Refactor page content generators

CHDataManagement/Generator/Commands/ImageCommand.swift

@@ -0,0 +1,66 @@
+
+struct ImageCommand: CommandProcessor {
+
+    static let commandType: CommandType = .image
+
+    let content: Content
+
+    let results: PageGenerationResults
+
+    let language: ContentLanguage
+
+    init(content: Content, results: PageGenerationResults, language: ContentLanguage) {
+        self.content = content
+        self.results = results
+        self.language = language
+    }
+
+    private var thumbnailWidth: Int {
+        content.settings.pages.contentWidth
+    }
+
+    private var largeImageWidth: Int {
+        content.settings.pages.largeImageWidth
+    }
+
+    /**
+     Format: `![image](<imageId>;<caption?>]`
+     */
+    func process(_ arguments: [String], markdown: Substring) -> String {
+        guard (1...2).contains(arguments.count) else {
+            invalid(markdown)
+            return ""
+        }
+        let imageId = arguments[0]
+
+        guard let image = content.image(imageId) else {
+            results.missing(file: imageId, source: "Image command")
+            return ""
+        }
+        results.used(file: image)
+
+        if image.type == .svg || image.type == .gif {
+            return simple(image: image)
+        }
+
+        let thumbnail = image.imageSet(width: thumbnailWidth, height: thumbnailWidth, language: language)
+        results.require(imageSet: thumbnail)
+
+        let largeImage = image.imageSet(width: largeImageWidth, height: largeImageWidth, language: language)
+        results.require(imageSet: largeImage)
+
+        let caption = arguments.count == 2 ? arguments[1] : nil
+        return PageImage(
+            imageId: imageId.replacingOccurrences(of: ".", with: "-"),
+            thumbnail: thumbnail,
+            largeImage: largeImage,
+            caption: caption).content
+    }
+
+    private func simple(image: FileResource) -> String {
+        results.require(file: image)
+        let path = image.absoluteUrl
+        let altText = image.localized(in: language)
+        return SimpleImage(imagePath: path, altText: altText).content
+    }
+}