[MBL-2883] RichText parsing and conversion to Swift-friendly normalized types

ServerDrivenUI/Sources/ServerDrivenUI/RichTextElement.swift

@@ -0,0 +1,104 @@
+import Foundation
+import GraphAPI
+
+/// Represents a single block-level element in a RichText list. Used to make implementing
+/// the different views in SwiftUI more easily and with a consistent interface.
+public indirect enum RichTextElement {
+  case text(Text, HeaderLevel?)
+  case listItemOpen
+  case listItemClose
+  case listItem(Text)
+  case audio(Audio)
+  case photo(Photo)
+  case video(Video)
+  case oembed(Oembed)
+
+  public struct Text {
+    let text: String
+    let link: URL?
+    let styles: [Style]
+    let children: [RichTextElement]
+
+    public enum Style: String {
+      case strong = "STRONG"
+      case emphasis = "EMPHASIS"
+      case heading1 = "HEADING_1"
+      case heading2 = "HEADING_2"
+      case heading3 = "HEADING_3"
+      case heading4 = "HEADING_4"
+
+      public init?(rawValue: String) {
+        switch rawValue {
+        case "STRONG":
+          self = .strong
+        case "EMPHASIS":
+          self = .emphasis
+        case "HEADING_1":
+          self = .heading1
+        case "HEADING_2":
+          self = .heading2
+        case "HEADING_3":
+          self = .heading3
+        case "HEADING_4":
+          self = .heading4
+        default:
+          assertionFailure("unknown style type: \(rawValue)")
+          return nil
+        }
+      }
+    }
+  }
+
+  public enum HeaderLevel: String {
+    case one = "HEADING_1"
+    case two = "HEADING_2"
+    case three = "HEADING_3"
+    case four = "HEADING_4"
+
+    init?(_ rawValues: [String]?) {
+      for rawValue in rawValues ?? [] {
+        if let level = HeaderLevel(rawValue: rawValue) {
+          self = level
+          return
+        }
+      }
+      return nil
+    }
+  }
+
+  public struct Audio {
+    let altText: String?
+    let assetID: String?
+    let caption: String?
+    let url: String?
+  }
+
+  public struct Photo {
+    let altText: String?
+    let assetID: String?
+    let caption: String?
+    let url: String?
+  }
+
+  public struct Video {
+    let altText: String?
+    let assetID: String?
+    let caption: String?
+    let url: String?
+  }
+
+  public struct Oembed {
+    let width: Int
+    let height: Int
+    let version: String
+    let title: String
+    let type: String
+
+    let iframeUrl: String?
+    let originalUrl: String?
+
+    let thumbnailUrl: String?
+    let thumbnailWidth: Int?
+    let thumbnailHeight: Int?
+  }
+}