/*
   Copyright (C) 2009 Her Majesty the Queen in Right of Canada (Communications
   Research Center Canada)

   Copyright (C) 2019
   Matthias P. Braendli, matthias.braendli@mpb.li

    http://www.opendigitalradio.org
   */
/*
   This file is part of ODR-DabMux.

   ODR-DabMux is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as
   published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   ODR-DabMux is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with ODR-DabMux.  If not, see <http://www.gnu.org/licenses/>.
   */

#include "input/Edi.h"

#include <regex>
#include <chrono>
#include <stdexcept>
#include <sstream>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <cerrno>
#include <climits>
#include "utils.h"

using namespace std;

namespace Inputs {

constexpr bool VERBOSE = false;
constexpr size_t TCP_BLOCKSIZE = 2048;

/* Absolute max number of frames to be queued, both with and without timestamping */
constexpr size_t MAX_FRAMES_QUEUED = 1000;

/* When using timestamping, start discarding the front of the queue once the queue
 * is this full. Must be smaller than MAX_FRAMES_QUEUED.  */
constexpr size_t MAX_FRAMES_QUEUED_PREBUFFERING = 500;

/* When not using timestamping, how many frames to prebuffer.
 * TODO should be configurable as ZMQ.  */
constexpr size_t NUM_FRAMES_PREBUFFERING = 10;
/* Consider the buffer to be full on the receive side if it's above the overrun threshold. */
constexpr size_t MAX_FRAMES_OVERRUN = 900;


Edi::Edi(const std::string& name) :
    m_tcp_receive_server(TCP_BLOCKSIZE),
    m_sti_writer(),
    m_sti_decoder(m_sti_writer, VERBOSE),
    m_name(name),
    m_stats(name)
{ }

Edi::~Edi() {
    m_running = false;
    if (m_thread.joinable()) {
        m_thread.join();
    }
}

void Edi::open(const std::string& name)
{
    const std::regex re_udp("udp://:([0-9]+)");
    const std::regex re_tcp("tcp://(.*):([0-9]+)");

    lock_guard<mutex> lock(m_mutex);

    m_running = false;
    if (m_thread.joinable()) {
        m_thread.join();
    }

    std::smatch m;
    if (std::regex_match(name, m, re_udp)) {
        const int udp_port = std::stoi(m[1].str());
        m_input_used = InputUsed::UDP;
        m_udp_sock.reinit(udp_port);
        m_udp_sock.setBlocking(false);
        // TODO multicast
    }
    else if (std::regex_match(name, m, re_tcp)) {
        m_input_used = InputUsed::TCP;
        const string addr = m[1].str();
        const int tcp_port = std::stoi(m[2].str());
        m_tcp_receive_server.start(tcp_port, addr);
    }
    else {
        throw runtime_error("Cannot parse EDI input URI");
    }

    m_stats.registerAtServer();

    m_running = true;
    m_thread = std::thread(&Edi::m_run, this);
}

size_t Edi::readFrame(uint8_t *buffer, size_t size)
{
    // Save stats data in bytes, not in frames
    m_stats.notifyBuffer(m_frames.size() * size);

    EdiDecoder::sti_frame_t sti;
    if (m_is_prebuffering) {
        m_is_prebuffering = m_frames.size() < NUM_FRAMES_PREBUFFERING;
        if (not m_is_prebuffering) {
            etiLog.level(info) << "EDI input " << m_name << " pre-buffering complete.";
        }
        memset(buffer, 0, size * sizeof(*buffer));
        return 0;
    }
    else if (not m_pending_sti_frame.frame.empty()) {
        // Can only happen when switching from timestamp-based buffer management!
        if (m_pending_sti_frame.frame.size() != size) {
            etiLog.level(debug) << "EDI input " << m_name << " size mismatch: " <<
                m_pending_sti_frame.frame.size() << " received, " << size << " requested";
            memset(buffer, 0, size * sizeof(*buffer));
            return 0;
        }
        else {
            if (not m_pending_sti_frame.version_data.version.empty()) {
                m_stats.notifyVersion(
                        m_pending_sti_frame.version_data.version,
                        m_pending_sti_frame.version_data.uptime_s);
            }
            m_stats.notifyPeakLevels(m_pending_sti_frame.audio_levels.left, m_pending_sti_frame.audio_levels.right);

            copy(m_pending_sti_frame.frame.begin(),
                    m_pending_sti_frame.frame.end(),
                    buffer);
            m_pending_sti_frame.frame.clear();
            return size;
        }
    }
    else if (m_frames.try_pop(sti)) {
        if (sti.frame.size() == 0) {
            etiLog.level(debug) << "EDI input " << m_name << " empty frame";
            return 0;
        }
        else if (sti.frame.size() == size) {
            // Steady-state when everything works well
            if (m_frames.size() > MAX_FRAMES_OVERRUN) {
                m_stats.notifyOverrun();

                /* If the buffer is too full, we drop as many frames as needed
                 * to get down to the prebuffering size. We would like to have our buffer
                 * filled to the prebuffering length. */
                size_t over_max = m_frames.size() - NUM_FRAMES_PREBUFFERING;

                while (over_max--) {
                    EdiDecoder::sti_frame_t discard;
                    m_frames.try_pop(discard);
                }
            }

            if (not sti.version_data.version.empty()) {
                m_stats.notifyVersion(
                        sti.version_data.version,
                        sti.version_data.uptime_s);
            }
            m_stats.notifyPeakLevels(sti.audio_levels.left, sti.audio_levels.right);

            copy(sti.frame.cbegin(), sti.frame.cend(), buffer);
            return size;
        }
        else {
            etiLog.level(debug) << "EDI input " << m_name << " size mismatch: " <<
                sti.frame.size() << " received, " << size << " requested";
            memset(buffer, 0, size * sizeof(*buffer));
            return 0;
        }
    }
    else {
        memset(buffer, 0, size * sizeof(*buffer));
        m_is_prebuffering = true;
        etiLog.level(info) << "EDI input " << m_name << " re-enabling pre-buffering";
        m_stats.notifyUnderrun();
        return 0;
    }
}

size_t Edi::readFrame(uint8_t *buffer, size_t size, std::time_t seconds, int utco, uint32_t tsta)
{
    if (m_pending_sti_frame.frame.empty()) {
        m_frames.try_pop(m_pending_sti_frame);
    }

    m_stats.notifyBuffer(m_frames.size() * size);

    if (m_is_prebuffering) {
        if (m_pending_sti_frame.frame.empty()) {
            memset(buffer, 0, size);
            return 0;
        }
        else if (m_pending_sti_frame.frame.size() == size) {
            // readFrame gets called every 24ms, so we allow max 24ms
            // difference between the input frame timestamp and the requested
            // timestamp.
            if (m_pending_sti_frame.timestamp.valid()) {
                const auto ts_req = EdiDecoder::frame_timestamp_t::from_unix_epoch(seconds, utco, tsta);
                const double offset = m_pending_sti_frame.timestamp.diff_ms(ts_req);

                if (offset < 24e-3) {
                    m_is_prebuffering = false;
                    etiLog.level(warn) << "EDI input " << m_name <<
                        " valid timestamp, pre-buffering complete";

                    if (not m_pending_sti_frame.version_data.version.empty()) {
                        m_stats.notifyVersion(
                                m_pending_sti_frame.version_data.version,
                                m_pending_sti_frame.version_data.uptime_s);
                    }

                    m_stats.notifyPeakLevels(m_pending_sti_frame.audio_levels.left,
                            m_pending_sti_frame.audio_levels.right);
                    copy(m_pending_sti_frame.frame.cbegin(), m_pending_sti_frame.frame.cend(), buffer);
                    m_pending_sti_frame.frame.clear();
                    return size;
                }
                else {
                    // Wait more, but erase the front of the frame queue to avoid
                    // stalling on one frame with incorrect timestamp
                    if (m_frames.size() >= MAX_FRAMES_QUEUED_PREBUFFERING) {
                        m_pending_sti_frame.frame.clear();
                    }
                    m_stats.notifyUnderrun();
                    memset(buffer, 0, size);
                    return 0;
                }
            }
            else {
                etiLog.level(debug) << "EDI input " << m_name <<
                    " skipping frame without timestamp";
                m_pending_sti_frame.frame.clear();
                memset(buffer, 0, size);
                return 0;
            }
        }
        else {
            etiLog.level(debug) << "EDI input " << m_name << " size mismatch: " <<
                m_pending_sti_frame.frame.size() << " received, " << size << " requested";
            m_pending_sti_frame.frame.clear();
            memset(buffer, 0, size);
            return 0;
        }
    }
    else {
        EdiDecoder::sti_frame_t sti_frame;
        m_frames.try_pop(sti_frame);
        if (sti_frame.frame.empty()) {
            etiLog.level(warn) << "EDI input " << m_name <<
                " empty, re-enabling pre-buffering";
            memset(buffer, 0, size);
            m_stats.notifyUnderrun();
            m_is_prebuffering = true;
            return 0;
        }
        else if (not sti_frame.timestamp.valid()) {
            etiLog.level(warn) << "EDI input " << m_name <<
                " invalid timestamp, ignoring";
            memset(buffer, 0, size);
            m_stats.notifyUnderrun();
            return 0;
        }
        else {
            const auto ts_req = EdiDecoder::frame_timestamp_t::from_unix_epoch(seconds, utco, tsta);
            const double offset = m_pending_sti_frame.timestamp.diff_ms(ts_req);

            if (offset > 24e-3) {
                m_stats.notifyUnderrun();
                m_is_prebuffering = true;
                etiLog.level(warn) << "EDI input " << m_name <<
                    " timestamp out of bounds, re-enabling pre-buffering";
                memset(buffer, 0, size);
                return 0;
            }
            else {
                if (not sti_frame.version_data.version.empty()) {
                    m_stats.notifyVersion(
                            sti_frame.version_data.version,
                            sti_frame.version_data.uptime_s);
                }

                m_stats.notifyPeakLevels(sti_frame.audio_levels.left,
                        sti_frame.audio_levels.right);
                copy(sti_frame.frame.cbegin(), sti_frame.frame.cend(), buffer);
                return size;
            }
        }
    }
}

void Edi::m_run()
{
    while (m_running) {
        bool work_done = false;

        switch (m_input_used) {
            case InputUsed::UDP:
                {
                    constexpr size_t packsize = 2048;
                    const auto packet = m_udp_sock.receive(packsize);
                    if (packet.buffer.size() == packsize) {
                        fprintf(stderr, "Warning, possible UDP truncation\n");
                    }
                    if (not packet.buffer.empty()) {
                        m_sti_decoder.push_packet(packet.buffer);
                        work_done = true;
                    }
                }
                break;
            case InputUsed::TCP:
                {
                    auto packet = m_tcp_receive_server.receive();
                    if (not packet.empty()) {
                        m_sti_decoder.push_bytes(packet);
                        work_done = true;
                    }
                }
                break;
            default:
                throw logic_error("unimplemented input");
        }

        const auto sti = m_sti_writer.getFrame();
        if (not sti.frame.empty()) {
            m_frames.push_wait_if_full(move(sti), MAX_FRAMES_QUEUED);
            work_done = true;
        }

        if (not work_done) {
            // Avoid fast loop
            this_thread::sleep_for(chrono::milliseconds(12));
        }
    }
}

int Edi::setBitrate(int bitrate)
{
    if (bitrate <= 0) {
        throw invalid_argument("Invalid bitrate " + to_string(bitrate) + " for " + m_name);
    }

    return bitrate;
}

void Edi::close()
{
    m_udp_sock.close();
}

}