#include "DeviceIdentityHelper.h"
#include "ConfigHelper.h"

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

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

namespace {

QString manifestPublicKeyPath(const QString &installDir)
{
    return QDir(installDir).filePath(QStringLiteral("config/manifest_public_key.pem"));
}

} // namespace

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 = QCoreApplication::translate(
        "DeviceIdentityHelper",
        "OpenSSL is unavailable, so device credential signature cannot be verified.");
    return false;
#else
    const QString keyPath = manifestPublicKeyPath(m_installDir);
    QFile keyFile(keyPath);
    if (!keyFile.open(QIODevice::ReadOnly)) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "Device public key is missing: %1").arg(keyPath);
        return false;
    }

    const QByteArray keyData = keyFile.readAll();
    BIO *bio = BIO_new_mem_buf(keyData.constData(), keyData.size());
    EVP_PKEY *publicKey = bio ? PEM_read_bio_PUBKEY(bio, nullptr, nullptr, nullptr) : nullptr;
    if (bio) {
        BIO_free(bio);
    }
    if (!publicKey) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "Device public key is invalid: %1").arg(keyPath);
        return false;
    }

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

    if (ctx) {
        EVP_MD_CTX_free(ctx);
    }
    EVP_PKEY_free(publicKey);

    if (!ok) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "Device credential signature is invalid. The local identity file may not match this server.");
    }
    return ok;
#endif
}

bool DeviceIdentityHelper::loadAndVerify(const QString &expectedAppId, const QString &expectedChannel)
{
    // client_identity.dat 是服务端签发的本机设备凭证，不是用户可手写配置。
    // 本地启动时先用公钥校验签名，再校验 app/channel/license/installation/device 和有效期。
    QString credentialPath = ConfigHelper::instance().clientIdentityPath();
    if (!QFile::exists(credentialPath)) {
        credentialPath = QDir(m_installDir).filePath(QStringLiteral("config/client_identity.dat"));
    }

    QFile credentialFile(credentialPath);
    if (!credentialFile.open(QIODevice::ReadOnly)) {
        return false;
    }

    QJsonParseError parseError;
    const QJsonDocument wrapperDoc = QJsonDocument::fromJson(credentialFile.readAll(), &parseError);
    if (parseError.error != QJsonParseError::NoError || !wrapperDoc.isObject()) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "Device credential file is not valid JSON: %1")
                      .arg(credentialPath);
        return false;
    }

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

    const QJsonDocument identityDoc = QJsonDocument::fromJson(identityText);
    const QJsonObject identity = identityDoc.object();
    const QDateTime expiry = QDateTime::fromString(
        identity.value(QStringLiteral("valid_until")).toString(),
        Qt::ISODate);

    const bool identityMatches = identity.value(QStringLiteral("app_id")).toString() == expectedAppId
        && identity.value(QStringLiteral("channel")).toString() == expectedChannel
        && !identity.value(QStringLiteral("license_id")).toString().isEmpty()
        && !identity.value(QStringLiteral("installation_id")).toString().isEmpty()
        && !identity.value(QStringLiteral("device_id")).toString().isEmpty();
    if (!identityMatches) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "Device credential does not match this application, channel, license, installation or device.");
        return false;
    }

    if (!expiry.isValid() || expiry <= QDateTime::currentDateTimeUtc()) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "License has expired. Please ask the administrator to issue a new License.");
        return false;
    }

    m_deviceId = identity.value(QStringLiteral("device_id")).toString();
    return true;
}

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

bool DeviceIdentityHelper::ensureIssued(
    const QString &apiBaseUrl,
    const QString &clientToken,
    const QString &appId,
    const QString &channel,
    const QString &licenseKey)
{
    // 首次启动或本地凭证失效时，Launcher 会拿 License 向服务端登记设备。
    // 服务端返回签名后的 identity_text，客户端保存为 client_identity.dat，并把真实 device_id 写入运行配置。
    m_error.clear();
    if (loadAndVerify(appId, channel)) {
        ConfigHelper::instance().setValue(QStringLiteral("Update"), QStringLiteral("device_id"), m_deviceId);
        return true;
    }

    const QString trimmedBaseUrl = apiBaseUrl.trimmed();
    if (appId.trimmed().isEmpty()) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "app_id is empty in app_config.json.");
        return false;
    }
    if (channel.trimmed().isEmpty()) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "channel is empty in app_config.json.");
        return false;
    }
    if (trimmedBaseUrl.isEmpty() || trimmedBaseUrl.contains(QStringLiteral("YOUR_SERVER_IP"), Qt::CaseInsensitive)) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "Server address is not configured. Set config/server_config.json before building Launcher, for example: http://192.168.229.128:8000");
        return false;
    }
    if (clientToken.trimmed().isEmpty()) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "client_token is empty. Copy the client_token generated by the admin page into app_config.json.");
        return false;
    }
    if (licenseKey.trimmed().isEmpty()) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "License is empty. Create or select a License in the admin page, then copy the generated client configuration.");
        return false;
    }

    ConfigHelper &config = ConfigHelper::instance();
    QString installationId = config.getValue(QStringLiteral("Device"), QStringLiteral("installation_id"));
    if (installationId.isEmpty()) {
        installationId = QUuid::createUuid().toString(QUuid::WithoutBraces);
        if (!config.setValue(QStringLiteral("Device"), QStringLiteral("installation_id"), installationId)) {
            m_error = QCoreApplication::translate("DeviceIdentityHelper", "Cannot save installation id to %1: %2")
                          .arg(config.configPath(), config.lastError());
            return false;
        }
    }

    const QByteArray machine = QSysInfo::machineUniqueId() + installationId.toUtf8();
    const QString machineHash = QString::fromLatin1(
        QCryptographicHash::hash(machine, QCryptographicHash::Sha256).toHex());
    const QJsonObject body{
        {QStringLiteral("app_id"), appId},
        {QStringLiteral("channel"), channel},
        {QStringLiteral("license_key"), licenseKey},
        {QStringLiteral("installation_id"), installationId},
        {QStringLiteral("machine_hash"), machineHash},
    };

    QNetworkAccessManager manager;
    QNetworkRequest request{QUrl(trimmedBaseUrl + QStringLiteral("/api/v1/device/issue"))};
    request.setHeader(QNetworkRequest::ContentTypeHeader, QStringLiteral("application/json"));
    request.setRawHeader("X-Client-Token", clientToken.toUtf8());

    QNetworkReply *reply = manager.post(request, QJsonDocument(body).toJson(QJsonDocument::Compact));
    QEventLoop loop;
    QTimer timer;
    timer.setSingleShot(true);

    bool timeoutOk = false;
    int timeoutMs = ConfigHelper::instance()
                        .getValue(QStringLiteral("Update"), QStringLiteral("request_timeout_ms"))
                        .toInt(&timeoutOk);
    if (!timeoutOk || timeoutMs < 1000) {
        timeoutMs = 5000;
    }

    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 QString networkError = reply->errorString();
    const QByteArray raw = reply->readAll();
    reply->deleteLater();
    if (status != 200) {
        QJsonParseError responseError;
        const QJsonDocument errorDoc = QJsonDocument::fromJson(raw, &responseError);
        QString serverMessage;
        if (responseError.error == QJsonParseError::NoError && errorDoc.isObject()) {
            const QJsonValue detail = errorDoc.object().value(QStringLiteral("detail"));
            serverMessage = detail.isObject()
                ? detail.toObject().value(QStringLiteral("msg")).toString()
                : detail.toString();
        }
        if (serverMessage.isEmpty())
            serverMessage = QString::fromUtf8(raw).trimmed();

        if (status == 0) {
            m_error = QCoreApplication::translate(
                "DeviceIdentityHelper",
                "Cannot contact the update server to issue device identity.\nServer: %1\nApp: %2\nChannel: %3\nNetwork error: %4\nTimeout: %5 ms")
                .arg(trimmedBaseUrl, appId, channel, networkError, QString::number(timeoutMs));
        } else {
            m_error = QCoreApplication::translate(
                "DeviceIdentityHelper",
                "Device identity request was rejected by the update server.\nServer: %1\nHTTP status: %2\nApp: %3\nChannel: %4\nServer message: %5")
                .arg(trimmedBaseUrl, QString::number(status), appId, channel,
                     serverMessage.isEmpty() ? QCoreApplication::translate("DeviceIdentityHelper", "<empty response>") : serverMessage);
        }
        return false;
    }

    const QJsonDocument responseDoc = QJsonDocument::fromJson(raw);
    const QJsonObject response = responseDoc.object();
    if (response.value(QStringLiteral("identity_text")).toString().isEmpty()
        || response.value(QStringLiteral("signature")).toString().isEmpty()) {
        m_error = QCoreApplication::translate(
            "DeviceIdentityHelper",
            "Server returned an invalid device identity response.");
        return false;
    }

    const QJsonObject wrapper{
        {QStringLiteral("identity_text"), response.value(QStringLiteral("identity_text"))},
        {QStringLiteral("signature"), response.value(QStringLiteral("signature"))},
    };
    const QByteArray credentialBytes = QJsonDocument(wrapper).toJson(QJsonDocument::Compact);
    const QString credentialPath = config.clientIdentityPath();

    QString writeError;
    if (!ConfigHelper::writeFileWithElevationIfNeeded(credentialPath, credentialBytes, &writeError)) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "Cannot save device credential to %1: %2")
                      .arg(credentialPath, writeError);
        return false;
    }
    if (!loadAndVerify(appId, channel)) {
        return false;
    }
    if (!config.setValue(QStringLiteral("Update"), QStringLiteral("device_id"), m_deviceId)) {
        m_error = QCoreApplication::translate("DeviceIdentityHelper", "Cannot save server device id to %1: %2")
                      .arg(config.configPath(), config.lastError());
        return false;
    }
    return true;
}