#include "Config.hpp"

#include <QFile>
#include <QSaveFile>
#include <QJsonDocument>
#include <QStandardPaths>
#include <QDir>
#include <QDebug>
#include <QFutureWatcher>

Config::Config(QObject* parent) : ConfigSection(parent) {
	m_appearance = new Appearance(this);
	m_background = new Background(this);
	m_bar = new Bar(this);
	m_clipboard = new Clipboard(this);
	m_colors = new Colors(this);
	m_dashboard = new Dashboard(this);
	m_dock = new Dock(this);
	m_general = new General(this);
	m_launcher = new Launcher(this);
	m_lock = new Lock(this);
	m_notifs = new Notifs(this);
	m_osd = new Osd(this);
	m_overview = new Overview(this);
	m_screenshot = new Screenshot(this);
	m_services = new Services(this);
	m_sidebar = new Sidebar(this);
	m_utilities = new Utilities(this);
	wireSignals(); // forwards every child's changed() up to our own changed()

	connect(this, &ConfigSection::changed, this, &Config::scheduleSave);

	m_saveTimer.setSingleShot(true);
	m_saveTimer.setInterval(
		300); // debounce: coalesce rapid-fire edits (e.g. dragging a slider)
	connect(&m_saveTimer, &QTimer::timeout, this, &Config::flushAsync);

	loadSync();
	m_firstLoadDone = true;
}

Config* Config::create(QQmlEngine*, QJSEngine*) {
	// The QML engine takes ownership of singletons created this way.
	return new Config();
}

QString Config::filePath() const {
	const QString dir =
		QStandardPaths::writableLocation(QStandardPaths::ConfigLocation) +
		QStringLiteral("/zshell");
	QDir().mkpath(dir);
	return dir + QStringLiteral("/config.json");
}

void Config::loadSync() {
	m_loading =
		true; // suppress scheduleSave() while properties are set from disk
	QFile f(filePath());
	if (f.open(QIODevice::ReadOnly)) {
		const auto doc = QJsonDocument::fromJson(f.readAll());
		if (doc.isObject()) fromJson(doc.object());
	} else {
		qInfo() << "Config: no existing config at" << filePath()
				<< "- using defaults";
	}
	m_loading = false;
}

void Config::loadAsync() {
	m_loading = true;
	auto future = QtConcurrent::run([this]() {
		QFile f(filePath());
		if (f.open(QIODevice::ReadOnly)) {
			const auto doc = QJsonDocument::fromJson(f.readAll());
			if (doc.isObject()) {
				QMetaObject::invokeMethod(this, [this, doc]() {
					fromJson(doc.object());
					m_loading = false;
				}, Qt::QueuedConnection);
			} else {
				QMetaObject::invokeMethod(this, [this]() {
					m_loading = false;
				}, Qt::QueuedConnection);
			}
		} else {
			qInfo() << "Config: failed to reload from" << filePath()
					<< "- using in-memory values";
			QMetaObject::invokeMethod(this, [this]() {
				m_loading = false;
			}, Qt::QueuedConnection);
		}
	});
	m_loadFuture = future;
}

void Config::load() {
	if (!m_firstLoadDone) {
		loadSync();
	} else {
		loadAsync();
	}
}

void Config::reloadAsync() {
	loadAsync();
}

void Config::scheduleSave() {
	if (m_loading) return;
	m_saveTimer.start(); // restarts the window if it's already running
}

void Config::flushAsync() {
	auto future = QtConcurrent::run([this]() {
		const QByteArray data = QJsonDocument(toJson()).toJson(QJsonDocument::Indented);
		writeAtomically(data);
	});
}

void Config::saveNow() {
	m_saveTimer.stop();
	flushAsync();
}

void Config::writeAtomically(const QByteArray& data) {
	// QSaveFile writes to a temp file next to the target and atomically
	// renames it into place on commit() - a crash or power loss mid-write
	// can never leave config.json half-written.
	QSaveFile f(filePath());
	if (!f.open(QIODevice::WriteOnly)) {
		qWarning() << "Config: failed to open for atomic write:"
				   << f.errorString();
		return;
	}
	f.write(data);
	if (!f.commit()) qWarning() << "Config: commit failed:" << f.errorString();
}