Nested support blockquotes on iOS

ios/MarkdownLayoutManager.mm

@@ -6,28 +6,32 @@ - (void)drawBackgroundForGlyphRange:(NSRange)glyphsToShow atPoint:(CGPoint)origi
   [super drawBackgroundForGlyphRange:glyphsToShow atPoint:origin];
 
   [self enumerateLineFragmentsForGlyphRange:glyphsToShow usingBlock:^(CGRect rect, CGRect usedRect, NSTextContainer * _Nonnull textContainer, NSRange glyphRange, BOOL * _Nonnull stop) {
-    __block BOOL isBlockquote = NO;
+    __block int nestingLevel = 0;
     RCTMarkdownUtils *markdownUtils = [self valueForKey:@"markdownUtils"];
     [markdownUtils.blockquoteRanges enumerateObjectsUsingBlock:^(NSValue *item, NSUInteger idx, BOOL * _Nonnull stop) {
       NSRange range = [item rangeValue];
       NSUInteger start = range.location;
       NSUInteger end = start + range.length;
       NSUInteger location = glyphRange.location;
       if (location >= start && location < end) {
-        isBlockquote = YES;
-        *stop = YES;
+          nestingLevel++;
       }
     }];
-    if (isBlockquote) {
+    if (nestingLevel > 0) {
       CGFloat paddingLeft = markdownUtils.backedTextInputView.textContainerInset.left;
       CGFloat paddingTop = markdownUtils.backedTextInputView.textContainerInset.top;
       CGFloat x = paddingLeft + markdownUtils.markdownStyle.blockquoteMarginLeft;
       CGFloat y = paddingTop + rect.origin.y;
       CGFloat width = markdownUtils.markdownStyle.blockquoteBorderWidth;
       CGFloat height = rect.size.height;
-      CGRect lineRect = CGRectMake(x, y, width, height);
-      [markdownUtils.markdownStyle.blockquoteBorderColor setFill];
-      UIRectFill(lineRect);
+
+      CGFloat nestShift = paddingLeft + width + markdownUtils.markdownStyle.blockquoteMarginLeft;
+
+      for(int strip = 0; strip < nestingLevel; strip++) {
+        CGRect lineRect = CGRectMake(x + (strip * nestShift), y, width, height);
+        [markdownUtils.markdownStyle.blockquoteBorderColor setFill];
+        UIRectFill(lineRect);
+      }
     }
   }];
 }

ios/RCTMarkdownUtils.h

@@ -13,6 +13,12 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (NSAttributedString *)parseMarkdown:(nullable NSAttributedString *)input;
 
+// returns the most outer blockquote range that surrounds the given range; if there is no such range, it returns the passed range
+- (NSRange)getCircumferencingBlockquoteRange:(NSRange)range;
+
+// counts the number of ranges the given range is contained within
+- (int)getBlockquoteNestLevel:(NSRange)range;
+
 @end
 
 NS_ASSUME_NONNULL_END

ios/RCTMarkdownUtils.mm

@@ -105,10 +105,12 @@ - (NSAttributedString *)parseMarkdown:(nullable NSAttributedString *)input
     } else if ([type isEqualToString:@"blockquote"]) {
       CGFloat indent = _markdownStyle.blockquoteMarginLeft + _markdownStyle.blockquoteBorderWidth + _markdownStyle.blockquotePaddingLeft;
       NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
-      paragraphStyle.firstLineHeadIndent = indent;
-      paragraphStyle.headIndent = indent;
-      [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:range];
-      [_blockquoteRanges addObject:[NSValue valueWithRange:range]];
+      NSRange circumferencingRange = [self getCircumferencingBlockquoteRange:range];
+      int blockquoteNestLevel = [self getBlockquoteNestLevel:range];
+      paragraphStyle.firstLineHeadIndent = indent * blockquoteNestLevel;
+      paragraphStyle.headIndent = indent * blockquoteNestLevel;
+      [_blockquoteRanges addObject:[NSValue valueWithRange:circumferencingRange]];
+      [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:circumferencingRange];
     } else if ([type isEqualToString:@"pre"]) {
       [attributedString addAttribute:NSForegroundColorAttributeName value:_markdownStyle.preColor range:range];
       NSRange rangeForBackground = [inputString characterAtIndex:range.location] == '\n' ? NSMakeRange(range.location + 1, range.length - 1) : range;
@@ -131,4 +133,27 @@ - (NSAttributedString *)parseMarkdown:(nullable NSAttributedString *)input
   return attributedString;
 }
 
+- (NSRange)getCircumferencingBlockquoteRange:(NSRange)range
+{
+  for (NSValue *quoteRange in _blockquoteRanges) {
+    NSRange quoteRangeValue = [quoteRange rangeValue];
+    if (quoteRangeValue.location < range.location && quoteRangeValue.location + quoteRangeValue.length >= range.location + range.length) {
+      return quoteRangeValue;
+    }
+  }
+  return range;
+}
+
+- (int)getBlockquoteNestLevel:(NSRange)range
+{
+  int nestLevel = 1;
+  for (NSValue *quoteRange in _blockquoteRanges) {
+    NSRange quoteRangeValue = [quoteRange rangeValue];
+    if (quoteRangeValue.location < range.location && quoteRangeValue.location + quoteRangeValue.length >= range.location + range.length) {
+      nestLevel++;
+    }
+  }
+  return nestLevel;
+}
+
 @end