Decode percent encodings for markdown images

Sources/Generator/Extensions/String+Extensions.swift

@@ -67,10 +67,21 @@ extension String {
 
 extension Substring {
 
+    func dropBeforeFirst(_ separator: String) -> String {
+        guard contains(separator) else {
+            return String(self)
+        }
+        return components(separatedBy: separator).dropFirst().joined(separator: separator)
+    }
+
     func between(_ start: String, and end: String) -> String {
         components(separatedBy: start).last!
             .components(separatedBy: end).first!
     }
+
+    func between(first: String, andLast last: String) -> String {
+        dropBeforeFirst(first).dropAfterLast(last)
+    }
 }
 
 extension String {

Sources/Generator/Generators/PageContentGenerator.swift

@@ -87,8 +87,11 @@ struct PageContentGenerator {
         // For a simple boxes: ![box](title;body)
         // A fancy page link: ![page](page_id)
         // External pages: ![external](url1, text1; url2, text2, ...)
-        let fileAndTitle = markdown.between("(", and: ")")
+        guard let fileAndTitle = markdown.between(first: "](", andLast: ")").removingPercentEncoding else {
-        let alt = markdown.between("[", and: "]").nonEmpty
+            results.warning("Invalid percent encoding for markdown image", source: page.path)
+            return ""
+        }
+        let alt = markdown.between("[", and: "]").nonEmpty?.removingPercentEncoding
         if let alt = alt, let command = ShorthandMarkdownKey(rawValue: alt) {
             return handleShortHandCommand(command, page: page, language: language, content: fileAndTitle)
         }
@@ -250,7 +253,7 @@ struct PageContentGenerator {
             .compactMap { button -> (file: String, text: String, downloadName: String?)? in
                 let parts = button.components(separatedBy: ",")
                 guard parts.count == 2 || parts.count == 3 else {
-                    results.warning("Invalid button definition", source: page.path)
+                    results.warning("Invalid download definition with \(parts)", source: page.path)
                     return nil
                 }
                 let file = parts[0].trimmed