#include "TicketHelper.h"
#include <QCoreApplication>
#include <QDateTime>
#include <QDir>
#include <QFile>
#include <QJsonDocument>
#include <QJsonObject>
#include <QMessageAuthenticationCode>
#include <QSaveFile>
#include <QStandardPaths>
#include <QStringList>
#include <QUuid>

static QByteArray ticketMac(const QJsonObject& payload, const QString& secret)
{
    return QMessageAuthenticationCode::hash(
        QJsonDocument(payload).toJson(QJsonDocument::Compact), secret.toUtf8(), QCryptographicHash::Sha256).toHex();
}

bool TicketHelper::createTicket(const QString& appId, const QString& deviceId,
                                const QString& version, const QString& secret,
                                QString* ticketPath, QString* errorMessage)
{
    // Launcher 启动业务主程序前生成一次性 ticket。
    // ticket 只保存在临时目录、有效期 60 秒，并用 launch_token 做 HMAC，防止用户绕过 Launcher 直接启动主程序。
    if (appId.isEmpty() || deviceId.isEmpty() || version.isEmpty() || secret.isEmpty()) {
        if (errorMessage) {
            QStringList missing;
            if (appId.isEmpty()) missing.append(QStringLiteral("app_id"));
            if (deviceId.isEmpty()) missing.append(QStringLiteral("device_id"));
            if (version.isEmpty()) missing.append(QStringLiteral("current_version"));
            if (secret.isEmpty()) missing.append(QStringLiteral("launch_token"));
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Cannot create launch ticket because required fields are empty: %1. Check app_config.json, registry-imported configuration and device authorization.")
                .arg(missing.join(QStringLiteral(", ")));
        }
        return false;
    }
    const QDateTime now = QDateTime::currentDateTimeUtc();
    QJsonObject payload{
        {"app_id", appId}, {"device_id", deviceId}, {"version", version},
        {"nonce", QUuid::createUuid().toString(QUuid::WithoutBraces)},
        {"issued_at", now.toString(Qt::ISODate)},
        {"expires_at", now.addSecs(60).toString(Qt::ISODate)},
        {"signature_alg", "HMAC-SHA256"}
    };
    QJsonObject wrapper{{"payload", payload}, {"signature", QString::fromLatin1(ticketMac(payload, secret))}};
    const QString dirPath = QDir(QStandardPaths::writableLocation(QStandardPaths::TempLocation)).filePath("marsco_tickets");
    if (!QDir().mkpath(dirPath)) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Cannot create launch ticket directory: %1.")
                .arg(dirPath);
        }
        return false;
    }
    const QString path = QDir(dirPath).filePath("ticket_" + QUuid::createUuid().toString(QUuid::WithoutBraces) + ".json");
    QSaveFile file(path);
    const QByteArray bytes = QJsonDocument(wrapper).toJson(QJsonDocument::Compact);
    if (!file.open(QIODevice::WriteOnly) || file.write(bytes) != bytes.size() || !file.commit()) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Cannot save launch ticket file: %1. Error: %2.")
                .arg(path, file.errorString());
        }
        return false;
    }
    QFile::setPermissions(path, QFileDevice::ReadOwner | QFileDevice::WriteOwner);
    if (ticketPath) *ticketPath = path;
    return true;
}

bool TicketHelper::consumeAndVerify(const QString& ticketPath, const QString& expectedAppId,
                                    const QString& expectedDeviceId, const QString& expectedVersion,
                                    const QString& secret, QString* errorMessage)
{
    // 主程序启动后第一时间把 ticket 改名成 .consuming，再读取并删除。
    // 这样同一张 ticket 即使校验失败也不能被重复使用，避免重放启动。
    const QString consumingPath = ticketPath + ".consuming."
        + QString::number(QCoreApplication::applicationPid());
    if (!QFile::rename(ticketPath, consumingPath)) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket is missing or has already been consumed. Ticket file: %1. Please start the application from Launcher.")
                .arg(ticketPath);
        }
        return false;
    }
    QFile file(consumingPath);
    if (!file.open(QIODevice::ReadOnly)) {
        QFile::remove(consumingPath);
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Cannot read claimed launch ticket: %1. Error: %2.")
                .arg(consumingPath, file.errorString());
        }
        return false;
    }
    const QByteArray raw = file.readAll(); file.close();
    QFile::remove(consumingPath); // Consume once; it must not be replayed regardless of success or failure.
    QJsonParseError parseError;
    const QJsonDocument doc = QJsonDocument::fromJson(raw, &parseError);
    if (parseError.error != QJsonParseError::NoError || !doc.isObject()) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket is not valid JSON. JSON error: %1.")
                .arg(parseError.errorString());
        }
        return false;
    }
    const QJsonObject wrapper = doc.object();
    const QJsonObject payload = wrapper.value("payload").toObject();
    const QByteArray actual = wrapper.value("signature").toString().toLatin1();
    const QByteArray expected = ticketMac(payload, secret);
    const QDateTime issued = QDateTime::fromString(payload.value("issued_at").toString(), Qt::ISODate);
    const QDateTime expires = QDateTime::fromString(payload.value("expires_at").toString(), Qt::ISODate);
    const QDateTime now = QDateTime::currentDateTimeUtc();
    const bool timeOk = issued.isValid() && expires.isValid() && issued <= now.addSecs(5)
        && expires >= now && issued.secsTo(expires) <= 65;
    if (actual.isEmpty() || actual != expected) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket signature is invalid. The launch_token used by Launcher and the main application is inconsistent, or the ticket content was changed.");
        }
        return false;
    }
    if (payload.value("app_id").toString() != expectedAppId) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket app_id does not match. Ticket app_id: %1. Expected app_id: %2.")
                .arg(payload.value("app_id").toString(), expectedAppId);
        }
        return false;
    }
    if (payload.value("device_id").toString() != expectedDeviceId) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket device_id does not match. Ticket device_id: %1. Expected device_id: %2. Reauthorize the device from Launcher if the configuration was regenerated.")
                .arg(payload.value("device_id").toString(), expectedDeviceId);
        }
        return false;
    }
    if (payload.value("version").toString() != expectedVersion) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket version does not match. Ticket version: %1. Expected version: %2.")
                .arg(payload.value("version").toString(), expectedVersion);
        }
        return false;
    }
    if (!timeOk) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket time is invalid or expired. Issued at: %1. Expires at: %2. Current UTC time: %3.")
                .arg(payload.value("issued_at").toString(),
                     payload.value("expires_at").toString(),
                     now.toString(Qt::ISODate));
        }
        return false;
    }
    if (payload.value("nonce").toString().isEmpty()) {
        if (errorMessage) {
            *errorMessage = QCoreApplication::translate(
                "TicketHelper",
                "Launch ticket nonce is missing. The ticket is incomplete.");
        }
        return false;
    }
    return true;
}