TextEditor: introduce text suggestion interface

And also a copilot suggestion implementing that interface that allows
reverting all changes done to a suggestion as well as applying it.

Change-Id: I236c1fc5e5844d19ac606672af54e273e9c42e1c
Reviewed-by: Marcus Tillmanns <[email protected]>

10 files changed, 190 insertions, 147 deletions

diff --git a/src/libs/languageserverprotocol/lsptypes.cpp b/src/libs/languageserverprotocol/lsptypes.cpp
index 4bf3f3746e2..bd7798dcef9 100644
--- a/src/libs/languageserverprotocol/lsptypes.cpp
+++ b/src/libs/languageserverprotocol/lsptypes.cpp
@@ -311,6 +311,16 @@ bool Range::overlaps(const Range &range) const
     return !isLeftOf(range) && !range.isLeftOf(*this);
 }
 
+QTextCursor Range::toSelection(QTextDocument *doc) const
+{
+    QTC_ASSERT(doc, return {});
+    if (!isValid())
+        return {};
+    QTextCursor cursor = start().toTextCursor(doc);
+    cursor.setPosition(end().toPositionInDocument(doc), QTextCursor::KeepAnchor);
+    return cursor;
+}
+
 QString expressionForGlob(QString globPattern)
 {
     const QString anySubDir("qtc_anysubdir_id");
diff --git a/src/libs/languageserverprotocol/lsptypes.h b/src/libs/languageserverprotocol/lsptypes.h
index 4adc35aa105..3a9adb1b0d8 100644
--- a/src/libs/languageserverprotocol/lsptypes.h
+++ b/src/libs/languageserverprotocol/lsptypes.h
@@ -117,6 +117,8 @@ public:
     bool isLeftOf(const Range &other) const
     { return isEmpty() || other.isEmpty() ? end() < other.start() : end() <= other.start(); }
 
+    QTextCursor toSelection(QTextDocument *doc) const;
+
     bool isValid() const override
     { return JsonObject::contains(startKey) && JsonObject::contains(endKey); }
 };
diff --git a/src/libs/languageserverprotocol/lsputils.h b/src/libs/languageserverprotocol/lsputils.h
index 5515b515767..0c815bafd8a 100644
--- a/src/libs/languageserverprotocol/lsputils.h
+++ b/src/libs/languageserverprotocol/lsputils.h
@@ -87,6 +87,13 @@ public:
         return QJsonValue();
     }
 
+    QList<T> toListOrEmpty() const
+    {
+        if (std::holds_alternative<QList<T>>(*this))
+            return std::get<QList<T>>(*this);
+        return {};
+    }
+
     QList<T> toList() const
     {
         QTC_ASSERT(std::holds_alternative<QList<T>>(*this), return {});
diff --git a/src/plugins/copilot/copilotclient.cpp b/src/plugins/copilot/copilotclient.cpp
index d245e68eaa3..27bcbacf476 100644
--- a/src/plugins/copilot/copilotclient.cpp
+++ b/src/plugins/copilot/copilotclient.cpp
@@ -11,6 +11,7 @@
 
 #include <utils/filepath.h>
 
+#include <texteditor/textdocumentlayout.h>
 #include <texteditor/texteditor.h>
 
 #include <languageserverprotocol/lsptypes.h>
@@ -128,6 +129,39 @@ void CopilotClient::requestCompletions(TextEditorWidget *editor)
     sendMessage(request);
 }
 
+class CopilotSuggestion final : public TextEditor::TextSuggestion
+{
+public:
+    CopilotSuggestion(const Completion &completion, QTextDocument *origin)
+        : m_completion(completion)
+    {
+        document()->setPlainText(completion.text());
+        m_start = completion.position().toTextCursor(origin);
+        m_start.setKeepPositionOnInsert(true);
+        setCurrentPosition(m_start.position());
+    }
+
+    bool apply() final
+    {
+        reset();
+        QTextCursor cursor = m_completion.range().toSelection(m_start.document());
+        cursor.insertText(m_completion.text());
+        return true;
+    }
+    void reset() final
+    {
+        m_start.removeSelectedText();
+    }
+    int position() final
+    {
+        return m_start.position();
+    }
+
+private:
+    Completion m_completion;
+    QTextCursor m_start;
+};
+
 void CopilotClient::handleCompletions(const GetCompletionRequest::Response &response,
                                       TextEditorWidget *editor)
 {
@@ -142,19 +176,15 @@ void CopilotClient::handleCompletions(const GetCompletionRequest::Response &resp
     if (cursors.hasMultipleCursors())
         return;
 
-    const QTextCursor cursor = cursors.mainCursor();
     if (cursors.hasSelection() || cursors.mainCursor().position() != requestPosition)
         return;
 
     if (const std::optional<GetCompletionResponse> result = response.result()) {
-        LanguageClientArray<Completion> completions = result->completions();
-        if (completions.isNull() || completions.toList().isEmpty())
+        QList<Completion> completions = result->completions().toListOrEmpty();
+        if (completions.isEmpty())
             return;
-
-        const Completion firstCompletion = completions.toList().first();
-        const QString content = firstCompletion.text().mid(firstCompletion.position().character());
-
-        editor->insertSuggestion(content);
+        editor->insertSuggestion(
+            std::make_unique<CopilotSuggestion>(completions.first(), editor->document()));
     }
 }
 
diff --git a/src/plugins/texteditor/textdocument.cpp b/src/plugins/texteditor/textdocument.cpp
index 966edd4e7d8..4a7e80f52ce 100644
--- a/src/plugins/texteditor/textdocument.cpp
+++ b/src/plugins/texteditor/textdocument.cpp
@@ -373,16 +373,13 @@ QAction *TextDocument::createDiffAgainstCurrentFileAction(
     return diffAction;
 }
 
-void TextDocument::insertSuggestion(const QString &text, const QTextCursor &cursor)
+void TextDocument::insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion)
 {
+    QTextCursor cursor(&d->m_document);
+    cursor.setPosition(suggestion->position());
     const QTextBlock block = cursor.block();
-    const QString blockText = block.text();
-    QString replacement = blockText.left(cursor.positionInBlock()) + text;
-    if (!text.contains('\n'))
-        replacement.append(blockText.mid(cursor.positionInBlock()));
-    TextDocumentLayout::userData(block)->setReplacement(replacement);
-    TextDocumentLayout::userData(block)->setReplacementPosition(cursor.positionInBlock());
-    TextDocumentLayout::updateReplacementFormats(block, fontSettings());
+    TextDocumentLayout::userData(block)->insertSuggestion(std::move(suggestion));
+    TextDocumentLayout::updateSuggestionFormats(block, fontSettings());
     updateLayout();
 }
 
@@ -434,7 +431,7 @@ void TextDocument::applyFontSettings()
     d->m_fontSettingsNeedsApply = false;
     QTextBlock block = document()->firstBlock();
     while (block.isValid()) {
-        TextDocumentLayout::updateReplacementFormats(block, fontSettings());
+        TextDocumentLayout::updateSuggestionFormats(block, fontSettings());
         block = block.next();
     }
     updateLayout();
diff --git a/src/plugins/texteditor/textdocument.h b/src/plugins/texteditor/textdocument.h
index 9ef556503fd..d1f686f6a0c 100644
--- a/src/plugins/texteditor/textdocument.h
+++ b/src/plugins/texteditor/textdocument.h
@@ -37,6 +37,7 @@ class SyntaxHighlighter;
 class TabSettings;
 class TextDocumentPrivate;
 class TextMark;
+class TextSuggestion;
 class TypingSettings;
 
 using TextMarks = QList<TextMark *>;
@@ -145,6 +146,7 @@ public:
         const std::function<Utils::FilePath()> &filePath);
 
     void insertSuggestion(const QString &text, const QTextCursor &cursor);
+    void insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion);
 
 #ifdef WITH_TESTS
     void setSilentReload();
diff --git a/src/plugins/texteditor/textdocumentlayout.cpp b/src/plugins/texteditor/textdocumentlayout.cpp
index 9c257d3a257..a80a1b77515 100644
--- a/src/plugins/texteditor/textdocumentlayout.cpp
+++ b/src/plugins/texteditor/textdocumentlayout.cpp
@@ -345,22 +345,19 @@ void TextBlockUserData::setCodeFormatterData(CodeFormatterData *data)
     m_codeFormatterData = data;
 }
 
-void TextBlockUserData::setReplacement(const QString &replacement)
+void TextBlockUserData::insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion)
 {
-    m_replacement.reset(new QTextDocument(replacement));
-    m_replacement->setDocumentLayout(new TextDocumentLayout(m_replacement.get()));
-    m_replacement->setDocumentMargin(0);
+    m_suggestion = std::move(suggestion);
 }
 
-void TextBlockUserData::setReplacementPosition(int replacementPosition)
+TextSuggestion *TextBlockUserData::suggestion() const
 {
-    m_replacementPosition = replacementPosition;
+    return m_suggestion.get();
 }
 
-void TextBlockUserData::clearReplacement()
+void TextBlockUserData::clearSuggestion()
 {
-    m_replacement.reset();
-    m_replacementPosition = -1;
+    m_suggestion.release();
 }
 
 void TextBlockUserData::addMark(TextMark *mark)
@@ -536,21 +533,29 @@ QByteArray TextDocumentLayout::expectedRawStringSuffix(const QTextBlock &block)
     return {};
 }
 
-void TextDocumentLayout::updateReplacementFormats(const QTextBlock &block,
+TextSuggestion *TextDocumentLayout::suggestion(const QTextBlock &block)
+{
+    if (TextBlockUserData *userData = textUserData(block))
+        return userData->suggestion();
+    return nullptr;
+}
+
+void TextDocumentLayout::updateSuggestionFormats(const QTextBlock &block,
                                                  const FontSettings &fontSettings)
 {
-    if (QTextDocument *replacement = replacementDocument(block)) {
+    if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(block)) {
+        QTextDocument *suggestionDoc = suggestion->document();
         const QTextCharFormat replacementFormat = fontSettings.toTextCharFormat(
             TextStyles{C_TEXT, {C_DISABLED_CODE}});
         QList<QTextLayout::FormatRange> formats = block.layout()->formats();
-        QTextCursor cursor(replacement);
+        QTextCursor cursor(suggestionDoc);
         cursor.select(QTextCursor::Document);
         cursor.setCharFormat(fontSettings.toTextCharFormat(C_TEXT));
-        const int position = replacementPosition(block);
+        const int position = suggestion->currentPosition() - block.position();
         cursor.setPosition(position);
         const QString trailingText = block.text().mid(position);
         if (!trailingText.isEmpty()) {
-            const int trailingIndex = replacement->firstBlock().text().indexOf(trailingText,
+            const int trailingIndex = suggestionDoc->firstBlock().text().indexOf(trailingText,
                                                                                position);
             if (trailingIndex >= 0) {
                 cursor.setPosition(trailingIndex, QTextCursor::KeepAnchor);
@@ -581,45 +586,22 @@ void TextDocumentLayout::updateReplacementFormats(const QTextBlock &block,
         }
         cursor.movePosition(QTextCursor::End, QTextCursor::KeepAnchor);
         cursor.setCharFormat(replacementFormat);
-        replacement->firstBlock().layout()->setFormats(formats);
-    }
-}
-
-QString TextDocumentLayout::replacement(const QTextBlock &block)
-{
-    if (QTextDocument *replacement = replacementDocument(block)) {
-        QTextCursor cursor(replacement);
-        const int position = replacementPosition(block);
-        cursor.setPosition(position);
-        cursor.movePosition(QTextCursor::End, QTextCursor::KeepAnchor);
-        return cursor.selectedText();
+        suggestionDoc->firstBlock().layout()->setFormats(formats);
     }
-    return {};
-}
-
-QTextDocument *TextDocumentLayout::replacementDocument(const QTextBlock &block)
-{
-    TextBlockUserData *userData = textUserData(block);
-    return userData ? userData->replacement() : nullptr;
-}
-
-int TextDocumentLayout::replacementPosition(const QTextBlock &block)
-{
-    TextBlockUserData *userData = textUserData(block);
-    return userData ? userData->replacementPosition() : -1;
 }
 
-bool TextDocumentLayout::updateReplacement(const QTextBlock &block,
-                                           int position,
-                                           const FontSettings &fontSettings)
+bool TextDocumentLayout::updateSuggestion(const QTextBlock &block,
+                                          int position,
+                                          const FontSettings &fontSettings)
 {
-    if (QTextDocument *replacementDocument = TextDocumentLayout::replacementDocument(block)) {
-        const QString start = block.text().left(position);
-        const QString end = block.text().mid(position);
-        const QString replacement = replacementDocument->firstBlock().text();
-        if (replacement.startsWith(start) && replacement.endsWith(end)) {
-            userData(block)->setReplacementPosition(position);
-            TextDocumentLayout::updateReplacementFormats(block, fontSettings);
+    if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(block)) {
+        auto positionInBlock = position - block.position();
+        const QString start = block.text().left(positionInBlock);
+        const QString end = block.text().mid(positionInBlock);
+        const QString replacement = suggestion->document()->firstBlock().text();
+        if (replacement.startsWith(start) && replacement.indexOf(end, start.size()) >= 0) {
+            suggestion->setCurrentPosition(position);
+            TextDocumentLayout::updateSuggestionFormats(block, fontSettings);
             return true;
         }
     }
@@ -756,11 +738,11 @@ static QRectF replacementBoundingRect(const QTextDocument *replacement)
 
 QRectF TextDocumentLayout::blockBoundingRect(const QTextBlock &block) const
 {
-    if (QTextDocument *replacement = replacementDocument(block)) {
+    if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(block)) {
         // since multiple code paths expects that we have a valid block layout after requesting the
         // block bounding rect explicitly create that layout here
         ensureBlockLayout(block);
-        return replacementBoundingRect(replacement);
+        return replacementBoundingRect(suggestion->document());
     }
 
     QRectF boundingRect = QPlainTextDocumentLayout::blockBoundingRect(block);
@@ -851,4 +833,10 @@ void insertSorted(Parentheses &list, const Parenthesis &elem)
     list.insert(it, elem);
 }
 
+TextSuggestion::TextSuggestion()
+{
+    m_replacementDocument.setDocumentLayout(new TextDocumentLayout(&m_replacementDocument));
+    m_replacementDocument.setDocumentMargin(0);
+}
+
 } // namespace TextEditor
diff --git a/src/plugins/texteditor/textdocumentlayout.h b/src/plugins/texteditor/textdocumentlayout.h
index 97fa5992abb..e02615b1063 100644
--- a/src/plugins/texteditor/textdocumentlayout.h
+++ b/src/plugins/texteditor/textdocumentlayout.h
@@ -42,6 +42,24 @@ public:
     virtual ~CodeFormatterData();
 };
 
+class TEXTEDITOR_EXPORT TextSuggestion
+{
+public:
+    TextSuggestion();
+    virtual bool apply() = 0;
+    virtual void reset() = 0;
+    virtual int position() = 0;
+
+    int currentPosition() const { return m_currentPosition; }
+    void setCurrentPosition(int position) { m_currentPosition = position; }
+
+    QTextDocument *document() { return &m_replacementDocument; }
+
+private:
+    QTextDocument m_replacementDocument;
+    int m_currentPosition = -1;
+};
+
 class TEXTEDITOR_EXPORT TextBlockUserData : public QTextBlockUserData
 {
 public:
@@ -126,11 +144,9 @@ public:
     QByteArray expectedRawStringSuffix() { return m_expectedRawStringSuffix; }
     void setExpectedRawStringSuffix(const QByteArray &suffix) { m_expectedRawStringSuffix = suffix; }
 
-    void setReplacement(const QString &replacement);
-    void setReplacementPosition(int replacementPosition);
-    void clearReplacement();
-    QTextDocument *replacement() const { return m_replacement.get(); }
-    int replacementPosition() const { return m_replacementPosition; }
+    void insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion);
+    TextSuggestion *suggestion() const;
+    void clearSuggestion();
 
 private:
     TextMarks m_marks;
@@ -146,7 +162,7 @@ private:
     KSyntaxHighlighting::State m_syntaxState;
     QByteArray m_expectedRawStringSuffix; // A bit C++-specific, but let's be pragmatic.
     std::unique_ptr<QTextDocument> m_replacement;
-    int m_replacementPosition = -1;
+    std::unique_ptr<TextSuggestion> m_suggestion;
 };
 
 
@@ -180,14 +196,12 @@ public:
     static void setFolded(const QTextBlock &block, bool folded);
     static void setExpectedRawStringSuffix(const QTextBlock &block, const QByteArray &suffix);
     static QByteArray expectedRawStringSuffix(const QTextBlock &block);
-    static void updateReplacementFormats(const QTextBlock &block,
+    static TextSuggestion *suggestion(const QTextBlock &block);
+    static void updateSuggestionFormats(const QTextBlock &block,
                                         const FontSettings &fontSettings);
-    static QString replacement(const QTextBlock &block);
-    static QTextDocument *replacementDocument(const QTextBlock &block);
-    static int replacementPosition(const QTextBlock &block);
-    static bool updateReplacement(const QTextBlock &block,
-                                  int position,
-                                  const FontSettings &fontSettings);
+    static bool updateSuggestion(const QTextBlock &block,
+                                 int position,
+                                 const FontSettings &fontSettings);
 
     class TEXTEDITOR_EXPORT FoldValidator
     {
diff --git a/src/plugins/texteditor/texteditor.cpp b/src/plugins/texteditor/texteditor.cpp
index ccbdb0467d0..c5783acb919 100644
--- a/src/plugins/texteditor/texteditor.cpp
+++ b/src/plugins/texteditor/texteditor.cpp
@@ -820,7 +820,7 @@ public:
     QList<int> m_visualIndentCache;
     int m_visualIndentOffset = 0;
 
-    void insertSuggestion(const QString &suggestion);
+    void insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion);
     void updateSuggestion();
     void clearCurrentSuggestion();
     QTextBlock m_suggestionBlock;
@@ -1651,12 +1651,13 @@ void TextEditorWidgetPrivate::handleMoveBlockSelection(QTextCursor::MoveOperatio
     q->setMultiTextCursor(MultiTextCursor(cursors));
 }
 
-void TextEditorWidgetPrivate::insertSuggestion(const QString &suggestion)
+void TextEditorWidgetPrivate::insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion)
 {
     clearCurrentSuggestion();
     auto cursor = q->textCursor();
+    cursor.setPosition(suggestion->position());
     m_suggestionBlock = cursor.block();
-    m_document->insertSuggestion(suggestion, cursor);
+    m_document->insertSuggestion(std::move(suggestion));
 }
 
 void TextEditorWidgetPrivate::updateSuggestion()
@@ -1666,10 +1667,9 @@ void TextEditorWidgetPrivate::updateSuggestion()
     if (m_cursors.mainCursor().block() != m_suggestionBlock) {
         clearCurrentSuggestion();
     } else {
-        const int position = m_cursors.mainCursor().position() - m_suggestionBlock.position();
-        if (!TextDocumentLayout::updateReplacement(m_suggestionBlock,
-                                                   position,
-                                                   m_document->fontSettings())) {
+        if (!TextDocumentLayout::updateSuggestion(m_suggestionBlock,
+                                                  m_cursors.mainCursor().position(),
+                                                  m_document->fontSettings())) {
             clearCurrentSuggestion();
         }
     }
@@ -1678,7 +1678,7 @@ void TextEditorWidgetPrivate::updateSuggestion()
 void TextEditorWidgetPrivate::clearCurrentSuggestion()
 {
     if (TextBlockUserData *userData = TextDocumentLayout::textUserData(m_suggestionBlock)) {
-        userData->clearReplacement();
+        userData->clearSuggestion();
         m_document->updateLayout();
     }
     m_suggestionBlock = QTextBlock();
@@ -2689,25 +2689,18 @@ void TextEditorWidget::keyPressEvent(QKeyEvent *e)
     case Qt::Key_Tab:
     case Qt::Key_Backtab: {
         if (ro) break;
-        if (d->m_suggestionBlock.isValid()) {
-            const int position = TextDocumentLayout::replacementPosition(d->m_suggestionBlock);
-            if (position >= 0) {
-                QTextCursor cursor(d->m_suggestionBlock);
-                cursor.setPosition(d->m_suggestionBlock.position() + position);
-                cursor.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
-                cursor.insertText(TextDocumentLayout::replacement(d->m_suggestionBlock));
-                setTextCursor(cursor);
-            }
-            d->clearCurrentSuggestion();
-            e->accept();
-            return;
-        }
         if (d->m_snippetOverlay->isVisible() && !d->m_snippetOverlay->isEmpty()) {
             d->snippetTabOrBacktab(e->key() == Qt::Key_Tab);
             e->accept();
             return;
         }
         QTextCursor cursor = textCursor();
+        if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(d->m_suggestionBlock)) {
+            suggestion->apply();
+            d->clearCurrentSuggestion();
+            e->accept();
+            return;
+        }
         if (d->m_skipAutoCompletedText && e->key() == Qt::Key_Tab) {
             bool skippedAutoCompletedText = false;
             while (!d->m_autoCompleteHighlightPos.isEmpty()
@@ -4067,10 +4060,10 @@ static TextMarks availableMarks(const TextMarks &marks,
 QRectF TextEditorWidgetPrivate::getLastLineLineRect(const QTextBlock &block)
 {
     QTextLayout *layout = nullptr;
-    if (block != m_suggestionBlock)
+    if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(block))
+        layout = suggestion->document()->firstBlock().layout();
+    else
         layout = block.layout();
-    else if (QTextDocument *replacement = TextDocumentLayout::replacementDocument(block))
-        layout = replacement->firstBlock().layout();
 
     QTC_ASSERT(layout, layout = block.layout());
     const int lineCount = layout->lineCount();
@@ -4467,18 +4460,18 @@ void TextEditorWidgetPrivate::paintAdditionalVisualWhitespaces(PaintEventData &d
                              visualArrow);
         }
         if (!nextBlockIsValid) { // paint EOF symbol
-            if (m_suggestionBlock.isValid() && data.block == m_suggestionBlock) {
-                if (QTextDocument *replacement = TextDocumentLayout::replacementDocument(
-                        m_suggestionBlock)) {
-                    const QTextBlock lastReplacementBlock = replacement->lastBlock();
-                    for (QTextBlock block = replacement->firstBlock();
-                         block != lastReplacementBlock && block.isValid();
-                         block = block.next()) {
-                        top += replacement->documentLayout()->blockBoundingRect(block).height();
-                    }
-                    layout = lastReplacementBlock.layout();
-                    lineCount = layout->lineCount();
+            if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(data.block)) {
+                const QTextBlock lastReplacementBlock = suggestion->document()->lastBlock();
+                for (QTextBlock block = suggestion->document()->firstBlock();
+                     block != lastReplacementBlock && block.isValid();
+                     block = block.next()) {
+                    top += suggestion->document()
+                               ->documentLayout()
+                               ->blockBoundingRect(block)
+                               .height();
                 }
+                layout = lastReplacementBlock.layout();
+                lineCount = layout->lineCount();
             }
             QTextLine line = layout->lineAt(lineCount - 1);
             QRectF lineRect = line.naturalTextRect().translated(data.offset.x(), top);
@@ -4739,17 +4732,14 @@ void TextEditorWidgetPrivate::setupSelections(const PaintEventData &data,
     int deltaPos = -1;
     int delta = 0;
 
-    if (m_suggestionBlock == data.block) {
-        if (QTextDocument *replacement = TextDocumentLayout::replacementDocument(
-                m_suggestionBlock)) {
-            deltaPos = TextDocumentLayout::replacementPosition(data.block);
-            const QString trailingText = data.block.text().mid(deltaPos);
-            if (!trailingText.isEmpty()) {
-                const int trailingIndex = replacement->firstBlock().text().indexOf(trailingText,
-                                                                                   deltaPos);
-                if (trailingIndex >= 0)
-                    delta = std::max(trailingIndex - deltaPos, 0);
-            }
+    if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(data.block)) {
+        deltaPos = suggestion->currentPosition() - data.block.position();
+        const QString trailingText = data.block.text().mid(deltaPos);
+        if (!trailingText.isEmpty()) {
+            const int trailingIndex
+                = suggestion->document()->firstBlock().text().indexOf(trailingText, deltaPos);
+            if (trailingIndex >= 0)
+                delta = std::max(trailingIndex - deltaPos, 0);
         }
     }
 
@@ -4994,21 +4984,23 @@ void TextEditorWidget::paintBlock(QPainter *painter,
                                   const QVector<QTextLayout::FormatRange> &selections,
                                   const QRect &clipRect) const
 {
-    if (QTextDocument *replacement = TextDocumentLayout::replacementDocument(block)) {
-        QTextBlock replacementBlock = replacement->firstBlock();
-        QPointF replacementOffset = offset;
-        replacementOffset.rx() += document()->documentMargin();
-        while (replacementBlock.isValid()) {
+    if (TextSuggestion *suggestion = TextDocumentLayout::suggestion(block)) {
+        QTextBlock suggestionBlock = suggestion->document()->firstBlock();
+        QPointF suggestionOffset = offset;
+        suggestionOffset.rx() += document()->documentMargin();
+        while (suggestionBlock.isValid()) {
             const QVector<QTextLayout::FormatRange> blockSelections
-                = replacementBlock.blockNumber() == 0 ? selections
+                = suggestionBlock.blockNumber() == 0 ? selections
                                                       : QVector<QTextLayout::FormatRange>{};
-            replacementBlock.layout()->draw(painter,
-                                            replacementOffset,
+            suggestionBlock.layout()->draw(painter,
+                                            suggestionOffset,
                                             blockSelections,
                                             clipRect);
-            replacementOffset.ry()
-                += replacement->documentLayout()->blockBoundingRect(replacementBlock).height();
-            replacementBlock = replacementBlock.next();
+            suggestionOffset.ry() += suggestion->document()
+                                         ->documentLayout()
+                                         ->blockBoundingRect(suggestionBlock)
+                                         .height();
+            suggestionBlock = suggestionBlock.next();
         }
         return;
     }
@@ -5992,9 +5984,9 @@ void TextEditorWidget::removeHoverHandler(BaseHoverHandler *handler)
     d->m_hoverHandlerRunner.handlerRemoved(handler);
 }
 
-void TextEditorWidget::insertSuggestion(const QString &suggestion)
+void TextEditorWidget::insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion)
 {
-    d->insertSuggestion(suggestion);
+    d->insertSuggestion(std::move(suggestion));
 }
 
 void TextEditorWidget::clearSuggestion()
diff --git a/src/plugins/texteditor/texteditor.h b/src/plugins/texteditor/texteditor.h
index 4234645d50a..8c6bbb688e3 100644
--- a/src/plugins/texteditor/texteditor.h
+++ b/src/plugins/texteditor/texteditor.h
@@ -42,15 +42,16 @@ class HighlightScrollBarController;
 }
 
 namespace TextEditor {
-class TextDocument;
-class TextMark;
-class BaseHoverHandler;
-class RefactorOverlay;
-class SyntaxHighlighter;
 class AssistInterface;
+class BaseHoverHandler;
+class CompletionAssistProvider;
 class IAssistProvider;
 class ICodeStylePreferences;
-class CompletionAssistProvider;
+class RefactorOverlay;
+class SyntaxHighlighter;
+class TextDocument;
+class TextMark;
+class TextSuggestion;
 using RefactorMarkers = QList<RefactorMarker>;
 using TextMarks = QList<TextMark *>;
 
@@ -470,7 +471,7 @@ public:
     void addHoverHandler(BaseHoverHandler *handler);
     void removeHoverHandler(BaseHoverHandler *handler);
 
-    void insertSuggestion(const QString &suggestion);
+    void insertSuggestion(std::unique_ptr<TextSuggestion> &&suggestion);
     void clearSuggestion();
     bool suggestionVisible() const;