/* SPDX-FileCopyrightText: 2026 Project Tick
 * SPDX-FileContributor: Project Tick
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 *   MeshMC - A Custom Launcher for Minecraft
 *   Copyright (C) 2026 Project Tick
 *
 *   This program 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 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 *  This file incorporates work covered by the following copyright and
 *  permission notice:
 *
 * Copyright 2013-2021 MultiMC Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "Download.h"

#include <QFileInfo>
#include <QDateTime>
#include <QDebug>

#include "FileSystem.h"
#include "ChecksumValidator.h"
#include "MetaCacheSink.h"
#include "ByteArraySink.h"

#include "BuildConfig.h"

namespace Net
{

	Download::Download() : NetAction()
	{
		m_status = Job_NotStarted;
	}

	Download::Ptr Download::makeCached(QUrl url, MetaEntryPtr entry,
									   Options options)
	{
		Download* dl = new Download();
		dl->m_url = url;
		dl->m_options = options;
		auto md5Node = new ChecksumValidator(QCryptographicHash::Md5);
		auto cachedNode = new MetaCacheSink(entry, md5Node);
		dl->m_sink.reset(cachedNode);
		dl->m_target_path = entry->getFullPath();
		return dl;
	}

	Download::Ptr Download::makeByteArray(QUrl url, QByteArray* output,
										  Options options)
	{
		Download* dl = new Download();
		dl->m_url = url;
		dl->m_options = options;
		dl->m_sink.reset(new ByteArraySink(output));
		return dl;
	}

	Download::Ptr Download::makeFile(QUrl url, QString path, Options options)
	{
		Download* dl = new Download();
		dl->m_url = url;
		dl->m_options = options;
		dl->m_sink.reset(new FileSink(path));
		return dl;
	}

	void Download::addValidator(Validator* v)
	{
		m_sink->addValidator(v);
	}

	void Download::startImpl()
	{
		if (m_status == Job_Aborted) {
			qWarning() << "Attempt to start an aborted Download:"
					   << m_url.toString();
			emit aborted(m_index_within_job);
			return;
		}
		QNetworkRequest request(m_url);
		m_status = m_sink->init(request);
		switch (m_status) {
			case Job_Finished:
				emit succeeded(m_index_within_job);
				qDebug() << "Download cache hit " << m_url.toString();
				return;
			case Job_InProgress:
				qDebug() << "Downloading " << m_url.toString();
				break;
			case Job_Failed_Proceed: // this is meaningless in this context. We
									 // do need a sink.
			case Job_NotStarted:
			case Job_Failed:
				emit failed(m_index_within_job);
				return;
			case Job_Aborted:
				return;
		}

		request.setHeader(QNetworkRequest::UserAgentHeader,
						  BuildConfig.USER_AGENT);

		if (!BuildConfig.CURSEFORGE_API_KEY.isEmpty() &&
			m_url.host() == "api.curseforge.com") {
			request.setRawHeader("x-api-key",
								 BuildConfig.CURSEFORGE_API_KEY.toUtf8());
			request.setRawHeader("Accept", "application/json");
		}

		QNetworkReply* rep = m_network->get(request);

		m_reply.reset(rep);
		connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
				SLOT(downloadProgress(qint64, qint64)));
		connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
		connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)),
				SLOT(downloadError(QNetworkReply::NetworkError)));
		connect(rep, &QNetworkReply::sslErrors, this, &Download::sslErrors);
		connect(rep, &QNetworkReply::readyRead, this,
				&Download::downloadReadyRead);
	}

	void Download::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
	{
		m_total_progress = bytesTotal;
		m_progress = bytesReceived;
		emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
	}

	void Download::downloadError(QNetworkReply::NetworkError error)
	{
		if (error == QNetworkReply::OperationCanceledError) {
			qCritical() << "Aborted " << m_url.toString();
			m_status = Job_Aborted;
		} else {
			if (m_options & Option::AcceptLocalFiles) {
				if (m_sink->hasLocalData()) {
					m_status = Job_Failed_Proceed;
					return;
				}
			}
			// error happened during download.
			qCritical() << "Failed " << m_url.toString() << " with reason "
						<< error;
			m_status = Job_Failed;
		}
	}

	void Download::sslErrors(const QList<QSslError>& errors)
	{
		int i = 1;
		for (auto error : errors) {
			qCritical() << "Download" << m_url.toString() << "SSL Error #" << i
						<< " : " << error.errorString();
			auto cert = error.certificate();
			qCritical() << "Certificate in question:\n" << cert.toText();
			i++;
		}
	}

	bool Download::handleRedirect()
	{
		QUrl redirect =
			m_reply->header(QNetworkRequest::LocationHeader).toUrl();
		if (!redirect.isValid()) {
			if (!m_reply->hasRawHeader("Location")) {
				// no redirect -> it's fine to continue
				return false;
			}
			// there is a Location header, but it's not correct. we need to
			// apply some workarounds...
			QByteArray redirectBA = m_reply->rawHeader("Location");
			if (redirectBA.size() == 0) {
				// empty, yet present redirect header? WTF?
				return false;
			}
			QString redirectStr = QString::fromUtf8(redirectBA);

			if (redirectStr.startsWith("//")) {
				/*
				 * IF the URL begins with //, we need to insert the URL scheme.
				 * See: https://bugreports.qt.io/browse/QTBUG-41061
				 * See: http://tools.ietf.org/html/rfc3986#section-4.2
				 */
				redirectStr = m_reply->url().scheme() + ":" + redirectStr;
			} else if (redirectStr.startsWith("/")) {
				/*
				 * IF the URL begins with /, we need to process it as a relative
				 * URL
				 */
				auto url = m_reply->url();
				url.setPath(redirectStr, QUrl::TolerantMode);
				redirectStr = url.toString();
			}

			/*
			 * Next, make sure the URL is parsed in tolerant mode. Qt doesn't
			 * parse the location header in tolerant mode, which causes issues.
			 * FIXME: report Qt bug for this
			 */
			redirect = QUrl(redirectStr, QUrl::TolerantMode);
			if (!redirect.isValid()) {
				qWarning() << "Failed to parse redirect URL:" << redirectStr;
				downloadError(QNetworkReply::ProtocolFailure);
				return false;
			}
			qDebug() << "Fixed location header:" << redirect;
		} else {
			qDebug() << "Location header:" << redirect;
		}

		m_url = QUrl(redirect.toString());
		qDebug() << "Following redirect to " << m_url.toString();
		start(m_network);
		return true;
	}

	void Download::downloadFinished()
	{
		// handle HTTP redirection first
		if (handleRedirect()) {
			qDebug() << "Download redirected:" << m_url.toString();
			return;
		}

		// if the download failed before this point ...
		if (m_status == Job_Failed_Proceed) {
			qDebug() << "Download failed but we are allowed to proceed:"
					 << m_url.toString();
			m_sink->abort();
			m_reply.reset();
			emit succeeded(m_index_within_job);
			return;
		} else if (m_status == Job_Failed) {
			qDebug() << "Download failed in previous step:" << m_url.toString();
			m_sink->abort();
			m_reply.reset();
			emit failed(m_index_within_job);
			return;
		} else if (m_status == Job_Aborted) {
			qDebug() << "Download aborted in previous step:"
					 << m_url.toString();
			m_sink->abort();
			m_reply.reset();
			emit aborted(m_index_within_job);
			return;
		}

		// make sure we got all the remaining data, if any
		auto data = m_reply->readAll();
		if (data.size()) {
			qDebug() << "Writing extra" << data.size() << "bytes to"
					 << m_target_path;
			m_status = m_sink->write(data);
		}

		// otherwise, finalize the whole graph
		m_status = m_sink->finalize(*m_reply.get());
		if (m_status != Job_Finished) {
			qDebug() << "Download failed to finalize:" << m_url.toString();
			m_sink->abort();
			m_reply.reset();
			emit failed(m_index_within_job);
			return;
		}
		m_reply.reset();
		qDebug() << "Download succeeded:" << m_url.toString();
		emit succeeded(m_index_within_job);
	}

	void Download::downloadReadyRead()
	{
		if (m_status == Job_InProgress) {
			auto data = m_reply->readAll();
			m_status = m_sink->write(data);
			if (m_status == Job_Failed) {
				qCritical()
					<< "Failed to process response chunk for " << m_target_path;
			}
			// qDebug() << "Download" << m_url.toString() << "gained" <<
			// data.size() << "bytes";
		} else {
			qCritical() << "Cannot write to " << m_target_path
						<< ", illegal status" << m_status;
		}
	}

} // namespace Net

bool Net::Download::abort()
{
	if (m_reply) {
		m_reply->abort();
	} else {
		m_status = Job_Aborted;
	}
	return true;
}

bool Net::Download::canAbort()
{
	return true;
}