Initial timeline HTML support.

2026-11-03 15:45:11 +00:00 · 2022-03-24 14:47:55 +02:00
parent d3588cf6f1
commit cf42d61d27
20 changed files with 683 additions and 51 deletions
@@ -116,7 +116,8 @@ class AppCoordinator: AuthenticationCoordinatorDelegate, Coordinator {
            let memberDetailsProvider = MemberDetailsProvider(roomProxy: roomProxy)
            
            let timelineItemFactory = RoomTimelineItemFactory(mediaProvider: userSession.mediaProvider,
-                                                              memberDetailsProvider: memberDetailsProvider)
+                                                              memberDetailsProvider: memberDetailsProvider,
+                                                              attributedStringBuilder: AttributedStringBuilder())
            
            let timelineController = RoomTimelineController(timelineProvider: RoomTimelineProvider(roomProxy: roomProxy),
                                                            timelineItemFactory: timelineItemFactory,
@@ -0,0 +1,85 @@
+//
+//  AttributedStringBuilder.swift
+//  ElementX
+//
+//  Created by Stefan Ceriu on 22/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+import Foundation
+import DTCoreText
+
+struct AttributedStringBuilder: AttributedStringBuilderProtocol {
+    
+    private var defaultCSS: String {
+        AttributedStringBuilderUtils.cssToMarkBlockquotes() +
+"""
+        pre,code {
+            background-color: #F5F7FA;
+            display: inline;
+            font-family: monospace;
+            white-space: pre;
+            -coretext-fontname: Menlo-Regular;
+        }
+        h1,h2,h3 {
+            font-size: 1.2em;
+        }
+"""
+    }
+    
+    // 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 htmlString = htmlString,
+              let data = htmlString.data(using: .utf8) else {
+                  return nil
+              }
+        
+        let defaultFont = UIFont.preferredFont(forTextStyle: .body)
+        let defaultColor = UIColor.black
+        
+        let parsingOptions: [String: Any] = [
+            DTUseiOS6Attributes: true,
+            DTDefaultFontFamily: defaultFont.familyName,
+            DTDefaultFontName: defaultFont.fontName,
+            DTDefaultFontSize: defaultFont.pointSize,
+            DTDefaultTextColor: defaultColor,
+            DTDefaultLinkDecoration: false,
+            DTDefaultStyleSheet: DTCSSStylesheet(styleBlock: self.defaultCSS) as Any
+        ]
+        
+        guard let builder = DTHTMLAttributedStringBuilder(html: data, options: parsingOptions, documentAttributes: nil) else {
+            return nil
+        }
+        
+        builder.willFlushCallback = { element in
+            element?.sanitize(font: defaultFont)
+        }
+            
+        guard var nsAttributedString = builder.generatedAttributedString() else {
+            return nil
+        }
+        
+        nsAttributedString = AttributedStringBuilderUtils.removeDTCoreTextArtifacts(nsAttributedString)
+        
+        nsAttributedString = AttributedStringBuilderUtils.removeMarkedBlockquotesArtifacts(nsAttributedString)
+        
+        return try? AttributedString(nsAttributedString, including: \.elementX)
+    }
+    
+    func blockquoteCoalescedComponentsFrom(_ attributedString: AttributedString?) -> [AttributedStringBuilderComponent]? {
+        guard let attributedString = attributedString else {
+            return nil
+        }
+
+        return attributedString.runs[\.blockquote].map { (value, range) in
+            AttributedStringBuilderComponent(attributedString: AttributedString(attributedString[range]),
+                                             isBlockquote: value != nil)
+        }
+    }
+}
@@ -0,0 +1,20 @@
+//
+//  AttributedStringBuilderProtocol.swift
+//  ElementX
+//
+//  Created by Stefan Ceriu on 24/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+import Foundation
+
+struct AttributedStringBuilderComponent: Hashable {
+    let attributedString: AttributedString
+    let isBlockquote: Bool
+}
+
+protocol AttributedStringBuilderProtocol {
+    func fromHTML(_ htmlString: String?) -> AttributedString?
+    
+    func blockquoteCoalescedComponentsFrom(_ attributedString: AttributedString?) -> [AttributedStringBuilderComponent]?
+}
@@ -0,0 +1,27 @@
+//
+//  AttributedStringBuilderUtils.h
+//  ElementX
+//
+//  Created by Stefan Ceriu on 23/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+FOUNDATION_EXPORT NSString *const kMXKToolsBlockquoteMarkAttribute;
+
+@interface AttributedStringBuilderUtils : NSObject
+
+ (NSAttributedString *)removeDTCoreTextArtifacts:(NSAttributedString *)attributedString;
+
+ (NSAttributedString*)removeMarkedBlockquotesArtifacts:(NSAttributedString*)attributedString;
+
+ (NSString*)cssToMarkBlockquotes;
+
+ (void)enumerateMarkedBlockquotesInAttributedString:(NSAttributedString*)attributedString usingBlock:(void (^)(NSRange range, BOOL *stop))block;
+
+@end
+
+NS_ASSUME_NONNULL_END
@@ -0,0 +1,200 @@
+//
+//  AttributedStringBuilderUtils.m
+//  ElementX
+//
+//  Created by Stefan Ceriu on 23/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+#import "AttributedStringBuilderUtils.h"
+@import DTCoreText;
+
+// Temporary background color used to identify blockquote blocks with DTCoreText.
+#define kMXKToolsBlockquoteMarkColor [UIColor magentaColor]
+
+// Attribute in an NSAttributeString that marks a blockquote block that was in the original HTML string.
+NSString *const kMXKToolsBlockquoteMarkAttribute = @"kMXKToolsBlockquoteMarkAttribute";
+
+@implementation AttributedStringBuilderUtils
+
+ (NSAttributedString *)removeDTCoreTextArtifacts:(NSAttributedString *)attributedString
+{
+    NSMutableAttributedString *mutableAttributedString = [[NSMutableAttributedString alloc] initWithAttributedString:attributedString];
+    
+    // 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 ([mutableAttributedString.string hasSuffixCharacterFromSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]])
+    {
+        [mutableAttributedString deleteCharactersInRange:NSMakeRange(mutableAttributedString.length - 1, 1)];
+    }
+    
+    // New lines may have also been introduced by the paragraph style
+    // Make sure the last paragraph style has no spacing
+    [mutableAttributedString enumerateAttributesInRange:NSMakeRange(0, mutableAttributedString.length) options:(NSAttributedStringEnumerationReverse) usingBlock:^(NSDictionary *attrs, NSRange range, BOOL *stop) {
+        
+        if (attrs[NSParagraphStyleAttributeName])
+        {
+            NSString *subString = [mutableAttributedString.string substringWithRange:range];
+            NSArray *components = [subString componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];
+            
+            NSMutableDictionary *updatedAttrs = [NSMutableDictionary dictionaryWithDictionary:attrs];
+            NSMutableParagraphStyle *paragraphStyle = [updatedAttrs[NSParagraphStyleAttributeName] mutableCopy];
+            paragraphStyle.paragraphSpacing = 0;
+            updatedAttrs[NSParagraphStyleAttributeName] = paragraphStyle;
+            
+            if (components.count > 1)
+            {
+                NSString *lastComponent = components.lastObject;
+                
+                NSRange range2 = NSMakeRange(range.location, range.length - lastComponent.length);
+                [mutableAttributedString setAttributes:attrs range:range2];
+                
+                range2 = NSMakeRange(range2.location + range2.length, lastComponent.length);
+                [mutableAttributedString setAttributes:updatedAttrs range:range2];
+            }
+            else
+            {
+                [mutableAttributedString setAttributes:updatedAttrs range:range];
+            }
+        }
+        
+        // Check only the last paragraph
+        *stop = YES;
+    }];
+    
+    // Image rendering failed on an exception until we replace the DTImageTextAttachments with a simple NSTextAttachment subclass
+    // (thanks to https://github.com/Cocoanetics/DTCoreText/issues/863).
+    [mutableAttributedString enumerateAttribute:NSAttachmentAttributeName
+                                        inRange:NSMakeRange(0, mutableAttributedString.length)
+                                        options:0
+                                     usingBlock:^(id value, NSRange range, BOOL *stop) {
+                                         
+                                         if ([value isKindOfClass:DTImageTextAttachment.class])
+                                         {
+                                             DTImageTextAttachment *attachment = (DTImageTextAttachment*)value;
+                                             NSTextAttachment *textAttachment = [[NSTextAttachment alloc] init];
+                                             if (attachment.image)
+                                             {
+                                                 textAttachment.image = attachment.image;
+                                                 
+                                                 CGRect frame = textAttachment.bounds;
+                                                 frame.size = attachment.displaySize;
+                                                 textAttachment.bounds = frame;
+                                             }
+                                             // Note we remove here attachment without image.
+                                             NSAttributedString *attrStringWithImage = [NSAttributedString attributedStringWithAttachment:textAttachment];
+                                             [mutableAttributedString replaceCharactersInRange:range withAttributedString:attrStringWithImage];
+                                         }
+                                     }];
+    
+    return mutableAttributedString;
+}
+
+ (NSString*)cssToMarkBlockquotes
+{
+    return [NSString stringWithFormat:@"blockquote {background: #%lX; display: block;}", (unsigned long)[[self class] rgbValueWithColor:kMXKToolsBlockquoteMarkColor]];
+}
+
+ (NSAttributedString*)removeMarkedBlockquotesArtifacts:(NSAttributedString*)attributedString
+{
+    NSMutableAttributedString *mutableAttributedString = [[NSMutableAttributedString alloc] initWithAttributedString:attributedString];
+
+    // Enumerate all sections marked thanks to `cssToMarkBlockquotes`
+    // and apply our own attribute instead.
+
+    // 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
+
+    // `DTTextBlocksAttribute` case
+    [attributedString enumerateAttribute:DTTextBlocksAttribute
+                                 inRange:NSMakeRange(0, attributedString.length)
+                                 options:0
+                              usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop)
+     {
+         if ([value isKindOfClass:NSArray.class])
+         {
+             NSArray *array = (NSArray*)value;
+             if (array.count > 0 && [array[0] isKindOfClass:DTTextBlock.class])
+             {
+                 DTTextBlock *dtTextBlock = (DTTextBlock *)array[0];
+                 if ([dtTextBlock.backgroundColor isEqual:kMXKToolsBlockquoteMarkColor])
+                 {
+                     // Apply our own attribute
+                     [mutableAttributedString addAttribute:kMXKToolsBlockquoteMarkAttribute value:@(YES) range:range];
+
+                     // Fix a boring behaviour where DTCoreText add a " " string before a string corresponding
+                     // to an HTML blockquote. This " " string has ParagraphStyle.headIndent = 0 which breaks
+                     // the blockquote block indentation
+                     if (range.location > 0)
+                     {
+                         NSRange prevRange = NSMakeRange(range.location - 1, 1);
+
+                         NSRange effectiveRange;
+                         NSParagraphStyle *paragraphStyle = [attributedString attribute:NSParagraphStyleAttributeName
+                                                                                atIndex:prevRange.location
+                                                                         effectiveRange:&effectiveRange];
+
+                         // Check if this is the " " string
+                         if (paragraphStyle && effectiveRange.length == 1 && paragraphStyle.firstLineHeadIndent != 25)
+                         {
+                             // Fix its paragraph style
+                             NSMutableParagraphStyle *newParagraphStyle = [paragraphStyle mutableCopy];
+                             newParagraphStyle.firstLineHeadIndent = 25.0;
+                             newParagraphStyle.headIndent = 25.0;
+
+                             [mutableAttributedString addAttribute:NSParagraphStyleAttributeName value:newParagraphStyle range:prevRange];
+                         }
+                     }
+                 }
+             }
+         }
+     }];
+
+    // `NSBackgroundColorAttributeName` case
+    [mutableAttributedString enumerateAttribute:NSBackgroundColorAttributeName
+                                        inRange:NSMakeRange(0, mutableAttributedString.length)
+                                        options:0
+                                     usingBlock:^(id value, NSRange range, BOOL *stop)
+     {
+
+         if ([value isKindOfClass:UIColor.class] && [(UIColor*)value isEqual:kMXKToolsBlockquoteMarkColor])
+         {
+             // Remove the marked background
+             [mutableAttributedString removeAttribute:NSBackgroundColorAttributeName range:range];
+
+             // And apply our own attribute
+             [mutableAttributedString addAttribute:kMXKToolsBlockquoteMarkAttribute value:@(YES) range:range];
+         }
+     }];
+
+    return mutableAttributedString;
+}
+
+ (NSUInteger)rgbValueWithColor:(UIColor*)color
+{
+    CGFloat red, green, blue, alpha;
+    
+    [color getRed:&red green:&green blue:&blue alpha:&alpha];
+    
+    NSUInteger rgbValue = ((int)(red * 255) << 16) + ((int)(green * 255) << 8) + (blue * 255);
+    
+    return rgbValue;
+}
+
+ (void)enumerateMarkedBlockquotesInAttributedString:(NSAttributedString*)attributedString usingBlock:(void (^)(NSRange range, BOOL *stop))block
+{
+    [attributedString enumerateAttribute:kMXKToolsBlockquoteMarkAttribute
+                                 inRange:NSMakeRange(0, attributedString.length)
+                                 options:0
+                              usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop)
+     {
+         if ([value isKindOfClass:NSNumber.class] && ((NSNumber*)value).boolValue)
+         {
+             block(range, stop);
+         }
+     }];
+}
+
+@end
@@ -0,0 +1,71 @@
+//
+//  DTHTMLElement+AttributedStringBuilder.swift
+//  ElementX
+//
+//  Created by Stefan Ceriu on 24/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+import Foundation
+import DTCoreText
+
+public extension DTHTMLElement {
+    /// Sanitize the element using the given parameters.
+    /// - Parameters:
+    ///   - allowedHTMLTags: An array of tags that are allowed. All other tags will be removed.
+    ///   - font: The default font to use when resetting the content of any unsupported tags.
+    ///   - imageHandler: An optional image handler to be run on `img` tags (if allowed) to update the `src` attribute.
+    @objc func sanitize(font: UIFont) {
+        if let name = name, !Self.allowedHTMLTags.contains(name) {
+            
+            // This is an unsupported tag.
+            // Remove any attachments to fix rendering.
+            textAttachment = nil
+            
+            // If the element has plain text content show that,
+            // otherwise prevent the tag from displaying.
+            if let stringContent = attributedString()?.string,
+               !stringContent.isEmpty,
+               let element = DTTextHTMLElement(name: nil, attributes: nil) {
+                element.setText(stringContent)
+                removeAllChildNodes()
+                addChildNode(element)
+                
+                if let parent = parent() {
+                    element.inheritAttributes(from: parent)
+                } else {
+                    fontDescriptor = DTCoreTextFontDescriptor()
+                    fontDescriptor.fontFamily = font.familyName
+                    fontDescriptor.fontName = font.fontName
+                    fontDescriptor.pointSize = font.pointSize
+                    paragraphStyle = DTCoreTextParagraphStyle.default()
+                    
+                    element.inheritAttributes(from: self)
+                }
+                element.interpretAttributes()
+                
+            } else if let parent = parent() {
+                parent.removeChildNode(self)
+            } else {
+                didOutput = true
+            }
+            
+        } else {
+            // This element is a supported tag, but it may contain children that aren't,
+            // so santize all child nodes to ensure correct tags.
+            if let childNodes = childNodes as? [DTHTMLElement] {
+                childNodes.forEach { $0.sanitize(font: font) }
+            }
+        }
+    }
+    
+    private static var allowedHTMLTags = {
+        ["font", // custom to matrix for IRC-style font coloring
+         "del", // for markdown
+         "body", // added internally by DTCoreText
+         "mx-reply",
+         "h1", "h2", "h3", "h4", "h5", "h6", "blockquote", "p", "a", "ul", "ol",
+         "nl", "li", "b", "i", "u", "strong", "em", "strike", "code", "hr", "br", "div",
+         "table", "thead", "caption", "tbody", "tr", "th", "td", "pre"]
+    }()
+}
@@ -0,0 +1,31 @@
+//
+//  ElementXAttributeScope.swift
+//  ElementX
+//
+//  Created by Stefan Ceriu on 23/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+import Foundation
+
+enum BlockquoteAttribute: AttributedStringKey {
+    typealias Value = Bool
+    public static var name = kMXKToolsBlockquoteMarkAttribute
+}
+
+extension AttributeScopes {
+    struct ElementXAttributes: AttributeScope {
+        let blockquote: BlockquoteAttribute
+        
+        let swiftUI: SwiftUIAttributes
+        let uiKit: UIKitAttributes
+    }
+    
+    var elementX: ElementXAttributes.Type { ElementXAttributes.self }
+}
+
+extension AttributeDynamicLookup {
+    subscript<T: AttributedStringKey>(dynamicMember keyPath: KeyPath<AttributeScopes.ElementXAttributes, T>) -> T {
+        return self[T.self]
+    }
+}
@@ -0,0 +1,19 @@
+//
+//  UIFont+AttributedStringBuilder.h
+//  ElementX
+//
+//  Created by Stefan Ceriu on 23/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+@import UIKit;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface UIFont(DTCoreTextFix)
+
+// Fix DTCoreText iOS 13 issue (https://github.com/Cocoanetics/DTCoreText/issues/1168)
+
+@end
+
+NS_ASSUME_NONNULL_END
@@ -0,0 +1,73 @@
+//
+//  UIFont+AttributedStringBuilder.h
+//  ElementX
+//
+//  Created by Stefan Ceriu on 23/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+#import "UIFont+AttributedStringBuilder.h"
+
+@import UIKit;
+@import CoreText;
+@import ObjectiveC;
+
+#pragma mark - UIFont DTCoreText fix
+
+@interface UIFont (vc_DTCoreTextFix)
+
+ (UIFont *)vc_fixedFontWithCTFont:(CTFontRef)ctFont;
+
+@end
+
+@implementation UIFont (vc_DTCoreTextFix)
+
+ (UIFont *)vc_fixedFontWithCTFont:(CTFontRef)ctFont {
+    NSString *fontName = (__bridge_transfer NSString *)CTFontCopyName(ctFont, kCTFontPostScriptNameKey);
+
+    CGFloat fontSize = CTFontGetSize(ctFont);
+    UIFont *font = [UIFont fontWithName:fontName size:fontSize];
+
+    // On iOS 13+ "TimesNewRomanPSMT" will be used instead of "SFUI"
+    // In case of "Times New Roman" fallback, use system font and reuse UIFontDescriptorSymbolicTraits.
+    if ([font.familyName.lowercaseString containsString:@"times"])
+    {
+        UIFontDescriptorSymbolicTraits symbolicTraits = (UIFontDescriptorSymbolicTraits)CTFontGetSymbolicTraits(ctFont);
+        
+        UIFontDescriptor *systemFontDescriptor = [UIFont systemFontOfSize:fontSize].fontDescriptor;
+        
+        UIFontDescriptor *finalFontDescriptor = [systemFontDescriptor fontDescriptorWithSymbolicTraits:symbolicTraits];
+        font = [UIFont fontWithDescriptor:finalFontDescriptor size:fontSize];
+    }
+
+    return font;
+}
+
+@end
+
+#pragma mark - Implementation
+
+@implementation UIFont(DTCoreTextFix)
+
+// DTCoreText iOS 13 fix. See issue and comment here: https://github.com/Cocoanetics/DTCoreText/issues/1168#issuecomment-583541514
+// Also see https://github.com/Cocoanetics/DTCoreText/pull/1245 for a possible future solution
+ (void)load
+{
+    static dispatch_once_t onceToken;
+    
+    dispatch_once(&onceToken, ^{
+        Class originalClass = object_getClass([UIFont class]);
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wundeclared-selector"
+        SEL originalSelector = @selector(fontWithCTFont:); // DTCoreText method we're overriding
+        SEL ourSelector = @selector(vc_fixedFontWithCTFont:); // Use custom implementation
+#pragma clang diagnostic pop
+        
+        Method originalMethod = class_getClassMethod(originalClass, originalSelector);
+        Method swizzledMethod = class_getClassMethod(originalClass, ourSelector);
+        
+        method_exchangeImplementations(originalMethod, swizzledMethod);
+    });
+}
+
+@end
@@ -14,10 +14,10 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
    let callbacks = PassthroughSubject<RoomTimelineControllerCallback, Never>()
    
    var timelineItems: [RoomTimelineItemProtocol] = [SeparatorRoomTimelineItem(id: UUID().uuidString, text: "Yesterday"),
-                                                     TextRoomTimelineItem(id: UUID().uuidString, body: "You rock!", timestamp: "10:10 AM", shouldShowSenderDetails: true, senderId: "Alice"),
-                                                     TextRoomTimelineItem(id: UUID().uuidString, body: "You also rule!", timestamp: "10:11 AM", shouldShowSenderDetails: false, senderId: "Alice"),
+                                                     TextRoomTimelineItem(id: UUID().uuidString, text: "You rock!", timestamp: "10:10 AM", shouldShowSenderDetails: true, senderId: "Alice"),
+                                                     TextRoomTimelineItem(id: UUID().uuidString, text: "You also rule!", timestamp: "10:11 AM", shouldShowSenderDetails: false, senderId: "Alice"),
                                                     SeparatorRoomTimelineItem(id: UUID().uuidString, text: "Today"),
-                                                     TextRoomTimelineItem(id: UUID().uuidString, body: "You too!", timestamp: "5 PM", shouldShowSenderDetails: true, senderId: "Bob")]
+                                                     TextRoomTimelineItem(id: UUID().uuidString, text: "You too!", timestamp: "5 PM", shouldShowSenderDetails: true, senderId: "Bob")]
    
    func paginateBackwards(_ count: UInt, callback: ((Result<Void, RoomTimelineControllerError>) -> Void)) {
        callbacks.send(.updatedTimelineItems)
@@ -10,7 +10,7 @@ import Foundation
 import UIKit

 protocol EventBasedTimelineItemProtocol: RoomTimelineItemProtocol {
-    var body: String { get }
+    var text: String { get }
    var timestamp: String { get }
    var shouldShowSenderDetails: Bool { get }
    
@@ -11,7 +11,7 @@ import UIKit

 struct ImageRoomTimelineItem: EventBasedTimelineItemProtocol, Identifiable, Equatable {
    let id: String
-    let body: String
+    let text: String
    let timestamp: String
    let shouldShowSenderDetails: Bool
    
@@ -11,8 +11,8 @@ import UIKit

 struct TextRoomTimelineItem: EventBasedTimelineItemProtocol, Identifiable, Equatable {
    let id: String
-    let body: String
-    var htmlBody: String?
+    let text: String
+    var attributedComponents: [AttributedStringBuilderComponent]?
    let timestamp: String
    let shouldShowSenderDetails: Bool
    
@@ -12,11 +12,14 @@ import UIKit
 struct RoomTimelineItemFactory {
    private let mediaProvider: MediaProviderProtocol
    private let memberDetailsProvider: MemberDetailsProviderProtocol
+    private let attributedStringBuilder: AttributedStringBuilderProtocol
    
    init(mediaProvider: MediaProviderProtocol,
-         memberDetailsProvider: MemberDetailsProviderProtocol) {
+         memberDetailsProvider: MemberDetailsProviderProtocol,
+         attributedStringBuilder: AttributedStringBuilderProtocol) {
        self.mediaProvider = mediaProvider
        self.memberDetailsProvider = memberDetailsProvider
+        self.attributedStringBuilder = attributedStringBuilder
    }
    
    func buildTimelineItemFor(_ roomMessage: RoomMessageProtocol, showSenderDetails: Bool) -> RoomTimelineItemProtocol {
@@ -27,9 +30,12 @@ struct RoomTimelineItemFactory {
        
        switch roomMessage {
        case let message as TextRoomMessage:
+            let attributedText = attributedStringBuilder.fromHTML(message.htmlBody)
+            let attributedComponents = attributedStringBuilder.blockquoteCoalescedComponentsFrom(attributedText)
+            
            return TextRoomTimelineItem(id: message.id,
-                                        body: message.body,
-                                        htmlBody: message.htmlBody,
+                                        text: message.body,
+                                        attributedComponents: attributedComponents,
                                        timestamp: message.originServerTs.formatted(date: .omitted, time: .shortened),
                                        shouldShowSenderDetails: showSenderDetails,
                                        senderId: message.sender,
@@ -37,7 +43,7 @@ struct RoomTimelineItemFactory {
                                        senderAvatar: avatarImage)
        case let message as ImageRoomMessage:
            return ImageRoomTimelineItem(id: message.id,
-                                         body: message.body,
+                                         text: message.body,
                                         timestamp: message.originServerTs.formatted(date: .omitted, time: .shortened),
                                         shouldShowSenderDetails: showSenderDetails,
                                         senderId: message.sender,
@@ -0,0 +1,33 @@
+//
+//  FormattedBodyText.swift
+//  ElementX
+//
+//  Created by Stefan Ceriu on 24/03/2022.
+//  Copyright © 2022 Element. All rights reserved.
+//
+
+import Foundation
+import SwiftUI
+
+struct FormattedBodyText: View {
+    let attributedComponents: [AttributedStringBuilderComponent]
+    
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0.0) {
+            ForEach(attributedComponents, id: \.self) { component in
+                if component.isBlockquote {
+                    HStack(spacing: 4.0) {
+                        Rectangle()
+                            .foregroundColor(Color.red)
+                            .frame(width: 4.0)
+                        Text(component.attributedString)
+                            .fixedSize(horizontal: false, vertical: true)
+                    }
+                } else {
+                    Text(component.attributedString)
+                        .fixedSize(horizontal: false, vertical: true)
+                }
+            }
+        }
+    }
+}
@@ -16,7 +16,7 @@ struct ImageRoomTimelineView: View {
        if let image = timelineItem.image {
            VStack(alignment: .leading) {
                EventBasedTimelineView(timelineItem: timelineItem)
-                Text(timelineItem.body)
+                Text(timelineItem.text)
                Image(uiImage: image)
                    .resizable()
                    .scaledToFit()
@@ -24,7 +24,7 @@ struct ImageRoomTimelineView: View {
        } else {
            VStack(alignment: .center) {
                HStack {
-                    Text(timelineItem.body)
+                    Text(timelineItem.text)
                    Spacer()
                }
                ProgressView("Loading")
@@ -37,7 +37,7 @@ struct ImageRoomTimelineView_Previews: PreviewProvider {
    static var previews: some View {
        VStack {
            let timelineItem = ImageRoomTimelineItem(id: UUID().uuidString,
-                                                     body: "Some image",
+                                                     text: "Some image",
                                                     timestamp: "Now",
                                                     shouldShowSenderDetails: false,
                                                     senderId: "Bob",
@@ -46,7 +46,7 @@ struct ImageRoomTimelineView_Previews: PreviewProvider {
            ImageRoomTimelineView(timelineItem: timelineItem)
            
            let timelineItem = ImageRoomTimelineItem(id: UUID().uuidString,
-                                                     body: "Some other image",
+                                                     text: "Some other image",
                                                     timestamp: "Now",
                                                     shouldShowSenderDetails: false,
                                                     senderId: "Bob",
@@ -15,52 +15,28 @@ struct TextRoomTimelineView: View {
    var body: some View {
        VStack(alignment: .leading) {
            EventBasedTimelineView(timelineItem: timelineItem)
-            
-            if let htmlString = buildHtmlString() {
-                Text(AttributedString(htmlString))
-                    .fixedSize(horizontal: false, vertical: true)
+            if let components = timelineItem.attributedComponents {
+                FormattedBodyText(attributedComponents: components)
            } else {
-                if let attributedString = try? AttributedString(markdown: timelineItem.body) {
-                    Text(attributedString)
-                        .fixedSize(horizontal: false, vertical: true)
-                } else {
-                    Text(timelineItem.body)
-                        .fixedSize(horizontal: false, vertical: true)
-                }
+                Text(timelineItem.text)
            }
        }
        .id(timelineItem.id)
    }
-    
-    private func buildHtmlString() -> NSAttributedString? {
-        guard let formattedText = timelineItem.htmlBody,
-              let encodedData = formattedText.data(using: String.Encoding.utf8) else {
-            return nil
-              }
-        
-        do {
-            return try NSAttributedString(data: encodedData, options: [
-                NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
-                NSAttributedString.DocumentReadingOptionKey.characterEncoding: NSNumber(value: String.Encoding.utf8.rawValue)
-            ], documentAttributes: nil)
-        } catch {
-            return nil
-        }
-    }
 }

 struct TextRoomTimelineView_Previews: PreviewProvider {
    static var previews: some View {
        VStack(spacing: 20.0) {
            let timelineItem = TextRoomTimelineItem(id: UUID().uuidString,
-                                                    body: "Short loin ground round tongue hamburger, fatback salami shoulder. Beef turkey sausage kielbasa strip steak. Alcatra capicola pig tail pancetta chislic.",
+                                                    text: "Short loin ground round tongue hamburger, fatback salami shoulder. Beef turkey sausage kielbasa strip steak. Alcatra capicola pig tail pancetta chislic.",
                                                    timestamp: "Now",
                                                    shouldShowSenderDetails: true,
                                                    senderId: "Bob")
            TextRoomTimelineView(timelineItem: timelineItem)
            
            let timelineItem = TextRoomTimelineItem(id: UUID().uuidString,
-                                                    body: "Some other text",
+                                                    text: "Some other text",
                                                    timestamp: "Later",
                                                    shouldShowSenderDetails: true,
                                                    senderId: "Anne")
@@ -0,0 +1,5 @@
+//
+//  Use this file to import your target's public headers that you would like to expose to Swift.
+//
+
+#import "AttributedStringBuilderUtils.h"