/****************************************************************************
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 *   Copyright (c) 2016 PX4 Development Team. All rights reserved.
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 * 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
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/**
 * @file spektrum_rc.cpp
 *
 * This is a driver for a Spektrum satellite receiver connected to a Snapdragon
 * on the serial port. By default port J12 (next to J13, power module side) is used.
 */

#include <string.h>

#include <px4_platform_common/tasks.h>
#include <px4_platform_common/posix.h>
#include <px4_platform_common/getopt.h>

#include <lib/rc/dsm.h>
#include <drivers/drv_hrt.h>

#include <uORB/uORB.h>
#include <uORB/topics/input_rc.h>

// Snapdraogon: use J12 (next to J13, power module side)
#define SPEKTRUM_UART_DEVICE_PATH "/dev/tty-3"

#define UNUSED(x) (void)(x)

extern "C" { __EXPORT int spektrum_rc_main(int argc, char *argv[]); }


namespace spektrum_rc
{

volatile bool _task_should_exit = false;
static bool _is_running = false;
static px4_task_t _task_handle = -1;

int start();
int stop();
int info();
void usage();
void task_main(int argc, char *argv[]);

void fill_input_rc(uint16_t raw_rc_count, uint16_t raw_rc_values[input_rc_s::RC_INPUT_MAX_CHANNELS],
		   hrt_abstime now, bool frame_drop, bool failsafe, unsigned frame_drops, int rssi,
		   input_rc_s &input_rc);

void task_main(int argc, char *argv[])
{
	const char *device_path = SPEKTRUM_UART_DEVICE_PATH;
	int ch;
	int myoptind = 1;
	const char *myoptarg = NULL;

	while ((ch = px4_getopt(argc, argv, "d:", &myoptind, &myoptarg)) != EOF) {
		switch (ch) {
		case 'd':
			device_path = myoptarg;
			break;

		default:
			break;
		}
	}

	int uart_fd = dsm_init(device_path);

	if (uart_fd < 1) {
		PX4_ERR("dsm init failed");
		return;
	}

	orb_advert_t rc_pub = nullptr;

	// Use a buffer size of the double of the minimum, just to be safe.
	uint8_t rx_buf[2 * DSM_BUFFER_SIZE];

	_is_running = true;
	uint16_t raw_rc_values[input_rc_s::RC_INPUT_MAX_CHANNELS];
	uint16_t raw_rc_count = 0;

	// Main loop
	while (!_task_should_exit) {

		int newbytes = ::read(uart_fd, &rx_buf[0], sizeof(rx_buf));

		if (newbytes < 0) {
			PX4_WARN("read failed");
			continue;
		}

		if (newbytes == 0) {
			continue;
		}

		const hrt_abstime now = hrt_absolute_time();

		bool dsm_11_bit;
		unsigned frame_drops;
		int8_t dsm_rssi;

		// parse new data
		bool rc_updated = dsm_parse(now, rx_buf, newbytes, &raw_rc_values[0], &raw_rc_count,
					    &dsm_11_bit, &frame_drops, &dsm_rssi, input_rc_s::RC_INPUT_MAX_CHANNELS);
		UNUSED(dsm_11_bit);

		if (rc_updated) {

			input_rc_s input_rc = {};

			fill_input_rc(raw_rc_count, raw_rc_values, now, false, false, frame_drops, dsm_rssi,
				      input_rc);

			if (rc_pub == nullptr) {
				rc_pub = orb_advertise(ORB_ID(input_rc), &input_rc);

			} else {
				orb_publish(ORB_ID(input_rc), rc_pub, &input_rc);
			}
		}

		// sleep since no poll for qurt
		usleep(10000);

	}

	orb_unadvertise(rc_pub);
	dsm_deinit();

	_is_running = false;
}

void fill_input_rc(uint16_t raw_rc_count, uint16_t raw_rc_values[input_rc_s::RC_INPUT_MAX_CHANNELS],
		   hrt_abstime now, bool frame_drop, bool failsafe, unsigned frame_drops, int rssi,
		   input_rc_s &input_rc)
{
	input_rc.input_source = input_rc_s::RC_INPUT_SOURCE_QURT;

	input_rc.channel_count = raw_rc_count;

	if (input_rc.channel_count > input_rc_s::RC_INPUT_MAX_CHANNELS) {
		input_rc.channel_count = input_rc_s::RC_INPUT_MAX_CHANNELS;
	}

	unsigned valid_chans = 0;

	for (unsigned i = 0; i < input_rc.channel_count; ++i) {
		input_rc.values[i] = raw_rc_values[i];

		if (raw_rc_values[i] != UINT16_MAX) {
			valid_chans++;
		}
	}

	input_rc.timestamp = now;
	input_rc.timestamp_last_signal = input_rc.timestamp;
	input_rc.rc_ppm_frame_length = 0;

	/* fake rssi if no value was provided */
	if (rssi == -1) {

		input_rc.rssi = 255;

	} else {
		input_rc.rssi = rssi;
	}

	if (valid_chans == 0) {
		input_rc.rssi = 0;
	}

	input_rc.rc_failsafe = failsafe;
	input_rc.rc_lost = (valid_chans == 0);
	input_rc.rc_lost_frame_count = frame_drops;
	input_rc.rc_total_frame_count = 0;

	input_rc.link_quality = -1;
	input_rc.rssi_dbm = NAN;
}

int start(int argc, char *argv[])
{
	if (_is_running) {
		PX4_WARN("already running");
		return -1;
	}

	_task_should_exit = false;

	_task_handle = px4_task_spawn_cmd("spektrum_rc_main",
					  SCHED_DEFAULT,
					  SCHED_PRIORITY_DEFAULT,
					  2000,
					  (px4_main_t)&task_main,
					  (char *const *)argv);

	if (_task_handle < 0) {
		PX4_ERR("task start failed");
		return -1;
	}

	return 0;
}

int stop()
{
	if (!_is_running) {
		PX4_WARN("not running");
		return -1;
	}

	_task_should_exit = true;

	while (_is_running) {
		usleep(200000);
		PX4_INFO(".");
	}

	_task_handle = -1;
	return 0;
}

int info()
{
	PX4_INFO("running: %s", _is_running ? "yes" : "no");

	return 0;
}

void
usage()
{
	PX4_INFO("Usage: spektrum_rc {start|info|stop}");
}

} // namespace spektrum_rc


int spektrum_rc_main(int argc, char *argv[])
{
	int myoptind = 1;

	if (argc <= 1) {
		spektrum_rc::usage();
		return 1;
	}

	const char *verb = argv[myoptind];


	if (!strcmp(verb, "start")) {
		return spektrum_rc::start(argc - 1, argv + 1);
	}

	else if (!strcmp(verb, "stop")) {
		return spektrum_rc::stop();
	}

	else if (!strcmp(verb, "info")) {
		return spektrum_rc::info();
	}

	else {
		spektrum_rc::usage();
		return 1;
	}
}