#include "UpdateManager.h"
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QStandardPaths>
#include <QDir>
#include <QDesktopServices>
#include <QUrl>
#include <algorithm>

UpdateManager::UpdateManager(const QString& currentVersion, QObject *parent)
    : QObject(parent), m_currentVersion(currentVersion), m_downloadFile(nullptr)
{
    m_network = new QNetworkAccessManager(this);
}

void UpdateManager::checkForUpdates() {
    emit checkStarted();
    // We check the raw version.txt on the master branch
    QUrl url("https://git.linology.tech/michael/PastorsSermonPro/raw/branch/master/version.txt");
    QNetworkRequest request;
    request.setUrl(url);
    QNetworkReply* reply = m_network->get(request);
    connect(reply, &QNetworkReply::finished, this, &UpdateManager::onVersionFetched);
}

void UpdateManager::onVersionFetched() {
    QNetworkReply* reply = qobject_cast<QNetworkReply*>(sender());
    if (!reply) return;

    if (reply->error() == QNetworkReply::NoError) {
        m_latestVersion = QString::fromUtf8(reply->readAll()).trimmed();
        
        // Smart semantic version comparison
        if (!m_latestVersion.isEmpty() && isNewer(m_currentVersion, m_latestVersion)) {
            // Construct the download URL for the Windows installer in the release
            m_downloadUrl = QString("https://git.linology.tech/michael/PastorsSermonPro/releases/download/v%1/PastorsSermonPro_Setup.exe").arg(m_latestVersion);
            emit updateAvailable(m_latestVersion, m_downloadUrl);
        } else {
            emit noUpdateFound();
        }
    } else {
        emit errorOccurred("Could not reach update server: " + reply->errorString());
    }
    reply->deleteLater();
}

void UpdateManager::startDownload(const QString& url) {
    m_downloadUrl = url;
    QString tempPath = QStandardPaths::writableLocation(QStandardPaths::TempLocation);
    QString fileName = tempPath + "/PastorsSermonPro_Update.exe";
    
    m_downloadFile = new QFile(fileName, this);
    if (!m_downloadFile->open(QIODevice::WriteOnly)) {
        emit errorOccurred("Could not create temporary file for download.");
        delete m_downloadFile;
        m_downloadFile = nullptr;
        return;
    }

    QNetworkRequest request;
    request.setUrl(QUrl(m_downloadUrl));
    QNetworkReply* reply = m_network->get(request);
    
    connect(reply, &QNetworkReply::downloadProgress, this, &UpdateManager::onDownloadProgress);
    connect(reply, &QNetworkReply::finished, this, &UpdateManager::onDownloadFinished);
}

void UpdateManager::onDownloadProgress(qint64 bytesReceived, qint64 bytesTotal) {
    if (bytesTotal > 0) {
        int percentage = static_cast<int>((bytesReceived * 100) / bytesTotal);
        emit progressUpdated(percentage);
    }
}

void UpdateManager::onDownloadFinished() {
    QNetworkReply* reply = qobject_cast<QNetworkReply*>(sender());
    if (!reply) return;

    if (reply->error() == QNetworkReply::NoError) {
        m_downloadFile->write(reply->readAll());
        m_downloadFile->flush();
        QString filePath = m_downloadFile->fileName();
        m_downloadFile->close();
        
        emit downloadFinished(filePath);
        
        // Launch the installer
        QProcess::startDetached(filePath);
    } else {
        emit errorOccurred("Download failed: " + reply->errorString());
        m_downloadFile->close();
        m_downloadFile->remove();
    }
    
    reply->deleteLater();
}

bool UpdateManager::isNewer(const QString& current, const QString& latest) {
    QStringList curParts = current.split('.');
    QStringList latParts = latest.split('.');
    
    int maxLen = std::max(curParts.size(), latParts.size());
    for (int i = 0; i < maxLen; ++i) {
        int cur = (i < curParts.size()) ? curParts[i].toInt() : 0;
        int lat = (i < latParts.size()) ? latParts[i].toInt() : 0;
        if (lat > cur) return true;
        if (lat < cur) return false;
    }
    return false;
}