/* SPDX-License-Identifier: GPL-3.0-or-later

 * Copyright © 2016-2026 The TokTok team.

 * Copyright © 2013-2015 Tox project.

 */

#include "bwcontroller.h"

#include <assert.h>

#include <errno.h>

#include <stdlib.h>

#include <string.h>

#include "ring_buffer.h"

#include "../toxcore/ccompat.h"

#include "../toxcore/logger.h"

#include "../toxcore/mono_time.h"

#include "../toxcore/network.h"

#include "../toxcore/util.h"

#define BWC_SEND_INTERVAL_MS 950     // 0.95s

#define BWC_AVG_PKT_COUNT 20

#define BWC_AVG_LOSS_OVER_CYCLES_COUNT 30

typedef struct BWCCycle {

    uint32_t last_recv_timestamp; /* Last recv update time stamp */

    uint32_t last_sent_timestamp; /* Last sent update time stamp */

    uint32_t last_refresh_timestamp; /* Last refresh time stamp */

    uint32_t lost;

    uint32_t recv;

} BWCCycle;

typedef struct BWCRcvPkt {

    uint32_t packet_length_array[BWC_AVG_PKT_COUNT];

    RingBuffer *_Nonnull rb;

} BWCRcvPkt;

struct BWController {

    bwc_loss_report_cb *_Nullable mcb;

    void *_Nullable mcb_user_data;

    bwc_send_packet_cb *_Nullable send_packet;

    void *_Nullable send_packet_user_data;

    const Logger *_Nonnull log;

    uint32_t friend_number;

    BWCCycle cycle;

    BWCRcvPkt rcvpkt; /* To calculate average received packet (this means split parts, not the full message!) */

    uint32_t packet_loss_counted_cycles;

    Mono_Time *_Nonnull bwc_mono_time;

    bool bwc_receive_active; /* if this is set to false then incoming bwc packets will not be processed by bwc_handle_data() */

};

struct BWCMessage {

    uint32_t lost;

    uint32_t recv;

};

static void send_update(BWController *_Nonnull bwc);

BWController *bwc_new(const Logger *log, uint32_t friendnumber,

                      bwc_loss_report_cb *mcb, void *mcb_user_data,

                      bwc_send_packet_cb *send_packet, void *send_packet_user_data,

                      Mono_Time *bwc_mono_time)

{

    BWController *retu = (BWController *)calloc(1, sizeof(BWController));

    if (retu == nullptr) {

        return nullptr;

    }

    LOGGER_DEBUG(log, "Creating bandwidth controller");

    retu->mcb = mcb;

    retu->mcb_user_data = mcb_user_data;

    retu->send_packet = send_packet;

    retu->send_packet_user_data = send_packet_user_data;

    retu->friend_number = friendnumber;

    retu->bwc_mono_time = bwc_mono_time;

    const uint64_t now = current_time_monotonic(bwc_mono_time);

    retu->cycle.last_sent_timestamp = now;

    retu->cycle.last_refresh_timestamp = now;

    retu->log = log;

    retu->bwc_receive_active = true;

    retu->rcvpkt.rb = rb_new(BWC_AVG_PKT_COUNT);

    retu->cycle.lost = 0;

    retu->cycle.recv = 0;

    retu->packet_loss_counted_cycles = 0;

    /* Fill with zeros */

    for (int i = 0; i < BWC_AVG_PKT_COUNT; ++i) {

        rb_write(retu->rcvpkt.rb, &retu->rcvpkt.packet_length_array[i]);

    }

    return retu;

}

void bwc_kill(BWController *bwc)

{

    if (bwc == nullptr) {

        return;

    }

    rb_kill(bwc->rcvpkt.rb);

    free(bwc);

}

void bwc_add_lost(BWController *bwc, uint32_t bytes_lost)

{

    if (bwc == nullptr) {

        return;

    }

    if (bytes_lost > 0) {

        LOGGER_DEBUG(bwc->log, "BWC lost(1): %d", (int)bytes_lost);

        bwc->cycle.lost += bytes_lost;

        send_update(bwc);

    }

}

void bwc_add_recv(BWController *bwc, uint32_t recv_bytes)

{

    if (bwc == nullptr || recv_bytes == 0) {

        return;

    }

    ++bwc->packet_loss_counted_cycles;

    bwc->cycle.recv += recv_bytes;

    send_update(bwc);

}

static void send_update(BWController *bwc)

{

    if (bwc->packet_loss_counted_cycles > BWC_AVG_LOSS_OVER_CYCLES_COUNT &&

            current_time_monotonic(bwc->bwc_mono_time) - bwc->cycle.last_sent_timestamp > BWC_SEND_INTERVAL_MS) {

        bwc->packet_loss_counted_cycles = 0;

        if (bwc->cycle.lost != 0) {

            LOGGER_DEBUG(bwc->log, "%p Sent update rcv: %u lost: %u percent: %f %%",

                         (void *)bwc, bwc->cycle.recv, bwc->cycle.lost,

                         ((double)bwc->cycle.lost / ((double)bwc->cycle.recv + (double)bwc->cycle.lost)) * 100.0);

            uint8_t bwc_packet[sizeof(struct BWCMessage) + 1];

            size_t offset = 0;

            bwc_packet[offset] = BWC_PACKET_ID; // set packet ID

            ++offset;

            offset += net_pack_u32(bwc_packet + offset, bwc->cycle.lost);

            offset += net_pack_u32(bwc_packet + offset, bwc->cycle.recv);

            assert(offset == sizeof(bwc_packet));

            if (bwc->send_packet != nullptr && bwc->send_packet(bwc->send_packet_user_data, bwc_packet, sizeof(bwc_packet)) != 0) {

                LOGGER_WARNING(bwc->log, "BWC send failed");

            }

        }

        bwc->cycle.last_sent_timestamp = current_time_monotonic(bwc->bwc_mono_time);

        bwc->cycle.lost = 0;

        bwc->cycle.recv = 0;

    }

}

static int on_update(BWController *_Nonnull bwc, const struct BWCMessage *_Nonnull msg)

{

    LOGGER_DEBUG(bwc->log, "%p Got update from peer", (void *)bwc);

    /* Peers sent update too soon */

    if (current_time_monotonic(bwc->bwc_mono_time) - bwc->cycle.last_recv_timestamp < BWC_SEND_INTERVAL_MS) {

        LOGGER_INFO(bwc->log, "%p Rejecting extra update", (void *)bwc);

        return -1;

    }

    bwc->cycle.last_recv_timestamp = current_time_monotonic(bwc->bwc_mono_time);

    const uint32_t lost = msg->lost;

    if (lost != 0 && bwc->mcb != nullptr) {

        const uint32_t recv = msg->recv;

        LOGGER_DEBUG(bwc->log, "recved: %u lost: %u percentage: %f %%", recv, lost,

                     ((double) lost / ((double)recv + (double)lost)) * 100.0);

        bwc->mcb(bwc, bwc->friend_number,

                 (float)((double)lost / ((double)recv + (double)lost)),

                 bwc->mcb_user_data);

    }

    return 0;

}

void bwc_handle_packet(BWController *bwc, const uint8_t *data, size_t length)

{

    if (bwc == nullptr) {

        return;

    }

    if (length - 1 != sizeof(struct BWCMessage)) {

        LOGGER_ERROR(bwc->log, "Got BWCMessage of insufficient size.");

        return;

    }

    if (!bwc->bwc_receive_active) {

        LOGGER_WARNING(bwc->log, "receiving not allowed!");

        return;

    }

    size_t offset = 1;  // Ignore packet id.

    struct BWCMessage msg;

    offset += net_unpack_u32(data + offset, &msg.lost);

    offset += net_unpack_u32(data + offset, &msg.recv);

    assert(offset == length);

    on_update(bwc, &msg);

}