Refactor page content generators

CHDataManagement/Generator/Commands/SvgCommand.swift

@@ -0,0 +1,52 @@
+
+struct SvgCommand: CommandProcessor {
+
+    static let commandType: CommandType = .svg
+
+    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
+    }
+
+    func process(_ arguments: [String], markdown: Substring) -> String {
+        guard arguments.count == 5 else {
+            invalid(markdown)
+            return ""
+        }
+
+        guard let x = Int(arguments[1]),
+              let y = Int(arguments[2]),
+              let partWidth = Int(arguments[3]),
+              let partHeight = Int(arguments[4]) else {
+            invalid(markdown)
+            return ""
+        }
+
+        let imageId = arguments[0]
+
+        guard let image = content.image(imageId) else {
+            results.missing(file: imageId, source: "SVG command")
+            return ""
+        }
+        guard image.type == .svg else {
+            invalid(markdown)
+            return ""
+        }
+
+        return PartialSvgImage(
+            imagePath: image.absoluteUrl,
+            altText: image.localized(in: language),
+            x: x,
+            y: y,
+            width: partWidth,
+            height: partHeight)
+        .content
+    }
+}