ClangFormat: Rework clangformatconfigwidget

- Move logic work with clang-format file to
additional class to make clangformatconfigwidget
responsible only for work with ui elements.
- Fix functionality: when new BasedOnStyle was
chosen all fields were empty or set in default,
now it fills with the corresponding value.

Change-Id: I2ee42a502e87da761274d293a7f0a38fda98804d
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangformat/clangformatfile.cpp

@@ -0,0 +1,116 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "clangformatfile.h"
+#include <sstream>
+
+using namespace ClangFormat;
+
+ClangFormatFile::ClangFormatFile(Utils::FilePath filePath)
+    : m_filePath(filePath)
+{
+    if (!m_filePath.exists()) {
+        resetStyleToLLVM();
+        return;
+    }
+
+    const std::error_code error
+        = clang::format::parseConfiguration(m_filePath.fileContents().toStdString(), &m_style);
+    if (error.value() != static_cast<int>(clang::format::ParseError::Success)) {
+        resetStyleToLLVM();
+    }
+}
+
+clang::format::FormatStyle ClangFormatFile::format() {
+    return m_style;
+}
+
+Utils::FilePath ClangFormatFile::filePath()
+{
+    return m_filePath;
+}
+
+void ClangFormatFile::setStyle(clang::format::FormatStyle style)
+{
+    m_style = style;
+    saveNewFormat();
+}
+
+void ClangFormatFile::resetStyleToLLVM()
+{
+    m_style = clang::format::getLLVMStyle();
+    saveNewFormat();
+}
+
+void ClangFormatFile::setBasedOnStyle(QString styleName)
+{
+    changeField({"BasedOnStyle", styleName});
+    saveNewFormat();
+}
+
+QString ClangFormatFile::setStyle(QString style)
+{
+    m_style.Language = clang::format::FormatStyle::LK_Cpp;
+    const std::error_code error = clang::format::parseConfiguration(style.toStdString(), &m_style);
+    if (error.value() != static_cast<int>(clang::format::ParseError::Success)) {
+        return QString::fromStdString(error.message());
+    }
+
+    saveNewFormat(style.toUtf8());
+    return "";
+}
+
+QString ClangFormatFile::changeField(Field field)
+{
+    return changeFields({field});
+}
+
+QString ClangFormatFile::changeFields(QList<Field> fields)
+{
+    std::stringstream content;
+    content << "---" << "\n";
+
+    for (const auto &field : fields) {
+        content << field.first.toStdString() << ": " << field.second.toStdString() << "\n";
+    }
+
+    return setStyle(QString::fromStdString(content.str()));
+}
+
+void ClangFormatFile::saveNewFormat()
+{
+    std::string style = clang::format::configurationAsText(m_style);
+
+    // workaround: configurationAsText() add comment "# " before BasedOnStyle line
+    const int pos = style.find("# BasedOnStyle");
+    if (pos < style.size())
+        style.erase(pos, 2);
+    m_filePath.writeFileContents(QByteArray::fromStdString(style));
+}
+
+void ClangFormatFile::saveNewFormat(QByteArray style)
+{
+    m_filePath.writeFileContents(style);
+}