#include "rakp34.hpp"

#include "comm_module.hpp"
#include "endian.hpp"
#include "guid.hpp"
#include "rmcp.hpp"
#include "sessions_manager.hpp"

#include <phosphor-logging/log.hpp>

#include <algorithm>
#include <cstring>

using namespace phosphor::logging;

namespace command
{

void applyIntegrityAlgo(const uint32_t bmcSessionID)
{
    auto session = session::Manager::get().getSession(bmcSessionID);

    auto authAlgo = session->getAuthAlgo();

    switch (authAlgo->intAlgo)
    {
        case cipher::integrity::Algorithms::HMAC_SHA1_96:
        {
            session->setIntegrityAlgo(
                std::make_unique<cipher::integrity::AlgoSHA1>(
                    authAlgo->sessionIntegrityKey));
            break;
        }
        case cipher::integrity::Algorithms::HMAC_SHA256_128:
        {
            session->setIntegrityAlgo(
                std::make_unique<cipher::integrity::AlgoSHA256>(
                    authAlgo->sessionIntegrityKey));
            break;
        }
        default:
            break;
    }
}

void applyCryptAlgo(const uint32_t bmcSessionID)
{
    auto session = session::Manager::get().getSession(bmcSessionID);

    auto authAlgo = session->getAuthAlgo();

    switch (authAlgo->cryptAlgo)
    {
        case cipher::crypt::Algorithms::AES_CBC_128:
        {
            auto intAlgo = session->getIntegrityAlgo();
            auto k2 = intAlgo->generateKn(authAlgo->sessionIntegrityKey,
                                          rmcp::const_2);
            session->setCryptAlgo(
                std::make_unique<cipher::crypt::AlgoAES128>(k2));
            break;
        }
        default:
            break;
    }
}

std::vector<uint8_t> RAKP34(const std::vector<uint8_t>& inPayload,
                            std::shared_ptr<message::Handler>& /* handler */)
{
    std::vector<uint8_t> outPayload(sizeof(RAKP4response));
    auto request = reinterpret_cast<const RAKP3request*>(inPayload.data());
    auto response = reinterpret_cast<RAKP4response*>(outPayload.data());

    // Check if the RAKP3 Payload Length is as expected
    if (inPayload.size() < sizeof(RAKP3request))
    {
        log<level::INFO>("RAKP34: Invalid RAKP3 request");
        response->rmcpStatusCode =
            static_cast<uint8_t>(RAKP_ReturnCode::INVALID_INTEGRITY_VALUE);
        return outPayload;
    }

    // Session ID zero is reserved for Session Setup
    if (endian::from_ipmi(request->managedSystemSessionID) ==
        session::sessionZero)
    {
        log<level::INFO>("RAKP34: BMC invalid Session ID");
        response->rmcpStatusCode =
            static_cast<uint8_t>(RAKP_ReturnCode::INVALID_SESSION_ID);
        return outPayload;
    }

    std::shared_ptr<session::Session> session;
    try
    {
        session =
            session::Manager::get().getSession(request->managedSystemSessionID);
    }
    catch (const std::exception& e)
    {
        log<level::ERR>("RAKP12 : session not found",
                        entry("EXCEPTION=%s", e.what()));
        response->rmcpStatusCode =
            static_cast<uint8_t>(RAKP_ReturnCode::INVALID_SESSION_ID);
        return outPayload;
    }

    session->updateLastTransactionTime();

    auto authAlgo = session->getAuthAlgo();
    /*
     * Key Authentication Code - RAKP 3
     *
     * 1) Managed System Random Number - 16 bytes
     * 2) Remote Console Session ID - 4 bytes
     * 3) Session Privilege Level - 1 byte
     * 4) User Name Length Byte - 1 byte (0 for 'null' username)
     * 5) User Name - variable (absent for 'null' username)
     */

    // Remote Console Session ID
    auto rcSessionID = endian::to_ipmi(session->getRCSessionID());

    // Session Privilege Level
    auto sessPrivLevel = static_cast<uint8_t>(session->reqMaxPrivLevel);

    // User Name Length Byte
    auto userLength = static_cast<uint8_t>(session->userName.size());

    std::vector<uint8_t> input;
    input.resize(cipher::rakp_auth::BMC_RANDOM_NUMBER_LEN +
                 sizeof(rcSessionID) + sizeof(sessPrivLevel) +
                 sizeof(userLength) + userLength);

    auto iter = input.begin();

    // Managed System Random Number
    std::copy(authAlgo->bmcRandomNum.begin(), authAlgo->bmcRandomNum.end(),
              iter);
    std::advance(iter, cipher::rakp_auth::BMC_RANDOM_NUMBER_LEN);

    // Remote Console Session ID
    std::copy_n(reinterpret_cast<uint8_t*>(&rcSessionID), sizeof(rcSessionID),
                iter);
    std::advance(iter, sizeof(rcSessionID));

    // Session Privilege Level
    std::copy_n(reinterpret_cast<uint8_t*>(&sessPrivLevel),
                sizeof(sessPrivLevel), iter);
    std::advance(iter, sizeof(sessPrivLevel));

    // User Name Length Byte
    std::copy_n(&userLength, sizeof(userLength), iter);
    std::advance(iter, sizeof(userLength));

    std::copy_n(session->userName.data(), userLength, iter);

    // Generate Key Exchange Authentication Code - RAKP2
    auto output = authAlgo->generateHMAC(input);

    if (inPayload.size() != (sizeof(RAKP3request) + output.size()) ||
        std::memcmp(output.data(), request + 1, output.size()))
    {
        log<level::INFO>("Mismatch in HMAC sent by remote console");

        response->messageTag = request->messageTag;
        response->rmcpStatusCode =
            static_cast<uint8_t>(RAKP_ReturnCode::INVALID_INTEGRITY_VALUE);
        response->reserved = 0;
        response->remoteConsoleSessionID = rcSessionID;

        // close the session
        session::Manager::get().stopSession(session->getBMCSessionID());

        return outPayload;
    }

    /*
     * Session Integrity Key
     *
     * 1) Remote Console Random Number - 16 bytes
     * 2) Managed System Random Number - 16 bytes
     * 3) Session Privilege Level - 1 byte
     * 4) User Name Length Byte - 1 byte (0 for 'null' username)
     * 5) User Name - variable (absent for 'null' username)
     */

    input.clear();

    input.resize(cipher::rakp_auth::REMOTE_CONSOLE_RANDOM_NUMBER_LEN +
                 cipher::rakp_auth::BMC_RANDOM_NUMBER_LEN +
                 sizeof(sessPrivLevel) + sizeof(userLength) + userLength);
    iter = input.begin();

    // Remote Console Random Number
    std::copy(authAlgo->rcRandomNum.begin(), authAlgo->rcRandomNum.end(), iter);
    std::advance(iter, cipher::rakp_auth::REMOTE_CONSOLE_RANDOM_NUMBER_LEN);

    // Managed Console Random Number
    std::copy(authAlgo->bmcRandomNum.begin(), authAlgo->bmcRandomNum.end(),
              iter);
    std::advance(iter, cipher::rakp_auth::BMC_RANDOM_NUMBER_LEN);

    // Session Privilege Level
    std::copy_n(reinterpret_cast<uint8_t*>(&sessPrivLevel),
                sizeof(sessPrivLevel), iter);
    std::advance(iter, sizeof(sessPrivLevel));

    // User Name Length Byte
    std::copy_n(&userLength, sizeof(userLength), iter);
    std::advance(iter, sizeof(userLength));

    std::copy_n(session->userName.data(), userLength, iter);

    // Generate Session Integrity Key
    auto sikOutput = authAlgo->generateHMAC(input);

    // Update the SIK in the Authentication Algo Interface
    authAlgo->sessionIntegrityKey.insert(authAlgo->sessionIntegrityKey.begin(),
                                         sikOutput.begin(), sikOutput.end());

    /*
     * Integrity Check Value
     *
     * 1) Remote Console Random Number - 16 bytes
     * 2) Managed System Session ID - 4 bytes
     * 3) Managed System GUID - 16 bytes
     */

    // Get Managed System Session ID
    auto bmcSessionID = endian::to_ipmi(session->getBMCSessionID());

    input.clear();

    input.resize(cipher::rakp_auth::REMOTE_CONSOLE_RANDOM_NUMBER_LEN +
                 sizeof(bmcSessionID) + BMC_GUID_LEN);
    iter = input.begin();

    // Remote Console Random Number
    std::copy(authAlgo->rcRandomNum.begin(), authAlgo->rcRandomNum.end(), iter);
    std::advance(iter, cipher::rakp_auth::REMOTE_CONSOLE_RANDOM_NUMBER_LEN);

    // Managed System Session ID
    std::copy_n(reinterpret_cast<uint8_t*>(&bmcSessionID), sizeof(bmcSessionID),
                iter);
    std::advance(iter, sizeof(bmcSessionID));

    // Managed System GUID
    std::copy_n(cache::guid.data(), cache::guid.size(), iter);

    // Integrity Check Value
    auto icv = authAlgo->generateICV(input);

    outPayload.resize(sizeof(RAKP4response));

    response->messageTag = request->messageTag;
    response->rmcpStatusCode = static_cast<uint8_t>(RAKP_ReturnCode::NO_ERROR);
    response->reserved = 0;
    response->remoteConsoleSessionID = rcSessionID;

    // Insert the HMAC output into the payload
    outPayload.insert(outPayload.end(), icv.begin(), icv.end());

    // Set the Integrity Algorithm
    applyIntegrityAlgo(session->getBMCSessionID());

    // Set the Confidentiality Algorithm
    applyCryptAlgo(session->getBMCSessionID());

    session->state(static_cast<uint8_t>(session::State::active));
    return outPayload;
}

} // namespace command