//
// Copyright 2017 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//


#include <mpm/exception.hpp>
#include <mpm/spi/spi_iface.hpp>
extern "C" {
#include "spidev.h"
}
#include <fcntl.h>
#include <linux/spi/spidev.h>
#include <unistd.h>
#include <iostream>

using namespace mpm::spi;

/******************************************************************************
 * Implementation
 *****************************************************************************/
class spidev_iface_impl : public spi_iface
{
public:
    spidev_iface_impl(
        const std::string& device, const int max_speed_hz, const int spi_mode)
        : _speed(max_speed_hz), _mode(spi_mode)
    {
        if (init_spi(&_fd, device.c_str(), _mode, _speed, _bits, _delay) < 0) {
            throw mpm::runtime_error(
                std::string("Could not initialize spidev device ") + device);
        }

        if (_fd < 0) {
            throw mpm::runtime_error(
                std::string("Could not open spidev device ") + device);
        }
    }

    ~spidev_iface_impl()
    {
        close(_fd);
    }

    uint32_t transfer24_8(const uint32_t data_)
    {
        int ret(0);

        uint32_t data    = data_;
        uint8_t* tx_data = reinterpret_cast<uint8_t*>(&data);

        // Create tx and rx buffers:
        uint8_t tx[] = {tx_data[2], tx_data[1], tx_data[0]}; // FIXME guarantee endianness
        uint8_t rx[3]; // Buffer length must match tx buffer

        if (transfer(_fd, &tx[0], &rx[0], 3, _speed, _bits, _delay) != 0) {
            throw mpm::runtime_error("SPI Transaction failed!");
        }

        return uint32_t(rx[2]);
    }

    uint32_t transfer24_16(const uint32_t data_)
    {
        int ret(0);

        uint32_t data    = data_;
        uint8_t* tx_data = reinterpret_cast<uint8_t*>(&data);

        // Create tx and rx buffers:
        uint8_t tx[] = {tx_data[2], tx_data[1], tx_data[0]}; // FIXME guarantee endianness
        uint8_t rx[3]; // Buffer length must match tx buffer

        if (transfer(_fd, &tx[0], &rx[0], 3, _speed, _bits, _delay) != 0) {
            throw mpm::runtime_error("SPI Transaction failed!");
        }

        return uint32_t(rx[1] << 8 | rx[2]);
    }

    uint64_t transfer64_40(const uint64_t data_)
    {
        uint64_t data    = data_;
        uint8_t* tx_data = reinterpret_cast<uint8_t*>(&data);

        // Create tx and rx buffers:
        /* Address and TX data only represents up to 6 out of 8 bytes to
           transfer. The remaining bytes are buffer for processing gap
           and response status. */
        uint8_t tx[] = {
            tx_data[5], tx_data[4], tx_data[3], tx_data[2], tx_data[1], tx_data[0], 0, 0};
        uint8_t rx[8]; // Buffer length must match tx buffer

        if (transfer(_fd, &tx[0], &rx[0], 8, _speed, _bits, _delay) != 0) {
            throw mpm::runtime_error("SPI Transaction failed!");
        }

        uint64_t result = rx[3];
        result          = (result << 8) | rx[4];
        result          = (result << 8) | rx[5];
        result          = (result << 8) | rx[6];
        result          = (result << 8) | rx[7];

        return result;
    }

private:
    int _fd;
    const uint32_t _mode;
    uint32_t _speed = 2000000;
    uint8_t _bits   = 8;
    uint16_t _delay = 0;
};

/******************************************************************************
 * Factory
 *****************************************************************************/
spi_iface::sptr spi_iface::make_spidev(
    const std::string& device, const int speed_hz, const int spi_mode)
{
    return std::make_shared<spidev_iface_impl>(device, speed_hz, spi_mode);
}
