Add automatic markdown formatting

src/libneochat/chatmarkdownhelper.h

@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: 2025 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+#pragma once
+
+#include <QObject>
+#include <QQmlEngine>
+
+#include "enums/richformat.h"
+
+class QTextDocument;
+
+class ChatDocumentHandler;
+
+class ChatMarkdownHelper : public QObject
+{
+    Q_OBJECT
+    QML_ELEMENT
+
+public:
+    explicit ChatMarkdownHelper(ChatDocumentHandler *parent);
+
+    void handleExternalFormatChange();
+
+private:
+    enum State {
+        None,
+        Pre,
+        Started,
+    };
+
+    QTextDocument *document() const;
+    void connectDocument();
+
+    State m_currentState = None;
+    int m_startPos = 0;
+    int m_endPos = 0;
+
+    QHash<RichFormat::Format, int> m_currentFormats;
+
+    void checkMarkdown(int position, int charsRemoved, int charsAdded);
+    void complete();
+};