// SPDX-FileCopyrightText: 2021 Nheko Contributors
//
// SPDX-License-Identifier: GPL-3.0-or-later

#include "Olm.h"

#include <QObject>
#include <QTimer>

#include <nlohmann/json.hpp>
#include <variant>

#include <mtx/responses/common.hpp>
#include <mtx/secret_storage.hpp>

#include "Cache.h"
#include "Cache_p.h"
#include "ChatPage.h"
#include "DeviceVerificationFlow.h"
#include "Logging.h"
#include "MatrixClient.h"
#include "UserSettingsPage.h"
#include "Utils.h"

namespace {
auto client_ = std::make_unique<mtx::crypto::OlmClient>();

std::map<std::string, std::string> request_id_to_secret_name;

constexpr auto MEGOLM_ALGO = "m.megolm.v1.aes-sha2";
}

namespace olm {
static void
backup_session_key(const MegolmSessionIndex &idx,
                   const GroupSessionData &data,
                   mtx::crypto::InboundGroupSessionPtr &session);

void
from_json(const nlohmann::json &obj, OlmMessage &msg)
{
        if (obj.at("type") != "m.room.encrypted")
                throw std::invalid_argument("invalid type for olm message");

        if (obj.at("content").at("algorithm") != OLM_ALGO)
                throw std::invalid_argument("invalid algorithm for olm message");

        msg.sender     = obj.at("sender");
        msg.sender_key = obj.at("content").at("sender_key");
        msg.ciphertext = obj.at("content")
                           .at("ciphertext")
                           .get<std::map<std::string, mtx::events::msg::OlmCipherContent>>();
}

mtx::crypto::OlmClient *
client()
{
        return client_.get();
}

static void
handle_secret_request(const mtx::events::DeviceEvent<mtx::events::msg::SecretRequest> *e,
                      const std::string &sender)
{
        using namespace mtx::events;

        if (e->content.action != mtx::events::msg::RequestAction::Request)
                return;

        auto local_user = http::client()->user_id();

        if (sender != local_user.to_string())
                return;

        auto verificationStatus = cache::verificationStatus(local_user.to_string());

        if (!verificationStatus)
                return;

        auto deviceKeys = cache::userKeys(local_user.to_string());
        if (!deviceKeys)
                return;

        if (std::find(verificationStatus->verified_devices.begin(),
                      verificationStatus->verified_devices.end(),
                      e->content.requesting_device_id) ==
            verificationStatus->verified_devices.end())
                return;

        // this is a verified device
        mtx::events::DeviceEvent<mtx::events::msg::SecretSend> secretSend;
        secretSend.type               = EventType::SecretSend;
        secretSend.content.request_id = e->content.request_id;

        auto secret = cache::client()->secret(e->content.name);
        if (!secret)
                return;
        secretSend.content.secret = secret.value();

        send_encrypted_to_device_messages(
          {{local_user.to_string(), {{e->content.requesting_device_id}}}}, secretSend);

        nhlog::net()->info("Sent secret '{}' to ({},{})",
                           e->content.name,
                           local_user.to_string(),
                           e->content.requesting_device_id);
}

void
handle_to_device_messages(const std::vector<mtx::events::collections::DeviceEvents> &msgs)
{
        if (msgs.empty())
                return;
        nhlog::crypto()->info("received {} to_device messages", msgs.size());
        nlohmann::json j_msg;

        for (const auto &msg : msgs) {
                j_msg = std::visit([](auto &e) { return json(e); }, std::move(msg));
                if (j_msg.count("type") == 0) {
                        nhlog::crypto()->warn("received message with no type field: {}",
                                              j_msg.dump(2));
                        continue;
                }

                std::string msg_type = j_msg.at("type");

                if (msg_type == to_string(mtx::events::EventType::RoomEncrypted)) {
                        try {
                                olm::OlmMessage olm_msg = j_msg;
                                cache::client()->query_keys(
                                  olm_msg.sender,
                                  [olm_msg](const UserKeyCache &userKeys, mtx::http::RequestErr e) {
                                          if (e) {
                                                  nhlog::crypto()->error(
                                                    "Failed to query user keys, dropping olm "
                                                    "message");
                                                  return;
                                          }
                                          handle_olm_message(std::move(olm_msg), userKeys);
                                  });
                        } catch (const nlohmann::json::exception &e) {
                                nhlog::crypto()->warn(
                                  "parsing error for olm message: {} {}", e.what(), j_msg.dump(2));
                        } catch (const std::invalid_argument &e) {
                                nhlog::crypto()->warn("validation error for olm message: {} {}",
                                                      e.what(),
                                                      j_msg.dump(2));
                        }

                } else if (msg_type == to_string(mtx::events::EventType::RoomKeyRequest)) {
                        nhlog::crypto()->warn("handling key request event: {}", j_msg.dump(2));
                        try {
                                mtx::events::DeviceEvent<mtx::events::msg::KeyRequest> req = j_msg;
                                if (req.content.action == mtx::events::msg::RequestAction::Request)
                                        handle_key_request_message(req);
                                else
                                        nhlog::crypto()->warn(
                                          "ignore key request (unhandled action): {}",
                                          req.content.request_id);
                        } catch (const nlohmann::json::exception &e) {
                                nhlog::crypto()->warn(
                                  "parsing error for key_request message: {} {}",
                                  e.what(),
                                  j_msg.dump(2));
                        }
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationAccept)) {
                        auto message = std::get<
                          mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationAccept>>(msg);
                        ChatPage::instance()->receivedDeviceVerificationAccept(message.content);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationRequest)) {
                        auto message = std::get<
                          mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationRequest>>(msg);
                        ChatPage::instance()->receivedDeviceVerificationRequest(message.content,
                                                                                message.sender);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationCancel)) {
                        auto message = std::get<
                          mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationCancel>>(msg);
                        ChatPage::instance()->receivedDeviceVerificationCancel(message.content);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationKey)) {
                        auto message =
                          std::get<mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationKey>>(
                            msg);
                        ChatPage::instance()->receivedDeviceVerificationKey(message.content);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationMac)) {
                        auto message =
                          std::get<mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationMac>>(
                            msg);
                        ChatPage::instance()->receivedDeviceVerificationMac(message.content);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationStart)) {
                        auto message = std::get<
                          mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationStart>>(msg);
                        ChatPage::instance()->receivedDeviceVerificationStart(message.content,
                                                                              message.sender);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationReady)) {
                        auto message = std::get<
                          mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationReady>>(msg);
                        ChatPage::instance()->receivedDeviceVerificationReady(message.content);
                } else if (msg_type == to_string(mtx::events::EventType::KeyVerificationDone)) {
                        auto message =
                          std::get<mtx::events::DeviceEvent<mtx::events::msg::KeyVerificationDone>>(
                            msg);
                        ChatPage::instance()->receivedDeviceVerificationDone(message.content);
                } else if (auto e =
                             std::get_if<mtx::events::DeviceEvent<mtx::events::msg::SecretRequest>>(
                               &msg)) {
                        handle_secret_request(e, e->sender);
                } else {
                        nhlog::crypto()->warn("unhandled event: {}", j_msg.dump(2));
                }
        }
}

void
handle_olm_message(const OlmMessage &msg, const UserKeyCache &otherUserDeviceKeys)
{
        nhlog::crypto()->info("sender    : {}", msg.sender);
        nhlog::crypto()->info("sender_key: {}", msg.sender_key);

        if (msg.sender_key == olm::client()->identity_keys().ed25519) {
                nhlog::crypto()->warn("Ignoring olm message from ourselves!");
                return;
        }

        const auto my_key = olm::client()->identity_keys().curve25519;

        bool failed_decryption = false;

        for (const auto &cipher : msg.ciphertext) {
                // We skip messages not meant for the current device.
                if (cipher.first != my_key) {
                        nhlog::crypto()->debug(
                          "Skipping message for {} since we are {}.", cipher.first, my_key);
                        continue;
                }

                const auto type = cipher.second.type;
                nhlog::crypto()->info("type: {}", type == 0 ? "OLM_PRE_KEY" : "OLM_MESSAGE");

                auto payload = try_olm_decryption(msg.sender_key, cipher.second);

                if (payload.is_null()) {
                        // Check for PRE_KEY message
                        if (cipher.second.type == 0) {
                                payload = handle_pre_key_olm_message(
                                  msg.sender, msg.sender_key, cipher.second);
                        } else {
                                nhlog::crypto()->error("Undecryptable olm message!");
                                failed_decryption = true;
                                continue;
                        }
                }

                if (!payload.is_null()) {
                        mtx::events::collections::DeviceEvents device_event;

                        // Other properties are included in order to prevent an attacker from
                        // publishing someone else's curve25519 keys as their own and subsequently
                        // claiming to have sent messages which they didn't. sender must correspond
                        // to the user who sent the event, recipient to the local user, and
                        // recipient_keys to the local ed25519 key.
                        std::string receiver_ed25519 = payload["recipient_keys"]["ed25519"];
                        if (receiver_ed25519.empty() ||
                            receiver_ed25519 != olm::client()->identity_keys().ed25519) {
                                nhlog::crypto()->warn(
                                  "Decrypted event doesn't include our ed25519: {}",
                                  payload.dump());
                                return;
                        }
                        std::string receiver = payload["recipient"];
                        if (receiver.empty() || receiver != http::client()->user_id().to_string()) {
                                nhlog::crypto()->warn(
                                  "Decrypted event doesn't include our user_id: {}",
                                  payload.dump());
                                return;
                        }

                        // Clients must confirm that the sender_key and the ed25519 field value
                        // under the keys property match the keys returned by /keys/query for the
                        // given user, and must also verify the signature of the payload. Without
                        // this check, a client cannot be sure that the sender device owns the
                        // private part of the ed25519 key it claims to have in the Olm payload.
                        // This is crucial when the ed25519 key corresponds to a verified device.
                        std::string sender_ed25519 = payload["keys"]["ed25519"];
                        if (sender_ed25519.empty()) {
                                nhlog::crypto()->warn(
                                  "Decrypted event doesn't include sender ed25519: {}",
                                  payload.dump());
                                return;
                        }

                        bool from_their_device = false;
                        for (auto [device_id, key] : otherUserDeviceKeys.device_keys) {
                                auto c_key = key.keys.find("curve25519:" + device_id);
                                auto e_key = key.keys.find("ed25519:" + device_id);

                                if (c_key == key.keys.end() || e_key == key.keys.end()) {
                                        nhlog::crypto()->warn(
                                          "Skipping device {} as we have no keys for it.",
                                          device_id);
                                } else if (c_key->second == msg.sender_key &&
                                           e_key->second == sender_ed25519) {
                                        from_their_device = true;
                                        break;
                                }
                        }
                        if (!from_their_device) {
                                nhlog::crypto()->warn("Decrypted event isn't sent from a device "
                                                      "listed by that user! {}",
                                                      payload.dump());
                                return;
                        }

                        {
                                std::string msg_type = payload["type"];
                                json event_array     = json::array();
                                event_array.push_back(payload);

                                std::vector<mtx::events::collections::DeviceEvents> temp_events;
                                mtx::responses::utils::parse_device_events(event_array,
                                                                           temp_events);
                                if (temp_events.empty()) {
                                        nhlog::crypto()->warn("Decrypted unknown event: {}",
                                                              payload.dump());
                                        return;
                                }
                                device_event = temp_events.at(0);
                        }

                        using namespace mtx::events;
                        if (auto e1 =
                              std::get_if<DeviceEvent<msg::KeyVerificationAccept>>(&device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationAccept(e1->content);
                        } else if (auto e2 = std::get_if<DeviceEvent<msg::KeyVerificationRequest>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationRequest(e2->content,
                                                                                        e2->sender);
                        } else if (auto e3 = std::get_if<DeviceEvent<msg::KeyVerificationCancel>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationCancel(e3->content);
                        } else if (auto e4 = std::get_if<DeviceEvent<msg::KeyVerificationKey>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationKey(e4->content);
                        } else if (auto e5 = std::get_if<DeviceEvent<msg::KeyVerificationMac>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationMac(e5->content);
                        } else if (auto e6 = std::get_if<DeviceEvent<msg::KeyVerificationStart>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationStart(e6->content,
                                                                                      e6->sender);
                        } else if (auto e7 = std::get_if<DeviceEvent<msg::KeyVerificationReady>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationReady(e7->content);
                        } else if (auto e8 = std::get_if<DeviceEvent<msg::KeyVerificationDone>>(
                                     &device_event)) {
                                ChatPage::instance()->receivedDeviceVerificationDone(e8->content);
                        } else if (auto roomKey =
                                     std::get_if<DeviceEvent<msg::RoomKey>>(&device_event)) {
                                create_inbound_megolm_session(
                                  *roomKey, msg.sender_key, sender_ed25519);
                        } else if (auto forwardedRoomKey =
                                     std::get_if<DeviceEvent<msg::ForwardedRoomKey>>(
                                       &device_event)) {
                                forwardedRoomKey->content.forwarding_curve25519_key_chain.push_back(
                                  msg.sender_key);
                                import_inbound_megolm_session(*forwardedRoomKey);
                        } else if (auto e =
                                     std::get_if<DeviceEvent<msg::SecretSend>>(&device_event)) {
                                auto local_user = http::client()->user_id();

                                if (msg.sender != local_user.to_string())
                                        return;

                                auto secret_name =
                                  request_id_to_secret_name.find(e->content.request_id);

                                if (secret_name != request_id_to_secret_name.end()) {
                                        nhlog::crypto()->info("Received secret: {}",
                                                              secret_name->second);

                                        mtx::events::msg::SecretRequest secretRequest{};
                                        secretRequest.action =
                                          mtx::events::msg::RequestAction::Cancellation;
                                        secretRequest.requesting_device_id =
                                          http::client()->device_id();
                                        secretRequest.request_id = e->content.request_id;

                                        auto verificationStatus =
                                          cache::verificationStatus(local_user.to_string());

                                        if (!verificationStatus)
                                                return;

                                        auto deviceKeys = cache::userKeys(local_user.to_string());
                                        std::string sender_device_id;
                                        if (deviceKeys) {
                                                for (auto &[dev, key] : deviceKeys->device_keys) {
                                                        if (key.keys["curve25519:" + dev] ==
                                                            msg.sender_key) {
                                                                sender_device_id = dev;
                                                                break;
                                                        }
                                                }
                                        }

                                        std::map<
                                          mtx::identifiers::User,
                                          std::map<std::string, mtx::events::msg::SecretRequest>>
                                          body;

                                        for (const auto &dev :
                                             verificationStatus->verified_devices) {
                                                if (dev != secretRequest.requesting_device_id &&
                                                    dev != sender_device_id)
                                                        body[local_user][dev] = secretRequest;
                                        }

                                        http::client()
                                          ->send_to_device<mtx::events::msg::SecretRequest>(
                                            http::client()->generate_txn_id(),
                                            body,
                                            [name =
                                               secret_name->second](mtx::http::RequestErr err) {
                                                    if (err) {
                                                            nhlog::net()->error(
                                                              "Failed to send request cancellation "
                                                              "for secrect "
                                                              "'{}'",
                                                              name);
                                                    }
                                            });

                                        nhlog::crypto()->info("Storing secret {}",
                                                              secret_name->second);
                                        cache::client()->storeSecret(secret_name->second,
                                                                     e->content.secret);

                                        request_id_to_secret_name.erase(secret_name);
                                }

                        } else if (auto sec_req =
                                     std::get_if<DeviceEvent<msg::SecretRequest>>(&device_event)) {
                                handle_secret_request(sec_req, msg.sender);
                        }

                        return;
                } else {
                        failed_decryption = true;
                }
        }

        if (failed_decryption) {
                try {
                        std::map<std::string, std::vector<std::string>> targets;
                        for (auto [device_id, key] : otherUserDeviceKeys.device_keys) {
                                if (key.keys.at("curve25519:" + device_id) == msg.sender_key)
                                        targets[msg.sender].push_back(device_id);
                        }

                        send_encrypted_to_device_messages(
                          targets, mtx::events::DeviceEvent<mtx::events::msg::Dummy>{}, true);
                        nhlog::crypto()->info("Recovering from broken olm channel with {}:{}",
                                              msg.sender,
                                              msg.sender_key);
                } catch (std::exception &e) {
                        nhlog::crypto()->error("Failed to recover from broken olm sessions: {}",
                                               e.what());
                }
        }
}

nlohmann::json
handle_pre_key_olm_message(const std::string &sender,
                           const std::string &sender_key,
                           const mtx::events::msg::OlmCipherContent &content)
{
        nhlog::crypto()->info("opening olm session with {}", sender);

        mtx::crypto::OlmSessionPtr inbound_session = nullptr;
        try {
                inbound_session =
                  olm::client()->create_inbound_session_from(sender_key, content.body);

                // We also remove the one time key used to establish that
                // session so we'll have to update our copy of the account object.
                cache::saveOlmAccount(olm::client()->save(cache::client()->pickleSecret()));
        } catch (const mtx::crypto::olm_exception &e) {
                nhlog::crypto()->critical(
                  "failed to create inbound session with {}: {}", sender, e.what());
                return {};
        }

        if (!mtx::crypto::matches_inbound_session_from(
              inbound_session.get(), sender_key, content.body)) {
                nhlog::crypto()->warn("inbound olm session doesn't match sender's key ({})",
                                      sender);
                return {};
        }

        mtx::crypto::BinaryBuf output;
        try {
                output =
                  olm::client()->decrypt_message(inbound_session.get(), content.type, content.body);
        } catch (const mtx::crypto::olm_exception &e) {
                nhlog::crypto()->critical(
                  "failed to decrypt olm message {}: {}", content.body, e.what());
                return {};
        }

        auto plaintext = json::parse(std::string((char *)output.data(), output.size()));
        nhlog::crypto()->debug("decrypted message: \n {}", plaintext.dump(2));

        try {
                nhlog::crypto()->debug("New olm session: {}",
                                       mtx::crypto::session_id(inbound_session.get()));
                cache::saveOlmSession(
                  sender_key, std::move(inbound_session), QDateTime::currentMSecsSinceEpoch());
        } catch (const lmdb::error &e) {
                nhlog::db()->warn(
                  "failed to save inbound olm session from {}: {}", sender, e.what());
        }

        return plaintext;
}

mtx::events::msg::Encrypted
encrypt_group_message(const std::string &room_id, const std::string &device_id, nlohmann::json body)
{
        using namespace mtx::events;
        using namespace mtx::identifiers;

        auto own_user_id = http::client()->user_id().to_string();

        auto members = cache::client()->getMembersWithKeys(
          room_id, UserSettings::instance()->onlyShareKeysWithVerifiedUsers());

        std::map<std::string, std::vector<std::string>> sendSessionTo;
        mtx::crypto::OutboundGroupSessionPtr session = nullptr;
        GroupSessionData group_session_data;

        if (cache::outboundMegolmSessionExists(room_id)) {
                auto res                = cache::getOutboundMegolmSession(room_id);
                auto encryptionSettings = cache::client()->roomEncryptionSettings(room_id);
                mtx::events::state::Encryption defaultSettings;

                // rotate if we crossed the limits for this key
                if (res.data.message_index <
                      encryptionSettings.value_or(defaultSettings).rotation_period_msgs &&
                    (QDateTime::currentMSecsSinceEpoch() - res.data.timestamp) <
                      encryptionSettings.value_or(defaultSettings).rotation_period_ms) {
                        auto member_it             = members.begin();
                        auto session_member_it     = res.data.currently.keys.begin();
                        auto session_member_it_end = res.data.currently.keys.end();

                        while (member_it != members.end() ||
                               session_member_it != session_member_it_end) {
                                if (member_it == members.end()) {
                                        // a member left, purge session!
                                        nhlog::crypto()->debug(
                                          "Rotating megolm session because of left member");
                                        break;
                                }

                                if (session_member_it == session_member_it_end) {
                                        // share with all remaining members
                                        while (member_it != members.end()) {
                                                sendSessionTo[member_it->first] = {};

                                                if (member_it->second)
                                                        for (const auto &dev :
                                                             member_it->second->device_keys)
                                                                if (member_it->first !=
                                                                      own_user_id ||
                                                                    dev.first != device_id)
                                                                        sendSessionTo[member_it
                                                                                        ->first]
                                                                          .push_back(dev.first);

                                                ++member_it;
                                        }

                                        session = std::move(res.session);
                                        break;
                                }

                                if (member_it->first > session_member_it->first) {
                                        // a member left, purge session
                                        nhlog::crypto()->debug(
                                          "Rotating megolm session because of left member");
                                        break;
                                } else if (member_it->first < session_member_it->first) {
                                        // new member, send them the session at this index
                                        sendSessionTo[member_it->first] = {};

                                        if (member_it->second) {
                                                for (const auto &dev :
                                                     member_it->second->device_keys)
                                                        if (member_it->first != own_user_id ||
                                                            dev.first != device_id)
                                                                sendSessionTo[member_it->first]
                                                                  .push_back(dev.first);
                                        }

                                        ++member_it;
                                } else {
                                        // compare devices
                                        bool device_removed = false;
                                        for (const auto &dev :
                                             session_member_it->second.deviceids) {
                                                if (!member_it->second ||
                                                    !member_it->second->device_keys.count(
                                                      dev.first)) {
                                                        device_removed = true;
                                                        break;
                                                }
                                        }

                                        if (device_removed) {
                                                // device removed, rotate session!
                                                nhlog::crypto()->debug(
                                                  "Rotating megolm session because of removed "
                                                  "device of {}",
                                                  member_it->first);
                                                break;
                                        }

                                        // check for new devices to share with
                                        if (member_it->second)
                                                for (const auto &dev :
                                                     member_it->second->device_keys)
                                                        if (!session_member_it->second.deviceids
                                                               .count(dev.first) &&
                                                            (member_it->first != own_user_id ||
                                                             dev.first != device_id))
                                                                sendSessionTo[member_it->first]
                                                                  .push_back(dev.first);

                                        ++member_it;
                                        ++session_member_it;
                                        if (member_it == members.end() &&
                                            session_member_it == session_member_it_end) {
                                                // all devices match or are newly added
                                                session = std::move(res.session);
                                        }
                                }
                        }
                }

                group_session_data = std::move(res.data);
        }

        if (!session) {
                nhlog::ui()->debug("creating new outbound megolm session");

                // Create a new outbound megolm session.
                session                = olm::client()->init_outbound_group_session();
                const auto session_id  = mtx::crypto::session_id(session.get());
                const auto session_key = mtx::crypto::session_key(session.get());

                // Saving the new megolm session.
                GroupSessionData session_data{};
                session_data.message_index              = 0;
                session_data.timestamp                  = QDateTime::currentMSecsSinceEpoch();
                session_data.sender_claimed_ed25519_key = olm::client()->identity_keys().ed25519;

                sendSessionTo.clear();

                for (const auto &[user, devices] : members) {
                        sendSessionTo[user]               = {};
                        session_data.currently.keys[user] = {};
                        if (devices) {
                                for (const auto &[device_id_, key] : devices->device_keys) {
                                        (void)key;
                                        if (device_id != device_id_ || user != own_user_id) {
                                                sendSessionTo[user].push_back(device_id_);
                                                session_data.currently.keys[user]
                                                  .deviceids[device_id_] = 0;
                                        }
                                }
                        }
                }

                {
                        MegolmSessionIndex index;
                        index.room_id    = room_id;
                        index.session_id = session_id;
                        index.sender_key = olm::client()->identity_keys().curve25519;
                        auto megolm_session =
                          olm::client()->init_inbound_group_session(session_key);
                        backup_session_key(index, session_data, megolm_session);
                        cache::saveInboundMegolmSession(
                          index, std::move(megolm_session), session_data);
                }

                cache::saveOutboundMegolmSession(room_id, session_data, session);
                group_session_data = std::move(session_data);
        }

        mtx::events::DeviceEvent<mtx::events::msg::RoomKey> megolm_payload{};
        megolm_payload.content.algorithm   = MEGOLM_ALGO;
        megolm_payload.content.room_id     = room_id;
        megolm_payload.content.session_id  = mtx::crypto::session_id(session.get());
        megolm_payload.content.session_key = mtx::crypto::session_key(session.get());
        megolm_payload.type                = mtx::events::EventType::RoomKey;

        if (!sendSessionTo.empty())
                olm::send_encrypted_to_device_messages(sendSessionTo, megolm_payload);

        // relations shouldn't be encrypted...
        mtx::common::Relations relations = mtx::common::parse_relations(body["content"]);

        auto payload = olm::client()->encrypt_group_message(session.get(), body.dump());

        // Prepare the m.room.encrypted event.
        msg::Encrypted data;
        data.ciphertext = std::string((char *)payload.data(), payload.size());
        data.sender_key = olm::client()->identity_keys().curve25519;
        data.session_id = mtx::crypto::session_id(session.get());
        data.device_id  = device_id;
        data.algorithm  = MEGOLM_ALGO;
        data.relations  = relations;

        group_session_data.message_index = olm_outbound_group_session_message_index(session.get());
        nhlog::crypto()->debug("next message_index {}", group_session_data.message_index);

        // update current set of members for the session with the new members and that message_index
        for (const auto &[user, devices] : sendSessionTo) {
                if (!group_session_data.currently.keys.count(user))
                        group_session_data.currently.keys[user] = {};

                for (const auto &device_id_ : devices) {
                        if (!group_session_data.currently.keys[user].deviceids.count(device_id_))
                                group_session_data.currently.keys[user].deviceids[device_id_] =
                                  group_session_data.message_index;
                }
        }

        // We need to re-pickle the session after we send a message to save the new message_index.
        cache::updateOutboundMegolmSession(room_id, group_session_data, session);

        return data;
}

nlohmann::json
try_olm_decryption(const std::string &sender_key, const mtx::events::msg::OlmCipherContent &msg)
{
        auto session_ids = cache::getOlmSessions(sender_key);

        nhlog::crypto()->info("attempt to decrypt message with {} known session_ids",
                              session_ids.size());

        for (const auto &id : session_ids) {
                auto session = cache::getOlmSession(sender_key, id);

                if (!session) {
                        nhlog::crypto()->warn("Unknown olm session: {}:{}", sender_key, id);
                        continue;
                }

                mtx::crypto::BinaryBuf text;

                try {
                        text = olm::client()->decrypt_message(session->get(), msg.type, msg.body);
                        nhlog::crypto()->debug("Updated olm session: {}",
                                               mtx::crypto::session_id(session->get()));
                        cache::saveOlmSession(
                          id, std::move(session.value()), QDateTime::currentMSecsSinceEpoch());
                } catch (const mtx::crypto::olm_exception &e) {
                        nhlog::crypto()->debug("failed to decrypt olm message ({}, {}) with {}: {}",
                                               msg.type,
                                               sender_key,
                                               id,
                                               e.what());
                        continue;
                } catch (const lmdb::error &e) {
                        nhlog::crypto()->critical("failed to save session: {}", e.what());
                        return {};
                }

                try {
                        return json::parse(std::string_view((char *)text.data(), text.size()));
                } catch (const json::exception &e) {
                        nhlog::crypto()->critical(
                          "failed to parse the decrypted session msg: {} {}",
                          e.what(),
                          std::string_view((char *)text.data(), text.size()));
                }
        }

        return {};
}

void
create_inbound_megolm_session(const mtx::events::DeviceEvent<mtx::events::msg::RoomKey> &roomKey,
                              const std::string &sender_key,
                              const std::string &sender_ed25519)
{
        MegolmSessionIndex index;
        index.room_id    = roomKey.content.room_id;
        index.session_id = roomKey.content.session_id;
        index.sender_key = sender_key;

        try {
                GroupSessionData data{};
                data.forwarding_curve25519_key_chain = {sender_key};
                data.sender_claimed_ed25519_key      = sender_ed25519;

                auto megolm_session =
                  olm::client()->init_inbound_group_session(roomKey.content.session_key);
                backup_session_key(index, data, megolm_session);
                cache::saveInboundMegolmSession(index, std::move(megolm_session), data);
        } catch (const lmdb::error &e) {
                nhlog::crypto()->critical("failed to save inbound megolm session: {}", e.what());
                return;
        } catch (const mtx::crypto::olm_exception &e) {
                nhlog::crypto()->critical("failed to create inbound megolm session: {}", e.what());
                return;
        }

        nhlog::crypto()->info(
          "established inbound megolm session ({}, {})", roomKey.content.room_id, roomKey.sender);

        ChatPage::instance()->receivedSessionKey(index.room_id, index.session_id);
}

void
import_inbound_megolm_session(
  const mtx::events::DeviceEvent<mtx::events::msg::ForwardedRoomKey> &roomKey)
{
        MegolmSessionIndex index;
        index.room_id    = roomKey.content.room_id;
        index.session_id = roomKey.content.session_id;
        index.sender_key = roomKey.content.sender_key;

        try {
                auto megolm_session =
                  olm::client()->import_inbound_group_session(roomKey.content.session_key);

                GroupSessionData data{};
                data.forwarding_curve25519_key_chain =
                  roomKey.content.forwarding_curve25519_key_chain;
                data.sender_claimed_ed25519_key = roomKey.content.sender_claimed_ed25519_key;
                // may have come from online key backup, so we can't trust it...
                data.trusted = false;
                // if we got it forwarded from the sender, assume it is trusted. They may still have
                // used key backup, but it is unlikely.
                if (roomKey.content.forwarding_curve25519_key_chain.size() == 1 &&
                    roomKey.content.forwarding_curve25519_key_chain.back() ==
                      roomKey.content.sender_key) {
                        data.trusted = true;
                }

                backup_session_key(index, data, megolm_session);
                cache::saveInboundMegolmSession(index, std::move(megolm_session), data);
        } catch (const lmdb::error &e) {
                nhlog::crypto()->critical("failed to save inbound megolm session: {}", e.what());
                return;
        } catch (const mtx::crypto::olm_exception &e) {
                nhlog::crypto()->critical("failed to import inbound megolm session: {}", e.what());
                return;
        }

        nhlog::crypto()->info(
          "established inbound megolm session ({}, {})", roomKey.content.room_id, roomKey.sender);

        ChatPage::instance()->receivedSessionKey(index.room_id, index.session_id);
}

void
backup_session_key(const MegolmSessionIndex &idx,
                   const GroupSessionData &data,
                   mtx::crypto::InboundGroupSessionPtr &session)
{
        try {
                if (!UserSettings::instance()->useOnlineKeyBackup()) {
                        // Online key backup disabled
                        return;
                }

                auto backupVersion = cache::client()->backupVersion();
                if (!backupVersion) {
                        // no trusted OKB
                        return;
                }

                using namespace mtx::crypto;

                auto decryptedSecret =
                  cache::secret(mtx::secret_storage::secrets::megolm_backup_v1);
                if (!decryptedSecret) {
                        // no backup key available
                        return;
                }
                auto sessionDecryptionKey = to_binary_buf(base642bin(*decryptedSecret));

                auto public_key =
                  mtx::crypto::CURVE25519_public_key_from_private(sessionDecryptionKey);

                mtx::responses::backup::SessionData sessionData;
                sessionData.algorithm                       = mtx::crypto::MEGOLM_ALGO;
                sessionData.forwarding_curve25519_key_chain = data.forwarding_curve25519_key_chain;
                sessionData.sender_claimed_keys["ed25519"]  = data.sender_claimed_ed25519_key;
                sessionData.sender_key                      = idx.sender_key;
                sessionData.session_key = mtx::crypto::export_session(session.get(), -1);

                auto encrypt_session = mtx::crypto::encrypt_session(sessionData, public_key);

                mtx::responses::backup::SessionBackup bk;
                bk.first_message_index = olm_inbound_group_session_first_known_index(session.get());
                bk.forwarded_count     = data.forwarding_curve25519_key_chain.size();
                bk.is_verified         = false;
                bk.session_data        = std::move(encrypt_session);

                http::client()->put_room_keys(
                  backupVersion->version,
                  idx.room_id,
                  idx.session_id,
                  bk,
                  [idx](mtx::http::RequestErr err) {
                          if (err) {
                                  nhlog::net()->warn(
                                    "failed to backup session key ({}:{}): {} ({})",
                                    idx.room_id,
                                    idx.session_id,
                                    err->matrix_error.error,
                                    static_cast<int>(err->status_code));
                          } else {
                                  nhlog::crypto()->debug(
                                    "backed up session key ({}:{})", idx.room_id, idx.session_id);
                          }
                  });
        } catch (std::exception &e) {
                nhlog::net()->warn("failed to backup session key: {}", e.what());
        }
}

void
mark_keys_as_published()
{
        olm::client()->mark_keys_as_published();
        cache::saveOlmAccount(olm::client()->save(cache::client()->pickleSecret()));
}

void
lookup_keybackup(const std::string room, const std::string session_id)
{
        if (!UserSettings::instance()->useOnlineKeyBackup()) {
                // Online key backup disabled
                return;
        }

        auto backupVersion = cache::client()->backupVersion();
        if (!backupVersion) {
                // no trusted OKB
                return;
        }

        using namespace mtx::crypto;

        auto decryptedSecret = cache::secret(mtx::secret_storage::secrets::megolm_backup_v1);
        if (!decryptedSecret) {
                // no backup key available
                return;
        }
        auto sessionDecryptionKey = to_binary_buf(base642bin(*decryptedSecret));

        http::client()->room_keys(
          backupVersion->version,
          room,
          session_id,
          [room, session_id, sessionDecryptionKey](const mtx::responses::backup::SessionBackup &bk,
                                                   mtx::http::RequestErr err) {
                  if (err) {
                          if (err->status_code != 404)
                                  nhlog::crypto()->error(
                                    "Failed to dowload key {}:{}: {} - {}",
                                    room,
                                    session_id,
                                    mtx::errors::to_string(err->matrix_error.errcode),
                                    err->matrix_error.error);
                          return;
                  }
                  try {
                          auto session = decrypt_session(bk.session_data, sessionDecryptionKey);

                          if (session.algorithm != mtx::crypto::MEGOLM_ALGO)
                                  // don't know this algorithm
                                  return;

                          MegolmSessionIndex index;
                          index.room_id    = room;
                          index.session_id = session_id;
                          index.sender_key = session.sender_key;

                          GroupSessionData data{};
                          data.forwarding_curve25519_key_chain =
                            session.forwarding_curve25519_key_chain;
                          data.sender_claimed_ed25519_key = session.sender_claimed_keys["ed25519"];
                          // online key backup can't be trusted, because anyone can upload to it.
                          data.trusted = false;

                          auto megolm_session =
                            olm::client()->import_inbound_group_session(session.session_key);

                          if (!cache::inboundMegolmSessionExists(index) ||
                              olm_inbound_group_session_first_known_index(megolm_session.get()) <
                                olm_inbound_group_session_first_known_index(
                                  cache::getInboundMegolmSession(index).get())) {
                                  cache::saveInboundMegolmSession(
                                    index, std::move(megolm_session), data);

                                  nhlog::crypto()->info("imported inbound megolm session "
                                                        "from key backup ({}, {})",
                                                        room,
                                                        session_id);

                                  // call on UI thread
                                  QTimer::singleShot(0, ChatPage::instance(), [index] {
                                          ChatPage::instance()->receivedSessionKey(
                                            index.room_id, index.session_id);
                                  });
                          }
                  } catch (const lmdb::error &e) {
                          nhlog::crypto()->critical("failed to save inbound megolm session: {}",
                                                    e.what());
                          return;
                  } catch (const mtx::crypto::olm_exception &e) {
                          nhlog::crypto()->critical("failed to import inbound megolm session: {}",
                                                    e.what());
                          return;
                  }
          });
}

void
send_key_request_for(mtx::events::EncryptedEvent<mtx::events::msg::Encrypted> e,
                     const std::string &request_id,
                     bool cancel)
{
        using namespace mtx::events;

        nhlog::crypto()->debug("sending key request: sender_key {}, session_id {}",
                               e.content.sender_key,
                               e.content.session_id);

        mtx::events::msg::KeyRequest request;
        request.action = cancel ? mtx::events::msg::RequestAction::Cancellation
                                : mtx::events::msg::RequestAction::Request;

        request.algorithm            = MEGOLM_ALGO;
        request.room_id              = e.room_id;
        request.sender_key           = e.content.sender_key;
        request.session_id           = e.content.session_id;
        request.request_id           = request_id;
        request.requesting_device_id = http::client()->device_id();

        nhlog::crypto()->debug("m.room_key_request: {}", json(request).dump(2));

        std::map<mtx::identifiers::User, std::map<std::string, decltype(request)>> body;
        body[mtx::identifiers::parse<mtx::identifiers::User>(e.sender)][e.content.device_id] =
          request;
        body[http::client()->user_id()]["*"] = request;

        http::client()->send_to_device(
          http::client()->generate_txn_id(), body, [e](mtx::http::RequestErr err) {
                  if (err) {
                          nhlog::net()->warn("failed to send "
                                             "send_to_device "
                                             "message: {}",
                                             err->matrix_error.error);
                  }

                  nhlog::net()->info("m.room_key_request sent to {}:{} and your own devices",
                                     e.sender,
                                     e.content.device_id);
          });

        // http::client()->room_keys
}

void
handle_key_request_message(const mtx::events::DeviceEvent<mtx::events::msg::KeyRequest> &req)
{
        if (req.content.algorithm != MEGOLM_ALGO) {
                nhlog::crypto()->debug("ignoring key request {} with invalid algorithm: {}",
                                       req.content.request_id,
                                       req.content.algorithm);
                return;
        }

        // Check if we were the sender of the session being requested (unless it is actually us
        // requesting the session).
        if (req.sender != http::client()->user_id().to_string() &&
            req.content.sender_key != olm::client()->identity_keys().curve25519) {
                nhlog::crypto()->debug(
                  "ignoring key request {} because we did not create the requested session: "
                  "\nrequested({}) ours({})",
                  req.content.request_id,
                  req.content.sender_key,
                  olm::client()->identity_keys().curve25519);
                return;
        }

        // Check that the requested session_id and the one we have saved match.
        MegolmSessionIndex index{};
        index.room_id    = req.content.room_id;
        index.session_id = req.content.session_id;
        index.sender_key = req.content.sender_key;

        // Check if we have the keys for the requested session.
        auto sessionData = cache::getMegolmSessionData(index);
        if (!sessionData) {
                nhlog::crypto()->warn("requested session not found in room: {}",
                                      req.content.room_id);
                return;
        }

        const auto session = cache::getInboundMegolmSession(index);
        if (!session) {
                nhlog::crypto()->warn("No session with id {} in db", req.content.session_id);
                return;
        }

        if (!cache::isRoomMember(req.sender, req.content.room_id)) {
                nhlog::crypto()->warn(
                  "user {} that requested the session key is not member of the room {}",
                  req.sender,
                  req.content.room_id);
                return;
        }

        // check if device is verified
        auto verificationStatus = cache::verificationStatus(req.sender);
        bool verifiedDevice     = false;
        if (verificationStatus &&
            // Share keys, if the option to share with trusted users is enabled or with yourself
            (ChatPage::instance()->userSettings()->shareKeysWithTrustedUsers() ||
             req.sender == http::client()->user_id().to_string())) {
                for (const auto &dev : verificationStatus->verified_devices) {
                        if (dev == req.content.requesting_device_id) {
                                verifiedDevice = true;
                                nhlog::crypto()->debug("Verified device: {}", dev);
                                break;
                        }
                }
        }

        bool shouldSeeKeys    = false;
        uint64_t minimumIndex = -1;
        if (sessionData->currently.keys.count(req.sender)) {
                if (sessionData->currently.keys.at(req.sender)
                      .deviceids.count(req.content.requesting_device_id)) {
                        shouldSeeKeys = true;
                        minimumIndex  = sessionData->currently.keys.at(req.sender)
                                         .deviceids.at(req.content.requesting_device_id);
                }
        }

        if (!verifiedDevice && !shouldSeeKeys) {
                nhlog::crypto()->debug("ignoring key request for room {}", req.content.room_id);
                return;
        }

        if (verifiedDevice) {
                // share the minimum index we have
                minimumIndex = -1;
        }

        try {
                auto session_key = mtx::crypto::export_session(session.get(), minimumIndex);

                //
                // Prepare the m.room_key event.
                //
                mtx::events::msg::ForwardedRoomKey forward_key{};
                forward_key.algorithm   = MEGOLM_ALGO;
                forward_key.room_id     = index.room_id;
                forward_key.session_id  = index.session_id;
                forward_key.session_key = session_key;
                forward_key.sender_key  = index.sender_key;

                // TODO(Nico): Figure out if this is correct
                forward_key.sender_claimed_ed25519_key = sessionData->sender_claimed_ed25519_key;
                forward_key.forwarding_curve25519_key_chain =
                  sessionData->forwarding_curve25519_key_chain;

                send_megolm_key_to_device(
                  req.sender, req.content.requesting_device_id, forward_key);
        } catch (std::exception &e) {
                nhlog::crypto()->error("Failed to forward session key: {}", e.what());
        }
}

void
send_megolm_key_to_device(const std::string &user_id,
                          const std::string &device_id,
                          const mtx::events::msg::ForwardedRoomKey &payload)
{
        mtx::events::DeviceEvent<mtx::events::msg::ForwardedRoomKey> room_key;
        room_key.content = payload;
        room_key.type    = mtx::events::EventType::ForwardedRoomKey;

        std::map<std::string, std::vector<std::string>> targets;
        targets[user_id] = {device_id};
        send_encrypted_to_device_messages(targets, room_key);
        nhlog::crypto()->debug("Forwarded key to {}:{}", user_id, device_id);
}

DecryptionResult
decryptEvent(const MegolmSessionIndex &index,
             const mtx::events::EncryptedEvent<mtx::events::msg::Encrypted> &event,
             bool dont_write_db)
{
        try {
                if (!cache::client()->inboundMegolmSessionExists(index)) {
                        return {DecryptionErrorCode::MissingSession, std::nullopt, std::nullopt};
                }
        } catch (const lmdb::error &e) {
                return {DecryptionErrorCode::DbError, e.what(), std::nullopt};
        }

        // TODO: Lookup index,event_id,origin_server_ts tuple for replay attack errors

        std::string msg_str;
        try {
                auto session = cache::client()->getInboundMegolmSession(index);
                auto sessionData =
                  cache::client()->getMegolmSessionData(index).value_or(GroupSessionData{});

                auto res =
                  olm::client()->decrypt_group_message(session.get(), event.content.ciphertext);
                msg_str = std::string((char *)res.data.data(), res.data.size());

                if (!event.event_id.empty() && event.event_id[0] == '$') {
                        auto oldIdx = sessionData.indices.find(res.message_index);
                        if (oldIdx != sessionData.indices.end()) {
                                if (oldIdx->second != event.event_id)
                                        return {DecryptionErrorCode::ReplayAttack,
                                                std::nullopt,
                                                std::nullopt};
                        } else if (!dont_write_db) {
                                sessionData.indices[res.message_index] = event.event_id;
                                cache::client()->saveInboundMegolmSession(
                                  index, std::move(session), sessionData);
                        }
                }
        } catch (const lmdb::error &e) {
                return {DecryptionErrorCode::DbError, e.what(), std::nullopt};
        } catch (const mtx::crypto::olm_exception &e) {
                if (e.error_code() == mtx::crypto::OlmErrorCode::UNKNOWN_MESSAGE_INDEX)
                        return {DecryptionErrorCode::MissingSessionIndex, e.what(), std::nullopt};
                return {DecryptionErrorCode::DecryptionFailed, e.what(), std::nullopt};
        }

        try {
                // Add missing fields for the event.
                json body                = json::parse(msg_str);
                body["event_id"]         = event.event_id;
                body["sender"]           = event.sender;
                body["origin_server_ts"] = event.origin_server_ts;
                body["unsigned"]         = event.unsigned_data;

                // relations are unencrypted in content...
                mtx::common::add_relations(body["content"], event.content.relations);

                mtx::events::collections::TimelineEvent te;
                mtx::events::collections::from_json(body, te);

                return {DecryptionErrorCode::NoError, std::nullopt, std::move(te.data)};
        } catch (std::exception &e) {
                return {DecryptionErrorCode::ParsingFailed, e.what(), std::nullopt};
        }
}

crypto::Trust
calculate_trust(const std::string &user_id, const MegolmSessionIndex &index)
{
        auto status              = cache::client()->verificationStatus(user_id);
        auto megolmData          = cache::client()->getMegolmSessionData(index);
        crypto::Trust trustlevel = crypto::Trust::Unverified;

        if (megolmData && megolmData->trusted &&
            status.verified_device_keys.count(index.sender_key))
                trustlevel = status.verified_device_keys.at(index.sender_key);

        return trustlevel;
}

//! Send encrypted to device messages, targets is a map from userid to device ids or {} for all
//! devices
void
send_encrypted_to_device_messages(const std::map<std::string, std::vector<std::string>> targets,
                                  const mtx::events::collections::DeviceEvents &event,
                                  bool force_new_session)
{
        static QMap<QPair<std::string, std::string>, qint64> rateLimit;

        nlohmann::json ev_json = std::visit([](const auto &e) { return json(e); }, event);

        std::map<std::string, std::vector<std::string>> keysToQuery;
        mtx::requests::ClaimKeys claims;
        std::map<mtx::identifiers::User, std::map<std::string, mtx::events::msg::OlmEncrypted>>
          messages;
        std::map<std::string, std::map<std::string, DevicePublicKeys>> pks;

        auto our_curve = olm::client()->identity_keys().curve25519;

        for (const auto &[user, devices] : targets) {
                auto deviceKeys = cache::client()->userKeys(user);

                // no keys for user, query them
                if (!deviceKeys) {
                        keysToQuery[user] = devices;
                        continue;
                }

                auto deviceTargets = devices;
                if (devices.empty()) {
                        deviceTargets.clear();
                        for (const auto &[device, keys] : deviceKeys->device_keys) {
                                (void)keys;
                                deviceTargets.push_back(device);
                        }
                }

                for (const auto &device : deviceTargets) {
                        if (!deviceKeys->device_keys.count(device)) {
                                keysToQuery[user] = {};
                                break;
                        }

                        auto d = deviceKeys->device_keys.at(device);

                        if (!d.keys.count("curve25519:" + device) ||
                            !d.keys.count("ed25519:" + device)) {
                                nhlog::crypto()->warn("Skipping device {} since it has no keys!",
                                                      device);
                                continue;
                        }

                        auto device_curve = d.keys.at("curve25519:" + device);
                        if (device_curve == our_curve) {
                                nhlog::crypto()->warn("Skipping our own device, since sending "
                                                      "ourselves olm messages makes no sense.");
                                continue;
                        }

                        auto session = cache::getLatestOlmSession(device_curve);
                        if (!session || force_new_session) {
                                auto currentTime = QDateTime::currentSecsSinceEpoch();
                                if (rateLimit.value(QPair(user, device)) + 60 * 60 * 10 <
                                    currentTime) {
                                        claims.one_time_keys[user][device] =
                                          mtx::crypto::SIGNED_CURVE25519;
                                        pks[user][device].ed25519 = d.keys.at("ed25519:" + device);
                                        pks[user][device].curve25519 =
                                          d.keys.at("curve25519:" + device);

                                        rateLimit.insert(QPair(user, device), currentTime);
                                } else {
                                        nhlog::crypto()->warn("Not creating new session with {}:{} "
                                                              "because of rate limit",
                                                              user,
                                                              device);
                                }
                                continue;
                        }

                        messages[mtx::identifiers::parse<mtx::identifiers::User>(user)][device] =
                          olm::client()
                            ->create_olm_encrypted_content(session->get(),
                                                           ev_json,
                                                           UserId(user),
                                                           d.keys.at("ed25519:" + device),
                                                           device_curve)
                            .get<mtx::events::msg::OlmEncrypted>();

                        try {
                                nhlog::crypto()->debug("Updated olm session: {}",
                                                       mtx::crypto::session_id(session->get()));
                                cache::saveOlmSession(d.keys.at("curve25519:" + device),
                                                      std::move(*session),
                                                      QDateTime::currentMSecsSinceEpoch());
                        } catch (const lmdb::error &e) {
                                nhlog::db()->critical("failed to save outbound olm session: {}",
                                                      e.what());
                        } catch (const mtx::crypto::olm_exception &e) {
                                nhlog::crypto()->critical(
                                  "failed to pickle outbound olm session: {}", e.what());
                        }
                }
        }

        if (!messages.empty())
                http::client()->send_to_device<mtx::events::msg::OlmEncrypted>(
                  http::client()->generate_txn_id(), messages, [](mtx::http::RequestErr err) {
                          if (err) {
                                  nhlog::net()->warn("failed to send "
                                                     "send_to_device "
                                                     "message: {}",
                                                     err->matrix_error.error);
                          }
                  });

        auto BindPks = [ev_json](decltype(pks) pks_temp) {
                return [pks = pks_temp, ev_json](const mtx::responses::ClaimKeys &res,
                                                 mtx::http::RequestErr) {
                        std::map<mtx::identifiers::User,
                                 std::map<std::string, mtx::events::msg::OlmEncrypted>>
                          messages;
                        for (const auto &[user_id, retrieved_devices] : res.one_time_keys) {
                                nhlog::net()->debug("claimed keys for {}", user_id);
                                if (retrieved_devices.size() == 0) {
                                        nhlog::net()->debug(
                                          "no one-time keys found for user_id: {}", user_id);
                                        continue;
                                }

                                for (const auto &rd : retrieved_devices) {
                                        const auto device_id = rd.first;

                                        nhlog::net()->debug(
                                          "{} : \n {}", device_id, rd.second.dump(2));

                                        if (rd.second.empty() ||
                                            !rd.second.begin()->contains("key")) {
                                                nhlog::net()->warn(
                                                  "Skipping device {} as it has no key.",
                                                  device_id);
                                                continue;
                                        }

                                        auto otk = rd.second.begin()->at("key");

                                        auto sign_key = pks.at(user_id).at(device_id).ed25519;
                                        auto id_key   = pks.at(user_id).at(device_id).curve25519;

                                        // Verify signature
                                        {
                                                auto signedKey = *rd.second.begin();
                                                std::string signature =
                                                  signedKey["signatures"][user_id].value(
                                                    "ed25519:" + device_id, "");

                                                if (signature.empty() ||
                                                    !mtx::crypto::ed25519_verify_signature(
                                                      sign_key, signedKey, signature)) {
                                                        nhlog::net()->warn(
                                                          "Skipping device {} as its one time key "
                                                          "has an invalid signature.",
                                                          device_id);
                                                        continue;
                                                }
                                        }

                                        auto session =
                                          olm::client()->create_outbound_session(id_key, otk);

                                        messages[mtx::identifiers::parse<mtx::identifiers::User>(
                                          user_id)][device_id] =
                                          olm::client()
                                            ->create_olm_encrypted_content(session.get(),
                                                                           ev_json,
                                                                           UserId(user_id),
                                                                           sign_key,
                                                                           id_key)
                                            .get<mtx::events::msg::OlmEncrypted>();

                                        try {
                                                nhlog::crypto()->debug(
                                                  "Updated olm session: {}",
                                                  mtx::crypto::session_id(session.get()));
                                                cache::saveOlmSession(
                                                  id_key,
                                                  std::move(session),
                                                  QDateTime::currentMSecsSinceEpoch());
                                        } catch (const lmdb::error &e) {
                                                nhlog::db()->critical(
                                                  "failed to save outbound olm session: {}",
                                                  e.what());
                                        } catch (const mtx::crypto::olm_exception &e) {
                                                nhlog::crypto()->critical(
                                                  "failed to pickle outbound olm session: {}",
                                                  e.what());
                                        }
                                }
                                nhlog::net()->info("send_to_device: {}", user_id);
                        }

                        if (!messages.empty())
                                http::client()->send_to_device<mtx::events::msg::OlmEncrypted>(
                                  http::client()->generate_txn_id(),
                                  messages,
                                  [](mtx::http::RequestErr err) {
                                          if (err) {
                                                  nhlog::net()->warn("failed to send "
                                                                     "send_to_device "
                                                                     "message: {}",
                                                                     err->matrix_error.error);
                                          }
                                  });
                };
        };

        if (!claims.one_time_keys.empty())
                http::client()->claim_keys(claims, BindPks(pks));

        if (!keysToQuery.empty()) {
                mtx::requests::QueryKeys req;
                req.device_keys = keysToQuery;
                http::client()->query_keys(
                  req,
                  [ev_json, BindPks, our_curve](const mtx::responses::QueryKeys &res,
                                                mtx::http::RequestErr err) {
                          if (err) {
                                  nhlog::net()->warn("failed to query device keys: {} {}",
                                                     err->matrix_error.error,
                                                     static_cast<int>(err->status_code));
                                  return;
                          }

                          nhlog::net()->info("queried keys");

                          cache::client()->updateUserKeys(cache::nextBatchToken(), res);

                          mtx::requests::ClaimKeys claim_keys;

                          std::map<std::string, std::map<std::string, DevicePublicKeys>> deviceKeys;

                          for (const auto &user : res.device_keys) {
                                  for (const auto &dev : user.second) {
                                          const auto user_id   = ::UserId(dev.second.user_id);
                                          const auto device_id = DeviceId(dev.second.device_id);

                                          if (user_id.get() ==
                                                http::client()->user_id().to_string() &&
                                              device_id.get() == http::client()->device_id())
                                                  continue;

                                          const auto device_keys = dev.second.keys;
                                          const auto curveKey    = "curve25519:" + device_id.get();
                                          const auto edKey       = "ed25519:" + device_id.get();

                                          if ((device_keys.find(curveKey) == device_keys.end()) ||
                                              (device_keys.find(edKey) == device_keys.end())) {
                                                  nhlog::net()->debug(
                                                    "ignoring malformed keys for device {}",
                                                    device_id.get());
                                                  continue;
                                          }

                                          DevicePublicKeys pks;
                                          pks.ed25519    = device_keys.at(edKey);
                                          pks.curve25519 = device_keys.at(curveKey);

                                          if (pks.curve25519 == our_curve) {
                                                  nhlog::crypto()->warn(
                                                    "Skipping our own device, since sending "
                                                    "ourselves olm messages makes no sense.");
                                                  continue;
                                          }

                                          try {
                                                  if (!mtx::crypto::verify_identity_signature(
                                                        dev.second, device_id, user_id)) {
                                                          nhlog::crypto()->warn(
                                                            "failed to verify identity keys: {}",
                                                            json(dev.second).dump(2));
                                                          continue;
                                                  }
                                          } catch (const json::exception &e) {
                                                  nhlog::crypto()->warn(
                                                    "failed to parse device key json: {}",
                                                    e.what());
                                                  continue;
                                          } catch (const mtx::crypto::olm_exception &e) {
                                                  nhlog::crypto()->warn(
                                                    "failed to verify device key json: {}",
                                                    e.what());
                                                  continue;
                                          }

                                          auto currentTime = QDateTime::currentSecsSinceEpoch();
                                          if (rateLimit.value(QPair(user.first, device_id.get())) +
                                                60 * 60 * 10 <
                                              currentTime) {
                                                  deviceKeys[user_id].emplace(device_id, pks);
                                                  claim_keys.one_time_keys[user.first][device_id] =
                                                    mtx::crypto::SIGNED_CURVE25519;

                                                  rateLimit.insert(
                                                    QPair(user.first, device_id.get()),
                                                    currentTime);
                                          } else {
                                                  nhlog::crypto()->warn(
                                                    "Not creating new session with {}:{} "
                                                    "because of rate limit",
                                                    user.first,
                                                    device_id.get());
                                                  continue;
                                          }

                                          nhlog::net()->info("{}", device_id.get());
                                          nhlog::net()->info("  curve25519 {}", pks.curve25519);
                                          nhlog::net()->info("  ed25519 {}", pks.ed25519);
                                  }
                          }

                          if (!claim_keys.one_time_keys.empty())
                                  http::client()->claim_keys(claim_keys, BindPks(deviceKeys));
                  });
        }
}

void
request_cross_signing_keys()
{
        mtx::events::msg::SecretRequest secretRequest{};
        secretRequest.action               = mtx::events::msg::RequestAction::Request;
        secretRequest.requesting_device_id = http::client()->device_id();

        auto local_user = http::client()->user_id();

        auto verificationStatus = cache::verificationStatus(local_user.to_string());

        if (!verificationStatus)
                return;

        auto request = [&](std::string secretName) {
                secretRequest.name       = secretName;
                secretRequest.request_id = "ss." + http::client()->generate_txn_id();

                request_id_to_secret_name[secretRequest.request_id] = secretRequest.name;

                std::map<mtx::identifiers::User,
                         std::map<std::string, mtx::events::msg::SecretRequest>>
                  body;

                for (const auto &dev : verificationStatus->verified_devices) {
                        if (dev != secretRequest.requesting_device_id)
                                body[local_user][dev] = secretRequest;
                }

                http::client()->send_to_device<mtx::events::msg::SecretRequest>(
                  http::client()->generate_txn_id(),
                  body,
                  [request_id = secretRequest.request_id, secretName](mtx::http::RequestErr err) {
                          if (err) {
                                  nhlog::net()->error("Failed to send request for secrect '{}'",
                                                      secretName);
                                  // Cancel request on UI thread
                                  QTimer::singleShot(1, cache::client(), [request_id]() {
                                          request_id_to_secret_name.erase(request_id);
                                  });
                                  return;
                          }
                  });

                for (const auto &dev : verificationStatus->verified_devices) {
                        if (dev != secretRequest.requesting_device_id)
                                body[local_user][dev].action =
                                  mtx::events::msg::RequestAction::Cancellation;
                }

                // timeout after 15 min
                QTimer::singleShot(15 * 60 * 1000, [secretRequest, body]() {
                        if (request_id_to_secret_name.count(secretRequest.request_id)) {
                                request_id_to_secret_name.erase(secretRequest.request_id);
                                http::client()->send_to_device<mtx::events::msg::SecretRequest>(
                                  http::client()->generate_txn_id(),
                                  body,
                                  [secretRequest](mtx::http::RequestErr err) {
                                          if (err) {
                                                  nhlog::net()->error(
                                                    "Failed to cancel request for secrect '{}'",
                                                    secretRequest.name);
                                                  return;
                                          }
                                  });
                        }
                });
        };

        request(mtx::secret_storage::secrets::cross_signing_self_signing);
        request(mtx::secret_storage::secrets::cross_signing_user_signing);
        request(mtx::secret_storage::secrets::megolm_backup_v1);
}

namespace {
void
unlock_secrets(const std::string &key,
               const std::map<std::string, mtx::secret_storage::AesHmacSha2EncryptedData> &secrets)
{
        http::client()->secret_storage_key(
          key,
          [secrets](mtx::secret_storage::AesHmacSha2KeyDescription keyDesc,
                    mtx::http::RequestErr err) {
                  if (err) {
                          nhlog::net()->error("Failed to download secret storage key");
                          return;
                  }

                  emit ChatPage::instance()->downloadedSecrets(keyDesc, secrets);
          });
}
}

void
download_cross_signing_keys()
{
        using namespace mtx::secret_storage;
        http::client()->secret_storage_secret(
          secrets::megolm_backup_v1, [](Secret secret, mtx::http::RequestErr err) {
                  std::optional<Secret> backup_key;
                  if (!err)
                          backup_key = secret;

                  http::client()->secret_storage_secret(
                    secrets::cross_signing_self_signing,
                    [backup_key](Secret secret, mtx::http::RequestErr err) {
                            std::optional<Secret> self_signing_key;
                            if (!err)
                                    self_signing_key = secret;

                            http::client()->secret_storage_secret(
                              secrets::cross_signing_user_signing,
                              [backup_key, self_signing_key](Secret secret,
                                                             mtx::http::RequestErr err) {
                                      std::optional<Secret> user_signing_key;
                                      if (!err)
                                              user_signing_key = secret;

                                      std::map<std::string,
                                               std::map<std::string, AesHmacSha2EncryptedData>>
                                        secrets;

                                      if (backup_key && !backup_key->encrypted.empty())
                                              secrets[backup_key->encrypted.begin()->first]
                                                     [secrets::megolm_backup_v1] =
                                                       backup_key->encrypted.begin()->second;
                                      if (self_signing_key && !self_signing_key->encrypted.empty())
                                              secrets[self_signing_key->encrypted.begin()->first]
                                                     [secrets::cross_signing_self_signing] =
                                                       self_signing_key->encrypted.begin()->second;
                                      if (user_signing_key && !user_signing_key->encrypted.empty())
                                              secrets[user_signing_key->encrypted.begin()->first]
                                                     [secrets::cross_signing_user_signing] =
                                                       user_signing_key->encrypted.begin()->second;

                                      for (const auto &[key, secrets] : secrets)
                                              unlock_secrets(key, secrets);
                              });
                    });
          });
}

} // namespace olm
