Lua: Add Lua plugin support

Adds basic support for writing Plugins using the lua scripting language.
Lua Plugins are registered just as native plugins are and can be enabled
or disabled via the plugin dialog.

see src/plugins/lua/README.md for further details.

Change-Id: I9f4d15e9632c46e1c6c132bcd0bbcdd70b150640
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/lua/luapluginspec.cpp

@@ -0,0 +1,140 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include "luapluginspec.h"
+
+#include "luaengine.h"
+#include "luatr.h"
+
+#include <extensionsystem/extensionsystemtr.h>
+
+#include <utils/algorithm.h>
+#include <utils/expected.h>
+
+#include <QJsonDocument>
+#include <QLoggingCategory>
+
+Q_LOGGING_CATEGORY(luaPluginSpecLog, "qtc.lua.pluginspec", QtWarningMsg)
+
+using namespace ExtensionSystem;
+using namespace Utils;
+
+namespace Lua {
+
+class LuaScriptPluginPrivate
+{
+public:
+    QString name;
+    QList<QString> cppDepends;
+    sol::function setup;
+    sol::environment pluginEnvironment;
+};
+
+class LuaPluginSpecPrivate
+{
+public:
+    FilePath pluginScriptPath;
+
+    sol::state lua;
+    sol::table pluginTable;
+
+    sol::function setupFunction;
+};
+
+LuaPluginSpec::LuaPluginSpec()
+    : d(new LuaPluginSpecPrivate())
+{}
+
+expected_str<LuaPluginSpec *> LuaPluginSpec::create(const FilePath &filePath,
+                                                    sol::state lua,
+                                                    sol::table pluginTable)
+{
+    std::unique_ptr<LuaPluginSpec> pluginSpec(new LuaPluginSpec());
+
+    pluginSpec->d->lua = std::move(lua);
+    pluginSpec->d->pluginTable = pluginTable;
+
+    pluginSpec->d->setupFunction = pluginTable.get_or<sol::function>("setup", {});
+    if (!pluginSpec->d->setupFunction)
+        return make_unexpected(QString("Plugin info table did not contain a setup function"));
+
+    QJsonValue v = LuaEngine::toJson(pluginTable);
+    if (luaPluginSpecLog().isDebugEnabled()) {
+        qCDebug(luaPluginSpecLog).noquote()
+            << "Plugin info table:" << QJsonDocument(v.toObject()).toJson(QJsonDocument::Indented);
+    }
+
+    QJsonObject obj = v.toObject();
+    obj["SoftLoadable"] = true;
+
+    auto r = pluginSpec->PluginSpec::readMetaData(obj);
+    if (!r)
+        return make_unexpected(r.error());
+
+    pluginSpec->setFilePath(filePath.toUserOutput());
+    pluginSpec->setLocation(filePath.parentDir().toUserOutput());
+
+    pluginSpec->d->pluginScriptPath = filePath;
+
+    return pluginSpec.release();
+}
+
+ExtensionSystem::IPlugin *LuaPluginSpec::plugin() const
+{
+    return nullptr;
+}
+
+// LuaPluginSpec::For internal use {}
+bool LuaPluginSpec::loadLibrary()
+{
+    // We are actually already loaded, but we need to set the state to loaded as well.
+    // We cannot set it earlier as it is used as a state machine that would break for earlier steps.
+    setState(PluginSpec::State::Loaded);
+    return true;
+}
+bool LuaPluginSpec::initializePlugin()
+{
+    std::optional<sol::table> hookTable = d->pluginTable.get<std::optional<sol::table>>("hooks");
+    if (hookTable) {
+        auto res = LuaEngine::connectHooks(d->lua, *hookTable);
+        if (!res) {
+            setError(Lua::Tr::tr("Failed to connect hooks: %1").arg(res.error()));
+            return false;
+        }
+    }
+    auto result = d->setupFunction.call();
+
+    if (result.get_type() == sol::type::boolean && result.get<bool>() == false) {
+        setError(Lua::Tr::tr("Plugin setup function returned false"));
+        return false;
+    } else if (result.get_type() == sol::type::string) {
+        std::string error = result.get<sol::error>().what();
+        if (!error.empty()) {
+            setError(Lua::Tr::tr("Plugin setup function returned error: %1")
+                         .arg(QString::fromStdString(error)));
+            return false;
+        }
+    }
+
+    setState(PluginSpec::State::Initialized);
+    return true;
+}
+
+bool LuaPluginSpec::initializeExtensions()
+{
+    setState(PluginSpec::State::Running);
+    return true;
+}
+
+bool LuaPluginSpec::delayedInitialize()
+{
+    return true;
+}
+ExtensionSystem::IPlugin::ShutdownFlag LuaPluginSpec::stop()
+{
+    return ExtensionSystem::IPlugin::ShutdownFlag::SynchronousShutdown;
+}
+
+void LuaPluginSpec::kill() {}
+
+} // namespace Lua