Add all video versions for video input

Sources/Generator/Files/VideoType.swift

@@ -3,6 +3,7 @@ import Foundation
 enum VideoType: String, CaseIterable {
     case mp4
     case m4v
+    case webm
 
     var htmlType: String {
         switch self {
@@ -10,6 +11,8 @@ enum VideoType: String, CaseIterable {
             return "video/mp4"
         case .m4v:
             return "video/mp4"
+        case .webm:
+            return "video/webm"
         }
     }
 }

Sources/Generator/Generators/PageContentGenerator.swift

@@ -201,14 +201,43 @@ struct PageContentGenerator {
                 return option
             }
         } ?? []
-        // TODO: Check page folder for alternative video versions
-        let sources: [PageVideoTemplate.VideoSource] = [(url: file, type: .mp4)]
 
-        let filePath = page.pathRelativeToRootForContainedInputFile(file)
+        let prefix = file.lastComponentAfter("/").dropAfterLast(".")
-        results.require(file: filePath, source: page.path)
+
+        // Find all video files starting with the name of the video as a prefix
+        var sources: [PageVideoTemplate.VideoSource] = []
+        do {
+            let folder = results.contentFolder.appendingPathComponent(page.path)
+            let filesInFolder = try FileManager.default.contentsOfDirectory(atPath: folder.path)
+            sources += selectVideoFiles(with: prefix, from: filesInFolder)
+        } catch {
+            results.warning("Failed to check for additional videos", source: page.path)
+        }
+        // Also look in external files
+        sources += selectVideoFiles(with: prefix, from: page.externalFiles)
+
+        // Require all video files
+        sources.forEach {
+            let path = page.pathRelativeToRootForContainedInputFile($0.url)
+            results.require(file: path, source: page.path)
+        }
+        // Sort, so that order of selection in browser is defined
+        sources.sort { $0.url < $1.url }
         return factory.video.generate(sources: sources, options: options)
     }
 
+    private func selectVideoFiles<T>(with prefix: String, from all: T) -> [PageVideoTemplate.VideoSource] where T: Sequence, T.Element == String {
+        all.compactMap {
+                guard $0.lastComponentAfter("/").hasPrefix(prefix) else {
+                    return nil
+                }
+                guard let type = VideoType(rawValue: $0.lastComponentAfter(".").lowercased()) else {
+                    return nil
+                }
+                return (url: $0, type: type)
+            }
+    }
+
     private func handleGif(page: Element, file: String, altText: String) -> String {
         let imagePath = page.pathRelativeToRootForContainedInputFile(file)
         results.require(file: imagePath, source: page.path)