GitLab: Introduce minimal GitLab plugin

So far only adding global settings and project settings.
Global settings allow to specify configurations used later
inside the project settings or when accessing GitLab
server instances.
Project settings already can "link" to GitLab projects,
which will allow to fetch notifications for the project
later on.
Real functionality is added in the follow ups.

Change-Id: I8a0f978001c58c6dc9e07917c183891abec9a3d0
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/gitlab/gitlabplugin.cpp

@@ -0,0 +1,110 @@
+/****************************************************************************
+**
+** Copyright (C) 2022 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 "gitlabplugin.h"
+
+#include "gitlaboptionspage.h"
+#include "gitlabparameters.h"
+#include "gitlabprojectsettings.h"
+
+#include <coreplugin/icore.h>
+#include <projectexplorer/project.h>
+#include <projectexplorer/projectpanelfactory.h>
+#include <utils/qtcassert.h>
+
+namespace GitLab {
+
+class GitLabPluginPrivate
+{
+public:
+    GitLabParameters parameters;
+    GitLabOptionsPage optionsPage{&parameters};
+    QHash<ProjectExplorer::Project *, GitLabProjectSettings *> projectSettings;
+};
+
+static GitLabPluginPrivate *dd = nullptr;
+
+GitLabPlugin::GitLabPlugin()
+{
+}
+
+GitLabPlugin::~GitLabPlugin()
+{
+    if (!dd->projectSettings.isEmpty()) {
+        qDeleteAll(dd->projectSettings);
+        dd->projectSettings.clear();
+    }
+    delete dd;
+    dd = nullptr;
+}
+
+bool GitLabPlugin::initialize(const QStringList & /*arguments*/, QString * /*errorString*/)
+{
+    dd = new GitLabPluginPrivate;
+    dd->parameters.fromSettings(Core::ICore::settings());
+    auto panelFactory = new ProjectExplorer::ProjectPanelFactory;
+    panelFactory->setPriority(999);
+    panelFactory->setDisplayName(tr("GitLab"));
+    panelFactory->setCreateWidgetFunction([](ProjectExplorer::Project *project) {
+        return new GitLabProjectSettingsWidget(project);
+    });
+    ProjectExplorer::ProjectPanelFactory::registerFactory(panelFactory);
+    return true;
+}
+
+QList<GitLabServer> GitLabPlugin::allGitLabServers()
+{
+    QTC_ASSERT(dd, return {});
+    return dd->parameters.gitLabServers;
+}
+
+GitLabServer GitLabPlugin::gitLabServerForId(const Utils::Id &id)
+{
+    QTC_ASSERT(dd, return {});
+    return dd->parameters.serverForId(id);
+}
+
+GitLabParameters *GitLabPlugin::globalParameters()
+{
+    return &dd->parameters;
+}
+
+GitLabProjectSettings *GitLabPlugin::projectSettings(ProjectExplorer::Project *project)
+{
+    QTC_ASSERT(project, return nullptr);
+    QTC_ASSERT(dd, return nullptr);
+    auto &settings = dd->projectSettings[project];
+    if (!settings)
+        settings = new GitLabProjectSettings(project);
+    return settings;
+}
+
+GitLabOptionsPage *GitLabPlugin::optionsPage()
+{
+    QTC_ASSERT(dd, return {});
+    return &dd->optionsPage;
+}
+
+} // namespace GitLab