        }
    }
}