From b50a2e01b259bbed6a21b34d1ccca59b2c45e33d Mon Sep 17 00:00:00 2001
From: Levi Neely <141506390+lneely@users.noreply.github.com>
Date: Sun, 2 Aug 2026 23:48:00 +0200
Subject: [PATCH] fix source block rendering

---
 gui/chatblockmodel.cpp | 116 +++++++++++++++++++++++++++++++++++++++--
 gui/chatblockmodel.h   |   8 +++
 2 files changed, 121 insertions(+), 3 deletions(-)

diff --git a/gui/chatblockmodel.cpp b/gui/chatblockmodel.cpp
index 957a0df..d14f910 100644
--- a/gui/chatblockmodel.cpp
+++ b/gui/chatblockmodel.cpp
@@ -2,7 +2,51 @@
 
 #include <QTextDocument>
 #include <QRegularExpressionMatch>
+#include <QApplication>
+#include <QPalette>
 
+#include <KSyntaxHighlighting/Repository>
+#include <KSyntaxHighlighting/Definition>
+#include <KSyntaxHighlighting/Theme>
+#include <KSyntaxHighlighting/AbstractHighlighter>
+#include <KSyntaxHighlighting/State>
+#include <KSyntaxHighlighting/Format>
+
+
+// --- Syntax highlighting ---
+
+class HtmlHighlighter : public KSyntaxHighlighting::AbstractHighlighter
+{
+public:
+    QString html;
+    using AbstractHighlighter::AbstractHighlighter;
+
+    KSyntaxHighlighting::State processLine(const QString &line,
+                                            const KSyntaxHighlighting::State &state)
+    {
+        m_line = line;
+        return highlightLine(line, state);
+    }
+
+protected:
+    void applyFormat(int offset, int length,
+                     const KSyntaxHighlighting::Format &format) override
+    {
+        const QString text = m_line.mid(offset, length).toHtmlEscaped()
+            .replace(" ", "&nbsp;")
+            .replace("\t", "&nbsp;&nbsp;&nbsp;&nbsp;");
+        if (format.hasTextColor(theme())) {
+            html += QStringLiteral("<span style=\"color:")
+                + format.textColor(theme()).name()
+                + QStringLiteral("\">") + text + QStringLiteral("</span>");
+        } else {
+            html += text;
+        }
+    }
+
+private:
+    QString m_line;
+};
 
 // --- Static helpers ---
 
@@ -29,9 +73,15 @@ const QRegularExpression ChatBlockModel::s_endRe(
 
 ChatBlockModel::ChatBlockModel(QObject *parent)
     : QAbstractListModel(parent)
+    , m_repo(new KSyntaxHighlighting::Repository())
 {
 }
 
+ChatBlockModel::~ChatBlockModel()
+{
+    delete m_repo;
+}
+
 int ChatBlockModel::rowCount(const QModelIndex &parent) const
 {
     if (parent.isValid()) return 0;
@@ -112,11 +162,71 @@ void ChatBlockModel::trimFront(int keepCount)
     emit countChanged();
 }
 
+QString ChatBlockModel::highlightCode(const QString &code, const QString &language) const
+{
+    auto definition = m_repo->definitionForName(language);
+    if (!definition.isValid())
+        definition = m_repo->definitionForFileName(QStringLiteral("file.") + language);
+    if (!definition.isValid())
+        return QStringLiteral("<pre style=\"white-space:pre-wrap;\">")
+            + code.toHtmlEscaped() + QStringLiteral("</pre>");
+
+    const bool dark = QApplication::palette().color(QPalette::Window).lightnessF() < 0.5;
+    const auto theme = dark
+        ? m_repo->defaultTheme(KSyntaxHighlighting::Repository::DarkTheme)
+        : m_repo->defaultTheme(KSyntaxHighlighting::Repository::LightTheme);
+
+    HtmlHighlighter highlighter;
+    highlighter.setDefinition(definition);
+    highlighter.setTheme(theme);
+
+    KSyntaxHighlighting::State state;
+    const QStringList lines = code.split('\n');
+    for (int i = 0; i < lines.size(); ++i) {
+        state = highlighter.processLine(lines[i], state);
+        if (i + 1 < lines.size())
+            highlighter.html += QStringLiteral("<br/>");
+    }
+    return QStringLiteral("<pre style=\"white-space:pre-wrap;\">")
+        + highlighter.html + QStringLiteral("</pre>");
+}
+
 QString ChatBlockModel::renderMarkdown(const QString &markdown) const
 {
-    QTextDocument document;
-    document.setMarkdown(markdown);
-    return document.toHtml();
+    static const QRegularExpression fenceRe(
+        R"(```([A-Za-z0-9_+.-]*)[^\n]*\n([\s\S]*?)```)");
+
+    QString result;
+    int cursor = 0;
+    auto it = fenceRe.globalMatch(markdown);
+    while (it.hasNext()) {
+        const auto match = it.next();
+        QTextDocument prose;
+        prose.setMarkdown(markdown.mid(cursor, match.capturedStart() - cursor));
+        result += prose.toHtml();
+        result += highlightCode(match.captured(2), match.captured(1));
+        cursor = match.capturedEnd();
+    }
+
+    // During streaming, the closing fence may not have arrived yet. Do not
+    // send the incomplete code block through Markdown, which collapses its
+    // newlines into prose spacing.
+    static const QRegularExpression openFenceRe(
+        R"(^```([A-Za-z0-9_+.-]*)[^\n]*\n([\s\S]*)$)",
+        QRegularExpression::MultilineOption);
+    const auto tail = markdown.mid(cursor);
+    const auto open = openFenceRe.match(tail);
+    if (open.hasMatch()) {
+        QTextDocument prose;
+        prose.setMarkdown(tail.left(open.capturedStart()));
+        result += prose.toHtml();
+        result += highlightCode(open.captured(2), open.captured(1));
+    } else {
+        QTextDocument prose;
+        prose.setMarkdown(tail);
+        result += prose.toHtml();
+    }
+    return result;
 }
 
 void ChatBlockModel::appendContent(const QString &line)
diff --git a/gui/chatblockmodel.h b/gui/chatblockmodel.h
index 1c4dbfe..a8fa2d9 100644
--- a/gui/chatblockmodel.h
+++ b/gui/chatblockmodel.h
@@ -4,8 +4,13 @@
 #include <QAbstractListModel>
 #include <QList>
 #include <QString>
+#include <QStringList>
 #include <QRegularExpression>
 
+namespace KSyntaxHighlighting {
+class Repository;
+}
+
 struct ChatBlock {
     enum Type {
         User,
@@ -46,6 +51,7 @@ public:
     };
 
     explicit ChatBlockModel(QObject *parent = nullptr);
+    ~ChatBlockModel() override;
 
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
@@ -63,8 +69,10 @@ private:
     void appendContent(const QString &line);
 
     QString renderMarkdown(const QString &markdown) const;
+    QString highlightCode(const QString &code, const QString &language) const;
 
     State m_state = State::BlockStart;
+    KSyntaxHighlighting::Repository *m_repo = nullptr;
 
     QList<ChatBlock> m_blocks;
     QString m_lineBuffer;