/*
 *    Copyright (c) 2021, The OpenThread Authors.
 *    All rights reserved.
 *
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 *    modification, are permitted provided that the following conditions are met:
 *    1. Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *    3. Neither the name of the copyright holder nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 *    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 *    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 */

/**
 * @file
 *   This file includes implementation of mDNS publisher.
 */

#define OTBR_LOG_TAG "MDNS"

#include "mdns/mdns.hpp"

#include <assert.h>

#include <algorithm>
#include <functional>

#include "common/code_utils.hpp"
#include "utils/dns_utils.hpp"

namespace otbr {

namespace Mdns {

void Publisher::PublishService(const std::string &aHostName,
                               const std::string &aName,
                               const std::string &aType,
                               const SubTypeList &aSubTypeList,
                               uint16_t           aPort,
                               const TxtList &    aTxtList,
                               ResultCallback &&  aCallback)
{
    mServiceRegistrationBeginTime[std::make_pair(aName, aType)] = Clock::now();

    PublishServiceImpl(aHostName, aName, aType, aSubTypeList, aPort, aTxtList, std::move(aCallback));
}

void Publisher::PublishHost(const std::string &aName, const std::vector<uint8_t> &aAddress, ResultCallback &&aCallback)
{
    mHostRegistrationBeginTime[aName] = Clock::now();

    PublishHostImpl(aName, aAddress, std::move(aCallback));
}

void Publisher::OnServiceResolveFailed(const std::string &aType, const std::string &aInstanceName, int32_t aErrorCode)
{
    UpdateMdnsResponseCounters(mTelemetryInfo.mServiceResolutions, DnsErrorToOtbrError(aErrorCode));
    UpdateServiceInstanceResolutionEmaLatency(aInstanceName, aType, DnsErrorToOtbrError(aErrorCode));
    OnServiceResolveFailedImpl(aType, aInstanceName, aErrorCode);
}

void Publisher::OnHostResolveFailed(const std::string &aHostName, int32_t aErrorCode)
{
    UpdateMdnsResponseCounters(mTelemetryInfo.mHostResolutions, DnsErrorToOtbrError(aErrorCode));
    UpdateHostResolutionEmaLatency(aHostName, DnsErrorToOtbrError(aErrorCode));
    OnHostResolveFailedImpl(aHostName, aErrorCode);
}

otbrError Publisher::EncodeTxtData(const TxtList &aTxtList, std::vector<uint8_t> &aTxtData)
{
    otbrError error = OTBR_ERROR_NONE;

    for (const auto &txtEntry : aTxtList)
    {
        const auto & name        = txtEntry.mName;
        const auto & value       = txtEntry.mValue;
        const size_t entryLength = name.length() + 1 + value.size();

        VerifyOrExit(entryLength <= kMaxTextEntrySize, error = OTBR_ERROR_INVALID_ARGS);

        aTxtData.push_back(static_cast<uint8_t>(entryLength));
        aTxtData.insert(aTxtData.end(), name.begin(), name.end());
        aTxtData.push_back('=');
        aTxtData.insert(aTxtData.end(), value.begin(), value.end());
    }

exit:
    return error;
}

otbrError Publisher::DecodeTxtData(Publisher::TxtList &aTxtList, const uint8_t *aTxtData, uint16_t aTxtLength)
{
    otbrError error = OTBR_ERROR_NONE;

    for (uint16_t r = 0; r < aTxtLength;)
    {
        uint16_t entrySize = aTxtData[r];
        uint16_t keyStart  = r + 1;
        uint16_t entryEnd  = keyStart + entrySize;
        uint16_t keyEnd    = keyStart;
        uint16_t valStart;

        while (keyEnd < entryEnd && aTxtData[keyEnd] != '=')
        {
            keyEnd++;
        }

        valStart = keyEnd;
        if (valStart < entryEnd && aTxtData[valStart] == '=')
        {
            valStart++;
        }

        aTxtList.emplace_back(reinterpret_cast<const char *>(&aTxtData[keyStart]), keyEnd - keyStart,
                              &aTxtData[valStart], entryEnd - valStart);

        r += entrySize + 1;
        VerifyOrExit(r <= aTxtLength, error = OTBR_ERROR_PARSE);
    }

exit:
    return error;
}

void Publisher::RemoveSubscriptionCallbacks(uint64_t aSubscriberId)
{
    size_t erased;

    OTBR_UNUSED_VARIABLE(erased);

    assert(aSubscriberId > 0);

    erased = mDiscoveredCallbacks.erase(aSubscriberId);

    assert(erased == 1);
}

uint64_t Publisher::AddSubscriptionCallbacks(Publisher::DiscoveredServiceInstanceCallback aInstanceCallback,
                                             Publisher::DiscoveredHostCallback            aHostCallback)
{
    uint64_t subscriberId = mNextSubscriberId++;

    assert(subscriberId > 0);

    mDiscoveredCallbacks.emplace(subscriberId, std::make_pair(std::move(aInstanceCallback), std::move(aHostCallback)));
    return subscriberId;
}

void Publisher::OnServiceResolved(const std::string &aType, const DiscoveredInstanceInfo &aInstanceInfo)
{
    otbrLogInfo("Service %s is resolved successfully: %s %s host %s addresses %zu", aType.c_str(),
                aInstanceInfo.mRemoved ? "remove" : "add", aInstanceInfo.mName.c_str(), aInstanceInfo.mHostName.c_str(),
                aInstanceInfo.mAddresses.size());

    DnsUtils::CheckServiceNameSanity(aType);

    assert(aInstanceInfo.mNetifIndex > 0);

    if (!aInstanceInfo.mRemoved)
    {
        DnsUtils::CheckHostnameSanity(aInstanceInfo.mHostName);
    }

    UpdateMdnsResponseCounters(mTelemetryInfo.mServiceResolutions, OTBR_ERROR_NONE);
    UpdateServiceInstanceResolutionEmaLatency(aInstanceInfo.mName, aType, OTBR_ERROR_NONE);

    for (const auto &subCallback : mDiscoveredCallbacks)
    {
        if (subCallback.second.first != nullptr)
        {
            subCallback.second.first(aType, aInstanceInfo);
        }
    }
}

void Publisher::OnServiceRemoved(uint32_t aNetifIndex, const std::string &aType, const std::string &aInstanceName)
{
    DiscoveredInstanceInfo instanceInfo;

    otbrLogInfo("Service %s.%s is removed from netif %u.", aInstanceName.c_str(), aType.c_str(), aNetifIndex);

    instanceInfo.mRemoved    = true;
    instanceInfo.mNetifIndex = aNetifIndex;
    instanceInfo.mName       = aInstanceName;

    OnServiceResolved(aType, instanceInfo);
}

void Publisher::OnHostResolved(const std::string &aHostName, const Publisher::DiscoveredHostInfo &aHostInfo)
{
    otbrLogInfo("Host %s is resolved successfully: host %s addresses %zu ttl %u", aHostName.c_str(),
                aHostInfo.mHostName.c_str(), aHostInfo.mAddresses.size(), aHostInfo.mTtl);

    if (!aHostInfo.mHostName.empty())
    {
        DnsUtils::CheckHostnameSanity(aHostInfo.mHostName);
    }

    UpdateMdnsResponseCounters(mTelemetryInfo.mHostResolutions, OTBR_ERROR_NONE);
    UpdateHostResolutionEmaLatency(aHostName, OTBR_ERROR_NONE);

    for (const auto &subCallback : mDiscoveredCallbacks)
    {
        if (subCallback.second.second != nullptr)
        {
            subCallback.second.second(aHostName, aHostInfo);
        }
    }
}

Publisher::SubTypeList Publisher::SortSubTypeList(SubTypeList aSubTypeList)
{
    std::sort(aSubTypeList.begin(), aSubTypeList.end());
    return aSubTypeList;
}

Publisher::TxtList Publisher::SortTxtList(TxtList aTxtList)
{
    std::sort(aTxtList.begin(), aTxtList.end(),
              [](const TxtEntry &aLhs, const TxtEntry &aRhs) { return aLhs.mName < aRhs.mName; });
    return aTxtList;
}

std::string Publisher::MakeFullServiceName(const std::string &aName, const std::string &aType)
{
    return aName + "." + aType + ".local";
}

std::string Publisher::MakeFullHostName(const std::string &aName)
{
    return aName + ".local";
}

void Publisher::AddServiceRegistration(ServiceRegistrationPtr &&aServiceReg)
{
    mServiceRegistrations.emplace(MakeFullServiceName(aServiceReg->mName, aServiceReg->mType), std::move(aServiceReg));
}

void Publisher::RemoveServiceRegistration(const std::string &aName, const std::string &aType, otbrError aError)
{
    auto                   it = mServiceRegistrations.find(MakeFullServiceName(aName, aType));
    ServiceRegistrationPtr serviceReg;

    otbrLogInfo("Removing service %s.%s", aName.c_str(), aType.c_str());
    VerifyOrExit(it != mServiceRegistrations.end());

    // Keep the ServiceRegistration around before calling `Complete`
    // to invoke the callback. This is for avoiding invalid access
    // to the ServiceRegistration when it's freed from the callback.
    serviceReg = std::move(it->second);
    mServiceRegistrations.erase(it);
    serviceReg->Complete(aError);

exit:
    return;
}

Publisher::ServiceRegistration *Publisher::FindServiceRegistration(const std::string &aName, const std::string &aType)
{
    auto it = mServiceRegistrations.find(MakeFullServiceName(aName, aType));

    return it != mServiceRegistrations.end() ? it->second.get() : nullptr;
}

Publisher::ResultCallback Publisher::HandleDuplicateServiceRegistration(const std::string &aHostName,
                                                                        const std::string &aName,
                                                                        const std::string &aType,
                                                                        const SubTypeList &aSubTypeList,
                                                                        uint16_t           aPort,
                                                                        const TxtList &    aTxtList,
                                                                        ResultCallback &&  aCallback)
{
    ServiceRegistration *serviceReg = FindServiceRegistration(aName, aType);

    VerifyOrExit(serviceReg != nullptr);

    if (serviceReg->IsOutdated(aHostName, aName, aType, aSubTypeList, aPort, aTxtList))
    {
        otbrLogInfo("Removing existing service %s.%s: outdated", aName.c_str(), aType.c_str());
        RemoveServiceRegistration(aName, aType, OTBR_ERROR_ABORTED);
    }
    else if (serviceReg->IsCompleted())
    {
        // Returns success if the same service has already been
        // registered with exactly the same parameters.
        std::move(aCallback)(OTBR_ERROR_NONE);
    }
    else
    {
        // If the same service is being registered with the same parameters,
        // let's join the waiting queue for the result.
        serviceReg->mCallback = std::bind(
            [](std::shared_ptr<ResultCallback> aExistingCallback, std::shared_ptr<ResultCallback> aNewCallback,
               otbrError aError) {
                std::move (*aExistingCallback)(aError);
                std::move (*aNewCallback)(aError);
            },
            std::make_shared<ResultCallback>(std::move(serviceReg->mCallback)),
            std::make_shared<ResultCallback>(std::move(aCallback)), std::placeholders::_1);
    }

exit:
    return std::move(aCallback);
}

Publisher::ResultCallback Publisher::HandleDuplicateHostRegistration(const std::string &         aName,
                                                                     const std::vector<uint8_t> &aAddress,
                                                                     ResultCallback &&           aCallback)
{
    HostRegistration *hostReg = FindHostRegistration(aName);

    VerifyOrExit(hostReg != nullptr);

    if (hostReg->IsOutdated(aName, aAddress))
    {
        otbrLogInfo("Removing existing host %s: outdated", aName.c_str());
        RemoveHostRegistration(hostReg->mName, OTBR_ERROR_ABORTED);
    }
    else if (hostReg->IsCompleted())
    {
        // Returns success if the same service has already been
        // registered with exactly the same parameters.
        std::move(aCallback)(OTBR_ERROR_NONE);
    }
    else
    {
        // If the same service is being registered with the same parameters,
        // let's join the waiting queue for the result.
        hostReg->mCallback = std::bind(
            [](std::shared_ptr<ResultCallback> aExistingCallback, std::shared_ptr<ResultCallback> aNewCallback,
               otbrError aError) {
                std::move (*aExistingCallback)(aError);
                std::move (*aNewCallback)(aError);
            },
            std::make_shared<ResultCallback>(std::move(hostReg->mCallback)),
            std::make_shared<ResultCallback>(std::move(aCallback)), std::placeholders::_1);
    }

exit:
    return std::move(aCallback);
}

void Publisher::AddHostRegistration(HostRegistrationPtr &&aHostReg)
{
    mHostRegistrations.emplace(MakeFullHostName(aHostReg->mName), std::move(aHostReg));
}

void Publisher::RemoveHostRegistration(const std::string &aName, otbrError aError)
{
    auto                it = mHostRegistrations.find(MakeFullHostName(aName));
    HostRegistrationPtr hostReg;

    otbrLogInfo("Removing host %s", aName.c_str());
    VerifyOrExit(it != mHostRegistrations.end());

    // Keep the HostRegistration around before calling `Complete`
    // to invoke the callback. This is for avoiding invalid access
    // to the HostRegistration when it's freed from the callback.
    hostReg = std::move(it->second);
    mHostRegistrations.erase(it);
    hostReg->Complete(aError);

exit:
    return;
}

Publisher::HostRegistration *Publisher::FindHostRegistration(const std::string &aName)
{
    auto it = mHostRegistrations.find(MakeFullHostName(aName));

    return it != mHostRegistrations.end() ? it->second.get() : nullptr;
}

Publisher::Registration::~Registration(void)
{
    TriggerCompleteCallback(OTBR_ERROR_ABORTED);
}

bool Publisher::ServiceRegistration::IsOutdated(const std::string &aHostName,
                                                const std::string &aName,
                                                const std::string &aType,
                                                const SubTypeList &aSubTypeList,
                                                uint16_t           aPort,
                                                const TxtList &    aTxtList) const
{
    return !(mHostName == aHostName && mName == aName && mType == aType && mSubTypeList == aSubTypeList &&
             mPort == aPort && mTxtList == aTxtList);
}

void Publisher::ServiceRegistration::Complete(otbrError aError)
{
    OnComplete(aError);
    Registration::TriggerCompleteCallback(aError);
}

void Publisher::ServiceRegistration::OnComplete(otbrError aError)
{
    if (!IsCompleted())
    {
        mPublisher->UpdateMdnsResponseCounters(mPublisher->mTelemetryInfo.mServiceRegistrations, aError);
        mPublisher->UpdateServiceRegistrationEmaLatency(mName, mType, aError);
    }
}

bool Publisher::HostRegistration::IsOutdated(const std::string &aName, const std::vector<uint8_t> &aAddress) const
{
    return !(mName == aName && mAddress == aAddress);
}

void Publisher::HostRegistration::Complete(otbrError aError)
{
    OnComplete(aError);
    Registration::TriggerCompleteCallback(aError);
}

void Publisher::HostRegistration::OnComplete(otbrError aError)
{
    if (!IsCompleted())
    {
        mPublisher->UpdateMdnsResponseCounters(mPublisher->mTelemetryInfo.mHostRegistrations, aError);
        mPublisher->UpdateHostRegistrationEmaLatency(mName, aError);
    }
}

void Publisher::UpdateMdnsResponseCounters(otbr::MdnsResponseCounters &aCounters, otbrError aError)
{
    switch (aError)
    {
    case OTBR_ERROR_NONE:
        ++aCounters.mSuccess;
        break;
    case OTBR_ERROR_NOT_FOUND:
        ++aCounters.mNotFound;
        break;
    case OTBR_ERROR_INVALID_ARGS:
        ++aCounters.mInvalidArgs;
        break;
    case OTBR_ERROR_DUPLICATED:
        ++aCounters.mDuplicated;
        break;
    case OTBR_ERROR_NOT_IMPLEMENTED:
        ++aCounters.mNotImplemented;
        break;
    case OTBR_ERROR_MDNS:
    default:
        ++aCounters.mUnknownError;
        break;
    }
}

void Publisher::UpdateEmaLatency(uint32_t &aEmaLatency, uint32_t aLatency, otbrError aError)
{
    VerifyOrExit(aError != OTBR_ERROR_ABORTED);

    if (!aEmaLatency)
    {
        aEmaLatency = aLatency;
    }
    else
    {
        aEmaLatency =
            (aLatency * MdnsTelemetryInfo::kEmaFactorNumerator +
             aEmaLatency * (MdnsTelemetryInfo::kEmaFactorDenominator - MdnsTelemetryInfo::kEmaFactorNumerator)) /
            MdnsTelemetryInfo::kEmaFactorDenominator;
    }

exit:
    return;
}

void Publisher::UpdateServiceRegistrationEmaLatency(const std::string &aInstanceName,
                                                    const std::string &aType,
                                                    otbrError          aError)
{
    auto it = mServiceRegistrationBeginTime.find(std::make_pair(aInstanceName, aType));

    if (it != mServiceRegistrationBeginTime.end())
    {
        uint32_t latency = std::chrono::duration_cast<Milliseconds>(Clock::now() - it->second).count();
        UpdateEmaLatency(mTelemetryInfo.mServiceRegistrationEmaLatency, latency, aError);
        mServiceRegistrationBeginTime.erase(it);
    }
}

void Publisher::UpdateHostRegistrationEmaLatency(const std::string &aHostName, otbrError aError)
{
    auto it = mHostRegistrationBeginTime.find(aHostName);

    if (it != mHostRegistrationBeginTime.end())
    {
        uint32_t latency = std::chrono::duration_cast<Milliseconds>(Clock::now() - it->second).count();
        UpdateEmaLatency(mTelemetryInfo.mHostRegistrationEmaLatency, latency, aError);
        mHostRegistrationBeginTime.erase(it);
    }
}

void Publisher::UpdateServiceInstanceResolutionEmaLatency(const std::string &aInstanceName,
                                                          const std::string &aType,
                                                          otbrError          aError)
{
    auto it = mServiceInstanceResolutionBeginTime.find(std::make_pair(aInstanceName, aType));

    if (it != mServiceInstanceResolutionBeginTime.end())
    {
        uint32_t latency = std::chrono::duration_cast<Milliseconds>(Clock::now() - it->second).count();
        UpdateEmaLatency(mTelemetryInfo.mServiceResolutionEmaLatency, latency, aError);
        mServiceInstanceResolutionBeginTime.erase(it);
    }
}

void Publisher::UpdateHostResolutionEmaLatency(const std::string &aHostName, otbrError aError)
{
    auto it = mHostResolutionBeginTime.find(aHostName);

    if (it != mHostResolutionBeginTime.end())
    {
        uint32_t latency = std::chrono::duration_cast<Milliseconds>(Clock::now() - it->second).count();
        UpdateEmaLatency(mTelemetryInfo.mHostResolutionEmaLatency, latency, aError);
        mHostResolutionBeginTime.erase(it);
    }
}

} // namespace Mdns

} // namespace otbr