iOS: Replace NBSP with ZWSP to allow block rendering

platforms/ios/lib/WysiwygComposer/Sources/HTMLParser/Extensions/DTCoreText/DTHTMLElement.swift

@@ -35,4 +35,70 @@ extension DTHTMLElement {
             }
         }
     }
+
+    func clearTrailingAndLeadingNewlinesInCodeblocks() {
+        guard let childNodes = childNodes as? [DTHTMLElement] else {
+            return
+        }
+
+        if name == "pre",
+           childNodes.count == 1,
+           let child = childNodes.first as? DTTextHTMLElement,
+           var text = child.text(),
+           text != .nbsp {
+            var leadingDiscardableElement: DiscardableTextHTMLElement?
+            var trailingDiscardableElement: DiscardableTextHTMLElement?
+            var shouldReplaceNodes = false
+
+            if text.hasPrefix("\(Character.nbsp)") {
+                shouldReplaceNodes = true
+                text.removeFirst()
+                leadingDiscardableElement = createDiscardableElement()
+            }
+
+            if text.hasSuffix("\(Character.nbsp)") {
+                shouldReplaceNodes = true
+                text.removeLast()
+                trailingDiscardableElement = createDiscardableElement()
+            }
+
+            if shouldReplaceNodes {
+                removeAllChildNodes()
+
+                if let leadingDiscardableElement = leadingDiscardableElement {
+                    addChildNode(leadingDiscardableElement)
+                    addChildNode(createLineBreak())
+                }
+
+                let newTextNode = DTTextHTMLElement()
+                newTextNode.inheritAttributes(from: self)
+                newTextNode.interpretAttributes()
+                newTextNode.setText(text)
+                addChildNode(newTextNode)
+
+                if let trailingDiscardableElement = trailingDiscardableElement {
+                    addChildNode(createLineBreak())
+                    addChildNode(trailingDiscardableElement)
+                }
+            }
+        } else {
+            for childNode in childNodes {
+                childNode.clearTrailingAndLeadingNewlinesInCodeblocks()
+            }
+        }
+    }
+
+    private func createDiscardableElement() -> DiscardableTextHTMLElement {
+        let discardableElement = DiscardableTextHTMLElement()
+        discardableElement.inheritAttributes(from: self)
+        discardableElement.interpretAttributes()
+        return discardableElement
+    }
+
+    private func createLineBreak() -> DTBreakHTMLElement {
+        let lineBreakElement = DTBreakHTMLElement()
+        lineBreakElement.inheritAttributes(from: self)
+        lineBreakElement.interpretAttributes()
+        return lineBreakElement
+    }
 }

platforms/ios/lib/WysiwygComposer/Sources/HTMLParser/Extensions/DTCoreText/DiscardableTextHTMLElement.swift

@@ -26,6 +26,11 @@ final class DiscardableTextHTMLElement: DTTextHTMLElement {
         setText(textNode.text())
     }
 
+    override init() {
+        super.init()
+        setText(.nbsp)
+    }
+
     override func attributesForAttributedStringRepresentation() -> [AnyHashable: Any]! {
         var dict = super.attributesForAttributedStringRepresentation() ?? [AnyHashable: Any]()
         // Insert a key to mark this as discardable post-parsing.

platforms/ios/lib/WysiwygComposer/Sources/HTMLParser/Extensions/NSAttributedString+Range.swift

@@ -83,6 +83,20 @@ extension NSAttributedString {
         return ranges
     }
 
+    func discardableTextRanges(in range: NSRange? = nil) -> [NSRange] {
+        let enumRange = range ?? .init(location: 0, length: length)
+        var ranges = [NSRange]()
+
+        enumerateAttribute(.discardableText,
+                           in: enumRange) { (attr: Any?, range: NSRange, _) in
+            if attr != nil {
+                ranges.append(range)
+            }
+        }
+
+        return ranges
+    }
+
     /// Computes index inside the HTML raw text from the index
     /// inside the attributed representation.
     ///
@@ -95,9 +109,17 @@ extension NSAttributedString {
                 .outOfBoundsAttributedIndex(index: attributedIndex)
         }
 
+        let discardableTextRanges = discardableTextRanges()
+        var actualIndex = attributedIndex
+
+        for discardableTextRange in discardableTextRanges {
+            if discardableTextRange.upperBound <= attributedIndex {
+                actualIndex -= discardableTextRange.length
+            }
+        }
+
         let prefixes = listPrefixesRanges()
-        var actualIndex: Int = attributedIndex
-
+
         for listPrefix in prefixes {
             if listPrefix.upperBound <= attributedIndex {
                 actualIndex -= listPrefix.length
@@ -117,8 +139,16 @@ extension NSAttributedString {
     ///   - htmlIndex: the index inside the HTML raw text
     /// - Returns: the index inside the attributed representation
     func attributedPosition(at htmlIndex: Int) throws -> Int {
+        let discardableTextRanges = discardableTextRanges()
+        var actualIndex = htmlIndex
+
+        for discardableTextRange in discardableTextRanges {
+            if discardableTextRange.location < actualIndex {
+                actualIndex += discardableTextRange.length
+            }
+        }
+
         let prefixes = listPrefixesRanges()
-        var actualIndex: Int = htmlIndex
 
         for listPrefix in prefixes {
             if listPrefix.location < actualIndex {

platforms/ios/lib/WysiwygComposer/Sources/HTMLParser/Extensions/NSMutableAttributedString.swift

@@ -53,12 +53,18 @@ extension NSMutableAttributedString {
         }
     }
 
-    /// Removes any text that has been marked as discardable.
-    func removeDiscardableText() {
+    /// Finds any text that has been marked as discardable
+    /// and either replaces it with ZWSP if contained overlaps with text marked with a background style
+    /// or removes it otherwise
+    func replaceOrDeleteDiscardableText() {
         enumerateTypedAttribute(.discardableText) { (discardable: Bool, range: NSRange, _) in
             guard discardable == true else { return }
-
-            self.deleteCharacters(in: range)
+            let attributes = self.attributes(at: range.location, effectiveRange: nil)
+            if attributes[.backgroundStyle] != nil {
+                self.replaceCharacters(in: range, with: String.zwsp)
+            } else {
+                self.deleteCharacters(in: range)
+            }
         }
     }
 

platforms/ios/lib/WysiwygComposer/Sources/HTMLParser/Extensions/String+Character.swift

@@ -16,8 +16,10 @@
 
 extension String {
     static let nbsp = "\(Character.nbsp)"
+    static let zwsp = "\(Character.zwsp)"
 }
 
 public extension Character {
     static let nbsp = Character("\u{00A0}")
+    static let zwsp = Character("\u{200B}")
 }

platforms/ios/lib/WysiwygComposer/Sources/HTMLParser/HTMLParser.swift

@@ -88,6 +88,7 @@ public final class HTMLParser {
             // Removing NBSP character from <p>&nbsp;</p> since it is only used to
             // make DTCoreText able to easily parse new lines.
             element.clearNbspNodes()
+            element.clearTrailingAndLeadingNewlinesInCodeblocks()
         }
 
         guard let attributedString = builder.generatedAttributedString() else {
@@ -114,7 +115,7 @@ public final class HTMLParser {
 
         mutableAttributedString.applyBackgroundStyles(style: style)
         mutableAttributedString.applyInlineCodeBackgroundStyle(codeBackgroundColor: style.codeBackgroundColor)
-        mutableAttributedString.removeDiscardableText()
+        mutableAttributedString.replaceOrDeleteDiscardableText()
         mutableAttributedString.removeParagraphVerticalSpacing()
 
         removeTrailingNewlineIfNeeded(from: mutableAttributedString, given: html)
@@ -124,14 +125,17 @@ public final class HTMLParser {
     private static func removeTrailingNewlineIfNeeded(from mutableAttributedString: NSMutableAttributedString, given html: String) {
         // DTCoreText always adds a \n at the end of the document, which we need to remove
         // however it does not add it if </code> </a> are the last nodes.
-        // Also we don't want to remove it if a codeblock contains that newline
-        // and is not empty, because DTCoreText does not add a newline if these blocks
-        // contain one at the end.
+        // It should give also issues with codeblock and blockquote when they contain newlines
+        // but the usage of nbsp and zwsp solves that
         if mutableAttributedString.string.last == "\n",
            !html.hasSuffix("</code>"),
-           !html.hasSuffix("</a>"),
-           !html.hasSuffix("\n</pre>") {
-            mutableAttributedString.deleteCharacters(in: NSRange(location: mutableAttributedString.length - 1, length: 1))
+           !html.hasSuffix("</a>") {
+            mutableAttributedString.deleteCharacters(
+                in: NSRange(
+                    location: mutableAttributedString.length - 1,
+                    length: 1
+                )
+            )
         }
     }
 }

platforms/ios/lib/WysiwygComposer/Sources/WysiwygComposer/Tools/StringDiffer.swift

@@ -117,7 +117,7 @@ private struct StringDiff {
 private extension String {
     /// Converts all whitespaces to NBSP to avoid diffs caused by HTML translations.
     var withNBSP: String {
-        String(map { $0.isWhitespace ? Character.nbsp : $0 })
+        String(map { $0.isWhitespace ? Character.nbsp : $0 }).trimmingCharacters(in: .whitespacesAndNewlines)
     }
 
     /// Computes the diff from provided string to self. Outputs UTF16 locations and lengths.