Add support for <details> and <summary> tags (#6077)

ElementX/Sources/Other/HTMLParsing/AttributedStringBuilder.swift

@@ -24,6 +24,7 @@ nonisolated protocol MentionBuilderProtocol: Sendable {
 
 nonisolated extension NSAttributedString.Key {
     static let MatrixBlockquote: NSAttributedString.Key = .init(rawValue: BlockquoteAttribute.name)
+    static let MatrixDetails: NSAttributedString.Key = .init(rawValue: DetailsAttribute.name)
     static let MatrixUserID: NSAttributedString.Key = .init(rawValue: UserIDAttribute.name)
     static let MatrixUserDisplayName: NSAttributedString.Key = .init(rawValue: UserDisplayNameAttribute.name)
     static let MatrixRoomDisplayName: NSAttributedString.Key = .init(rawValue: RoomDisplayNameAttribute.name)
@@ -203,6 +204,22 @@ nonisolated struct AttributedStringBuilder: AttributedStringBuilderProtocol {
                 content = attributedString(element: childElement, documentBody: documentBody, preserveFormatting: preserveFormatting, listTag: listTag, listIndex: &childIndex, indentLevel: indentLevel)
                 content.addAttribute(.MatrixBlockquote, value: true, range: NSRange(location: 0, length: content.length))
                 
+            case "details":
+                // Pull the summary out of the tree so that it isn't rendered inline with the content,
+                // it is used as the title of the collapsed component instead.
+                let summaryElement = childElement.getChildNodes()
+                    .lazy
+                    .compactMap { $0 as? Element }
+                    .first { $0.tagName().lowercased() == "summary" }
+                let summary = summaryElement.flatMap { try? $0.text() } ?? ""
+                try? summaryElement?.remove()
+                
+                content = attributedString(element: childElement, documentBody: documentBody, preserveFormatting: preserveFormatting, listTag: listTag, listIndex: &childIndex, indentLevel: indentLevel)
+                
+                // Browsers fall back to a default title when the summary is missing, match them.
+                let title = summary.isEmpty ? L10n.a11yViewDetails : summary
+                content.addAttribute(.MatrixDetails, value: title, range: NSRange(location: 0, length: content.length))
+                
             case "code", "pre":
                 let isCodeBlock = tag == "pre"
                 

ElementX/Sources/Other/HTMLParsing/AttributedStringBuilderProtocol.swift

@@ -9,10 +9,11 @@
 import Foundation
 
 nonisolated struct AttributedStringBuilderComponent: Hashable, Identifiable {
-    enum ComponentType {
+    enum ComponentType: Hashable {
         case plainText
         case blockquote
         case codeBlock
+        case details(summary: String)
     }
     
     /// Identifier for the `Identifiable` conformance, allows edits to the `FormattedBodyText` to animate seamlessly

ElementX/Sources/Other/HTMLParsing/ElementXAttributeScope.swift

@@ -8,11 +8,6 @@
 
 import Foundation
 
-enum BlockquoteAttribute: AttributedStringKey {
-    typealias Value = Bool
-    static let name = "MXBlockquoteAttribute"
-}
-
 enum UserIDAttribute: AttributedStringKey {
     typealias Value = String
     static let name = "MXUserIDAttribute"
@@ -65,6 +60,17 @@ enum AllUsersMentionAttribute: AttributedStringKey {
     static let name = "MXAllUsersMentionAttribute"
 }
 
+enum BlockquoteAttribute: AttributedStringKey {
+    typealias Value = Bool
+    static let name = "MXBlockquoteAttribute"
+}
+
+/// Marks the content of a `<details>` element, carrying its `<summary>` as the value.
+enum DetailsAttribute: AttributedStringKey {
+    typealias Value = String
+    static let name = "MXDetailsAttribute"
+}
+
 enum CodeBlockAttribute: AttributedStringKey {
     typealias Value = Bool
     static let name = "MXCodeBlockAttribute"
@@ -78,6 +84,7 @@ enum InlineCodeAttribute: AttributedStringKey {
 nonisolated extension AttributeScopes {
     struct ElementXAttributes: AttributeScope {
         let blockquote: BlockquoteAttribute
+        let details: DetailsAttribute
         
         let userID: UserIDAttribute
         // periphery:ignore - required to make NSAttributedString to AttributedString conversion even if not used directly

ElementX/Sources/Other/HTMLParsing/HTMLFixtures.swift

@@ -19,6 +19,7 @@ nonisolated enum HTMLFixtures: String, CaseIterable {
     case wideCodeBlock
     case unorderedList
     case orderedList
+    case details
     
     var rawValue: String {
         switch self {
@@ -123,6 +124,13 @@ nonisolated enum HTMLFixtures: String, CaseIterable {
             <li>Skittles</li>
             </ol>
             """
+        case .details:
+            """
+            Text before the details\
+            <details><summary>Expand me</summary><p>Hidden <b>content</b> with a <a href="https://www.matrix.org">link</a> in it.</p></details>\
+            <details><p>These details have no summary.</p></details>\
+            Text after the details
+            """
         }
     }
 }