#include "encryptionmanager.h"

#include "connection.h"
#include "e2ee.h"

#include "csapi/keys.h"

#include <QtCore/QHash>
#include <QtCore/QStringBuilder>

#include <account.h> // QtOlm
#include <functional>
#include <memory>

using namespace Quotient;
using namespace QtOlm;
using std::move;

class EncryptionManager::Private {
public:
    explicit Private(const QByteArray& encryptionAccountPickle,
                     float signedKeysProportion, float oneTimeKeyThreshold)
        : signedKeysProportion(move(signedKeysProportion))
        , oneTimeKeyThreshold(move(oneTimeKeyThreshold))
    {
        Q_ASSERT((0 <= signedKeysProportion) && (signedKeysProportion <= 1));
        Q_ASSERT((0 <= oneTimeKeyThreshold) && (oneTimeKeyThreshold <= 1));
        if (encryptionAccountPickle.isEmpty()) {
            olmAccount.reset(new Account());
        } else {
            olmAccount.reset(
                new Account(encryptionAccountPickle)); // TODO: passphrase even
                                                       // with qtkeychain?
        }
        /*
         * Note about targetKeysNumber:
         *
         * From: https://github.com/Zil0/matrix-python-sdk/
         * File: matrix_client/crypto/olm_device.py
         *
         * Try to maintain half the number of one-time keys libolm can hold
         * uploaded on the HS. This is because some keys will be claimed by
         * peers but not used instantly, and we want them to stay in libolm,
         * until the limit is reached and it starts discarding keys, starting by
         * the oldest.
         */
        targetKeysNumber = olmAccount->maxOneTimeKeys(); // 2 // see note below
        targetOneTimeKeyCounts = {
            { SignedCurve25519Key,
              qRound(signedKeysProportion * targetKeysNumber) },
            { Curve25519Key,
              qRound((1 - signedKeysProportion) * targetKeysNumber) }
        };
    }
    ~Private() = default;

    UploadKeysJob* uploadIdentityKeysJob = nullptr;
    UploadKeysJob* uploadOneTimeKeysJob = nullptr;

    QScopedPointer<Account> olmAccount;

    float signedKeysProportion;
    float oneTimeKeyThreshold;
    int targetKeysNumber;

    void updateKeysToUpload();
    bool oneTimeKeyShouldUpload();

    QHash<QString, int> oneTimeKeyCounts;
    void setOneTimeKeyCounts(const QHash<QString, int> oneTimeKeyCountsNewValue)
    {
        oneTimeKeyCounts = oneTimeKeyCountsNewValue;
        updateKeysToUpload();
    }
    QHash<QString, int> oneTimeKeysToUploadCounts;
    QHash<QString, int> targetOneTimeKeyCounts;
};

EncryptionManager::EncryptionManager(const QByteArray& encryptionAccountPickle,
                                     float signedKeysProportion,
                                     float oneTimeKeyThreshold, QObject* parent)
    : QObject(parent)
    , d(std::make_unique<Private>(std::move(encryptionAccountPickle),
                                  std::move(signedKeysProportion),
                                  std::move(oneTimeKeyThreshold)))
{}

EncryptionManager::~EncryptionManager() = default;

void EncryptionManager::uploadIdentityKeys(Connection* connection)
{
    // https://matrix.org/docs/spec/client_server/latest#post-matrix-client-r0-keys-upload
    DeviceKeys deviceKeys {
        /*
         * The ID of the user the device belongs to. Must match the user ID used
         * when logging in. The ID of the device these keys belong to. Must
         * match the device ID used when logging in. The encryption algorithms
         * supported by this device.
         */
        connection->userId(),
        connection->deviceId(),
        SupportedAlgorithms,
        /*
         * Public identity keys. The names of the properties should be in the
         * format <algorithm>:<device_id>. The keys themselves should be encoded
         * as specified by the key algorithm.
         */
        { { Curve25519Key + QStringLiteral(":") + connection->deviceId(),
            d->olmAccount->curve25519IdentityKey() },
          { Ed25519Key + QStringLiteral(":") + connection->deviceId(),
            d->olmAccount->ed25519IdentityKey() } },
        /* signatures should be provided after the unsigned deviceKeys
           generation */
        {}
    };

    QJsonObject deviceKeysJsonObject = toJson(deviceKeys);
    /* additionally removing signatures key,
     * since we could not initialize deviceKeys
     * without an empty signatures value:
     */
    deviceKeysJsonObject.remove(QStringLiteral("signatures"));
    /*
     * Signatures for the device key object.
     * A map from user ID, to a map from <algorithm>:<device_id> to the
     * signature. The signature is calculated using the process called Signing
     * JSON.
     */
    deviceKeys.signatures = {
        { connection->userId(),
          { { Ed25519Key + QStringLiteral(":") + connection->deviceId(),
              d->olmAccount->sign(deviceKeysJsonObject) } } }
    };

    connect(d->uploadIdentityKeysJob, &BaseJob::success, this, [this] {
        d->setOneTimeKeyCounts(d->uploadIdentityKeysJob->oneTimeKeyCounts());
        qDebug() << QString("Uploaded identity keys.");
    });
    d->uploadIdentityKeysJob = connection->callApi<UploadKeysJob>(deviceKeys);
}

void EncryptionManager::uploadOneTimeKeys(Connection* connection,
                                          bool forceUpdate)
{
    if (forceUpdate || d->oneTimeKeyCounts.isEmpty()) {
        auto job = connection->callApi<UploadKeysJob>();
        connect(job, &BaseJob::success, this, [job, this] {
            d->setOneTimeKeyCounts(job->oneTimeKeyCounts());
        });
    }

    int signedKeysToUploadCount =
        d->oneTimeKeysToUploadCounts.value(SignedCurve25519Key, 0);
    int unsignedKeysToUploadCount =
        d->oneTimeKeysToUploadCounts.value(Curve25519Key, 0);

    d->olmAccount->generateOneTimeKeys(signedKeysToUploadCount
                                       + unsignedKeysToUploadCount);

    QHash<QString, QVariant> oneTimeKeys = {};
    const auto& olmAccountCurve25519OneTimeKeys =
        d->olmAccount->curve25519OneTimeKeys();

    int oneTimeKeysCounter = 0;
    for (auto it = olmAccountCurve25519OneTimeKeys.cbegin();
         it != olmAccountCurve25519OneTimeKeys.cend(); ++it) {
        QString keyId = it.key();
        QString keyType;
        QVariant key;
        if (oneTimeKeysCounter < signedKeysToUploadCount) {
            QJsonObject message { { QStringLiteral("key"),
                                    it.value().toString() } };
            key = d->olmAccount->sign(message);
            keyType = SignedCurve25519Key;

        } else {
            key = it.value();
            keyType = Curve25519Key;
        }
        ++oneTimeKeysCounter;
        oneTimeKeys.insert(QString("%1:%2").arg(keyType).arg(keyId), key);
    }

    d->uploadOneTimeKeysJob = connection->callApi<UploadKeysJob>(none,
                                                                 oneTimeKeys);
    d->olmAccount->markKeysAsPublished();
    qDebug() << QString("Uploaded new one-time keys: %1 signed, %2 unsigned.")
                    .arg(signedKeysToUploadCount)
                    .arg(unsignedKeysToUploadCount);
}

QByteArray EncryptionManager::olmAccountPickle()
{
    return d->olmAccount->pickle(); // TODO: passphrase even with qtkeychain?
}

QtOlm::Account* EncryptionManager::account() const
{
    return d->olmAccount.data();
}

void EncryptionManager::Private::updateKeysToUpload()
{
    for (auto it = targetOneTimeKeyCounts.cbegin();
         it != targetOneTimeKeyCounts.cend(); ++it) {
        int numKeys = oneTimeKeyCounts.value(it.key(), 0);
        int numToCreate = qMax(it.value() - numKeys, 0);
        oneTimeKeysToUploadCounts.insert(it.key(), numToCreate);
    }
}

bool EncryptionManager::Private::oneTimeKeyShouldUpload()
{
    if (oneTimeKeyCounts.empty())
        return true;
    for (auto it = targetOneTimeKeyCounts.cbegin();
         it != targetOneTimeKeyCounts.cend(); ++it) {
        if (oneTimeKeyCounts.value(it.key(), 0)
            < it.value() * oneTimeKeyThreshold)
            return true;
    }
    return false;
}