#include "DeviceIdentityHelper.h"

#include "ConfigHelper.h"

#include <QCryptographicHash>
#include <QDateTime>
#include <QDir>
#include <QEventLoop>
#include <QFile>
#include <QFileInfo>
#include <QJsonDocument>
#include <QJsonObject>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QSaveFile>
#include <QSysInfo>
#include <QTimer>
#include <QUuid>

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

namespace
{
QString machineHash(const QString& installationId)
{
    const QByteArray identity =
        QSysInfo::machineUniqueId() + installationId.toUtf8();
    return QString::fromLatin1(
        QCryptographicHash::hash(identity, QCryptographicHash::Sha256).toHex());
}
}

DeviceIdentityHelper::DeviceIdentityHelper(const QString& installDir)
    : m_installDir(installDir)
{
}

QString DeviceIdentityHelper::deviceId() const
{
    return m_deviceId;
}

QString DeviceIdentityHelper::errorString() const
{
    return m_error;
}

bool DeviceIdentityHelper::verifySignature(const QByteArray& payload,
                                           const QString& signatureBase64)
{
#ifndef HAVE_OPENSSL
    Q_UNUSED(payload);
    Q_UNUSED(signatureBase64);
    m_error = "OpenSSL unavailable";
    return false;
#else
    QFile keyFile(
        QStringLiteral(":/simcae/update-client/manifest-public-key.pem"));
    if (!keyFile.open(QIODevice::ReadOnly))
    {
        m_error = "embedded device public key missing";
        return false;
    }

    const QByteArray keyData = keyFile.readAll();
    BIO* bio = BIO_new_mem_buf(keyData.constData(), keyData.size());
    EVP_PKEY* key = bio
                        ? PEM_read_bio_PUBKEY(bio, nullptr, nullptr, nullptr)
                        : nullptr;
    if (bio)
        BIO_free(bio);
    if (!key)
    {
        m_error = "device public key invalid";
        return false;
    }

    EVP_MD_CTX* context = EVP_MD_CTX_new();
    const QByteArray signature =
        QByteArray::fromBase64(signatureBase64.toUtf8());
    const bool valid =
        context
        && EVP_DigestVerifyInit(
               context, nullptr, EVP_sha256(), nullptr, key)
               == 1
        && EVP_DigestVerifyUpdate(
               context, payload.constData(), payload.size())
               == 1
        && EVP_DigestVerifyFinal(
               context,
               reinterpret_cast<const unsigned char*>(signature.constData()),
               signature.size())
               == 1;

    if (context)
        EVP_MD_CTX_free(context);
    EVP_PKEY_free(key);
    if (!valid)
        m_error = "device credential RSA signature invalid";
    return valid;
#endif
}

bool DeviceIdentityHelper::loadAndVerify(const QString& expectedAppId,
                                         const QString& expectedChannel)
{
    QFile credential(
        QDir(m_installDir).filePath("config/client_identity.dat"));
    if (!credential.open(QIODevice::ReadOnly))
    {
        m_error = "device credential is missing or unreadable";
        return false;
    }

    QJsonParseError wrapperError;
    const QJsonDocument wrapperDocument =
        QJsonDocument::fromJson(credential.readAll(), &wrapperError);
    if (wrapperError.error != QJsonParseError::NoError
        || !wrapperDocument.isObject())
    {
        m_error = "device credential JSON invalid";
        return false;
    }

    const QJsonObject wrapper = wrapperDocument.object();
    const QByteArray identityText =
        wrapper.value("identity_text").toString().toUtf8();
    if (identityText.isEmpty()
        || !verifySignature(
            identityText, wrapper.value("signature").toString()))
    {
        return false;
    }

    QJsonParseError identityError;
    const QJsonDocument identityDocument =
        QJsonDocument::fromJson(identityText, &identityError);
    if (identityError.error != QJsonParseError::NoError
        || !identityDocument.isObject())
    {
        m_error = "signed device identity JSON invalid";
        return false;
    }

    const QJsonObject identity = identityDocument.object();
    const QString signedInstallationId =
        identity.value("installation_id").toString();
    const QString signedDeviceId = identity.value("device_id").toString();
    ConfigHelper& config = ConfigHelper::instance();
    const QString localInstallationId =
        config.getValue("Device", "installation_id").trimmed();
    const QString localDeviceId =
        config.getValue("Update", "device_id").trimmed();

    if (identity.value("app_id").toString() != expectedAppId
        || identity.value("channel").toString() != expectedChannel
        || identity.value("license_id").toString().isEmpty()
        || signedInstallationId.isEmpty() || signedDeviceId.isEmpty())
    {
        m_error = "device/license credential identity mismatch";
        return false;
    }
    if (localInstallationId.isEmpty()
        || signedInstallationId != localInstallationId)
    {
        m_error = "device credential belongs to another installation";
        return false;
    }
    if (!localDeviceId.isEmpty() && signedDeviceId != localDeviceId)
    {
        m_error = "device credential does not match the registered device";
        return false;
    }

    const QString signedMachineHash =
        identity.value("machine_hash").toString();
    if (!signedMachineHash.isEmpty()
        && signedMachineHash.compare(
               machineHash(localInstallationId), Qt::CaseInsensitive)
               != 0)
    {
        m_error = "device credential belongs to another machine";
        return false;
    }

    const QDateTime expiry = QDateTime::fromString(
        identity.value("valid_until").toString(), Qt::ISODate);
    if (!expiry.isValid() || expiry <= QDateTime::currentDateTimeUtc())
    {
        m_error = "license expired";
        return false;
    }

    m_deviceId = signedDeviceId;
    return true;
}

bool DeviceIdentityHelper::verifyLocal(const QString& appId,
                                       const QString& channel)
{
    m_error.clear();
    m_deviceId.clear();
    return loadAndVerify(appId, channel);
}

bool DeviceIdentityHelper::ensureIssued(const QString& apiBaseUrl,
                                        const QString& clientToken,
                                        const QString& appId,
                                        const QString& channel,
                                        const QString& licenseKey)
{
    m_error.clear();
    m_deviceId.clear();
    ConfigHelper& config = ConfigHelper::instance();
    if (loadAndVerify(appId, channel))
    {
        if (!config.setValue("Update", "device_id", m_deviceId))
        {
            m_error = QString("cannot save server device id to %1: %2")
                          .arg(config.configPath(), config.lastError());
            return false;
        }
        return true;
    }

    const QString server = apiBaseUrl.trimmed();
    if (appId.trimmed().isEmpty())
    {
        m_error = "app_id is empty in the embedded product configuration";
        return false;
    }
    if (channel.trimmed().isEmpty())
    {
        m_error = "channel is empty in the embedded product configuration";
        return false;
    }
    if (server.isEmpty()
        || server.contains("YOUR_SERVER_IP", Qt::CaseInsensitive))
    {
        m_error = "api_base_url is not configured";
        return false;
    }
    if (clientToken.trimmed().isEmpty())
    {
        m_error = "client_token is empty in the embedded product configuration";
        return false;
    }
    if (licenseKey.trimmed().isEmpty())
    {
        m_error = "license_key is empty";
        return false;
    }

    QString installationId =
        config.getValue("Device", "installation_id").trimmed();
    if (installationId.isEmpty())
    {
        installationId =
            QUuid::createUuid().toString(QUuid::WithoutBraces);
        if (!config.setValue("Device", "installation_id", installationId))
        {
            m_error = QString("cannot save installation id to %1: %2")
                          .arg(config.configPath(), config.lastError());
            return false;
        }
    }

    const QJsonObject requestBody{
        {"app_id", appId},
        {"channel", channel},
        {"license_key", licenseKey},
        {"installation_id", installationId},
        {"machine_hash", machineHash(installationId)}};
    QNetworkAccessManager manager;
    QNetworkRequest request{QUrl(server + "/api/v1/device/issue")};
    request.setHeader(QNetworkRequest::ContentTypeHeader, "application/json");
    request.setRawHeader("X-Client-Token", clientToken.toUtf8());
    QNetworkReply* reply = manager.post(
        request, QJsonDocument(requestBody).toJson(QJsonDocument::Compact));

    QEventLoop loop;
    bool timeoutValid = false;
    int timeoutMs =
        config.getValue("Update", "request_timeout_ms").toInt(&timeoutValid);
    if (!timeoutValid || timeoutMs < 1000)
        timeoutMs = 5000;
    QTimer timer;
    timer.setSingleShot(true);
    QObject::connect(&timer, &QTimer::timeout, [&]() {
        if (reply && reply->isRunning())
            reply->abort();
    });
    QObject::connect(reply, &QNetworkReply::finished,
                     &loop, &QEventLoop::quit);
    timer.start(timeoutMs);
    loop.exec();
    timer.stop();

    const int status =
        reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
    const QByteArray responseBytes = reply->readAll();
    const QString networkError = reply->errorString();
    reply->deleteLater();
    if (status != 200)
    {
        m_error = QString("device issue failed (HTTP %1): %2 %3")
                      .arg(status)
                      .arg(networkError, QString::fromUtf8(responseBytes));
        return false;
    }

    QJsonParseError responseError;
    const QJsonDocument responseDocument =
        QJsonDocument::fromJson(responseBytes, &responseError);
    if (responseError.error != QJsonParseError::NoError
        || !responseDocument.isObject())
    {
        m_error = "device issue response is invalid JSON";
        return false;
    }
    const QJsonObject response = responseDocument.object();
    const QJsonObject wrapper{
        {"identity_text", response.value("identity_text")},
        {"signature", response.value("signature")}};
    if (!wrapper.value("identity_text").isString()
        || wrapper.value("identity_text").toString().isEmpty()
        || !wrapper.value("signature").isString()
        || wrapper.value("signature").toString().isEmpty())
    {
        m_error = "device issue response is missing signed identity fields";
        return false;
    }

    const QString credentialPath =
        QDir(m_installDir).filePath("config/client_identity.dat");
    if (!QDir().mkpath(QFileInfo(credentialPath).path()))
    {
        m_error = "cannot create the device credential directory";
        return false;
    }
    QSaveFile output(credentialPath);
    const QByteArray credentialBytes =
        QJsonDocument(wrapper).toJson(QJsonDocument::Compact);
    if (!output.open(QIODevice::WriteOnly)
        || output.write(credentialBytes) != credentialBytes.size()
        || !output.commit())
    {
        m_error = QString("cannot save device credential to %1: %2")
                      .arg(credentialPath, output.errorString());
        return false;
    }

    if (!loadAndVerify(appId, channel))
        return false;
    if (!config.setValue("Update", "device_id", m_deviceId))
    {
        m_error = QString("cannot save server device id to %1: %2")
                      .arg(config.configPath(), config.lastError());
        return false;
    }
    return true;
}