Move the initial attributed string builder to its own file

ElementX.xcodeproj/project.pbxproj

@@ -148,6 +148,8 @@
 		18386B777FDA74E4B3282D4F /* TimelineItemThreadSummary.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98C6A082F2B2A15E1B9BE280 /* TimelineItemThreadSummary.swift */; };
 		18867F4F1C8991EEC56EA932 /* UTType.swift in Sources */ = {isa = PBXBuildFile; fileRef = 897DF5E9A70CE05A632FC8AF /* UTType.swift */; };
 		18978C9438206828C1D5AF2A /* test_animated_image.gif in Resources */ = {isa = PBXBuildFile; fileRef = 53FD6D3D38F556CEAA280C58 /* test_animated_image.gif */; };
+		18DB2F782E572636003155CF /* AttributedStringBuilderV1.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18DB2F772E57262F003155CF /* AttributedStringBuilderV1.swift */; };
+		18DB2F792E572636003155CF /* AttributedStringBuilderV1.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18DB2F772E57262F003155CF /* AttributedStringBuilderV1.swift */; };
 		18E3786918486D4C9726BC84 /* FormButtonStyles.swift in Sources */ = {isa = PBXBuildFile; fileRef = 89FBFC09F9DAFF1E4BA97849 /* FormButtonStyles.swift */; };
 		18FDE4ED6D83B0771452B43D /* RoomSelectionScreenCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = F104596B0620CEFE5DFD31B1 /* RoomSelectionScreenCoordinator.swift */; };
 		192A3CDCD0174AD1E4A128E4 /* AudioRecorderTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2441E2424E78A40FC95DBA76 /* AudioRecorderTests.swift */; };
@@ -1607,6 +1609,7 @@
 		18486B87745B1811E7FBD3D2 /* AnalyticsPromptScreenModels.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AnalyticsPromptScreenModels.swift; sourceTree = "<group>"; };
 		184CF8C196BE143AE226628D /* DecorationTimelineItemProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DecorationTimelineItemProtocol.swift; sourceTree = "<group>"; };
 		18B223FA339BF53085328DEE /* SpaceScreenViewModelTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SpaceScreenViewModelTests.swift; sourceTree = "<group>"; };
+		18DB2F772E57262F003155CF /* AttributedStringBuilderV1.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AttributedStringBuilderV1.swift; sourceTree = "<group>"; };
 		18F2958E6D247AE2516BEEE8 /* ClientProxy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ClientProxy.swift; sourceTree = "<group>"; };
 		190EC7285D3CFEF0D3011BCF /* GeoURI.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GeoURI.swift; sourceTree = "<group>"; };
 		196004E7695FBA292A7944AF /* ScreenTrackerViewModifier.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ScreenTrackerViewModifier.swift; sourceTree = "<group>"; };
@@ -5041,6 +5044,7 @@
 		8F9A844EB44B6AD7CA18FD96 /* HTMLParsing */ = {
 			isa = PBXGroup;
 			children = (
+				18DB2F772E57262F003155CF /* AttributedStringBuilderV1.swift */,
 				2A5C6FBF97B6EED3D4FA5EFF /* AttributedStringBuilder.swift */,
 				72F37B5DA798C9AE436F2C2C /* AttributedStringBuilderProtocol.swift */,
 				1E508AB0EDEE017FF4F6F8D1 /* DTHTMLElement+AttributedStringBuilder.swift */,
@@ -7178,6 +7182,7 @@
 				761EA50B2619307AB30891B8 /* PhishingDetector.swift in Sources */,
 				5DFC2A889D3B39DD47AC63A8 /* PillUtilities.swift in Sources */,
 				55CDD3968D95D1A820B5491E /* PlaceholderAvatarImage.swift in Sources */,
+				18DB2F782E572636003155CF /* AttributedStringBuilderV1.swift in Sources */,
 				F12F6BED7B6D7EE4BEE55039 /* PlainMentionBuilder.swift in Sources */,
 				76C874243A8C440D6CF7B344 /* ProcessInfo.swift in Sources */,
 				88272A714D81BC507F76A1EE /* RageshakeConfiguration.swift in Sources */,
@@ -7672,6 +7677,7 @@
 				F3F9D61C53C348043D3D6F51 /* EncryptionResetScreen.swift in Sources */,
 				3041EBA2660F28FFB7BDA339 /* EncryptionResetScreenCoordinator.swift in Sources */,
 				97BAEDD9054FB5F233EE928B /* EncryptionResetScreenModels.swift in Sources */,
+				18DB2F792E572636003155CF /* AttributedStringBuilderV1.swift in Sources */,
 				EC3320639828BED8B3E5F2C6 /* EncryptionResetScreenViewModel.swift in Sources */,
 				A0868BDE84D2140A885BE3C9 /* EncryptionResetScreenViewModelProtocol.swift in Sources */,
 				4D2B54233C7B2C04B4ABE55A /* EncryptionSettingsFlowCoordinator.swift in Sources */,

ElementX/Sources/Other/HTMLParsing/AttributedStringBuilder.swift

@@ -47,402 +47,3 @@ struct AttributedStringBuilder: AttributedStringBuilderProtocol {
         builder.addMatrixEntityPermalinkAttributesTo(attributedString)
     }
 }
-
-private struct AttributedStringBuilderV1: AttributedStringBuilderProtocol {
-    private let cacheKey: String
-    private let temporaryBlockquoteMarkingColor = UIColor.magenta
-    private let temporaryCodeBlockMarkingColor = UIColor.cyan
-    private let mentionBuilder: MentionBuilderProtocol
-    
-    private static let cacheDispatchQueue = DispatchQueue(label: "io.element.elementx.attributed_string_builder_cache")
-    private static var caches: [String: LRUCache<String, AttributedString>] = [:]
-
-    static func invalidateCaches() {
-        caches.removeAll()
-    }
-    
-    init(cacheKey: String, mentionBuilder: MentionBuilderProtocol) {
-        self.cacheKey = cacheKey
-        self.mentionBuilder = mentionBuilder
-    }
-        
-    func fromPlain(_ string: String?) -> AttributedString? {
-        guard let string else {
-            return nil
-        }
-        
-        if let cached = Self.cachedValue(forKey: string, cacheKey: cacheKey) {
-            return cached
-        }
-
-        let mutableAttributedString = NSMutableAttributedString(string: string)
-        removeDefaultForegroundColors(mutableAttributedString)
-        addLinksAndMentions(mutableAttributedString)
-        addMatrixEntityPermalinkAttributesTo(mutableAttributedString)
-        
-        let result = try? AttributedString(mutableAttributedString, including: \.elementX)
-        Self.cacheValue(result, forKey: string, cacheKey: cacheKey)
-        
-        return result
-    }
-        
-    // Do not use the default HTML renderer of NSAttributedString because this method
-    // runs on the UI thread which we want to avoid because renderHTMLString is called
-    // most of the time from a background thread.
-    // Use DTCoreText HTML renderer instead.
-    // Using DTCoreText, which renders static string, helps to avoid code injection attacks
-    // that could happen with the default HTML renderer of NSAttributedString which is a
-    // webview.
-    func fromHTML(_ htmlString: String?) -> AttributedString? {
-        guard let originalHTMLString = htmlString else {
-            return nil
-        }
-        
-        if let cached = Self.cachedValue(forKey: originalHTMLString, cacheKey: cacheKey) {
-            return cached
-        }
-                
-        let htmlString = originalHTMLString.replacingHtmlBreaksOccurrences()
-        
-        guard let data = htmlString.data(using: .utf8) else {
-            return nil
-        }
-        
-        let defaultFont = UIFont.preferredFont(forTextStyle: .body)
-        
-        let parsingOptions: [String: Any] = [
-            DTUseiOS6Attributes: true,
-            DTDefaultFontFamily: defaultFont.familyName,
-            DTDefaultFontName: defaultFont.fontName,
-            DTDefaultFontSize: defaultFont.pointSize,
-            DTDefaultStyleSheet: DTCSSStylesheet(styleBlock: defaultCSS) as Any,
-            DTDefaultLinkDecoration: false
-        ]
-        
-        guard let builder = DTHTMLAttributedStringBuilder(html: data, options: parsingOptions, documentAttributes: nil) else {
-            return nil
-        }
-        
-        builder.willFlushCallback = { element in
-            element?.sanitize(font: defaultFont)
-        }
-            
-        guard let attributedString = builder.generatedAttributedString() else {
-            return nil
-        }
-        
-        let mutableAttributedString = NSMutableAttributedString(attributedString: attributedString)
-        removeDefaultForegroundColors(mutableAttributedString)
-        detectPhishingAttempts(mutableAttributedString)
-        addLinksAndMentions(mutableAttributedString)
-        replaceMarkedBlockquotes(mutableAttributedString)
-        replaceMarkedCodeBlocks(mutableAttributedString)
-        addMatrixEntityPermalinkAttributesTo(mutableAttributedString)
-        removeDTCoreTextArtifacts(mutableAttributedString)
-        
-        let result = try? AttributedString(mutableAttributedString, including: \.elementX)
-        Self.cacheValue(result, forKey: htmlString, cacheKey: cacheKey)
-        
-        return result
-    }
-    
-    // MARK: - Private
-    
-    private static func cacheValue(_ value: AttributedString?, forKey key: String, cacheKey: String) {
-        cacheDispatchQueue.sync {
-            if caches[cacheKey] == nil {
-                caches[cacheKey] = LRUCache<String, AttributedString>(countLimit: 1000)
-            }
-            
-            caches[cacheKey]?.setValue(value, forKey: key)
-        }
-    }
-    
-    private static func cachedValue(forKey key: String, cacheKey: String) -> AttributedString? {
-        var result: AttributedString?
-        cacheDispatchQueue.sync {
-            result = caches[cacheKey]?.value(forKey: key)
-        }
-        
-        return result
-    }
-    
-    private func removeDefaultForegroundColors(_ attributedString: NSMutableAttributedString) {
-        attributedString.removeAttribute(.foregroundColor, range: .init(location: 0, length: attributedString.length))
-    }
-    
-    // swiftlint:disable:next cyclomatic_complexity
-    private func addLinksAndMentions(_ attributedString: NSMutableAttributedString) {
-        let string = attributedString.string
-        
-        // Event identifiers and room aliases and identifiers detected in plain text are techincally incomplete
-        // without via parameters and we won't bother detecting them
-        
-        var matches: [TextParsingMatch] = MatrixEntityRegex.userIdentifierRegex.matches(in: string).compactMap { match in
-            guard let matchRange = Range(match.range, in: string) else {
-                return nil
-            }
-            
-            let identifier = String(string[matchRange])
-
-            return TextParsingMatch(type: .userID(identifier: identifier), range: match.range)
-        }
-        
-        matches.append(contentsOf: MatrixEntityRegex.roomAliasRegex.matches(in: string).compactMap { match in
-            guard let matchRange = Range(match.range, in: string) else {
-                return nil
-            }
-            
-            let alias = String(string[matchRange])
-            
-            return TextParsingMatch(type: .roomAlias(alias: alias), range: match.range)
-        })
-        
-        matches.append(contentsOf: MatrixEntityRegex.uriRegex.matches(in: string).compactMap { match in
-            guard let matchRange = Range(match.range, in: string) else {
-                return nil
-            }
-            
-            let uri = String(string[matchRange])
-            
-            return TextParsingMatch(type: .matrixURI(uri: uri), range: match.range)
-        })
-        
-        matches.append(contentsOf: MatrixEntityRegex.linkRegex.matches(in: string).compactMap { match in
-            guard let matchRange = Range(match.range, in: string) else {
-                return nil
-            }
-            
-            let link = String(string[matchRange]).asSanitizedLink
-            return TextParsingMatch(type: .link(urlString: link), range: match.range)
-        })
-        
-        matches.append(contentsOf: MatrixEntityRegex.allUsersRegex.matches(in: attributedString.string).map { match in
-            TextParsingMatch(type: .atRoom, range: match.range)
-        })
-        
-        guard matches.count > 0 else {
-            return
-        }
-        
-        // Sort the links by length so the longest one always takes priority
-        matches.sorted { $0.range.length > $1.range.length }.forEach { [attributedString] match in
-            var hasLink = false
-            attributedString.enumerateAttribute(.link, in: match.range, options: []) { value, _, stop in
-                if value != nil {
-                    hasLink = true
-                    stop.pointee = true
-                }
-            }
-            
-            if hasLink {
-                return
-            }
-            
-            // Don't add any extra attributes within codeblocks
-            if attributedString.attribute(.backgroundColor, at: match.range.location, effectiveRange: nil) as? UIColor == temporaryCodeBlockMarkingColor {
-                return
-            }
-            
-            switch match.type {
-            case .atRoom:
-                attributedString.addAttribute(.MatrixAllUsersMention, value: true, range: match.range)
-            case .roomAlias(let alias):
-                if let urlString = try? matrixToRoomAliasPermalink(roomAlias: alias),
-                   let url = URL(string: urlString) {
-                    attributedString.addAttribute(.link, value: url, range: match.range)
-                }
-            case .matrixURI(let uri):
-                if let url = URL(string: uri) {
-                    attributedString.addAttribute(.link, value: url, range: match.range)
-                }
-            case .userID, .link:
-                if let url = match.link {
-                    attributedString.addAttribute(.link, value: url, range: match.range)
-                }
-            }
-        }
-    }
-    
-    private func replaceMarkedBlockquotes(_ attributedString: NSMutableAttributedString) {
-        // According to blockquotes in the string, DTCoreText can apply 2 policies:
-        //     - define a `DTTextBlocksAttribute` attribute on a <blockquote> block
-        //     - or, just define a `NSBackgroundColorAttributeName` attribute
-        attributedString.enumerateAttribute(.DTTextBlocks, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
-            guard let value = value as? NSArray,
-                  let dtTextBlock = value.firstObject as? DTTextBlock,
-                  dtTextBlock.backgroundColor == temporaryBlockquoteMarkingColor else {
-                return
-            }
-            
-            attributedString.addAttribute(.MatrixBlockquote, value: true, range: range)
-        }
-        
-        attributedString.enumerateAttribute(.backgroundColor, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
-            guard let value = value as? UIColor,
-                  value == temporaryBlockquoteMarkingColor else {
-                return
-            }
-            
-            attributedString.removeAttribute(.backgroundColor, range: range)
-            attributedString.addAttribute(.MatrixBlockquote, value: true, range: range)
-        }
-    }
-    
-    private func replaceMarkedCodeBlocks(_ attributedString: NSMutableAttributedString) {
-        attributedString.enumerateAttribute(.backgroundColor, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
-            if let value = value as? UIColor,
-               value == temporaryCodeBlockMarkingColor {
-                attributedString.addAttribute(.backgroundColor, value: UIColor.compound._bgCodeBlock as Any, range: range)
-                attributedString.removeAttribute(.link, range: range)
-            }
-        }
-    }
-    
-    func addMatrixEntityPermalinkAttributesTo(_ attributedString: NSMutableAttributedString) {
-        attributedString.enumerateAttribute(.link, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
-            if value != nil {
-                if let url = value as? URL,
-                   let matrixEntity = parseMatrixEntityFrom(uri: url.absoluteString) {
-                    switch matrixEntity.id {
-                    case .user(let userID):
-                        mentionBuilder.handleUserMention(for: attributedString, in: range, url: url, userID: userID, userDisplayName: nil)
-                    case .room(let roomID):
-                        mentionBuilder.handleRoomIDMention(for: attributedString, in: range, url: url, roomID: roomID)
-                    case .roomAlias(let alias):
-                        mentionBuilder.handleRoomAliasMention(for: attributedString, in: range, url: url, roomAlias: alias, roomDisplayName: nil)
-                    case .eventOnRoomId(let roomID, let eventID):
-                        mentionBuilder.handleEventOnRoomIDMention(for: attributedString, in: range, url: url, eventID: eventID, roomID: roomID)
-                    case .eventOnRoomAlias(let alias, let eventID):
-                        mentionBuilder.handleEventOnRoomAliasMention(for: attributedString, in: range, url: url, eventID: eventID, roomAlias: alias)
-                    }
-                }
-            }
-        }
-        
-        attributedString.enumerateAttribute(.MatrixAllUsersMention, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
-            if let value = value as? Bool,
-               value {
-                mentionBuilder.handleAllUsersMention(for: attributedString, in: range)
-            }
-        }
-    }
-        
-    private func detectPhishingAttempts(_ attributedString: NSMutableAttributedString) {
-        attributedString.enumerateAttribute(.link, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
-            guard value != nil, let internalURL = value as? URL else {
-                return
-            }
-            let displayString = attributedString.attributedSubstring(from: range).string
-            
-            guard PhishingDetector.isPhishingAttempt(displayString: displayString, internalURL: internalURL) else {
-                return
-            }
-            handlePhishingAttempt(for: attributedString, in: range, internalURL: internalURL, displayString: displayString)
-        }
-    }
-    
-    private func handlePhishingAttempt(for attributedString: NSMutableAttributedString,
-                                       in range: NSRange,
-                                       internalURL: URL,
-                                       displayString: String) {
-        // Let's remove the existing link attribute
-        attributedString.removeAttribute(.link, range: range)
-        
-        var urlComponents = URLComponents()
-        urlComponents.scheme = URL.confirmationScheme
-        urlComponents.host = ""
-        let parameters = ConfirmURLParameters(internalURL: internalURL, displayString: displayString)
-        urlComponents.queryItems = parameters.urlQueryItems
-        
-        guard let finalURL = urlComponents.url else {
-            return
-        }
-        
-        attributedString.addAttribute(.link, value: finalURL, range: range)
-    }
-        
-    private func removeDTCoreTextArtifacts(_ attributedString: NSMutableAttributedString) {
-        guard attributedString.length > 0 else {
-            return
-        }
-        
-        // DTCoreText adds a newline at the end of plain text ( https://github.com/Cocoanetics/DTCoreText/issues/779 )
-        // or after a blockquote section.
-        // Trim trailing whitespace and newlines in the string content
-        while (attributedString.string as NSString).hasSuffixCharacter(from: .whitespacesAndNewlines) {
-            attributedString.deleteCharacters(in: .init(location: attributedString.length - 1, length: 1))
-        }
-    }
-    
-    private var defaultCSS: String {
-        """
-                blockquote {
-                    background: \(temporaryBlockquoteMarkingColor.toHexString());
-                    display: block;
-                }
-                pre,code {
-                    background-color: \(temporaryCodeBlockMarkingColor.toHexString());
-                    display: inline;
-                    white-space: pre;
-                    font-size: 0.9em;
-                    -coretext-fontname: .AppleSystemUIFontMonospaced-Regular;
-                }
-                h1,h2,h3 {
-                    font-size: 1.2em;
-                }
-        """
-    }
-}
-
-private extension UIColor {
-    func toHexString() -> String {
-        var red: CGFloat = 0.0
-        var green: CGFloat = 0.0
-        var blue: CGFloat = 0.0
-        var alpha: CGFloat = 0.0
-        
-        getRed(&red, green: &green, blue: &blue, alpha: &alpha)
-        
-        let rgb = Int(red * 255) << 16 | Int(green * 255) << 8 | Int(blue * 255) << 0
-        
-        return NSString(format: "#%06x", rgb) as String
-    }
-}
-
-extension NSAttributedString.Key {
-    static let DTTextBlocks: NSAttributedString.Key = .init(rawValue: DTTextBlocksAttribute)
-    static let MatrixBlockquote: NSAttributedString.Key = .init(rawValue: BlockquoteAttribute.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)
-    static let MatrixRoomID: NSAttributedString.Key = .init(rawValue: RoomIDAttribute.name)
-    static let MatrixRoomAlias: NSAttributedString.Key = .init(rawValue: RoomAliasAttribute.name)
-    static let MatrixEventOnRoomID: NSAttributedString.Key = .init(rawValue: EventOnRoomIDAttribute.name)
-    static let MatrixEventOnRoomAlias: NSAttributedString.Key = .init(rawValue: EventOnRoomAliasAttribute.name)
-    static let MatrixAllUsersMention: NSAttributedString.Key = .init(rawValue: AllUsersMentionAttribute.name)
-}
-
-private struct TextParsingMatch {
-    enum MatchType {
-        case userID(identifier: String)
-        case roomAlias(alias: String)
-        case matrixURI(uri: String)
-        case link(urlString: String)
-        case atRoom
-    }
-    
-    let type: MatchType
-    let range: NSRange
-    
-    var link: URL? {
-        switch type {
-        case .userID(let identifier):
-            return try? URL(string: matrixToUserPermalink(userId: identifier))
-        case .link(let urlString):
-            return URL(string: urlString)
-        default:
-            return nil
-        }
-    }
-}

ElementX/Sources/Other/HTMLParsing/AttributedStringBuilderV1.swift

@@ -0,0 +1,411 @@
+//
+// Copyright 2025 New Vector Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Compound
+import DTCoreText
+import LRUCache
+import MatrixRustSDK
+import UIKit
+
+struct AttributedStringBuilderV1: AttributedStringBuilderProtocol {
+    private let cacheKey: String
+    private let temporaryBlockquoteMarkingColor = UIColor.magenta
+    private let temporaryCodeBlockMarkingColor = UIColor.cyan
+    private let mentionBuilder: MentionBuilderProtocol
+    
+    private static let cacheDispatchQueue = DispatchQueue(label: "io.element.elementx.attributed_string_builder_cache")
+    private static var caches: [String: LRUCache<String, AttributedString>] = [:]
+
+    static func invalidateCaches() {
+        caches.removeAll()
+    }
+    
+    init(cacheKey: String, mentionBuilder: MentionBuilderProtocol) {
+        self.cacheKey = cacheKey
+        self.mentionBuilder = mentionBuilder
+    }
+        
+    func fromPlain(_ string: String?) -> AttributedString? {
+        guard let string else {
+            return nil
+        }
+        
+        if let cached = Self.cachedValue(forKey: string, cacheKey: cacheKey) {
+            return cached
+        }
+
+        let mutableAttributedString = NSMutableAttributedString(string: string)
+        removeDefaultForegroundColors(mutableAttributedString)
+        addLinksAndMentions(mutableAttributedString)
+        addMatrixEntityPermalinkAttributesTo(mutableAttributedString)
+        
+        let result = try? AttributedString(mutableAttributedString, including: \.elementX)
+        Self.cacheValue(result, forKey: string, cacheKey: cacheKey)
+        
+        return result
+    }
+        
+    // Do not use the default HTML renderer of NSAttributedString because this method
+    // runs on the UI thread which we want to avoid because renderHTMLString is called
+    // most of the time from a background thread.
+    // Use DTCoreText HTML renderer instead.
+    // Using DTCoreText, which renders static string, helps to avoid code injection attacks
+    // that could happen with the default HTML renderer of NSAttributedString which is a
+    // webview.
+    func fromHTML(_ htmlString: String?) -> AttributedString? {
+        guard let originalHTMLString = htmlString else {
+            return nil
+        }
+        
+        if let cached = Self.cachedValue(forKey: originalHTMLString, cacheKey: cacheKey) {
+            return cached
+        }
+                
+        let htmlString = originalHTMLString.replacingHtmlBreaksOccurrences()
+        
+        guard let data = htmlString.data(using: .utf8) else {
+            return nil
+        }
+        
+        let defaultFont = UIFont.preferredFont(forTextStyle: .body)
+        
+        let parsingOptions: [String: Any] = [
+            DTUseiOS6Attributes: true,
+            DTDefaultFontFamily: defaultFont.familyName,
+            DTDefaultFontName: defaultFont.fontName,
+            DTDefaultFontSize: defaultFont.pointSize,
+            DTDefaultStyleSheet: DTCSSStylesheet(styleBlock: defaultCSS) as Any,
+            DTDefaultLinkDecoration: false
+        ]
+        
+        guard let builder = DTHTMLAttributedStringBuilder(html: data, options: parsingOptions, documentAttributes: nil) else {
+            return nil
+        }
+        
+        builder.willFlushCallback = { element in
+            element?.sanitize(font: defaultFont)
+        }
+            
+        guard let attributedString = builder.generatedAttributedString() else {
+            return nil
+        }
+        
+        let mutableAttributedString = NSMutableAttributedString(attributedString: attributedString)
+        removeDefaultForegroundColors(mutableAttributedString)
+        detectPhishingAttempts(mutableAttributedString)
+        addLinksAndMentions(mutableAttributedString)
+        replaceMarkedBlockquotes(mutableAttributedString)
+        replaceMarkedCodeBlocks(mutableAttributedString)
+        addMatrixEntityPermalinkAttributesTo(mutableAttributedString)
+        removeDTCoreTextArtifacts(mutableAttributedString)
+        
+        let result = try? AttributedString(mutableAttributedString, including: \.elementX)
+        Self.cacheValue(result, forKey: htmlString, cacheKey: cacheKey)
+        
+        return result
+    }
+    
+    // MARK: - Private
+    
+    private static func cacheValue(_ value: AttributedString?, forKey key: String, cacheKey: String) {
+        cacheDispatchQueue.sync {
+            if caches[cacheKey] == nil {
+                caches[cacheKey] = LRUCache<String, AttributedString>(countLimit: 1000)
+            }
+            
+            caches[cacheKey]?.setValue(value, forKey: key)
+        }
+    }
+    
+    private static func cachedValue(forKey key: String, cacheKey: String) -> AttributedString? {
+        var result: AttributedString?
+        cacheDispatchQueue.sync {
+            result = caches[cacheKey]?.value(forKey: key)
+        }
+        
+        return result
+    }
+    
+    private func removeDefaultForegroundColors(_ attributedString: NSMutableAttributedString) {
+        attributedString.removeAttribute(.foregroundColor, range: .init(location: 0, length: attributedString.length))
+    }
+    
+    // swiftlint:disable:next cyclomatic_complexity
+    private func addLinksAndMentions(_ attributedString: NSMutableAttributedString) {
+        let string = attributedString.string
+        
+        // Event identifiers and room aliases and identifiers detected in plain text are techincally incomplete
+        // without via parameters and we won't bother detecting them
+        
+        var matches: [TextParsingMatch] = MatrixEntityRegex.userIdentifierRegex.matches(in: string).compactMap { match in
+            guard let matchRange = Range(match.range, in: string) else {
+                return nil
+            }
+            
+            let identifier = String(string[matchRange])
+
+            return TextParsingMatch(type: .userID(identifier: identifier), range: match.range)
+        }
+        
+        matches.append(contentsOf: MatrixEntityRegex.roomAliasRegex.matches(in: string).compactMap { match in
+            guard let matchRange = Range(match.range, in: string) else {
+                return nil
+            }
+            
+            let alias = String(string[matchRange])
+            
+            return TextParsingMatch(type: .roomAlias(alias: alias), range: match.range)
+        })
+        
+        matches.append(contentsOf: MatrixEntityRegex.uriRegex.matches(in: string).compactMap { match in
+            guard let matchRange = Range(match.range, in: string) else {
+                return nil
+            }
+            
+            let uri = String(string[matchRange])
+            
+            return TextParsingMatch(type: .matrixURI(uri: uri), range: match.range)
+        })
+        
+        matches.append(contentsOf: MatrixEntityRegex.linkRegex.matches(in: string).compactMap { match in
+            guard let matchRange = Range(match.range, in: string) else {
+                return nil
+            }
+            
+            let link = String(string[matchRange]).asSanitizedLink
+            return TextParsingMatch(type: .link(urlString: link), range: match.range)
+        })
+        
+        matches.append(contentsOf: MatrixEntityRegex.allUsersRegex.matches(in: attributedString.string).map { match in
+            TextParsingMatch(type: .atRoom, range: match.range)
+        })
+        
+        guard matches.count > 0 else {
+            return
+        }
+        
+        // Sort the links by length so the longest one always takes priority
+        matches.sorted { $0.range.length > $1.range.length }.forEach { [attributedString] match in
+            var hasLink = false
+            attributedString.enumerateAttribute(.link, in: match.range, options: []) { value, _, stop in
+                if value != nil {
+                    hasLink = true
+                    stop.pointee = true
+                }
+            }
+            
+            if hasLink {
+                return
+            }
+            
+            // Don't add any extra attributes within codeblocks
+            if attributedString.attribute(.backgroundColor, at: match.range.location, effectiveRange: nil) as? UIColor == temporaryCodeBlockMarkingColor {
+                return
+            }
+            
+            switch match.type {
+            case .atRoom:
+                attributedString.addAttribute(.MatrixAllUsersMention, value: true, range: match.range)
+            case .roomAlias(let alias):
+                if let urlString = try? matrixToRoomAliasPermalink(roomAlias: alias),
+                   let url = URL(string: urlString) {
+                    attributedString.addAttribute(.link, value: url, range: match.range)
+                }
+            case .matrixURI(let uri):
+                if let url = URL(string: uri) {
+                    attributedString.addAttribute(.link, value: url, range: match.range)
+                }
+            case .userID, .link:
+                if let url = match.link {
+                    attributedString.addAttribute(.link, value: url, range: match.range)
+                }
+            }
+        }
+    }
+    
+    private func replaceMarkedBlockquotes(_ attributedString: NSMutableAttributedString) {
+        // According to blockquotes in the string, DTCoreText can apply 2 policies:
+        //     - define a `DTTextBlocksAttribute` attribute on a <blockquote> block
+        //     - or, just define a `NSBackgroundColorAttributeName` attribute
+        attributedString.enumerateAttribute(.DTTextBlocks, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
+            guard let value = value as? NSArray,
+                  let dtTextBlock = value.firstObject as? DTTextBlock,
+                  dtTextBlock.backgroundColor == temporaryBlockquoteMarkingColor else {
+                return
+            }
+            
+            attributedString.addAttribute(.MatrixBlockquote, value: true, range: range)
+        }
+        
+        attributedString.enumerateAttribute(.backgroundColor, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
+            guard let value = value as? UIColor,
+                  value == temporaryBlockquoteMarkingColor else {
+                return
+            }
+            
+            attributedString.removeAttribute(.backgroundColor, range: range)
+            attributedString.addAttribute(.MatrixBlockquote, value: true, range: range)
+        }
+    }
+    
+    private func replaceMarkedCodeBlocks(_ attributedString: NSMutableAttributedString) {
+        attributedString.enumerateAttribute(.backgroundColor, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
+            if let value = value as? UIColor,
+               value == temporaryCodeBlockMarkingColor {
+                attributedString.addAttribute(.backgroundColor, value: UIColor.compound._bgCodeBlock as Any, range: range)
+                attributedString.removeAttribute(.link, range: range)
+            }
+        }
+    }
+    
+    func addMatrixEntityPermalinkAttributesTo(_ attributedString: NSMutableAttributedString) {
+        attributedString.enumerateAttribute(.link, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
+            if value != nil {
+                if let url = value as? URL,
+                   let matrixEntity = parseMatrixEntityFrom(uri: url.absoluteString) {
+                    switch matrixEntity.id {
+                    case .user(let userID):
+                        mentionBuilder.handleUserMention(for: attributedString, in: range, url: url, userID: userID, userDisplayName: nil)
+                    case .room(let roomID):
+                        mentionBuilder.handleRoomIDMention(for: attributedString, in: range, url: url, roomID: roomID)
+                    case .roomAlias(let alias):
+                        mentionBuilder.handleRoomAliasMention(for: attributedString, in: range, url: url, roomAlias: alias, roomDisplayName: nil)
+                    case .eventOnRoomId(let roomID, let eventID):
+                        mentionBuilder.handleEventOnRoomIDMention(for: attributedString, in: range, url: url, eventID: eventID, roomID: roomID)
+                    case .eventOnRoomAlias(let alias, let eventID):
+                        mentionBuilder.handleEventOnRoomAliasMention(for: attributedString, in: range, url: url, eventID: eventID, roomAlias: alias)
+                    }
+                }
+            }
+        }
+        
+        attributedString.enumerateAttribute(.MatrixAllUsersMention, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
+            if let value = value as? Bool,
+               value {
+                mentionBuilder.handleAllUsersMention(for: attributedString, in: range)
+            }
+        }
+    }
+        
+    private func detectPhishingAttempts(_ attributedString: NSMutableAttributedString) {
+        attributedString.enumerateAttribute(.link, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
+            guard value != nil, let internalURL = value as? URL else {
+                return
+            }
+            let displayString = attributedString.attributedSubstring(from: range).string
+            
+            guard PhishingDetector.isPhishingAttempt(displayString: displayString, internalURL: internalURL) else {
+                return
+            }
+            handlePhishingAttempt(for: attributedString, in: range, internalURL: internalURL, displayString: displayString)
+        }
+    }
+    
+    private func handlePhishingAttempt(for attributedString: NSMutableAttributedString,
+                                       in range: NSRange,
+                                       internalURL: URL,
+                                       displayString: String) {
+        // Let's remove the existing link attribute
+        attributedString.removeAttribute(.link, range: range)
+        
+        var urlComponents = URLComponents()
+        urlComponents.scheme = URL.confirmationScheme
+        urlComponents.host = ""
+        let parameters = ConfirmURLParameters(internalURL: internalURL, displayString: displayString)
+        urlComponents.queryItems = parameters.urlQueryItems
+        
+        guard let finalURL = urlComponents.url else {
+            return
+        }
+        
+        attributedString.addAttribute(.link, value: finalURL, range: range)
+    }
+        
+    private func removeDTCoreTextArtifacts(_ attributedString: NSMutableAttributedString) {
+        guard attributedString.length > 0 else {
+            return
+        }
+        
+        // DTCoreText adds a newline at the end of plain text ( https://github.com/Cocoanetics/DTCoreText/issues/779 )
+        // or after a blockquote section.
+        // Trim trailing whitespace and newlines in the string content
+        while (attributedString.string as NSString).hasSuffixCharacter(from: .whitespacesAndNewlines) {
+            attributedString.deleteCharacters(in: .init(location: attributedString.length - 1, length: 1))
+        }
+    }
+    
+    private var defaultCSS: String {
+        """
+                blockquote {
+                    background: \(temporaryBlockquoteMarkingColor.toHexString());
+                    display: block;
+                }
+                pre,code {
+                    background-color: \(temporaryCodeBlockMarkingColor.toHexString());
+                    display: inline;
+                    white-space: pre;
+                    font-size: 0.9em;
+                    -coretext-fontname: .AppleSystemUIFontMonospaced-Regular;
+                }
+                h1,h2,h3 {
+                    font-size: 1.2em;
+                }
+        """
+    }
+}
+
+private extension UIColor {
+    func toHexString() -> String {
+        var red: CGFloat = 0.0
+        var green: CGFloat = 0.0
+        var blue: CGFloat = 0.0
+        var alpha: CGFloat = 0.0
+        
+        getRed(&red, green: &green, blue: &blue, alpha: &alpha)
+        
+        let rgb = Int(red * 255) << 16 | Int(green * 255) << 8 | Int(blue * 255) << 0
+        
+        return NSString(format: "#%06x", rgb) as String
+    }
+}
+
+extension NSAttributedString.Key {
+    static let DTTextBlocks: NSAttributedString.Key = .init(rawValue: DTTextBlocksAttribute)
+    static let MatrixBlockquote: NSAttributedString.Key = .init(rawValue: BlockquoteAttribute.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)
+    static let MatrixRoomID: NSAttributedString.Key = .init(rawValue: RoomIDAttribute.name)
+    static let MatrixRoomAlias: NSAttributedString.Key = .init(rawValue: RoomAliasAttribute.name)
+    static let MatrixEventOnRoomID: NSAttributedString.Key = .init(rawValue: EventOnRoomIDAttribute.name)
+    static let MatrixEventOnRoomAlias: NSAttributedString.Key = .init(rawValue: EventOnRoomAliasAttribute.name)
+    static let MatrixAllUsersMention: NSAttributedString.Key = .init(rawValue: AllUsersMentionAttribute.name)
+}
+
+private struct TextParsingMatch {
+    enum MatchType {
+        case userID(identifier: String)
+        case roomAlias(alias: String)
+        case matrixURI(uri: String)
+        case link(urlString: String)
+        case atRoom
+    }
+    
+    let type: MatchType
+    let range: NSRange
+    
+    var link: URL? {
+        switch type {
+        case .userID(let identifier):
+            return try? URL(string: matrixToUserPermalink(userId: identifier))
+        case .link(let urlString):
+            return URL(string: urlString)
+        default:
+            return nil
+        }
+    }
+}