#include "giantswdefimporter.h"

#include <QOperatingSystemVersion>
#include <QSettings>
#include <QMessageBox>
#include <QFileDialog>
#include <QFile>
#include <QProcess>
#include <QDebug>

#include <vector>
#include <string>

#include "zlib.h"

GiantsWdefImporter::GiantsWdefImporter()
{

}

fs::path GiantsWdefImporter::askGiantsDirectory()
{
	QMessageBox::information(
				nullptr,
				"wdefs",
				"Could not locate your Giants installation automatically.\nPlease browse to your Giants folder and select GiantsMain.exe."
	);

	QString filename { QFileDialog::getOpenFileName(nullptr, "wdefs", "C:\\", "GiantsMain.exe") };

	if (!filename.isEmpty()) {
		return fs::path(filename.toStdString()).parent_path();
	}

	return fs::path();
}

fs::path GiantsWdefImporter::locateGiantsFolder()
{
	if (QOperatingSystemVersion::Windows == QOperatingSystemVersion::currentType()) {
		std::vector<std::string> possiblePaths {
			"C:\\Program Files (x86)\\GOG Galaxy\\Games\\Giants - Citizen Kabuto",
			"C:\\Program Files\\GOG Galaxy\\Games\\Giants - Citizen Kabuto",
			"C:\\Program Files (x86)\\GOG.com\\Games\\Giants - Citizen Kabuto",
			"C:\\Program Files\\GOG.com\\Games\\Giants - Citizen Kabuto",
			"C:\\Program Files (x86)\\Steam\\steamapps\\common\\Giants Citizen Kabuto",
			"C:\\Program Files\\Steam\\steamapps\\common\\Giants Citizen Kabuto"
		};

		for (auto& path : possiblePaths) {
			if (fs::exists(path + "\\GiantsMain.exe")) {
				return fs::path(path);
			}
		}

		QSettings reg {"HKEY_CURRENT_USER\\Software\\PlanetMoon\\Giants", QSettings::NativeFormat };

		QString regPath { reg.value("DestDir", QString()).toString().replace("\\", "\\\\") };
		std::string fullPath { regPath.toStdString() + "\\GiantsMain.exe" };

		if (fs::exists(fullPath)) {
			return fs::path(regPath.toStdString());
		}
	}

	return askGiantsDirectory();
}

void GiantsWdefImporter::backupFile(fs::path const& path)
{
	std::string parent = path.parent_path().string();
	std::string stem = path.stem().string();

	std::string dest { fs::path(path.parent_path() / path.stem()).string().append("_original").append(path.extension().string()) };

	if (fs::exists(dest)) {
		return;
	}

	// TODO implement error handling
	fs::copy(path, dest);
}

void GiantsWdefImporter::revertFile(const std::filesystem::path& path)
{
	std::string dest { fs::path(path.parent_path() / path.stem()).string().append("_original").append(path.extension().string()) };

	if (!fs::exists(dest)) {
		QMessageBox::critical(nullptr, "wdefs", "There was a critical error while applying the mod. Your game couldn't be restored to original state. Please message the mods on Discord.");

		exit(-1);
	}

	// TODO implement error handling
	fs::copy(dest, path, fs::copy_options::overwrite_existing);
}

void GiantsWdefImporter::giantsFinished(const std::filesystem::path& giantsMainPath, const std::filesystem::path& wdefsPath, QPushButton* btn)
{
	revertFile(giantsMainPath);
	revertFile(wdefsPath);

	QMessageBox::information(nullptr, "wdefs", "Giants has been reverted to original state.");

	btn->setText("Play");
	btn->setEnabled(true);
}

void GiantsWdefImporter::setParent(QObject* parent)
{
	_parent = parent;
}

int GiantsWdefImporter::crc(const QByteArray &bytes)
{
	uLong prev { crc32(0L, reinterpret_cast<const unsigned char*>(bytes.data()), bytes.length()) };
	return static_cast<int>(prev);
}

QByteArray GiantsWdefImporter::newExeBytes(const QByteArray& wdefsBytes, const std::filesystem::path& giantsMainPath)
{
	// Look for checksum in exe file

	// subject to change
	QByteArray checksum { "\x78\x05\x44\xb6" }; // should be at offset 0x152bff in giantsmain.exe

	QFile exeFile { QString::fromStdString(giantsMainPath.string()) };

	if (!exeFile.exists()) {
		QMessageBox::critical(nullptr, "wdefs", "GiantsMain.exe doesn't exist in " + QString::fromStdString(giantsMainPath.string()) + "!");
	}

	if (!exeFile.open(QIODevice::ReadOnly)) {
		QMessageBox::critical(nullptr, "wdefs", "Unable to open GiantsMain.exe for reading.");
	}

	QByteArray content { exeFile.readAll() };

	int index { content.indexOf(checksum) };

	if (index < 0) {
		QMessageBox::critical(nullptr, "wdefs", "Could not find wdefs checksum in embedded GiantsMain.exe. If you are 100% sure this is unmodded Giants 1.502.1 please report this to Amazed#0001 on Discord or create an issue on the Git project.");
		exit(-1);
	}

	int wdefsCrc { crc(wdefsBytes) };

	QByteArray wdefsCrcBytes;
	wdefsCrcBytes.setNum(wdefsCrc);

	content.replace(index, checksum.length(), wdefsCrcBytes);

	return content;
}

GiantsWdefImporter::StartResult GiantsWdefImporter::startGiantsWithWdefsBytes(QByteArray const& wdefsBytes, fs::path const& wdefsPath, fs::path const& giantsMainPath, QPushButton* button)
{
	// Try writing the wdefs file

	// Switching to QFile here from filesystem for ease of use
	QFile wdefsFile(QString::fromStdString(wdefsPath.string()));
	wdefsFile.open(QIODevice::WriteOnly);

	bool wasWriteSuccess = -1 != wdefsFile.write(wdefsBytes);

	if (!wasWriteSuccess) {
		return StartResult::FAILURE;
	}

	// Try writing the exe file

	QByteArray newBytes = newExeBytes(wdefsBytes, giantsMainPath);

	QFile exeFile(QString::fromStdString(giantsMainPath.string()));
	exeFile.open(QIODevice::WriteOnly);

	wasWriteSuccess = -1 != exeFile.write(newBytes);

	if (!wasWriteSuccess) {
		return StartResult::FAILURE;
	}

	// Try starting GiantsMain.exe

	if (QOperatingSystemVersion::Windows != QOperatingSystemVersion::currentType()) {
		QMessageBox::warning(nullptr, "wdefs", "For now, this program only works on Windows. Please consider contacting taibsu#1841 or Amazed#0001 in the GiantsWD Discord channel for further usage.");

		return StartResult::FAILURE;
	}

	_giantsMainProcess = new QProcess(_parent);

	QObject::connect(_giantsMainProcess, &QProcess::stateChanged, [&](QProcess::ProcessState state) {
		qDebug() << "[STATE] " << state;
		switch (state) {
			case QProcess::ProcessState::Starting:
				button->setText("Starting");
				break;
			case QProcess::ProcessState::Running:
				button->setText("Running.");
				break;
			default:
				button->setText("Not running.");
				break;
		}
	});

	QObject::connect(_giantsMainProcess, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), [&]() {
		qDebug() << "[FINISHED]";
		giantsFinished(giantsMainPath, wdefsPath, button);
	});
	QObject::connect(_giantsMainProcess, &QProcess::errorOccurred, [&]() {
		qDebug() << "[ERROR] " << _giantsMainProcess->errorString();
		giantsFinished(giantsMainPath, wdefsPath, button);
	});

	_giantsMainProcess->setWorkingDirectory(QString::fromStdString(giantsMainPath.parent_path().string()));
	_giantsMainProcess->start(QString::fromStdString(giantsMainPath.string()), { "-launcher" });

	// temporary
	_giantsMainProcess->waitForFinished();

	return StartResult::SUCCESS;
}