#include "IntegrityHelper.h"
#include "ConfigHelper.h"
#include <QCryptographicHash>
#include <QDir>
#include <QDirIterator>
#include <QFile>
#include <QFileInfo>
#include <QJsonArray>
#include <QJsonDocument>
#include <QJsonObject>
#include <QSet>
#ifdef HAVE_OPENSSL
#include <openssl/evp.h>
#include <openssl/pem.h>
#endif

IntegrityHelper::IntegrityHelper(const QString& installDir)
    : m_installDir(QDir::cleanPath(installDir)) {}

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

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

bool IntegrityHelper::runtimeProtectedPath(const QString& path) const
{
    const QString p = QDir::fromNativeSeparators(path).toCaseFolded();
    QSet<QString> protectedPaths{
        "client.ini", "config/app_config.json", "config/local_state.json",
        "config/client_identity.dat", "config/version_policy.dat"
    };
    const QString runtimePrefix = ConfigHelper::instance().runtimeRelativePath().toCaseFolded();
    if (!runtimePrefix.isEmpty()) {
        const QStringList runtimeProtected{
            "client.ini", "config/app_config.json", "config/local_state.json",
            "config/client_identity.dat", "config/version_policy.dat"
        };
        for (const QString& protectedPath : runtimeProtected)
            protectedPaths.insert(runtimePrefix + "/" + protectedPath);
    }
    return protectedPaths.contains(p);
}

QString IntegrityHelper::sha256(const QString& filePath) const
{
    QFile file(filePath);
    if (!file.open(QIODevice::ReadOnly)) return {};
    QCryptographicHash hash(QCryptographicHash::Sha256);
    while (!file.atEnd()) hash.addData(file.read(1024 * 1024));
    return QString::fromLatin1(hash.result().toHex());
}

bool IntegrityHelper::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 manifest 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 = "manifest public key invalid"; 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, key) == 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(key);
    if (!ok) m_error = "manifest RSA signature invalid";
    return ok;
#endif
}

bool IntegrityHelper::verifyInstalledVersion(const QString& appId, const QString& channel,
                                             const QString& version)
{
    m_error.clear();
    QString cachePath = QDir(ConfigHelper::instance().updateRoot()).filePath(
        "manifest_cache/manifest_" + version + ".json");
    const QString legacyCachePath = QDir(m_installDir).filePath(
        "update/manifest_cache/manifest_" + version + ".json");
    if (!QFile::exists(cachePath))
        cachePath = legacyCachePath;
    QFile cache(cachePath);
    if (!cache.open(QIODevice::ReadOnly)) { m_error = "signed manifest cache missing for " + version; return false; }
    QJsonParseError wrapperError;
    const QJsonDocument wrapperDoc = QJsonDocument::fromJson(cache.readAll(), &wrapperError);
    if (wrapperError.error != QJsonParseError::NoError || !wrapperDoc.isObject()) {
        m_error = "manifest cache JSON invalid"; return false;
    }
    const QJsonObject wrapper = wrapperDoc.object();
    const QByteArray manifestText = wrapper.value("manifest_text").toString().toUtf8();
    const QString signature = wrapper.value("manifest").toObject().value("signature").toString();
    if (manifestText.isEmpty() || signature.isEmpty() || !verifySignature(manifestText, signature)) return false;

    QJsonParseError manifestError;
    const QJsonDocument manifestDoc = QJsonDocument::fromJson(manifestText, &manifestError);
    if (manifestError.error != QJsonParseError::NoError || !manifestDoc.isObject()) {
        m_error = "signed manifest payload invalid"; return false;
    }
    const QJsonObject manifest = manifestDoc.object();
    if (manifest.value("app_id").toString() != appId
        || manifest.value("channel").toString() != channel
        || manifest.value("version").toString() != version) {
        m_error = "manifest identity does not match local application"; return false;
    }

    QSet<QString> declaredExecutables;
    for (const QJsonValue& value : manifest.value("files").toArray()) {
        const QJsonObject item = value.toObject();
        const QString path = QDir::fromNativeSeparators(item.value("path").toString());
        if (!safeRelativePath(path)) { m_error = "unsafe manifest path: " + path; return false; }
        if (runtimeProtectedPath(path)) continue;
        const QString fullPath = QDir(m_installDir).filePath(path);
        if (!QFile::exists(fullPath)) { m_error = "required file missing: " + path; return false; }
        const QString expected = item.value("sha256").toString();
        const QString actual = sha256(fullPath);
        if (actual.isEmpty() || actual.compare(expected, Qt::CaseInsensitive) != 0) {
            m_error = "file hash mismatch: " + path; return false;
        }
        const QString suffix = QFileInfo(path).suffix().toCaseFolded();
        if (suffix == "exe" || suffix == "dll") declaredExecutables.insert(path.toCaseFolded());
    }

    QDir root(m_installDir);
    QDirIterator it(m_installDir, QDir::Files, QDirIterator::Subdirectories);
    while (it.hasNext()) {
        const QString fullPath = it.next();
        const QString relative = QDir::fromNativeSeparators(root.relativeFilePath(fullPath));
        const QString folded = relative.toCaseFolded();
        const QString runtimePrefix = ConfigHelper::instance().runtimeRelativePath().toCaseFolded();
        const bool runtimeWorkDir = !runtimePrefix.isEmpty()
            && (folded.startsWith(runtimePrefix + "/update/")
                || folded.startsWith(runtimePrefix + "/update_temp/"));
        if (folded.startsWith("update/") || folded.startsWith("update_temp/")
            || runtimeWorkDir || runtimeProtectedPath(relative)) continue;
        const QString suffix = QFileInfo(relative).suffix().toCaseFolded();
        if ((suffix == "exe" || suffix == "dll") && !declaredExecutables.contains(folded)) {
            m_error = "undeclared executable or plugin: " + relative; return false;
        }
    }
    return true;
}