Add tag command

CHDataManagement/Generator/PageContentGenerator.swift

@@ -252,9 +252,8 @@ final class PageContentParser {
             return handleSvg(arguments, markdown: markdown)
         case .audioPlayer:
             return audioPlayer.process(arguments, markdown: markdown)
-        default:
-            results.invalid(command: nil, markdown)
-            return ""
+        case .tagLink:
+            return handleTagLink(arguments, markdown: markdown)
         }
     }
 
@@ -439,6 +438,45 @@ final class PageContentParser {
             .content
     }
 
+    /**
+     Format: `![tag](<tagId>)`
+     */
+    private func handleTagLink(_ arguments: [String], markdown: Substring) -> String {
+        guard arguments.count == 1 else {
+            results.invalid(command: .tagLink, markdown)
+            return ""
+        }
+        let tagId = arguments[0]
+
+        guard let tag = content.tag(tagId) else {
+            results.missing(tag: tagId, markdown: markdown)
+            return ""
+        }
+
+        let localized = tag.localized(in: language)
+        let url = tag.absoluteUrl(for: language)
+        let title = localized.name
+        let description = localized.description ?? ""
+
+        let image = localized.linkPreviewImage.map { image in
+            let size = content.settings.pages.pageLinkImageSize
+            results.files.insert(image)
+            results.imagesToGenerate.insert(.init(size: size, image: image))
+
+            return RelatedPageLink.Image(
+                url: image.absoluteUrl,
+                description: image.getDescription(for: language),
+                size: size)
+        }
+
+        return RelatedPageLink(
+            title: title,
+            description: description,
+            url: url,
+            image: image)
+            .content
+    }
+
     /**
      Format: `![model](<file>)`
      */

CHDataManagement/Generator/ShorthandMarkdownKey.swift

@@ -5,10 +5,6 @@ import Foundation
  */
 enum ShorthandMarkdownKey: String {
 
-    /// A standard url
-    /// Format:  `![url](<url>;<text>)`
-    case url
-
     /// An image
     /// Format:  `![image](<imageId>;<caption?>]`
     case image
@@ -37,6 +33,10 @@ enum ShorthandMarkdownKey: String {
     /// Format: `![page](<pageId>)`
     case pageLink = "page"
 
+    /// A pretty link to a tag list on the site.
+    /// Format: `![tag](<tagId>)`
+    case tagLink = "tag"
+
     /// Additional HTML code include verbatim into the page.
     /// Format: `![html](<fileId>)`
     case includedHtml = "html"