/****************************************************************************
 *
 *   Copyright (c) 2019 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

#include "DShotTelemetry.h"

#include <px4_platform_common/log.h>

#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>

using namespace time_literals;

#define DSHOT_TELEMETRY_UART_BAUDRATE 115200

DShotTelemetry::~DShotTelemetry()
{
	deinit();
}

int DShotTelemetry::init(const char *uart_device)
{
	deinit();
	_uart_fd = ::open(uart_device, O_RDONLY | O_NOCTTY);

	if (_uart_fd < 0) {
		PX4_ERR("failed to open serial port: %s err: %d", uart_device, errno);
		return -errno;
	}

	_num_timeouts = 0;
	_num_successful_responses = 0;
	_current_motor_index_request = -1;
	return setBaudrate(DSHOT_TELEMETRY_UART_BAUDRATE);
}

void DShotTelemetry::deinit()
{
	if (_uart_fd >= 0) {
		close(_uart_fd);
		_uart_fd = -1;
	}
}

int DShotTelemetry::redirectOutput(OutputBuffer &buffer)
{
	if (expectingData()) {
		// Error: cannot override while we already expect data
		return -EBUSY;
	}

	_current_motor_index_request = buffer.motor_index;
	_current_request_start = hrt_absolute_time();
	_redirect_output = &buffer;
	_redirect_output->buf_pos = 0;
	return 0;
}

int DShotTelemetry::update()
{
	if (_uart_fd < 0) {
		return -1;
	}

	if (_current_motor_index_request == -1) {
		// nothing in progress, start a request
		_current_motor_index_request = 0;
		_current_request_start = 0;
		_frame_position = 0;
		return -1;
	}

	// read from the uart. This must be non-blocking, so check first if there is data available
	int bytes_available = 0;
	int ret = ioctl(_uart_fd, FIONREAD, (unsigned long)&bytes_available);

	if (ret != 0 || bytes_available <= 0) {
		// no data available. Check for a timeout
		const hrt_abstime now = hrt_absolute_time();

		if (_current_request_start > 0 && now - _current_request_start > 30_ms) {
			if (_redirect_output) {
				// clear and go back to internal buffer
				_redirect_output = nullptr;
				_current_motor_index_request = -1;

			} else {
				PX4_DEBUG("ESC telemetry timeout for motor %i (frame pos=%i)", _current_motor_index_request, _frame_position);
				++_num_timeouts;
			}

			requestNextMotor();
			return -2;
		}

		return -1;
	}

	const int buf_length = ESC_FRAME_SIZE;
	uint8_t buf[buf_length];

	int num_read = read(_uart_fd, buf, buf_length);
	ret = -1;

	for (int i = 0; i < num_read && ret == -1; ++i) {
		if (_redirect_output) {
			_redirect_output->buffer[_redirect_output->buf_pos++] = buf[i];

			if (_redirect_output->buf_pos == sizeof(_redirect_output->buffer)) {
				// buffer full: return & go back to internal buffer
				_redirect_output = nullptr;
				ret = _current_motor_index_request;
				_current_motor_index_request = -1;
				requestNextMotor();
			}

		} else {
			bool successful_decoding;

			if (decodeByte(buf[i], successful_decoding)) {
				if (successful_decoding) {
					ret = _current_motor_index_request;
				}

				requestNextMotor();
			}
		}
	}

	return ret;
}

bool DShotTelemetry::decodeByte(uint8_t byte, bool &successful_decoding)
{
	_frame_buffer[_frame_position++] = byte;
	successful_decoding = false;

	if (_frame_position == ESC_FRAME_SIZE) {
		PX4_DEBUG("got ESC frame for motor %i", _current_motor_index_request);
		uint8_t checksum = crc8(_frame_buffer, ESC_FRAME_SIZE - 1);
		uint8_t checksum_data = _frame_buffer[ESC_FRAME_SIZE - 1];

		if (checksum == checksum_data) {
			_latest_data.time = hrt_absolute_time();
			_latest_data.temperature = _frame_buffer[0];
			_latest_data.voltage = (_frame_buffer[1] << 8) | _frame_buffer[2];
			_latest_data.current = (_frame_buffer[3] << 8) | _frame_buffer[4];
			_latest_data.consumption = (_frame_buffer[5]) << 8 | _frame_buffer[6];
			_latest_data.erpm = (_frame_buffer[7] << 8) | _frame_buffer[8];
			PX4_DEBUG("Motor %i: temp=%i, V=%i, cur=%i, consumpt=%i, rpm=%i", _current_motor_index_request,
				  _latest_data.temperature, _latest_data.voltage, _latest_data.current, _latest_data.consumption,
				  _latest_data.erpm);
			++_num_successful_responses;
			successful_decoding = true;
		}

		return true;
	}

	return false;
}

void DShotTelemetry::printStatus() const
{
	PX4_INFO("Number of successful ESC frames: %i", _num_successful_responses);
	PX4_INFO("Number of timeouts: %i", _num_timeouts);
}

uint8_t DShotTelemetry::updateCrc8(uint8_t crc, uint8_t crc_seed)
{
	uint8_t crc_u = crc ^ crc_seed;

	for (int i = 0; i < 8; ++i) {
		crc_u = (crc_u & 0x80) ? 0x7 ^ (crc_u << 1) : (crc_u << 1);
	}

	return crc_u;
}


uint8_t DShotTelemetry::crc8(const uint8_t *buf, uint8_t len)
{
	uint8_t crc = 0;

	for (int i = 0; i < len; ++i) {
		crc = updateCrc8(buf[i], crc);
	}

	return crc;
}


void DShotTelemetry::requestNextMotor()
{
	_current_motor_index_request = (_current_motor_index_request + 1) % _num_motors;
	_current_request_start = 0;
	_frame_position = 0;
}

int DShotTelemetry::getRequestMotorIndex()
{
	if (_current_request_start != 0) {
		// already in progress, do not send another request
		return -1;
	}

	_current_request_start = hrt_absolute_time();
	return _current_motor_index_request;
}

void DShotTelemetry::decodeAndPrintEscInfoPacket(const OutputBuffer &buffer)
{
	static constexpr int version_position = 12;
	const uint8_t *data = buffer.buffer;

	if (buffer.buf_pos < version_position) {
		PX4_ERR("Not enough data received");
		return;
	}

	enum class ESCVersionInfo {
		BLHELI32,
		KissV1,
		KissV2,
	};
	ESCVersionInfo version;
	int packet_length;

	if (data[version_position] == 254) {
		version = ESCVersionInfo::BLHELI32;
		packet_length = esc_info_size_blheli32;

	} else if (data[version_position] == 255) {
		version = ESCVersionInfo::KissV2;
		packet_length = esc_info_size_kiss_v2;

	} else {
		version = ESCVersionInfo::KissV1;
		packet_length = esc_info_size_kiss_v1;
	}

	if (buffer.buf_pos != packet_length) {
		PX4_ERR("Packet length mismatch (%i != %i)", buffer.buf_pos, packet_length);
		return;
	}

	if (DShotTelemetry::crc8(data, packet_length - 1) != data[packet_length - 1]) {
		PX4_ERR("Checksum mismatch");
		return;
	}

	uint8_t esc_firmware_version = 0;
	uint8_t esc_firmware_subversion = 0;
	uint8_t esc_type = 0;

	switch (version) {
	case ESCVersionInfo::KissV1:
		esc_firmware_version = data[12];
		esc_firmware_subversion = (data[13] & 0x1f) + 97;
		esc_type = (data[13] & 0xe0) >> 5;
		break;

	case ESCVersionInfo::KissV2:
	case ESCVersionInfo::BLHELI32:
		esc_firmware_version = data[13];
		esc_firmware_subversion = data[14];
		esc_type = data[15];
		break;
	}

	const char *esc_type_str = "";

	switch (version) {
	case ESCVersionInfo::KissV1:
	case ESCVersionInfo::KissV2:
		switch (esc_type) {
		case 1: esc_type_str = "KISS8A";
			break;

		case 2: esc_type_str = "KISS16A";
			break;

		case 3: esc_type_str = "KISS24A";
			break;

		case 5: esc_type_str = "KISS Ultralite";
			break;

		default: esc_type_str = "KISS (unknown)";
			break;
		}

		break;

	case ESCVersionInfo::BLHELI32: {
			char *esc_type_mutable = (char *)(data + 31);
			esc_type_mutable[32] = 0;
			esc_type_str = esc_type_mutable;
		}
		break;
	}

	PX4_INFO("ESC Type: %s", esc_type_str);

	PX4_INFO("MCU Serial Number: %02x%02x%02x-%02x%02x%02x-%02x%02x%02x-%02x%02x%02x",
		 data[0], data[1], data[2], data[3], data[4], data[5], data[6], data[7], data[8],
		 data[9], data[10], data[11]);

	switch (version) {
	case ESCVersionInfo::KissV1:
	case ESCVersionInfo::KissV2:
		PX4_INFO("Firmware version: %d.%d%c", esc_firmware_version / 100, esc_firmware_version % 100,
			 (char)esc_firmware_subversion);
		break;

	case ESCVersionInfo::BLHELI32:
		PX4_INFO("Firmware version: %d.%d", esc_firmware_version, esc_firmware_subversion);
		break;
	}

	if (version == ESCVersionInfo::KissV2 || version == ESCVersionInfo::BLHELI32) {
		PX4_INFO("Rotation Direction: %s", data[16] ? "reversed" : "normal");
		PX4_INFO("3D Mode: %s", data[17] ? "on" : "off");
	}

	if (version == ESCVersionInfo::BLHELI32) {
		uint8_t setting = data[18];

		switch (setting) {
		case 0:
			PX4_INFO("Low voltage Limit: off");
			break;

		case 255:
			PX4_INFO("Low voltage Limit: unsupported");
			break;

		default:
			PX4_INFO("Low voltage Limit: %d.%01d V", setting / 10, setting % 10);
			break;
		}

		setting = data[19];

		switch (setting) {
		case 0:
			PX4_INFO("Current Limit: off");
			break;

		case 255:
			PX4_INFO("Current Limit: unsupported");
			break;

		default:
			PX4_INFO("Current Limit: %d A", setting);
			break;
		}

		for (int i = 0; i < 4; ++i) {
			setting = data[i + 20];
			PX4_INFO("LED %d: %s", i, setting ? (setting == 255 ? "unsupported" : "on") : "off");
		}
	}


}

int DShotTelemetry::setBaudrate(unsigned baud)
{
	int speed;

	switch (baud) {
	case 9600:   speed = B9600;   break;

	case 19200:  speed = B19200;  break;

	case 38400:  speed = B38400;  break;

	case 57600:  speed = B57600;  break;

	case 115200: speed = B115200; break;

	case 230400: speed = B230400; break;

	default:
		return -EINVAL;
	}

	struct termios uart_config;

	int termios_state;

	/* fill the struct for the new configuration */
	tcgetattr(_uart_fd, &uart_config);

	//
	// Input flags - Turn off input processing
	//
	// convert break to null byte, no CR to NL translation,
	// no NL to CR translation, don't mark parity errors or breaks
	// no input parity check, don't strip high bit off,
	// no XON/XOFF software flow control
	//
	uart_config.c_iflag &= ~(IGNBRK | BRKINT | ICRNL |
				 INLCR | PARMRK | INPCK | ISTRIP | IXON);
	//
	// Output flags - Turn off output processing
	//
	// no CR to NL translation, no NL to CR-NL translation,
	// no NL to CR translation, no column 0 CR suppression,
	// no Ctrl-D suppression, no fill characters, no case mapping,
	// no local output processing
	//
	// config.c_oflag &= ~(OCRNL | ONLCR | ONLRET |
	//                     ONOCR | ONOEOT| OFILL | OLCUC | OPOST);
	uart_config.c_oflag = 0;

	//
	// No line processing
	//
	// echo off, echo newline off, canonical mode off,
	// extended input processing off, signal chars off
	//
	uart_config.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);

	/* no parity, one stop bit, disable flow control */
	uart_config.c_cflag &= ~(CSTOPB | PARENB | CRTSCTS);

	/* set baud rate */
	if ((termios_state = cfsetispeed(&uart_config, speed)) < 0) {
		return -errno;
	}

	if ((termios_state = cfsetospeed(&uart_config, speed)) < 0) {
		return -errno;
	}

	if ((termios_state = tcsetattr(_uart_fd, TCSANOW, &uart_config)) < 0) {
		return -errno;
	}

	return 0;
}