#include "UpdaterLogic.h"
#include <QSet>
#include <QDebug>
#include <QFileInfo>
#include <QFile>
#include <QEventLoop>
#include <QElapsedTimer>
#include <QThread>
#include <QNetworkRequest>
#include <QNetworkProxy>
#include <QJsonArray>
#include <QCryptographicHash>
#include <QDir>
#include <QJsonDocument>
#include <QSaveFile>
#include <QApplication>
#include <QCoreApplication>
#include <QUrl>
#include <algorithm>
#include <cmath>
#include "ConfigHelper.h"
#include "RuntimeProtectionPolicy.h"

#ifdef HAVE_OPENSSL
#include <openssl/pem.h>
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/err.h>
#endif

namespace
{
bool jsonNonNegativeInteger(const QJsonValue& value, qint64* result)
{
    constexpr double maxExactJsonInteger = 9007199254740991.0;
    if (!value.isDouble())
        return false;

    const double number = value.toDouble();
    if (!std::isfinite(number) || number < 0.0 || number > maxExactJsonInteger
        || std::floor(number) != number)
        return false;

    if (result)
        *result = static_cast<qint64>(number);
    return true;
}

bool isSha256(const QString& value)
{
    if (value.size() != 64)
        return false;

    for (const QChar ch : value)
    {
        const ushort code = ch.unicode();
        if (!((code >= '0' && code <= '9')
              || (code >= 'a' && code <= 'f')
              || (code >= 'A' && code <= 'F')))
            return false;
    }
    return true;
}
}

UpdaterLogic::UpdaterLogic(QObject* parent)
    : QObject(parent)
{
    m_serverAddr = ConfigHelper::instance().getValue("Server", "api_base_url");
}

void UpdaterLogic::getManifest(const QString& appId, const QString& channel, const QString& targetVer, int versionId)
{
    m_manifest = QJsonObject();
    m_manifestText.clear();
    m_fileItems.clear();
    m_manifestSignatureVerified = false;

    QString url = m_serverAddr + "/api/v1/update/manifest";
    QJsonObject body;
    body["app_id"] = appId;
    body["channel"] = channel;
    body["version"] = targetVer;
    body["version_id"] = versionId;

    m_http.postRequest(url, body, [this, appId, channel, targetVer, versionId](int code, const QJsonObject& resp)
        {
            qDebug() << "Manifest API returned code:" << code;
            m_manifest = QJsonObject();
            m_manifestText.clear();
            m_fileItems.clear();
            m_manifestSignatureVerified = false;

            if (code == 200)
            {
                const QJsonValue manifestTextValue = resp.value("manifest_text");
                const QJsonValue responseManifestValue = resp.value("manifest");
                if (!manifestTextValue.isString() || !responseManifestValue.isObject())
                {
                    qDebug() << "Manifest response fields have invalid types";
                }
                else
                {
                    const QString manifestText = manifestTextValue.toString();
                    const QJsonObject responseManifest = responseManifestValue.toObject();
                    const QJsonValue signatureValue = responseManifest.value("signature");
                    QJsonParseError parseError;
                    const QJsonDocument manifestDocument =
                        QJsonDocument::fromJson(manifestText.toUtf8(), &parseError);

                    if (manifestText.isEmpty() || !signatureValue.isString()
                        || signatureValue.toString().trimmed().isEmpty()
                        || parseError.error != QJsonParseError::NoError
                        || !manifestDocument.isObject())
                    {
                        qDebug() << "Manifest response JSON or signature field is invalid";
                    }
                    else
                    {
                        QJsonObject trustedManifest = manifestDocument.object();
                        QList<FileDownloadItem> trustedFiles;
                        if (trustedManifest.contains("signature"))
                        {
                            qDebug() << "Signed manifest text unexpectedly contains a signature field";
                        }
                        else
                        {
                            trustedManifest.insert("signature", signatureValue.toString());
                            if (validateOnlineManifest(trustedManifest, appId, channel,
                                                       targetVer, versionId, &trustedFiles))
                            {
                                m_manifestText = manifestText;
                                m_manifest = trustedManifest;
                                m_fileItems = trustedFiles;
                                qDebug() << "Received trusted manifest version:"
                                         << m_manifest.value("version").toString();
                            }
                            else
                            {
                                qDebug() << "Manifest fields or request identity are invalid";
                            }
                        }
                    }
                }
            }
            else
            {
                qDebug() << "Failed to get manifest";
            }
            emit fetchUrlFinished();
        });
}

bool UpdaterLogic::validateOnlineManifest(const QJsonObject& manifest, const QString& appId,
                                          const QString& channel, const QString& targetVer,
                                          int versionId, QList<FileDownloadItem>* fileItems) const
{
    if (!fileItems)
        return false;
    fileItems->clear();

    const QJsonValue appValue = manifest.value("app_id");
    const QJsonValue channelValue = manifest.value("channel");
    const QJsonValue versionValue = manifest.value("version");
    const QJsonValue sequenceValue = manifest.value("manifest_seq");
    const QJsonValue filesValue = manifest.value("files");
    const QJsonValue signatureValue = manifest.value("signature");
    qint64 manifestSequence = -1;
    if (!appValue.isString() || appValue.toString().isEmpty()
        || !channelValue.isString() || channelValue.toString().isEmpty()
        || !versionValue.isString() || versionValue.toString().isEmpty()
        || !jsonNonNegativeInteger(sequenceValue, &manifestSequence)
        || !filesValue.isArray()
        || !signatureValue.isString() || signatureValue.toString().trimmed().isEmpty()
        || appValue.toString() != appId
        || channelValue.toString() != channel
        || versionValue.toString() != targetVer
        || manifestSequence != static_cast<qint64>(versionId))
        return false;

    QSet<QString> pathKeys;
    const QJsonArray files = filesValue.toArray();
    fileItems->reserve(files.size());
    for (const QJsonValue& value : files)
    {
        if (!value.isObject())
        {
            fileItems->clear();
            return false;
        }

        const QJsonObject file = value.toObject();
        const QJsonValue pathValue = file.value("path");
        const QJsonValue shaValue = file.value("sha256");
        const QJsonValue sizeValue = file.value("size");
        qint64 size = -1;
        if (!pathValue.isString() || pathValue.toString().isEmpty()
            || !shaValue.isString() || !isSha256(shaValue.toString())
            || !jsonNonNegativeInteger(sizeValue, &size))
        {
            fileItems->clear();
            return false;
        }

        const QString path = pathValue.toString();
        const QString normalizedPath = QDir::cleanPath(QDir::fromNativeSeparators(path));
        const QString pathKey = normalizedPath.toCaseFolded();
        if (!isSafeRelativePath(path) || pathKeys.contains(pathKey))
        {
            fileItems->clear();
            return false;
        }
        pathKeys.insert(pathKey);

        FileDownloadItem item;
        item.path = path;
        item.sha256 = shaValue.toString();
        item.size = size;
        fileItems->append(item);
    }
    return true;
}

bool UpdaterLogic::verifySignature(const QByteArray& payload, const QString& signatureBase64, const QString& publicKeyPath) const
{
#ifndef HAVE_OPENSSL
    Q_UNUSED(payload);
    Q_UNUSED(signatureBase64);
    Q_UNUSED(publicKeyPath);
    qDebug() << "OpenSSL not available, cannot verify manifest signature";
    return false;
#else
    QFile keyFile(publicKeyPath);
    if (!keyFile.open(QIODevice::ReadOnly))
    {
        qDebug() << "Cannot open public key file:" << publicKeyPath;
        return false;
    }

    QByteArray keyData = keyFile.readAll();
    keyFile.close();

    BIO* bio = BIO_new_mem_buf(keyData.constData(), keyData.size());
    if (!bio)
    {
        qDebug() << "BIO_new_mem_buf failed";
        return false;
    }

    EVP_PKEY* pkey = PEM_read_bio_PUBKEY(bio, NULL, NULL, NULL);
    BIO_free(bio);
    if (!pkey)
    {
        qDebug() << "PEM_read_bio_PUBKEY failed";
        return false;
    }

    QByteArray signature = QByteArray::fromBase64(signatureBase64.toUtf8());
    EVP_MD_CTX* mdctx = EVP_MD_CTX_new();
    if (!mdctx)
    {
        EVP_PKEY_free(pkey);
        qDebug() << "EVP_MD_CTX_new failed";
        return false;
    }

    bool ok = false;
    if (EVP_DigestVerifyInit(mdctx, NULL, EVP_sha256(), NULL, pkey) == 1)
    {
        if (EVP_DigestVerifyUpdate(mdctx, payload.constData(), payload.size()) == 1)
        {
            if (EVP_DigestVerifyFinal(mdctx, reinterpret_cast<const unsigned char*>(signature.constData()), signature.size()) == 1)
            {
                ok = true;
            }
        }
    }

    EVP_MD_CTX_free(mdctx);
    EVP_PKEY_free(pkey);

    if (!ok)
    {
        qDebug() << "Manifest signature verification failed";
    }
    return ok;
#endif
}

bool UpdaterLogic::verifyManifestSignature(const QString& publicKeyPath) const
{
    m_manifestSignatureVerified = false;
    if (m_manifest.isEmpty() || m_manifestText.isEmpty())
    {
        qDebug() << "No manifest available to verify";
        return false;
    }
    QString signature = m_manifest.value("signature").toString();
    if (signature.isEmpty())
    {
        qDebug() << "Manifest signature empty";
        return false;
    }

    m_manifestSignatureVerified = verifySignature(m_manifestText.toUtf8(), signature, publicKeyPath);
    return m_manifestSignatureVerified;
}

bool UpdaterLogic::saveManifestCache(const QString& cacheDir) const
{
    if (m_manifest.isEmpty() || !m_manifestSignatureVerified)
        return false;

    QDir dir(cacheDir);
    if (!dir.exists() && !dir.mkpath("."))
        return false;

    QString version = m_manifest.value("version").toString();
    QString filePath = cacheDir + "/manifest_" + version + ".json";
    QFile file(filePath);
    if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate))
        return false;

    QJsonObject wrapper;
    wrapper["manifest"] = m_manifest;
    wrapper["manifest_text"] = m_manifestText;

    QJsonDocument doc(wrapper);
    file.write(doc.toJson(QJsonDocument::Indented));
    file.close();
    qDebug() << "Manifest cached to" << filePath;
    return true;
}

bool UpdaterLogic::loadManifestCache(const QString& cacheDir, const QString& version)
{
    m_manifest = QJsonObject();
    m_manifestText.clear();
    m_fileItems.clear();
    m_manifestSignatureVerified = false;

    QString filePath = cacheDir + "/manifest_" + version + ".json";
    QFile file(filePath);
    if (!file.exists() || !file.open(QIODevice::ReadOnly))
        return false;

    QByteArray raw = file.readAll();
    file.close();
    QJsonParseError wrapperError;
    const QJsonDocument doc = QJsonDocument::fromJson(raw, &wrapperError);
    if (wrapperError.error != QJsonParseError::NoError || !doc.isObject())
        return false;

    const QJsonObject wrapper = doc.object();
    const QJsonValue manifestTextValue = wrapper.value("manifest_text");
    const QJsonValue cachedManifestValue = wrapper.value("manifest");
    if (!manifestTextValue.isString() || manifestTextValue.toString().isEmpty()
        || !cachedManifestValue.isObject())
        return false;

    const QJsonValue signatureValue = cachedManifestValue.toObject().value("signature");
    QJsonParseError manifestError;
    const QString manifestText = manifestTextValue.toString();
    const QJsonDocument manifestDocument =
        QJsonDocument::fromJson(manifestText.toUtf8(), &manifestError);
    if (!signatureValue.isString() || signatureValue.toString().trimmed().isEmpty()
        || manifestError.error != QJsonParseError::NoError
        || !manifestDocument.isObject())
        return false;

    QJsonObject trustedManifest = manifestDocument.object();
    const QJsonValue versionValue = trustedManifest.value("version");
    if (trustedManifest.contains("signature") || !versionValue.isString()
        || versionValue.toString() != version)
        return false;

    trustedManifest.insert("signature", signatureValue.toString());
    m_manifest = trustedManifest;
    m_manifestText = manifestText;
    qDebug() << "Loaded cached manifest" << version;
    return true;
}

QByteArray UpdaterLogic::canonicalManifestBytes(const QJsonObject& manifest) const
{
    QJsonObject copy = manifest;
    copy.remove("signature");

    auto sortObject = [&](auto&& self, const QJsonObject& obj) -> QJsonObject {
        QStringList keys = obj.keys();
        std::sort(keys.begin(), keys.end(), std::less<QString>());
        QJsonObject sorted;
        for (const auto& key : keys)
        {
            QJsonValue value = obj.value(key);
            if (value.isObject())
                sorted.insert(key, self(self, value.toObject()));
            else if (value.isArray())
            {
                QJsonArray sortedArray;
                for (const auto& element : value.toArray())
                {
                    if (element.isObject())
                        sortedArray.append(self(self, element.toObject()));
                    else
                        sortedArray.append(element);
                }
                sorted.insert(key, sortedArray);
            }
            else
            {
                sorted.insert(key, value);
            }
        }
        return sorted;
    };

    QJsonObject sorted = sortObject(sortObject, copy);
    QJsonDocument doc(sorted);
    return doc.toJson(QJsonDocument::Compact);
}


QStringList UpdaterLogic::obsoleteFilesComparedTo(const QJsonObject& oldManifest) const
{
    QSet<QString> newPaths;
    for (const QJsonValue& value : m_manifest.value("files").toArray()) {
        const QString path = QDir::fromNativeSeparators(value.toObject().value("path").toString());
        if (isSafeRelativePath(path)) newPaths.insert(path.toCaseFolded());
    }

    QSet<QString> protectedPaths{
        QStringLiteral("bootstrap.exe"),
        QStringLiteral("launcher.exe"),
        QStringLiteral("updater.exe"),
        QStringLiteral("client.ini"),
        QStringLiteral("config/app_config.json"),
        QStringLiteral("config/local_state.json"),
        QStringLiteral("config/client_identity.dat"),
        QStringLiteral("config/version_policy.dat")
    };
    const QString runtimePrefix = ConfigHelper::instance().runtimeRelativePath().toCaseFolded();
    if (!runtimePrefix.isEmpty()) {
        const QStringList runtimeProtected{
            QStringLiteral("bootstrap.exe"), QStringLiteral("launcher.exe"), QStringLiteral("updater.exe"),
            QStringLiteral("client.ini"), QStringLiteral("config/app_config.json"),
            QStringLiteral("config/local_state.json"), QStringLiteral("config/client_identity.dat"),
            QStringLiteral("config/version_policy.dat")
        };
        for (const QString& path : runtimeProtected)
            protectedPaths.insert(runtimePrefix + "/" + path);
    }
    QStringList obsolete;
    QSet<QString> seen;
    for (const QJsonValue& value : oldManifest.value("files").toArray()) {
        const QString path = QDir::fromNativeSeparators(value.toObject().value("path").toString());
        const QString folded = path.toCaseFolded();
        if (!isSafeRelativePath(path) || protectedPaths.contains(folded)
            || newPaths.contains(folded) || seen.contains(folded))
            continue;
        seen.insert(folded);
        obsolete.append(path);
    }
    obsolete.sort(Qt::CaseInsensitive);
    return obsolete;
}

bool UpdaterLogic::validateLocalFiles(const QString& stagingDir, const QString& installedDir) const
{
    if (m_manifest.isEmpty())
        return false;

    const QJsonArray files = m_manifest.value("files").toArray();
    for (const auto& item : files)
    {
        const QJsonObject fileObject = item.toObject();
        const QString path = QDir::fromNativeSeparators(fileObject.value("path").toString());
        const QString expectedSha = fileObject.value("sha256").toString();
        if (!isSafeRelativePath(path))
            return false;
        if (isRuntimeProtectedPath(path)) {
            qDebug() << "Runtime-protected manifest entry ignored:" << path;
            continue;
        }

        QString fullPath = QDir(stagingDir).filePath(path);
        if (!QFile::exists(fullPath) && !installedDir.isEmpty())
            fullPath = QDir(installedDir).filePath(path);

        if (!QFile::exists(fullPath))
        {
            qDebug() << "Manifest file missing from staging and installation:" << path;
            return false;
        }
        const QString actualSha = calcLocalFileSha256(fullPath);
        if (actualSha.compare(expectedSha, Qt::CaseInsensitive) != 0)
        {
            qDebug() << "File hash mismatch:" << path << actualSha << expectedSha;
            return false;
        }
    }
    qDebug() << "Full manifest validation passed using staging plus installed files";
    return true;
}

bool UpdaterLogic::loadOfflinePackage(const QString& packagePath, const QString& stagingDir)
{
    m_offlineError.clear();
    QFile package(packagePath);
    if (!package.open(QIODevice::ReadOnly)) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "Cannot open the offline update package."); return false; }
    if (package.read(8) != QByteArray("MUPD0001", 8)) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline package format identifier is invalid."); return false; }
    const QByteArray lengthBytes = package.read(8);
    if (lengthBytes.size() != 8) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline package header is incomplete."); return false; }
    quint64 headerSize = 0;
    for (int i = 0; i < 8; ++i) headerSize |= quint64(static_cast<unsigned char>(lengthBytes[i])) << (i * 8);
    if (headerSize == 0 || headerSize > 64ULL * 1024 * 1024 || headerSize > quint64(package.size() - 16)) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline package header length is invalid."); return false; }
    QJsonParseError error;
    const QJsonDocument wrapperDoc = QJsonDocument::fromJson(package.read(qint64(headerSize)), &error);
    if (error.error != QJsonParseError::NoError || !wrapperDoc.isObject()) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline package header contains invalid JSON."); return false; }
    const QJsonObject wrapper = wrapperDoc.object();
    const QByteArray packageText = wrapper.value("package_text").toString().toUtf8();
    const QByteArray manifestText = wrapper.value("manifest_text").toString().toUtf8();
    const QString publicKey = QStringLiteral(":/simcae/update-client/manifest-public-key.pem");
    if (!verifySignature(packageText, wrapper.value("package_signature").toString(), publicKey)) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline package RSA signature is invalid."); return false; }
    const QJsonObject packageMeta = QJsonDocument::fromJson(packageText, &error).object();
    if (error.error != QJsonParseError::NoError || packageMeta.value("format").toString() != "MUPD0001") { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The signed offline package metadata is invalid."); return false; }
    if (QString::fromLatin1(QCryptographicHash::hash(manifestText, QCryptographicHash::Sha256).toHex()) != packageMeta.value("manifest_sha256").toString()) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The manifest digest does not match the package signature."); return false; }
    QJsonObject manifest = QJsonDocument::fromJson(manifestText, &error).object();
    if (error.error != QJsonParseError::NoError || manifest.isEmpty()) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline manifest is invalid."); return false; }
    manifest.insert("signature", wrapper.value("manifest_signature").toString());
    m_manifest = manifest; m_manifestText = QString::fromUtf8(manifestText); m_fileItems.clear();
    if (manifest.value("app_id") != packageMeta.value("app_id") || manifest.value("channel") != packageMeta.value("channel") || manifest.value("version") != packageMeta.value("version")) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The package metadata and manifest identity do not match."); return false; }
    if (!verifyManifestSignature()) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline manifest RSA signature is invalid."); return false; }
    const qint64 payloadStart = 16 + qint64(headerSize);
    const QJsonArray entries = packageMeta.value("files").toArray();
    for (const QJsonValue& value : entries) {
        const QJsonObject item = value.toObject(); const QString path = QDir::fromNativeSeparators(item.value("path").toString());
        const qint64 offset = item.value("offset").toVariant().toLongLong(); const qint64 size = item.value("size").toVariant().toLongLong();
        if (!isSafeRelativePath(path) || offset < 0 || size < 0 || payloadStart + offset + size > package.size()) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The offline package contains an unsafe path or out-of-bounds data: %1").arg(path); return false; }
        FileDownloadItem fi{path, QString(), item.value("sha256").toString(), size}; m_fileItems.append(fi);
        if (stagingDir.isEmpty()) continue;
        const QString target = QDir(stagingDir).filePath(path); if (!QDir().mkpath(QFileInfo(target).path()) || !package.seek(payloadStart + offset)) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "Cannot prepare the offline file: %1").arg(path); return false; }
        QSaveFile output(target); if (!output.open(QIODevice::WriteOnly)) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "Cannot create the staged file: %1").arg(path); return false; }
        QCryptographicHash hash(QCryptographicHash::Sha256); qint64 remaining = size;
        while (remaining > 0) { const QByteArray block = package.read(qMin<qint64>(remaining, 1024 * 1024)); if (block.isEmpty() || output.write(block) != block.size()) { output.cancelWriting(); m_offlineError = QCoreApplication::translate("UpdaterLogic", "Failed to read the offline file: %1").arg(path); return false; } hash.addData(block); remaining -= block.size(); }
        if (QString::fromLatin1(hash.result().toHex()).compare(fi.sha256, Qt::CaseInsensitive) != 0 || !output.commit()) { output.cancelWriting(); m_offlineError = QCoreApplication::translate("UpdaterLogic", "Offline file hash validation or writing failed: %1").arg(path); return false; }
    }
    if (entries.size() != m_manifest.value("files").toArray().size()) { m_offlineError = QCoreApplication::translate("UpdaterLogic", "The number of files in the offline package does not match the manifest."); return false; }
    return true;
}

void UpdaterLogic::getDownloadUrl(const QString& appId, const QString& channel, const QString& targetVer, int versionId)
{
    QList<FileDownloadItem> signedFiles;
    m_fileItems.clear();
    if (!m_manifestSignatureVerified
        || !validateOnlineManifest(m_manifest, appId, channel, targetVer, versionId, &signedFiles))
    {
        qDebug() << "Download URL request rejected because the signed manifest is not valid for the request";
        emit fetchUrlFinished();
        return;
    }
    if (signedFiles.isEmpty())
    {
        qDebug() << "Download URL request rejected because the signed manifest has no files";
        emit fetchUrlFinished();
        return;
    }

    QString url = m_serverAddr + "/api/v1/update/download-url";
    QJsonObject body;
    body["app_id"] = appId;
    body["channel"] = channel;
    body["version"] = targetVer;
    body["version_id"] = versionId;

    QJsonArray emptyFiles;
    body["files"] = emptyFiles;

    m_http.postRequest(url, body, [this, signedFiles](int code, const QJsonObject& resp)
        {
            qDebug() << "Download URL API returned code:" << code;
            m_fileItems.clear();

            if (code == 200)
            {
                const QJsonValue filesValue = resp.value("files");
                if (!filesValue.isArray())
                {
                    qDebug() << "Download URL response files field is invalid";
                    emit fetchUrlFinished();
                    return;
                }

                const QJsonArray responseFiles = filesValue.toArray();
                if (responseFiles.size() != signedFiles.size())
                {
                    qDebug() << "Download URL response file count does not match the signed manifest";
                    emit fetchUrlFinished();
                    return;
                }

                QMap<QString, int> signedIndexes;
                for (int index = 0; index < signedFiles.size(); ++index)
                    signedIndexes.insert(signedFiles.at(index).path, index);

                QList<FileDownloadItem> boundFiles = signedFiles;
                QSet<QString> responsePaths;
                for (const QJsonValue& value : responseFiles)
                {
                    if (!value.isObject())
                    {
                        qDebug() << "Download URL response contains a non-object file item";
                        emit fetchUrlFinished();
                        return;
                    }

                    const QJsonObject responseFile = value.toObject();
                    const QJsonValue pathValue = responseFile.value("path");
                    const QJsonValue urlValue = responseFile.value("url");
                    const QJsonValue shaValue = responseFile.value("sha256");
                    const QUrl downloadUrl(urlValue.toString());
                    qint64 size = -1;
                    if (!pathValue.isString() || pathValue.toString().isEmpty()
                        || !urlValue.isString() || urlValue.toString().trimmed().isEmpty()
                        || !downloadUrl.isValid() || downloadUrl.host().isEmpty()
                        || (downloadUrl.scheme().compare("http", Qt::CaseInsensitive) != 0
                            && downloadUrl.scheme().compare("https", Qt::CaseInsensitive) != 0)
                        || !shaValue.isString() || !isSha256(shaValue.toString())
                        || !jsonNonNegativeInteger(responseFile.value("size"), &size))
                    {
                        qDebug() << "Download URL response contains invalid file metadata";
                        emit fetchUrlFinished();
                        return;
                    }

                    const QString path = pathValue.toString();
                    if (responsePaths.contains(path) || !signedIndexes.contains(path))
                    {
                        qDebug() << "Download URL response contains a duplicate or extra file:" << path;
                        emit fetchUrlFinished();
                        return;
                    }
                    responsePaths.insert(path);

                    const int index = signedIndexes.value(path);
                    const FileDownloadItem& signedFile = signedFiles.at(index);
                    if (shaValue.toString().compare(signedFile.sha256, Qt::CaseInsensitive) != 0
                        || size != signedFile.size)
                    {
                        qDebug() << "Download URL response metadata differs from the signed manifest:" << path;
                        emit fetchUrlFinished();
                        return;
                    }
                    boundFiles[index].url = urlValue.toString();
                }

                if (responsePaths.size() != signedFiles.size())
                {
                    qDebug() << "Download URL response is missing signed manifest files";
                    emit fetchUrlFinished();
                    return;
                }

                m_fileItems = boundFiles;
                qDebug() << "Bound download URLs to" << m_fileItems.size()
                         << "signed manifest files";
            }
            else
            {
                qDebug() << "Failed to get download URL";
            }
            emit fetchUrlFinished();
        });
}


QString UpdaterLogic::calcLocalFileSha256(const QString& filePath) const
{
    QFile f(filePath);
    if (!f.open(QIODevice::ReadOnly))
        return "";
    QCryptographicHash hash(QCryptographicHash::Sha256);
    while (!f.atEnd())
    {
        QByteArray block = f.read(4096);
        hash.addData(block);
    }
    f.close();
    return hash.result().toHex();
}

bool UpdaterLogic::downloadSingleFile(const QString& url, const QString& savePath,
                                      const QString& expectSha256, qint64 expectedSize,
                                      const QString& resumePartPath)
{
    const QString partPath = resumePartPath.isEmpty() ? savePath + ".part" : resumePartPath;
    if (!QDir().mkpath(QFileInfo(partPath).path())) return false;
    if (QFile::exists(savePath)
        && calcLocalFileSha256(savePath).compare(expectSha256, Qt::CaseInsensitive) == 0)
        return true;
    QFile::remove(savePath);

    for (int attempt = 0; attempt < 4; ++attempt)
    {
        qint64 existingSize = QFileInfo(partPath).size();
        if (expectedSize >= 0 && existingSize > expectedSize)
        {
            QFile::remove(partPath);
            existingSize = 0;
        }
        if (expectedSize >= 0 && existingSize == expectedSize && existingSize > 0)
        {
            if (calcLocalFileSha256(partPath).compare(expectSha256, Qt::CaseInsensitive) == 0)
            {
                QFile::remove(savePath);
                return QFile::rename(partPath, savePath);
            }
            QFile::remove(partPath);
            existingSize = 0;
        }

        QFile partFile(partPath);
        const QIODevice::OpenMode mode = QIODevice::WriteOnly
            | (existingSize > 0 ? QIODevice::Append : QIODevice::Truncate);
        if (!partFile.open(mode))
        {
            qDebug() << "Cannot open partial download:" << partPath;
            return false;
        }

        QNetworkAccessManager manager;
        manager.setProxy(QNetworkProxy::NoProxy);
        QNetworkRequest request(url);
        request.setTransferTimeout(60000);
        if (existingSize > 0)
            request.setRawHeader("Range", QByteArray("bytes=") + QByteArray::number(existingSize) + "-");

        QNetworkReply* reply = manager.get(request);
        QEventLoop loop;
        bool writeOk = true;
        QObject::connect(reply, &QNetworkReply::readyRead, [&]() {
            const QByteArray data = reply->readAll();
            if (!data.isEmpty()) {
                if (partFile.write(data) != data.size()) writeOk = false;
                m_sessionDownloadedBytes += data.size();
                const qint64 received = qMin(m_downloadTotalBytes,
                    m_downloadCompletedBytes + partFile.size());
                const double speed = m_downloadTimer.elapsed() > 0
                    ? (m_sessionDownloadedBytes * 1000.0 / m_downloadTimer.elapsed()) : 0.0;
                emit downloadProgress(received, m_downloadTotalBytes, m_currentDownloadPath, speed);
            }
        });
        QObject::connect(reply, &QNetworkReply::finished, &loop, &QEventLoop::quit);
        loop.exec();
        const QByteArray remaining = reply->readAll();
        if (!remaining.isEmpty() && partFile.write(remaining) != remaining.size()) writeOk = false;
        partFile.flush();
        partFile.close();

        const int httpStatus = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        const bool networkOk = reply->error() == QNetworkReply::NoError;
        const QString networkError = reply->errorString();
        reply->deleteLater();

        if (existingSize > 0 && httpStatus == 200)
        {
            // The server ignored Range, so restart instead of appending a full response to the partial file.
            qDebug() << "Server ignored Range; restart full download:" << savePath;
            QFile::remove(partPath);
        }
        else if (networkOk && writeOk && (httpStatus == 200 || httpStatus == 206))
        {
            const qint64 actualSize = QFileInfo(partPath).size();
            if ((expectedSize < 0 || actualSize == expectedSize)
                && calcLocalFileSha256(partPath).compare(expectSha256, Qt::CaseInsensitive) == 0)
            {
                QFile::remove(savePath);
                if (QFile::rename(partPath, savePath))
                {
                    qDebug() << "Download completed/resumed & sha pass:" << savePath;
                    return true;
                }
            }
            else if (expectedSize >= 0 && actualSize >= expectedSize)
            {
                qDebug() << "Completed partial file has invalid size or SHA; restart:" << savePath;
                QFile::remove(partPath);
            }
        }
        else
        {
            qDebug() << "Download attempt failed; partial file retained:" << attempt + 1
                     << savePath << httpStatus << networkError << "bytes" << QFileInfo(partPath).size();
        }

        if (attempt < 3)
        {
            const unsigned long delayMs = static_cast<unsigned long>(500 * (1 << attempt));
            QElapsedTimer delay;
            delay.start();
            while (delay.elapsed() < static_cast<qint64>(delayMs))
            {
                QApplication::processEvents();
                QThread::msleep(50);
            }
        }
    }
    return false;
}

bool UpdaterLogic::isRuntimeProtectedPath(const QString& path) const
{
    return UpdateClient::isRuntimeProtectedPath(
        path, ConfigHelper::instance().runtimeRelativePath());
}

bool UpdaterLogic::isSafeRelativePath(const QString& path) const
{
    const QString normalized = QDir::fromNativeSeparators(path);
    const QString clean = QDir::cleanPath(normalized);
    return !clean.isEmpty()
        && !QDir::isAbsolutePath(clean)
        && clean != ".."
        && !clean.startsWith("../")
        && !clean.contains(":");
}

qint64 UpdaterLogic::estimateAdditionalDiskBytes(const QString& targetDir,
                                                   const QStringList& obsoletePaths) const
{
    qint64 required = 0;
    const QString cacheDir = QDir(ConfigHelper::instance().updateRoot()).filePath("download_cache");
    for (const auto& item : m_fileItems) {
        const QString relativePath = QDir::fromNativeSeparators(item.path);
        if (isRuntimeProtectedPath(relativePath)) continue;
        const QString installed = QDir(targetDir).filePath(relativePath);
        if (QFile::exists(installed)
            && calcLocalFileSha256(installed).compare(item.sha256, Qt::CaseInsensitive) == 0)
            continue;

        const qint64 partialSize = QFileInfo(QDir(cacheDir).filePath(
            item.sha256.toLower() + ".part")).size();
        required += qMax<qint64>(0, item.size - qMin(item.size, partialSize));
        if (QFile::exists(installed)) required += QFileInfo(installed).size();
    }
    for (const QString& path : obsoletePaths) {
        const QString installed = QDir(targetDir).filePath(path);
        if (QFile::exists(installed)) required += QFileInfo(installed).size();
    }
    const qint64 reserve = qMax<qint64>(128LL * 1024 * 1024, required / 10);
    return required + reserve;
}

bool UpdaterLogic::downloadAllFiles(const QString& tempDir, const QString& targetDir)
{
    if (m_fileItems.isEmpty())
    {
        m_downloadAllOk = false;
        return false;
    }

    QDir stagingDir(tempDir);
    if (!FileHelper::createDir(tempDir))
        return false;
    const QString resumeCacheDir = QDir(ConfigHelper::instance().updateRoot()).filePath("download_cache");
    if (!FileHelper::createDir(resumeCacheDir))
        return false;
    QSet<QString> activePartialNames;
    for (const auto& item : m_fileItems)
        activePartialNames.insert(item.sha256.toLower() + ".part");
    QDir cacheDir(resumeCacheDir);
    for (const QString& fileName : cacheDir.entryList(QStringList() << "*.part", QDir::Files)) {
        if (!activePartialNames.contains(fileName.toLower()))
            cacheDir.remove(fileName);
    }

    m_downloadTotalBytes = 0;
    m_downloadCompletedBytes = 0;
    m_sessionDownloadedBytes = 0;
    for (const auto& item : m_fileItems) {
        const QString itemPath = QDir::fromNativeSeparators(item.path);
        if (isRuntimeProtectedPath(itemPath)) continue;
        const QString installed = QDir(targetDir).filePath(itemPath);
        if (!QFile::exists(installed)
            || calcLocalFileSha256(installed).compare(item.sha256, Qt::CaseInsensitive) != 0)
            m_downloadTotalBytes += item.size;
    }
    m_downloadTimer.restart();
    emit downloadProgress(0, m_downloadTotalBytes, QString(), 0.0);

    for (const auto& fi : m_fileItems)
    {
        if (!isSafeRelativePath(fi.path))
        {
            qDebug() << "Unsafe relative path in manifest:" << fi.path;
            m_downloadAllOk = false;
            return false;
        }

        const QString relativePath = QDir::fromNativeSeparators(fi.path);
        if (isRuntimeProtectedPath(relativePath)) {
            qDebug() << "Runtime-protected file skipped:" << relativePath;
            continue;
        }
        const QString installedFile = QDir(targetDir).filePath(relativePath);
        if (QFile::exists(installedFile)
            && calcLocalFileSha256(installedFile).compare(fi.sha256, Qt::CaseInsensitive) == 0)
        {
            qDebug() << "Unchanged file, skip download:" << relativePath;
            continue;
        }

        const QString tempFile = QDir(tempDir).filePath(relativePath);
        const QString parentDir = QFileInfo(tempFile).path();
        if (!QDir().mkpath(parentDir))
        {
            qDebug() << "Cannot create staging subdirectory:" << parentDir;
            m_downloadAllOk = false;
            return false;
        }

        const QString resumePartPath = QDir(resumeCacheDir).filePath(fi.sha256.toLower() + ".part");
        m_currentDownloadPath = relativePath;
        const qint64 resumedBytes = qMin(fi.size, QFileInfo(resumePartPath).size());
        const double speed = m_downloadTimer.elapsed() > 0
            ? (m_sessionDownloadedBytes * 1000.0 / m_downloadTimer.elapsed()) : 0.0;
        emit downloadProgress(m_downloadCompletedBytes + resumedBytes,
                              m_downloadTotalBytes, m_currentDownloadPath, speed);
        if (!downloadSingleFile(fi.url, tempFile, fi.sha256, fi.size, resumePartPath))
        {
            m_downloadAllOk = false;
            return false;
        }
        m_downloadCompletedBytes += fi.size;
        emit downloadProgress(m_downloadCompletedBytes, m_downloadTotalBytes,
                              m_currentDownloadPath, speed);
    }

    m_downloadAllOk = true;
    return true;
}

void UpdaterLogic::reportDownloadResult(const QString& appId, const QString& channel,
                                             const QString& version, bool success)
{
    QJsonArray files;
    for (const FileDownloadItem& item : m_fileItems)
        files.append(QJsonObject{{"path", item.path}, {"size", item.size}});
    QJsonObject body{{"app_id", appId}, {"channel", channel}, {"version", version},
                     {"result", success ? "success" : "fail"}, {"files", files}};
    m_http.postRequest(m_serverAddr + "/api/v1/update/download-report", body,
        [](int code, const QJsonObject&) { qDebug() << "Download result report returned code:" << code; });
}

void UpdaterLogic::reportResult(const QString& deviceId,
    const QString& fromVer,
    const QString& toVer,
    bool success)
{
    QString url = m_serverAddr + "/api/v1/update/report";

    QJsonObject body;
    body["app_id"] = ConfigHelper::instance().getValue("App", "app_id");
    body["device_id"] = deviceId;
    body["from_version"] = fromVer;
    body["to_version"] = toVer;

    if (success)
        body["result"] = "success";
    else
        body["result"] = "fail";

    m_http.postRequest(url, body, [](int code, const QJsonObject& resp)
        {
            Q_UNUSED(resp);
            qDebug() << "Update result report returned code:" << code;
        });
}

QList<FileDownloadItem> UpdaterLogic::getFileList() const
{
    return m_fileItems;
}