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

#pragma once

#include <QObject>

#include <mtx/responses/crypto.hpp>
#include <nlohmann/json.hpp>

#include "CacheCryptoStructs.h"
#include "Logging.h"
#include "MatrixClient.h"
#include "Olm.h"
#include "timeline/TimelineModel.h"

class QTimer;

using sas_ptr = std::unique_ptr<mtx::crypto::SAS>;

// clang-format off
/*
 * Stolen from fluffy chat :D
 *
 *      State         |   +-------------+                    +-----------+                                  |
 *                    |   | AliceDevice |                    | BobDevice |                                  |
 *                    |   | (sender)    |                    |           |                                  |
 *                    |   +-------------+                    +-----------+                                  |
 * promptStartVerify  |         |                                 |                                         |
 *                    |      o  | (m.key.verification.request)    |                                         |
 *                    |      p  |-------------------------------->| (ASK FOR VERIFICATION REQUEST)          |
 * waitForOtherAccept |      t  |                                 |                                         | promptStartVerify
 * &&                 |      i  |      (m.key.verification.ready) |                                         |
 * no commitment      |      o  |<--------------------------------|                                         |
 * &&                 |      n  |                                 |                                         |
 * no canonical_json  |      a  |      (m.key.verification.start) |                                         | waitingForKeys
 *                    |      l  |<--------------------------------| Not sending to prevent the glare resolve| && no commitment
 *                    |         |                                 |                                         | && no canonical_json
 *                    |         | m.key.verification.start        |                                         |
 * waitForOtherAccept |         |-------------------------------->| (IF NOT ALREADY ASKED,                  |
 * &&                 |         |                                 |  ASK FOR VERIFICATION REQUEST)          | promptStartVerify, if not accepted
 * canonical_json     |         |       m.key.verification.accept |                                         |
 *                    |         |<--------------------------------|                                         |
 * waitForOtherAccept |         |                                 |                                         | waitingForKeys
 * &&                 |         | m.key.verification.key          |                                         | && canonical_json
 * commitment         |         |-------------------------------->|                                         | && commitment
 *                    |         |                                 |                                         |
 *                    |         |          m.key.verification.key |                                         |
 *                    |         |<--------------------------------|                                         |
 * compareEmoji/Number|         |                                 |                                         | compareEmoji/Number
 *                    |         |     COMPARE EMOJI / NUMBERS     |                                         |
 *                    |         |                                 |                                         |
 * waitingForMac      |         |     m.key.verification.mac      |                                         | waitingForMac
 *                    | success |<------------------------------->|  success                                |
 *                    |         |                                 |                                         |
 * success/fail       |         |         m.key.verification.done |                                         | success/fail
 *                    |         |<------------------------------->|                                         |
 */
// clang-format on
class DeviceVerificationFlow : public QObject
{
        Q_OBJECT
        Q_PROPERTY(QString state READ state NOTIFY stateChanged)
        Q_PROPERTY(Error error READ error NOTIFY errorChanged)
        Q_PROPERTY(QString userId READ getUserId CONSTANT)
        Q_PROPERTY(QString deviceId READ getDeviceId CONSTANT)
        Q_PROPERTY(bool sender READ getSender CONSTANT)
        Q_PROPERTY(std::vector<int> sasList READ getSasList CONSTANT)
        Q_PROPERTY(bool isDeviceVerification READ isDeviceVerification CONSTANT)
        Q_PROPERTY(bool isSelfVerification READ isSelfVerification CONSTANT)

public:
        enum State
        {
                PromptStartVerification,
                WaitingForOtherToAccept,
                WaitingForKeys,
                CompareEmoji,
                CompareNumber,
                WaitingForMac,
                Success,
                Failed,
        };
        Q_ENUM(State)

        enum Type
        {
                ToDevice,
                RoomMsg
        };

        enum Error
        {
                UnknownMethod,
                MismatchedCommitment,
                MismatchedSAS,
                KeyMismatch,
                Timeout,
                User,
                OutOfOrder,
        };
        Q_ENUM(Error)

        static QSharedPointer<DeviceVerificationFlow> NewInRoomVerification(
          QObject *parent_,
          TimelineModel *timelineModel_,
          const mtx::events::msg::KeyVerificationRequest &msg,
          QString other_user_,
          QString event_id_);
        static QSharedPointer<DeviceVerificationFlow> NewToDeviceVerification(
          QObject *parent_,
          const mtx::events::msg::KeyVerificationRequest &msg,
          QString other_user_,
          QString txn_id_);
        static QSharedPointer<DeviceVerificationFlow> NewToDeviceVerification(
          QObject *parent_,
          const mtx::events::msg::KeyVerificationStart &msg,
          QString other_user_,
          QString txn_id_);
        static QSharedPointer<DeviceVerificationFlow>
        InitiateUserVerification(QObject *parent_, TimelineModel *timelineModel_, QString userid);
        static QSharedPointer<DeviceVerificationFlow> InitiateDeviceVerification(QObject *parent,
                                                                                 QString userid,
                                                                                 QString device);

        // getters
        QString state();
        Error error() { return error_; }
        QString getUserId();
        QString getDeviceId();
        bool getSender();
        std::vector<int> getSasList();
        QString transactionId() { return QString::fromStdString(this->transaction_id); }
        // setters
        void setDeviceId(QString deviceID);
        void setEventId(std::string event_id);
        bool isDeviceVerification() const
        {
                return this->type == DeviceVerificationFlow::Type::ToDevice;
        }
        bool isSelfVerification() const;

        void callback_fn(const UserKeyCache &res, mtx::http::RequestErr err, std::string user_id);

public slots:
        //! unverifies a device
        void unverify();
        //! Continues the flow
        void next();
        //! Cancel the flow
        void cancel() { cancelVerification(User); }

signals:
        void refreshProfile();
        void stateChanged();
        void errorChanged();

private:
        DeviceVerificationFlow(QObject *,
                               DeviceVerificationFlow::Type flow_type,
                               TimelineModel *model,
                               QString userID,
                               QString deviceId_);
        void setState(State state)
        {
                if (state != state_) {
                        state_ = state;
                        emit stateChanged();
                }
        }

        void handleStartMessage(const mtx::events::msg::KeyVerificationStart &msg, std::string);
        //! sends a verification request
        void sendVerificationRequest();
        //! accepts a verification request
        void sendVerificationReady();
        //! completes the verification flow();
        void sendVerificationDone();
        //! accepts a verification
        void acceptVerificationRequest();
        //! starts the verification flow
        void startVerificationRequest();
        //! cancels a verification flow
        void cancelVerification(DeviceVerificationFlow::Error error_code);
        //! sends the verification key
        void sendVerificationKey();
        //! sends the mac of the keys
        void sendVerificationMac();
        //! Completes the verification flow
        void acceptDevice();

        std::string transaction_id;

        bool sender;
        Type type;
        mtx::identifiers::User toClient;
        QString deviceId;

        // public part of our master key, when trusted or empty
        std::string our_trusted_master_key;

        mtx::events::msg::SASMethods method = mtx::events::msg::SASMethods::Emoji;
        QTimer *timeout                     = nullptr;
        sas_ptr sas;
        std::string mac_method;
        std::string commitment;
        nlohmann::json canonical_json;

        std::vector<int> sasList;
        UserKeyCache their_keys;
        TimelineModel *model_;
        mtx::common::Relation relation;

        State state_ = PromptStartVerification;
        Error error_ = UnknownMethod;

        bool isMacVerified = false;

        template<typename T>
        void send(T msg)
        {
                if (this->type == DeviceVerificationFlow::Type::ToDevice) {
                        mtx::requests::ToDeviceMessages<T> body;
                        msg.transaction_id                           = this->transaction_id;
                        body[this->toClient][deviceId.toStdString()] = msg;

                        http::client()->send_to_device<T>(
                          this->transaction_id, body, [](mtx::http::RequestErr err) {
                                  if (err)
                                          nhlog::net()->warn(
                                            "failed to send verification to_device message: {} {}",
                                            err->matrix_error.error,
                                            static_cast<int>(err->status_code));
                          });
                } else if (this->type == DeviceVerificationFlow::Type::RoomMsg && model_) {
                        if constexpr (!std::is_same_v<T,
                                                      mtx::events::msg::KeyVerificationRequest>) {
                                msg.relations.relations.push_back(this->relation);
                                // Set synthesized to surpress the nheko relation extensions
                                msg.relations.synthesized = true;
                        }
                        (model_)->sendMessageEvent(msg, mtx::events::to_device_content_to_type<T>);
                }

                nhlog::net()->debug(
                  "Sent verification step: {} in state: {}",
                  mtx::events::to_string(mtx::events::to_device_content_to_type<T>),
                  state().toStdString());
        }
};