Improve video and image handling in markdown

WebsiteGenerator/Templates/Elements/PageImageTemplate.swift

@@ -0,0 +1,18 @@
+import Foundation
+
+struct PageImageTemplate: Template {
+
+    enum Key: String, CaseIterable {
+        case image = "IMAGE"
+        case image2x = "IMAGE_2X"
+        case width = "WIDTH"
+        case height = "HEIGHT"
+        case leftText = "LEFT_TEXT"
+        case rightText = "RIGHT_TEXT"
+    }
+
+    static let templateName = "image.html"
+
+    let raw: String
+
+}

WebsiteGenerator/Templates/Elements/PageVideoTemplate.swift

@@ -0,0 +1,37 @@
+import Foundation
+
+struct PageVideoTemplate: Template {
+
+    typealias VideoSource = (url: String, type: VideoType)
+
+    enum Key: String, CaseIterable {
+        case options = "OPTIONS"
+        case sources = "SOURCES"
+    }
+
+    enum VideoOption: String {
+        case controls
+        case autoplay
+        case muted
+        case loop
+        case playsinline
+        case poster
+        case preload
+    }
+
+    static let templateName = "video.html"
+
+    let raw: String
+
+    func generate<T>(sources: [VideoSource], options: T) -> String where T: Sequence, T.Element == VideoOption {
+        let sourcesCode = sources.map(makeSource).joined(separator: "\n")
+        let optionCode = options.map { $0.rawValue }.joined(separator: " ")
+        return generate([.sources: sourcesCode, .options: optionCode])
+    }
+
+    private func makeSource(_ source: VideoSource) -> String {
+        """
+        <source src="\(source.url)" type="\(source.type.htmlType)">
+        """
+    }
+}