#include "device.h"

#include <signal.h>
#include <QDebug>
#include <QString>
#include <QMessageBox>
#include <mutex>

using namespace std;

using USBID = struct {
    int VID;
    int PID;
};
static constexpr USBID IDs[] = {
    {0x0483, 0x564e},
    {0x0483, 0x4121},
};

USBInBuffer::USBInBuffer(libusb_device_handle *handle, unsigned char endpoint, int buffer_size) :
    buffer_size(buffer_size),
    received_size(0),
    inCallback(false)
{
    buffer = new unsigned char[buffer_size];
    transfer = libusb_alloc_transfer(0);
    libusb_fill_bulk_transfer(transfer, handle, endpoint, buffer, buffer_size, CallbackTrampoline, this, 100);
    libusb_submit_transfer(transfer);
}

USBInBuffer::~USBInBuffer()
{
    if(transfer) {
        libusb_cancel_transfer(transfer);
        // wait for cancellation to complete
        mutex mtx;
        unique_lock<mutex> lck(mtx);
        cv.wait(lck);
    }
    delete buffer;
}

void USBInBuffer::removeBytes(int handled_bytes)
{
    if(!inCallback) {
        throw runtime_error("Removing of bytes is only allowed from within receive callback");
    }
    if(handled_bytes >= received_size) {
        received_size = 0;
    } else {
        // not removing all bytes, have to move remaining data to the beginning of the buffer
        memmove(buffer, &buffer[handled_bytes], received_size - handled_bytes);
        received_size -= handled_bytes;
    }
}

int USBInBuffer::getReceived() const
{
    return received_size;
}

void USBInBuffer::Callback(libusb_transfer *transfer)
{
    switch(transfer->status) {
    case LIBUSB_TRANSFER_COMPLETED:
        received_size += transfer->actual_length;
        inCallback = true;
        emit DataReceived();
        inCallback = false;
        break;
    case LIBUSB_TRANSFER_ERROR:
    case LIBUSB_TRANSFER_NO_DEVICE:
    case LIBUSB_TRANSFER_OVERFLOW:
    case LIBUSB_TRANSFER_STALL:
        qCritical() << "LIBUSB_TRANSFER_ERROR";
        libusb_free_transfer(transfer);
        this->transfer = nullptr;
        emit TransferError();
        return;
        break;
    case LIBUSB_TRANSFER_TIMED_OUT:
        // nothing to do
        break;
    case LIBUSB_TRANSFER_CANCELLED:
        // destructor called, do not resubmit
        libusb_free_transfer(transfer);
        this->transfer = nullptr;
        cv.notify_all();
        return;
        break;
    }
    // Resubmit the transfer
    transfer->buffer = &buffer[received_size];
    transfer->length = buffer_size - received_size;
    libusb_submit_transfer(transfer);
}

void USBInBuffer::CallbackTrampoline(libusb_transfer *transfer)
{
    auto usb = (USBInBuffer*) transfer->user_data;
    usb->Callback(transfer);
}

uint8_t *USBInBuffer::getBuffer() const
{
    return buffer;
}

static Protocol::DeviceLimits limits = {
    .minFreq = 0,
    .maxFreq = 6000000000,
    .minIFBW = 10,
    .maxIFBW = 50000,
    .maxPoints = 4501,
    .cdbm_min = -4000,
    .cdbm_max = 0,
    .minRBW = 10,
    .maxRBW = 100000,
};

Device::Device(QString serial)
{
    qDebug() << "Starting device connection...";

    m_handle = nullptr;
    libusb_init(&m_context);

    SearchDevices([=](libusb_device_handle *handle, QString found_serial) -> bool {
        if(serial.isEmpty() || serial == found_serial) {
            // accept connection to this device
            m_serial = found_serial;
            m_handle = handle;
            // abort device search
            return false;
        } else {
            // not the requested device, continue search
            return true;
        }
    }, m_context);

    if(!m_handle) {
        QString message =  "No device found";
        auto msg = new QMessageBox(QMessageBox::Icon::Warning, "Error opening device", message);
        msg->exec();
        libusb_exit(m_context);
        throw std::runtime_error(message.toStdString());
        return;
    }

    // Found the correct device, now connect
    /* claim the interfaces */
    for (int if_num = 0; if_num < 1; if_num++) {
        int ret = libusb_claim_interface(m_handle, if_num);
        if (ret < 0) {
            libusb_close(m_handle);
            /* Failed to open */
            QString message =  "Failed to claim interface: \"";
            message.append(libusb_strerror((libusb_error) ret));
            message.append("\" Maybe you are already connected to this device?");
            qWarning() << message;
            auto msg = new QMessageBox(QMessageBox::Icon::Warning, "Error opening device", message);
            msg->exec();
            libusb_exit(m_context);
            throw std::runtime_error(message.toStdString());
        }
    }
    qInfo() << "USB connection established" << flush;
    m_connected = true;
    m_receiveThread = new std::thread(&Device::USBHandleThread, this);
    dataBuffer = new USBInBuffer(m_handle, EP_Data_In_Addr, 2048);
    logBuffer = new USBInBuffer(m_handle, EP_Log_In_Addr, 2048);
    connect(dataBuffer, &USBInBuffer::DataReceived, this, &Device::ReceivedData, Qt::DirectConnection);
    connect(dataBuffer, &USBInBuffer::TransferError, this, &Device::ConnectionLost);
    connect(logBuffer, &USBInBuffer::DataReceived, this, &Device::ReceivedLog, Qt::DirectConnection);
    connect(&transmissionTimer, &QTimer::timeout, this, &Device::transmissionTimeout);
    transmissionTimer.setSingleShot(true);
    transmissionActive = false;
    // got a new connection, request limits
    SendCommandWithoutPayload(Protocol::PacketType::RequestDeviceLimits);
}

Device::~Device()
{
    if(m_connected) {
        delete dataBuffer;
        delete logBuffer;
        m_connected = false;
        for (int if_num = 0; if_num < 1; if_num++) {
            int ret = libusb_release_interface(m_handle, if_num);
            if (ret < 0) {
                qCritical() << "Error releasing interface" << libusb_error_name(ret);
            }
        }
        libusb_close(m_handle);
        m_receiveThread->join();
        libusb_exit(m_context);
    }
}

bool Device::SendPacket(Protocol::PacketInfo packet, std::function<void(TransmissionResult)> cb, unsigned int timeout)
{
    Transmission t;
    t.packet = packet;
    t.timeout = timeout;
    t.callback = cb;
    transmissionQueue.enqueue(t);
    if(!transmissionActive) {
        startNextTransmission();
    }
    return true;
}

bool Device::Configure(Protocol::SweepSettings settings)
{
    Protocol::PacketInfo p;
    p.type = Protocol::PacketType::SweepSettings;
    p.settings = settings;
    return SendPacket(p);
}

bool Device::Configure(Protocol::SpectrumAnalyzerSettings settings)
{
    Protocol::PacketInfo p;
    p.type = Protocol::PacketType::SpectrumAnalyzerSettings;
    p.spectrumSettings = settings;
    return SendPacket(p);
}

bool Device::SetManual(Protocol::ManualControl manual)
{
    Protocol::PacketInfo p;
    p.type = Protocol::PacketType::ManualControl;
    p.manual = manual;
    return SendPacket(p);
}

bool Device::SendFirmwareChunk(Protocol::FirmwarePacket &fw)
{
    Protocol::PacketInfo p;
    p.type = Protocol::PacketType::FirmwarePacket;
    p.firmware = fw;
    return SendPacket(p);
}

bool Device::SendCommandWithoutPayload(Protocol::PacketType type)
{
    Protocol::PacketInfo p;
    p.type = type;
    return SendPacket(p);
}

std::set<QString> Device::GetDevices()
{
    std::set<QString> serials;

    libusb_context *ctx;
    libusb_init(&ctx);

    SearchDevices([&serials](libusb_device_handle *, QString serial) -> bool {
        serials.insert(serial);
        return true;
    }, ctx);

    libusb_exit(ctx);

    return serials;
}

Protocol::DeviceLimits Device::Limits()
{
    return limits;
}

void Device::USBHandleThread()
{
    qInfo() << "Receive thread started" << flush;
    while (m_connected) {
        libusb_handle_events(m_context);
    }
    qDebug() << "Disconnected, receive thread exiting";
}

void Device::SearchDevices(std::function<bool (libusb_device_handle *, QString)> foundCallback, libusb_context *context)
{
    libusb_device **devList;
    auto ndevices = libusb_get_device_list(context, &devList);

    for (ssize_t idx = 0; idx < ndevices; idx++) {
        int ret;
        libusb_device *device = devList[idx];
        libusb_device_descriptor desc = {};

        ret = libusb_get_device_descriptor(device, &desc);
        if (ret) {
            /* some error occured */
            qCritical() << "Failed to get device descriptor: "
                    << libusb_strerror((libusb_error) ret);
            continue;
        }

        bool correctID = false;
        int numIDs = sizeof(IDs)/sizeof(IDs[0]);
        for(int i=0;i<numIDs;i++) {
            if(desc.idVendor == IDs[i].VID && desc.idProduct == IDs[i].PID) {
                correctID = true;
                break;
            }
        }
        if(!correctID) {
            continue;
        }

        /* Try to open the device */
        libusb_device_handle *handle = nullptr;
        ret = libusb_open(device, &handle);
        if (ret) {
            /* Failed to open */
            QString message =  "Found potential device but failed to open usb connection: \"";
            message.append(libusb_strerror((libusb_error) ret));
            message.append("\" On Linux this is most likely caused by a missing udev rule. On Windows it could be a missing driver. Try installing the WinUSB driver using Zadig (https://zadig.akeo.ie/)");
            qWarning() << message;
            auto msg = new QMessageBox(QMessageBox::Icon::Warning, "Error opening device", message);
            msg->exec();
            continue;
        }

        char c_product[256];
        char c_serial[256];
        libusb_get_string_descriptor_ascii(handle, desc.iSerialNumber,
                (unsigned char*) c_serial, sizeof(c_serial));
        ret = libusb_get_string_descriptor_ascii(handle, desc.iProduct,
                (unsigned char*) c_product, sizeof(c_product));
        if (ret > 0) {
            /* managed to read the product string */
            QString product(c_product);
            qDebug() << "Opened device: " << product;
            if (product == "VNA") {
                // this is a match
                if(!foundCallback(handle, QString(c_serial))) {
                    // abort search
                    break;
                }
            }
        } else {
            qWarning() << "Failed to get product descriptor: "
                    << libusb_strerror((libusb_error) ret);
        }
        libusb_close(handle);
    }
    libusb_free_device_list(devList, 1);
}

Protocol::DeviceInfo Device::getLastInfo() const
{
    return lastInfo;
}

QString Device::getLastDeviceInfoString()
{
    QString ret;
    if(!lastInfoValid) {
        ret.append("No device information available yet");
    } else {
        ret.append("HW Rev.");
        ret.append(lastInfo.HW_Revision);
        ret.append(" FW "+QString::number(lastInfo.FW_major)+"."+QString::number(lastInfo.FW_minor).rightJustified(2, '0'));
        ret.append(" Temps: "+QString::number(lastInfo.temperatures.source)+"°C/"+QString::number(lastInfo.temperatures.LO1)+"°C/"+QString::number(lastInfo.temperatures.MCU)+"°C");
        ret.append(" Reference:");
        if(lastInfo.extRefInUse) {
            ret.append("External");
        } else {
            ret.append("Internal");
            if(lastInfo.extRefAvailable) {
                ret.append(" (External available)");
            }
        }
    }
    return ret;
}

void Device::ReceivedData()
{
    Protocol::PacketInfo packet;
    uint16_t handled_len;
    do {
        handled_len = Protocol::DecodeBuffer(dataBuffer->getBuffer(), dataBuffer->getReceived(), &packet);
        dataBuffer->removeBytes(handled_len);
        switch(packet.type) {
        case Protocol::PacketType::Datapoint:
            emit DatapointReceived(packet.datapoint);
            break;
        case Protocol::PacketType::Status:
            emit ManualStatusReceived(packet.status);
            break;
        case Protocol::PacketType::SpectrumAnalyzerResult:
            emit SpectrumResultReceived(packet.spectrumResult);
            break;
        case Protocol::PacketType::DeviceInfo:
            lastInfo = packet.info;
            lastInfoValid = true;
            emit DeviceInfoUpdated();
            break;
        case Protocol::PacketType::Ack:
            emit AckReceived();
//            transmissionFinished(TransmissionResult::Ack);
            break;
        case Protocol::PacketType::Nack:
            emit NackReceived();
//            transmissionFinished(TransmissionResult::Nack);
            break;
        case Protocol::PacketType::DeviceLimits:
            limits = packet.limits;
            break;
        default:
            break;
        }
    } while (handled_len > 0);
}

void Device::ReceivedLog()
{
    uint16_t handled_len;
    do {
        handled_len = 0;
        auto firstLinebreak = (uint8_t*) memchr(logBuffer->getBuffer(), '\n', logBuffer->getReceived());
        if(firstLinebreak) {
            handled_len = firstLinebreak - logBuffer->getBuffer();
            auto line = QString::fromLatin1((const char*) logBuffer->getBuffer(), handled_len - 1);
            emit LogLineReceived(line);
            logBuffer->removeBytes(handled_len + 1);
        }
    } while(handled_len > 0);
}

QString Device::serial() const
{
    return m_serial;
}

void Device::startNextTransmission()
{
    if(transmissionQueue.isEmpty() || !m_connected) {
        // nothing more to transmit
        transmissionActive = false;
        return;
    }
    transmissionActive = true;
    auto t = transmissionQueue.head();
    unsigned char buffer[1024];
    unsigned int length = Protocol::EncodePacket(t.packet, buffer, sizeof(buffer));
    if(!length) {
        qCritical() << "Failed to encode packet";
        transmissionFinished(TransmissionResult::InternalError);
    }
    int actual_length;
    auto ret = libusb_bulk_transfer(m_handle, EP_Data_Out_Addr, buffer, length, &actual_length, 0);
    if(ret < 0) {
        qCritical() << "Error sending data: "
                                << libusb_strerror((libusb_error) ret);
        transmissionFinished(TransmissionResult::InternalError);
    }
    transmissionTimer.start(t.timeout);
}

void Device::transmissionFinished(TransmissionResult result)
{
    transmissionTimer.stop();
    // remove transmitted packet
    if(!transmissionQueue.isEmpty()) {
        auto t = transmissionQueue.dequeue();
        if(t.callback) {
            t.callback(result);
        }
        startNextTransmission();
    } else {
        transmissionActive = false;
    }
}