//
// Copyright (c) 2013-2021 John
//
// SPDX-License-Identifier: MIT
//

#include <srs_app_rtc_queue.hpp>

#include <string.h>
#include <unistd.h>
#include <sstream>

using namespace std;

#include <srs_kernel_error.hpp>
#include <srs_kernel_rtc_rtp.hpp>
#include <srs_kernel_utility.hpp>
#include <srs_app_utility.hpp>
#include <srs_app_threads.hpp>

#include <srs_protocol_kbps.hpp>

extern SrsPps* _srs_pps_snack3;
extern SrsPps* _srs_pps_snack4;

SrsRtpRingBuffer::SrsRtpRingBuffer(int capacity)
{
    nn_seq_flip_backs = 0;
    begin = end = 0;
    capacity_ = (uint16_t)capacity;
    initialized_ = false;

    queue_ = new SrsRtpPacket*[capacity_];
    memset(queue_, 0, sizeof(SrsRtpPacket*) * capacity);
}

SrsRtpRingBuffer::~SrsRtpRingBuffer()
{
    for (int i = 0; i < capacity_; ++i) {
        SrsRtpPacket* pkt = queue_[i];
        srs_freep(pkt);
    }
    srs_freepa(queue_);
}

bool SrsRtpRingBuffer::empty()
{
    return begin == end;
}

int SrsRtpRingBuffer::size()
{
    int size = srs_rtp_seq_distance(begin, end);
    srs_assert(size >= 0);
    return size;
}

void SrsRtpRingBuffer::advance_to(uint16_t seq)
{
    begin = seq;
}

void SrsRtpRingBuffer::set(uint16_t at, SrsRtpPacket* pkt)
{
    SrsRtpPacket* p = queue_[at % capacity_];
    srs_freep(p);

    queue_[at % capacity_] = pkt;
}

void SrsRtpRingBuffer::remove(uint16_t at)
{
    set(at, NULL);
}

uint32_t SrsRtpRingBuffer::get_extended_highest_sequence()
{
    return nn_seq_flip_backs * 65536 + end - 1;
}

bool SrsRtpRingBuffer::update(uint16_t seq, uint16_t& nack_first, uint16_t& nack_last)
{
    if (!initialized_) {
        initialized_ = true;
        begin = seq;
        end = seq + 1;
        return true;
    }

    // Normal sequence, seq follows high_.
    if (srs_rtp_seq_distance(end, seq) >= 0) {
        //TODO: FIXME: if diff_upper > limit_max_size clear?
        // int16_t diff_upper = srs_rtp_seq_distance(end, seq)
        // notify_nack_list_full()
        nack_first = end;
        nack_last = seq;

        // When distance(seq,high_)>0 and seq<high_, seq must flip back,
        // for example, high_=65535, seq=1, distance(65535,1)>0 and 1<65535.
        // TODO: FIXME: The first flip may be dropped.
        if (seq < end) {
            ++nn_seq_flip_backs;
        }
        end = seq + 1;
        // TODO: FIXME: check whether is neccessary?
        // srs_rtp_seq_distance(begin, end) > max_size
        // advance_to(), srs_rtp_seq_distance(begin, end) < max_size;
        return true;
    }

    // Out-of-order sequence, seq before low_.
    if (srs_rtp_seq_distance(seq, begin) > 0) {
        nack_first = seq;
        nack_last = begin;
        begin = seq;

        // TODO: FIXME: Maybe should support startup drop.
        return true;
        // When startup, we may receive packets in chaos order.
        // Because we don't know the ISN(initiazlie sequence number), the first packet
        // we received maybe no the first packet client sent.
        // @remark We only log a warning, because it seems ok for publisher.
        //return false;
    }

    return true;
}

SrsRtpPacket* SrsRtpRingBuffer::at(uint16_t seq) {
    return queue_[seq % capacity_];
}

void SrsRtpRingBuffer::notify_nack_list_full()
{
    clear_all_histroy();

    begin = end = 0;
    initialized_ = false;
}

void SrsRtpRingBuffer::notify_drop_seq(uint16_t seq)
{
    remove(seq);
    advance_to(seq+1);
}

void SrsRtpRingBuffer::clear_histroy(uint16_t seq)
{
    // TODO FIXME Did not consider loopback
    for (uint16_t i = 0; i < capacity_; i++) {
        SrsRtpPacket* p = queue_[i];
        if (p && p->header.get_sequence() < seq) {
            srs_freep(p);
            queue_[i] = NULL;
        }
    }
}

void SrsRtpRingBuffer::clear_all_histroy()
{
    for (uint16_t i = 0; i < capacity_; i++) {
        SrsRtpPacket* p = queue_[i];
        if (p) {
            srs_freep(p);
            queue_[i] = NULL;
        }
    }
}

SrsNackOption::SrsNackOption()
{
    max_count = 15;
    max_alive_time = 1000 * SRS_UTIME_MILLISECONDS;
    first_nack_interval = 10 * SRS_UTIME_MILLISECONDS;
    nack_interval = 50 * SRS_UTIME_MILLISECONDS;
    max_nack_interval = 500 * SRS_UTIME_MILLISECONDS;
    min_nack_interval = 20 * SRS_UTIME_MILLISECONDS;

    nack_check_interval = 20 * SRS_UTIME_MILLISECONDS;

    //TODO: FIXME: audio and video using diff nack strategy
    // video:
    // max_alive_time = 1 * SRS_UTIME_SECONDS
    // max_count = 15;
    // nack_interval = 50 * SRS_UTIME_MILLISECONDS
    // 
    // audio:
    // DefaultRequestNackDelay = 30; //ms
    // DefaultLostPacketLifeTime = 600; //ms
    // FirstRequestInterval = 50;//ms
}

SrsRtpNackInfo::SrsRtpNackInfo()
{
    generate_time_ = srs_update_system_time();
    pre_req_nack_time_ = 0;
    req_nack_count_ = 0;
}

SrsRtpNackForReceiver::SrsRtpNackForReceiver(SrsRtpRingBuffer* rtp, size_t queue_size)
{
    max_queue_size_ = queue_size;
    rtp_ = rtp;
    pre_check_time_ = 0;
    rtt_ = 0;

    srs_info("max_queue_size=%u, nack opt: max_count=%d, max_alive_time=%us, first_nack_interval=%" PRId64 ", nack_interval=%" PRId64,
        max_queue_size_, opts_.max_count, opts_.max_alive_time, opts_.first_nack_interval, opts_.nack_interval);
}

SrsRtpNackForReceiver::~SrsRtpNackForReceiver()
{
}

void SrsRtpNackForReceiver::insert(uint16_t first, uint16_t last)
{
    // If circuit-breaker is enabled, disable nack.
    if (_srs_circuit_breaker->hybrid_high_water_level()) {
        ++_srs_pps_snack4->sugar;
        return;
    }

    for (uint16_t s = first; s != last; ++s) {
        queue_[s] = SrsRtpNackInfo();
    }
}

void SrsRtpNackForReceiver::remove(uint16_t seq)
{
    queue_.erase(seq);
}

SrsRtpNackInfo* SrsRtpNackForReceiver::find(uint16_t seq)
{
    std::map<uint16_t, SrsRtpNackInfo>::iterator iter = queue_.find(seq);

    if (iter == queue_.end()) {
        return NULL;
    }

    return &(iter->second);
}

void SrsRtpNackForReceiver::check_queue_size()
{
    if (queue_.size() >= max_queue_size_) {
        rtp_->notify_nack_list_full();
        queue_.clear();
    }
}

void SrsRtpNackForReceiver::get_nack_seqs(SrsRtcpNack& seqs, uint32_t& timeout_nacks)
{
    // If circuit-breaker is enabled, disable nack.
    if (_srs_circuit_breaker->hybrid_high_water_level()) {
        queue_.clear();
        ++_srs_pps_snack4->sugar;
        return;
    }

    srs_utime_t now = srs_get_system_time();

    srs_utime_t interval = now - pre_check_time_;
    if (interval < opts_.nack_check_interval) {
        return;
    }
    pre_check_time_ = now;

    std::map<uint16_t, SrsRtpNackInfo>::iterator iter = queue_.begin();
    while (iter != queue_.end()) {
        const uint16_t& seq = iter->first;
        SrsRtpNackInfo& nack_info = iter->second;

        int alive_time = now - nack_info.generate_time_;
        if (alive_time > opts_.max_alive_time || nack_info.req_nack_count_ > opts_.max_count) {
            ++timeout_nacks;
            rtp_->notify_drop_seq(seq);
            queue_.erase(iter++);
            continue;
        }

        // TODO:Statistics unorder packet.
        if (now - nack_info.generate_time_ < opts_.first_nack_interval) {
            break;
        }

        srs_utime_t nack_interval = srs_max(opts_.min_nack_interval, opts_.nack_interval / 3);
        if(opts_.nack_interval < 50 * SRS_UTIME_MILLISECONDS){
            nack_interval = srs_max(opts_.min_nack_interval, opts_.nack_interval);
        }

        if (now - nack_info.pre_req_nack_time_ >= nack_interval ) {
            ++nack_info.req_nack_count_;
            nack_info.pre_req_nack_time_ = now;
            seqs.add_lost_sn(seq);
        }

        ++iter;
    }
}

void SrsRtpNackForReceiver::update_rtt(int rtt)
{
    rtt_ = rtt * SRS_UTIME_MILLISECONDS;

    if (rtt_ > opts_.nack_interval) {
        opts_.nack_interval = opts_.nack_interval  * 0.8 + rtt_ * 0.2;
    } else {
        opts_.nack_interval = rtt_;
    }

    opts_.nack_interval = srs_min(opts_.nack_interval, opts_.max_nack_interval);
}

