#include "../pchheader.hpp"
#include "../jsonschema/usrmsg_helpers.hpp"
#include "../comm/comm_server.hpp"
#include "../comm/comm_session.hpp"
#include "../util.hpp"
#include "../conf.hpp"
#include "../crypto.hpp"
#include "../hplog.hpp"
#include "usr.hpp"
#include "user_session_handler.hpp"
#include "user_input.hpp"

namespace jusrmsg = jsonschema::usrmsg;

namespace usr
{

    // Holds global connected-users and related objects.
    connected_context ctx;

    bool init_success = false;

    /**
 * Initializes the usr subsystem. Must be called once during application startup.
 * @return 0 for successful initialization. -1 for failure.
 */
    int init()
    {
        // Start listening for incoming user connections.
        if (start_listening() == -1)
            return -1;

        init_success = true;
        return 0;
    }

    /**
 * Cleanup any running processes.
 */
    void deinit()
    {
        if (init_success)
            ctx.listener.stop();
    }

    /**
 * Starts listening for incoming user websocket connections.
 */
    int start_listening()
    {
        const uint64_t metric_thresholds[] = {conf::cfg.pubmaxcpm, 0, 0, conf::cfg.pubmaxbadmpm};
        if (ctx.listener.start(
                conf::cfg.pubport, ".sock-user", comm::SESSION_TYPE::USER, true, true, metric_thresholds, std::set<conf::ip_port_pair>(), conf::cfg.pubmaxsize) == -1)
            return -1;

        LOG_INFO << "Started listening for user connections on " << std::to_string(conf::cfg.pubport);
        return 0;
    }

    /**
 * Verifies the given message for a previously issued user challenge.
 * @param message Challenge response.
 * @param session The socket session that received the response.
 * @return 0 for successful verification. -1 for failure.
 */
    int verify_challenge(std::string_view message, comm::comm_session &session)
    {
        // The received message must be the challenge response. We need to verify it.
        if (session.issued_challenge.empty())
        {
            LOG_DBG << "No challenge found for the session " << session.uniqueid;
            return -1;
        }

        std::string userpubkeyhex;
        std::string_view original_challenge = session.issued_challenge;
        if (jusrmsg::verify_user_challenge_response(userpubkeyhex, message, original_challenge) == 0)
        {
            // Challenge signature verification successful.

            // Decode hex pubkey and get binary pubkey. We are only going to keep
            // the binary pubkey due to reduced memory footprint.
            std::string userpubkey;
            userpubkey.resize(userpubkeyhex.length() / 2);
            util::hex2bin(
                reinterpret_cast<unsigned char *>(userpubkey.data()),
                userpubkey.length(),
                userpubkeyhex);

            // Now check whether this user public key is a duplicate.
            if (ctx.sessionids.count(userpubkey) == 0)
            {
                // All good. Unique public key.
                // Promote the connection from pending-challenges to authenticated users.

                session.challenge_status = comm::CHALLENGE_VERIFIED; // Set as challenge verified
                add_user(session, userpubkey);                       // Add the user to the global authed user list
                session.issued_challenge.clear();                    // Remove the stored challenge

                LOG_DBG << "User connection " << session.uniqueid << " authenticated. Public key "
                        << userpubkeyhex;
                return 0;
            }
            else
            {
                LOG_DBG << "Duplicate user public key " << session.uniqueid;
            }
        }
        else
        {
            LOG_DBG << "Challenge verification failed " << session.uniqueid;
        }

        return -1;
    }

    /**
 * Processes a message sent by a connected user. This will be invoked by web socket on_message handler.
 * @param user The authenticated user who sent the message.
 * @param message The message sent by user.
 * @return 0 on successful processing. -1 for failure.
 */
    int handle_user_message(connected_user &user, std::string_view message)
    {
        rapidjson::Document d;
        const char *msg_type = jusrmsg::MSGTYPE_UNKNOWN;

        if (jusrmsg::parse_user_message(d, message) == 0)
        {
            const char *msg_type = d[jusrmsg::FLD_TYPE].GetString();

            // Message is a contract input message.
            if (d[jusrmsg::FLD_TYPE] == jusrmsg::MSGTYPE_CONTRACT_INPUT)
            {
                std::string contentjson;
                std::string sig;
                if (jusrmsg::extract_signed_input_container(contentjson, sig, d) == 0)
                {
                    std::lock_guard<std::mutex> lock(ctx.users_mutex);

                    //Add to the submitted input list.
                    user.submitted_inputs.push_back(user_submitted_message(
                        std::move(contentjson),
                        std::move(sig)));
                    return 0;
                }
                else
                {
                    send_request_status_result(user.session, jusrmsg::STATUS_REJECTED, jusrmsg::REASON_BAD_SIG, msg_type, jusrmsg::origin_data_for_contract_input(sig));
                    return -1;
                }
            }
            else if (d[jusrmsg::FLD_TYPE] == jusrmsg::MSGTYPE_STAT)
            {
                std::string msg;
                jusrmsg::create_status_response(msg);
                user.session.send(msg);
                return 0;
            }
            else
            {
                LOG_DBG << "Invalid user message type: " << msg_type;
                send_request_status_result(user.session, jusrmsg::STATUS_REJECTED, jusrmsg::REASON_INVALID_MSG_TYPE, msg_type, "");
                return -1;
            }
        }
        else
        {
            // Bad message.
            send_request_status_result(user.session, jusrmsg::STATUS_REJECTED, jusrmsg::REASON_BAD_MSG_FORMAT, msg_type, "");
            return -1;
        }
    }

    /**
 * Send the specified status result via the provided session.
 */
    void send_request_status_result(const comm::comm_session &session, std::string_view status, std::string_view reason, std::string_view origin_type, std::string_view origin_extra_data)
    {
        std::string msg;
        jusrmsg::create_request_status_result(msg, status, reason, origin_type, origin_extra_data);
        session.send(msg);
    }

    /**
 * Adds the user denoted by specified session id and public key to the global authed user list.
 * This should get called after the challenge handshake is verified.
 * 
 * @param session User socket session.
 * @param pubkey User's binary public key.
 * @return 0 on successful additions. -1 on failure.
 */
    int add_user(const comm::comm_session &session, const std::string &pubkey)
    {
        const std::string &sessionid = session.uniqueid;
        if (ctx.users.count(sessionid) == 1)
        {
            LOG_INFO << sessionid << " already exist. Cannot add user.";
            return -1;
        }

        {
            std::lock_guard<std::mutex> lock(ctx.users_mutex);
            ctx.users.emplace(sessionid, usr::connected_user(session, pubkey));
        }

        // Populate sessionid map so we can lookup by user pubkey.
        ctx.sessionids.try_emplace(pubkey, sessionid);

        return 0;
    }

    /**
 * Removes the specified public key from the global user list.
 * This must get called when a user disconnects from HP.
 * 
 * @param sessionid User socket session id.
 * @return 0 on successful removals. -1 on failure.
 */
    int remove_user(const std::string &sessionid)
    {
        const auto itr = ctx.users.find(sessionid);

        if (itr == ctx.users.end())
        {
            LOG_INFO << sessionid << " does not exist. Cannot remove user.";
            return -1;
        }

        usr::connected_user &user = itr->second;

        {
            std::lock_guard<std::mutex> lock(ctx.users_mutex);
            ctx.sessionids.erase(user.pubkey);
        }

        ctx.users.erase(itr);
        return 0;
    }

    /**
 * Finds and returns the socket session for the proided user pubkey.
 * @param pubkey User binary pubkey.
 * @return Pointer to the socket session. NULL of not found.
 */
    const comm::comm_session *get_session_by_pubkey(const std::string &pubkey)
    {
        const auto sessionid_itr = ctx.sessionids.find(pubkey);
        if (sessionid_itr != ctx.sessionids.end())
        {
            const auto user_itr = ctx.users.find(sessionid_itr->second);
            if (user_itr != ctx.users.end())
                return &user_itr->second.session;
        }

        return NULL;
    }

} // namespace usr