/*
	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 "previousversions.h"

#include <QCryptographicHash>
#include <QDateTime>
#include <QDir>
#include <QFile>
#include <QFileInfo>
#include <QSettings>

namespace {
const QString CountKey = QStringLiteral("diagrameditor/previous-versions");
constexpr int DefaultCount = 5;

	//What a version of @p info is named, without the extension: its base
	//name and a time
QString versionPrefix(const QFileInfo &info)
{
	return info.completeBaseName() + QLatin1Char(' ');
}

QByteArray digest(const QString &path)
{
	QFile file(path);
	if (!file.open(QIODevice::ReadOnly)) return {};
	QCryptographicHash hash(QCryptographicHash::Sha256);
	hash.addData(&file);
	return hash.result();
}
}

int PreviousVersions::count()
{
	return qMax(0, QSettings().value(CountKey, DefaultCount).toInt());
}

void PreviousVersions::setCount(int count)
{
	QSettings().setValue(CountKey, qMax(0, count));
}

QString PreviousVersions::folder(const QString &file_path)
{
	const QFileInfo info(file_path);
	return info.absoluteDir().filePath(info.completeBaseName() + QStringLiteral("-backups"));
}

QStringList PreviousVersions::kept(const QString &file_path)
{
	const QFileInfo info(file_path);
	const QDir dir(folder(file_path));
		//Each copy has the time its version was saved (keep()); a .qet and
		//a .qetz of the same project are versions of it alike
	QStringList names = dir.entryList({versionPrefix(info) + QStringLiteral("????-??-?? ??-??-??*.qet"),
									   versionPrefix(info) + QStringLiteral("????-??-?? ??-??-??*.qetz")},
									  QDir::Files, QDir::Time);
	QStringList paths;
	for (const QString &name : std::as_const(names))
		paths << dir.filePath(name);
	return paths;
}

bool PreviousVersions::keep(const QString &file_path, int count, QString *error)
{
	const QFileInfo info(file_path);
	if (count <= 0 || !info.isFile()) return true;

	const QStringList versions = kept(file_path);
	if (!versions.isEmpty() && QFileInfo(versions.first()).size() == info.size()
			&& digest(versions.first()) == digest(file_path))
		return true;

	QDir dir(folder(file_path));
	if (!dir.exists() && !QDir().mkpath(dir.path())) {
		if (error) *error = QStringLiteral("cannot create the folder %1").arg(dir.path());
		return false;
	}
		//Named by the time this version was saved, made unique if another
		//was saved the same second
	const QDateTime saved = info.lastModified();
	const QString stem = versionPrefix(info) + saved.toString(QStringLiteral("yyyy-MM-dd HH-mm-ss"));
	QString target = dir.filePath(stem + QLatin1Char('.') + info.suffix());
	for (int n = 2 ; QFileInfo::exists(target) ; ++n)
		target = dir.filePath(stem + QStringLiteral(" (%1).").arg(n) + info.suffix());
	if (!QFile::copy(file_path, target)) {
		if (error) *error = QStringLiteral("cannot copy %1 to %2").arg(file_path, target);
		return false;
	}
	QFile copy(target);
	if (copy.open(QIODevice::ReadWrite))
		copy.setFileTime(saved, QFileDevice::FileModificationTime);

	const QStringList all = kept(file_path);
	for (int i = count ; i < all.size() ; ++i)
		QFile::remove(all.at(i));
	return true;
}