/*
	Copyright 2006-2026 The QElectroTech Team
	This file is part of QElectroTech.

	QElectroTech is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 2 of the License, or
	(at your option) any later version.

	QElectroTech is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "qetscripting.h"

#include "qetscriptapi.h"
#include "../qetmessagebox.h"
#include "../qetproject.h"
#include "../utils/qetsettings.h"

#include <QFile>
#include <QFileInfo>
#include <QObject>
#include <QTextStream>

#ifdef QET_HAS_SCRIPTING
#include <QJSEngine>
#include <chrono>
#include <condition_variable>
#include <mutex>
#include <thread>
#endif

namespace {
	QTextStream out(stdout);
	QTextStream err(stderr);
}

namespace QetScripting {

bool isRunRequest(const QStringList &args)
{
	return args.contains(QStringLiteral("--run"));
}

#ifdef QET_HAS_SCRIPTING

namespace {
	/**
		@brief refusalMessage
		What to tell somebody whose script was not run, and how to change
		that. Written once because the command line and the graphical
		editor both need to say it, and an explanation that names only one
		of the two ways out sends half the people down the wrong path.
	*/
	QString refusalMessage()
	{
		return QObject::tr(
			"Les scripts sont désactivés.\n\n"
			"Un script a accès à l'ensemble du projet et peut écrire des "
			"fichiers, aussi cette fonction est-elle désactivée par défaut.\n\n"
			"Pour l'activer : Configurer QElectroTech > Général > Projets, "
			"ou définir la variable d'environnement QET_ENABLE_SCRIPTING=1 "
			"pour une exécution sans interface (CI, traitement par lot).");
	}
}

int run(const QStringList &args)
{
	if (!QetSettings::scriptingEnabled()) {
		err << refusalMessage() << "\n";
		return 3;
	}

	const int idx = args.indexOf(QStringLiteral("--run"));
	const QString script_path = args.value(idx + 1);
	const QString project_path = args.value(idx + 2);
	if (script_path.isEmpty() || project_path.isEmpty()) {
		err << "Usage: qelectrotech --run <script.js> <project.qet>\n";
		return 2;
	}
	if (!QFileInfo::exists(script_path)) {
		err << "Script not found: " << script_path << "\n";
		return 2;
	}
	if (!QFileInfo::exists(project_path)) {
		err << "Project not found: " << project_path << "\n";
		return 2;
	}

	QETProject project(project_path);
	if (project.state() != QETProject::Ok) {
		err << "Failed to open project: " << project_path
			<< " (state " << project.state() << ")\n";
		return 1;
	}

	return runOnProject(script_path, &project, nullptr) ? 0 : 1;
}

namespace {
	// A runaway script (an infinite loop, or just a very slow one) would
	// otherwise freeze the GUI forever, or hang a CI job running --run with
	// no way out. QJSEngine::setInterrupted() is documented callable from
	// another thread; the engine polls it during evaluation and returns an
	// error QJSValue, which the normal error-reporting path below already
	// handles.
	constexpr int kScriptTimeoutMs = 30000;
}

bool runOnProject(const QString &scriptPath, QETProject *project, DiagramView *view)
{
	// Checked here as well as at each caller, deliberately: this is the
	// one function that actually evaluates JavaScript, so it is the one
	// place a future caller cannot forget to ask. The callers check first
	// only to give a better answer than this one can -- a usable exit code
	// on the command line, an offer to switch the setting on in the editor.
	if (!QetSettings::scriptingEnabled()) {
		err << refusalMessage() << "\n";
		if (view) {
			QET::QetMessageBox::warning(nullptr, QObject::tr("Script"),
						    refusalMessage());
		}
		return false;
	}

	QFile file(scriptPath);
	if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
		err << "Cannot open script: " << scriptPath << "\n";
		return false;
	}
	const QString source = QString::fromUtf8(file.readAll());
	file.close();

	QJSEngine engine;
	auto *api = new QetScriptApi(project, view, &engine);
	QJSValue qet_value = engine.newQObject(api);
	// newQObject() takes ownership by default (QJSEngine::JavaScriptOwnership),
	// which would delete api as soon as the engine's GC decides to -- api's
	// real owner is the engine itself via the parent-child relationship set
	// above, so keep the engine, not the GC, in charge of its lifetime.
	engine.setObjectOwnership(api, QJSEngine::CppOwnership);
	engine.globalObject().setProperty(QStringLiteral("qet"), qet_value);

	// wait_for(), not sleep_for(): a script that finishes well inside the
	// timeout must let the watchdog thread wake immediately, not force
	// every run -- including a fast, successful one -- to block on join()
	// for the full budget. Caught by testing this against a one-line
	// script: it took the full 30 seconds to exit before this fix.
	bool finished = false;
	std::mutex mtx;
	std::condition_variable cv;
	std::thread watchdog([&]() {
		std::unique_lock<std::mutex> lock(mtx);
		cv.wait_for(lock, std::chrono::milliseconds(kScriptTimeoutMs), [&finished]{ return finished; });
		if (!finished) {
			engine.setInterrupted(true);
		}
	});

	QJSValue result = engine.evaluate(source, scriptPath);
	{
		std::lock_guard<std::mutex> lock(mtx);
		finished = true;
	}
	cv.notify_one();
	watchdog.join();

	if (result.isError()) {
		const QString message = QStringLiteral("Script error: %1:%2: %3")
				.arg(scriptPath)
				.arg(result.property(QStringLiteral("lineNumber")).toInt())
				.arg(result.toString());
		err << message << "\n";
		// Interactive "Run Script...": stderr is invisible to a user who
		// launched the GUI normally (nowhere on Windows, easy to miss
		// everywhere else). Headless --run has no GUI to show this in, and
		// no session for it to block.
		if (view) {
			QET::QetMessageBox::critical(nullptr, QObject::tr("Script"), message);
		}
		return false;
	}
	return true;
}

#else // !QET_HAS_SCRIPTING

// Qt::Qml was not found at configure time (see the QET_HAS_SCRIPTING probe
// in the top-level CMakeLists.txt). Compile to a clear, non-silent failure
// rather than omitting these symbols -- the same "always compiled, the
// disabled path says why" shape as the QtPdf feature guard.

int run(const QStringList &)
{
	err << "This build of QElectroTech was compiled without the Qt Qml "
		   "module, so JavaScript scripting (--run) is not available.\n";
	return 1;
}

bool runOnProject(const QString &, QETProject *, DiagramView *)
{
	err << "This build of QElectroTech was compiled without the Qt Qml "
		   "module, so JavaScript scripting is not available.\n";
	return false;
}

#endif // QET_HAS_SCRIPTING

}