/****************************************************************************
 *
 *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
 *   Author: 	@author Thomas Gubler <thomasgubler@student.ethz.ch>
 *   			@author Doug Weibel <douglas.weibel@colorado.edu>
 *
 * 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.
 *
 ****************************************************************************/
/**
 * @file fixedwing_pos_control.c
 * Implementation of a fixed wing attitude controller.
 */

#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <math.h>
#include <poll.h>
#include <time.h>
#include <drivers/drv_hrt.h>
#include <arch/board/board.h>
#include <uORB/uORB.h>
#include <uORB/topics/vehicle_global_position.h>
#include <uORB/topics/vehicle_global_position_setpoint.h>
#include <uORB/topics/vehicle_attitude_setpoint.h>
#include <uORB/topics/manual_control_setpoint.h>
#include <uORB/topics/actuator_controls.h>
#include <uORB/topics/vehicle_rates_setpoint.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/parameter_update.h>
#include <systemlib/param/param.h>
#include <systemlib/pid/pid.h>
#include <systemlib/geo/geo.h>
#include <systemlib/perf_counter.h>
#include <systemlib/systemlib.h>

/*
 * Controller parameters, accessible via MAVLink
 *
 */
PARAM_DEFINE_FLOAT(FW_HEAD_P, 0.1f);
PARAM_DEFINE_FLOAT(FW_HEADR_I, 0.1f);
PARAM_DEFINE_FLOAT(FW_HEADR_LIM, 1.5f); //TODO: think about reasonable value
PARAM_DEFINE_FLOAT(FW_XTRACK_P, 0.01745f);		// Radians per meter off track
PARAM_DEFINE_FLOAT(FW_ALT_P, 0.1f);
PARAM_DEFINE_FLOAT(FW_ROLL_LIM, 0.7f);	// Roll angle limit in radians
PARAM_DEFINE_FLOAT(FW_HEADR_P, 0.1f);
PARAM_DEFINE_FLOAT(FW_PITCH_LIM, 0.35f);	/**< Pitch angle limit in radians per second */

struct fw_pos_control_params {
	float heading_p;
	float headingr_p;
	float headingr_i;
	float headingr_lim;
	float xtrack_p;
	float altitude_p;
	float roll_lim;
	float pitch_lim;
};

struct fw_pos_control_param_handles {
	param_t heading_p;
	param_t headingr_p;
	param_t headingr_i;
	param_t headingr_lim;
	param_t xtrack_p;
	param_t altitude_p;
	param_t roll_lim;
	param_t pitch_lim;
};


struct planned_path_segments_s {
	bool segment_type;
	double start_lat;			// Start of line or center of arc
	double start_lon;
	double end_lat;
	double end_lon;
	float radius;				// Radius of arc
	float arc_start_bearing;		// Bearing from center to start of arc
	float arc_sweep;				// Angle (radians) swept out by arc around center.
	// Positive for clockwise, negative for counter-clockwise
};


/* Prototypes */
/* Internal Prototypes */
static int parameters_init(struct fw_pos_control_param_handles *h);
static int parameters_update(const struct fw_pos_control_param_handles *h, struct fw_pos_control_params *p);

/**
 * Deamon management function.
 */
__EXPORT int fixedwing_pos_control_main(int argc, char *argv[]);

/**
 * Mainloop of deamon.
 */
int fixedwing_pos_control_thread_main(int argc, char *argv[]);

/**
 * Print the correct usage.
 */
static void usage(const char *reason);

/* Variables */
static bool thread_should_exit = false;		/**< Deamon exit flag */
static bool thread_running = false;		/**< Deamon status flag */
static int deamon_task;				/**< Handle of deamon task / thread */


/**
 * Parameter management
 */
static int parameters_init(struct fw_pos_control_param_handles *h)
{
	/* PID parameters */
	h->heading_p 		=	param_find("FW_HEAD_P");
	h->headingr_p 		=	param_find("FW_HEADR_P");
	h->headingr_i 		=	param_find("FW_HEADR_I");
	h->headingr_lim 	=	param_find("FW_HEADR_LIM");
	h->xtrack_p 		=	param_find("FW_XTRACK_P");
	h->altitude_p 		=	param_find("FW_ALT_P");
	h->roll_lim 		=	param_find("FW_ROLL_LIM");
	h->pitch_lim 		=	param_find("FW_PITCH_LIM");

	return OK;
}

static int parameters_update(const struct fw_pos_control_param_handles *h, struct fw_pos_control_params *p)
{
	param_get(h->heading_p, &(p->heading_p));
	param_get(h->headingr_p, &(p->headingr_p));
	param_get(h->headingr_i, &(p->headingr_i));
	param_get(h->headingr_lim, &(p->headingr_lim));
	param_get(h->xtrack_p, &(p->xtrack_p));
	param_get(h->altitude_p, &(p->altitude_p));
	param_get(h->roll_lim, &(p->roll_lim));
	param_get(h->pitch_lim, &(p->pitch_lim));

	return OK;
}


/* Main Thread */
int fixedwing_pos_control_thread_main(int argc, char *argv[])
{
	/* read arguments */
	bool verbose = false;

	for (int i = 1; i < argc; i++) {
		if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
			verbose = true;
		}
	}

	/* welcome user */
	printf("[fixedwing pos control] started\n");

	/* declare and safely initialize all structs */
	struct vehicle_global_position_s global_pos;
	memset(&global_pos, 0, sizeof(global_pos));
	struct vehicle_global_position_s start_pos;		// Temporary variable, replace with
	memset(&start_pos, 0, sizeof(start_pos));		// previous waypoint when available
	struct vehicle_global_position_setpoint_s global_setpoint;
	memset(&global_setpoint, 0, sizeof(global_setpoint));
	struct vehicle_attitude_s att;
	memset(&att, 0, sizeof(att));
	struct crosstrack_error_s xtrack_err;
	memset(&xtrack_err, 0, sizeof(xtrack_err));
	struct parameter_update_s param_update;
	memset(&param_update, 0, sizeof(param_update));

	/* output structs */
	struct vehicle_attitude_setpoint_s attitude_setpoint;
	memset(&attitude_setpoint, 0, sizeof(attitude_setpoint));

	/* publish attitude setpoint */
	attitude_setpoint.roll_body = 0.0f;
	attitude_setpoint.pitch_body = 0.0f;
	attitude_setpoint.yaw_body = 0.0f;
	attitude_setpoint.thrust = 0.0f;
	orb_advert_t attitude_setpoint_pub = orb_advertise(ORB_ID(vehicle_attitude_setpoint), &attitude_setpoint);

	/* subscribe */
	int global_pos_sub = orb_subscribe(ORB_ID(vehicle_global_position));
	int global_setpoint_sub = orb_subscribe(ORB_ID(vehicle_global_position_setpoint));
	int att_sub = orb_subscribe(ORB_ID(vehicle_attitude));
	int param_sub = orb_subscribe(ORB_ID(parameter_update));

	/* Setup of loop */
	struct pollfd fds[2] = {
		{ .fd = param_sub, .events = POLLIN },
		{ .fd = att_sub, .events = POLLIN }
	};
	bool global_sp_updated_set_once = false;

	float psi_track = 0.0f;

	int counter = 0;

	struct fw_pos_control_params p;
	struct fw_pos_control_param_handles h;

	PID_t heading_controller;
	PID_t heading_rate_controller;
	PID_t offtrack_controller;
	PID_t altitude_controller;

	parameters_init(&h);
	parameters_update(&h, &p);
	pid_init(&heading_controller, p.heading_p, 0.0f, 0.0f, 0.0f, 10000.0f, PID_MODE_DERIVATIV_NONE); //arbitrary high limit
	pid_init(&heading_rate_controller, p.headingr_p, p.headingr_i, 0.0f, 0.0f, p.roll_lim, PID_MODE_DERIVATIV_NONE);
	pid_init(&altitude_controller, p.altitude_p, 0.0f, 0.0f, 0.0f, p.pitch_lim, PID_MODE_DERIVATIV_NONE);
	pid_init(&offtrack_controller, p.xtrack_p, 0.0f, 0.0f, 0.0f , 60.0f * M_DEG_TO_RAD, PID_MODE_DERIVATIV_NONE); //TODO: remove hardcoded value

	/* error and performance monitoring */
	perf_counter_t fw_interval_perf = perf_alloc(PC_INTERVAL, "fixedwing_pos_control_interval");
	perf_counter_t fw_err_perf = perf_alloc(PC_COUNT, "fixedwing_pos_control_err");

	while (!thread_should_exit) {
		/* wait for a sensor update, check for exit condition every 500 ms */
		int ret = poll(fds, 2, 500);

		if (ret < 0) {
			/* poll error, count it in perf */
			perf_count(fw_err_perf);

		} else if (ret == 0) {
			/* no return value, ignore */
		} else {

			/* only update parameters if they changed */
			if (fds[0].revents & POLLIN) {
				/* read from param to clear updated flag */
				struct parameter_update_s update;
				orb_copy(ORB_ID(parameter_update), param_sub, &update);

				/* update parameters from storage */
				parameters_update(&h, &p);
				pid_set_parameters(&heading_controller, p.heading_p, 0, 0, 0, 10000.0f); //arbitrary high limit
				pid_set_parameters(&heading_rate_controller, p.headingr_p, p.headingr_i, 0, 0, p.roll_lim);
				pid_set_parameters(&altitude_controller, p.altitude_p, 0, 0, 0, p.pitch_lim);
				pid_set_parameters(&offtrack_controller, p.xtrack_p, 0, 0, 0, 60.0f * M_DEG_TO_RAD); //TODO: remove hardcoded value
			}

			/* only run controller if attitude changed */
			if (fds[1].revents & POLLIN) {


				static uint64_t last_run = 0;
				const float deltaT = (hrt_absolute_time() - last_run) / 1000000.0f;
				last_run = hrt_absolute_time();

				/* check if there is a new position or setpoint */
				bool pos_updated;
				orb_check(global_pos_sub, &pos_updated);
				bool global_sp_updated;
				orb_check(global_setpoint_sub, &global_sp_updated);

				/* load local copies */
				orb_copy(ORB_ID(vehicle_attitude), att_sub, &att);

				if (pos_updated) {
					orb_copy(ORB_ID(vehicle_global_position), global_pos_sub, &global_pos);
				}

				if (global_sp_updated) {
					orb_copy(ORB_ID(vehicle_global_position_setpoint), global_setpoint_sub, &global_setpoint);
					start_pos = global_pos; //for now using the current position as the startpoint (= approx. last waypoint because the setpoint switch occurs at the waypoint)
					global_sp_updated_set_once = true;
					psi_track = get_bearing_to_next_waypoint((double)global_pos.lat / (double)1e7d, (double)global_pos.lon / (double)1e7d,
							(double)global_setpoint.lat / (double)1e7d, (double)global_setpoint.lon / (double)1e7d);

					printf("next wp direction: %0.4f\n", (double)psi_track);
				}

				/* Simple Horizontal Control */
				if (global_sp_updated_set_once) {
					//				if (counter % 100 == 0)
					//					printf("lat_sp %d, ln_sp %d, lat: %d, lon: %d\n", global_setpoint.lat, global_setpoint.lon, global_pos.lat, global_pos.lon);

					/* calculate crosstrack error */
					// Only the case of a straight line track following handled so far
					int distance_res = get_distance_to_line(&xtrack_err, (double)global_pos.lat / (double)1e7d, (double)global_pos.lon / (double)1e7d,
										(double)start_pos.lat / (double)1e7d, (double)start_pos.lon / (double)1e7d,
										(double)global_setpoint.lat / (double)1e7d, (double)global_setpoint.lon / (double)1e7d);

					// XXX what is xtrack_err.past_end?
					if (distance_res == OK /*&& !xtrack_err.past_end*/) {

						float delta_psi_c = pid_calculate(&offtrack_controller, 0, xtrack_err.distance, 0.0f, 0.0f); //p.xtrack_p * xtrack_err.distance

						float psi_c = psi_track + delta_psi_c;
						float psi_e = psi_c - att.yaw;

						/* wrap difference back onto -pi..pi range */
						psi_e = _wrap_pi(psi_e);

						if (verbose) {
							printf("xtrack_err.distance %.4f ", (double)xtrack_err.distance);
							printf("delta_psi_c %.4f ", (double)delta_psi_c);
							printf("psi_c %.4f ", (double)psi_c);
							printf("att.yaw %.4f ", (double)att.yaw);
							printf("psi_e %.4f ", (double)psi_e);
						}

						/* calculate roll setpoint, do this artificially around zero */
						float delta_psi_rate_c = pid_calculate(&heading_controller, psi_e, 0.0f, 0.0f, 0.0f);
						float psi_rate_track = 0; //=V_gr/r_track , this will be needed for implementation of arc following
						float psi_rate_c = delta_psi_rate_c + psi_rate_track;

						/* limit turn rate */
						if (psi_rate_c > p.headingr_lim) {
							psi_rate_c = p.headingr_lim;

						} else if (psi_rate_c < -p.headingr_lim) {
							psi_rate_c = -p.headingr_lim;
						}

						float psi_rate_e = psi_rate_c - att.yawspeed;

						// XXX sanity check: Assume 10 m/s stall speed and no stall condition
						float ground_speed = sqrtf(global_pos.vx * global_pos.vx + global_pos.vy * global_pos.vy);

						if (ground_speed < 10.0f) {
							ground_speed = 10.0f;
						}

						float psi_rate_e_scaled = psi_rate_e * ground_speed / 9.81f; //* V_gr / g

						attitude_setpoint.roll_body = pid_calculate(&heading_rate_controller, psi_rate_e_scaled, 0.0f, 0.0f, deltaT);

						if (verbose) {
							printf("psi_rate_c %.4f ", (double)psi_rate_c);
							printf("psi_rate_e_scaled %.4f ", (double)psi_rate_e_scaled);
							printf("rollbody %.4f\n", (double)attitude_setpoint.roll_body);
						}

						if (verbose && counter % 100 == 0)
							printf("xtrack_err.distance: %0.4f, delta_psi_c: %0.4f\n", xtrack_err.distance, delta_psi_c);

					} else {
						if (verbose && counter % 100 == 0)
							printf("distance_res: %d, past_end %d\n", distance_res, xtrack_err.past_end);
					}

					/* Very simple Altitude Control */
					if (pos_updated) {

						//TODO: take care of relative vs. ab. altitude
						attitude_setpoint.pitch_body = pid_calculate(&altitude_controller, global_setpoint.altitude, global_pos.alt, 0.0f, 0.0f);

					}

					// XXX need speed control
					attitude_setpoint.thrust = 0.7f;

					/* publish the attitude setpoint */
					orb_publish(ORB_ID(vehicle_attitude_setpoint), attitude_setpoint_pub, &attitude_setpoint);

					/* measure in what intervals the controller runs */
					perf_count(fw_interval_perf);

					counter++;

				} else {
					// XXX no setpoint, decent default needed (loiter?)
				}
			}
		}
	}

	printf("[fixedwing_pos_control] exiting.\n");
	thread_running = false;


	close(attitude_setpoint_pub);

	fflush(stdout);
	exit(0);

	return 0;

}

/* Startup Functions */

static void
usage(const char *reason)
{
	if (reason)
		fprintf(stderr, "%s\n", reason);

	fprintf(stderr, "usage: fixedwing_pos_control {start|stop|status}\n\n");
	exit(1);
}

/**
 * The deamon app only briefly exists to start
 * the background job. The stack size assigned in the
 * Makefile does only apply to this management task.
 *
 * The actual stack size should be set in the call
 * to task_create().
 */
int fixedwing_pos_control_main(int argc, char *argv[])
{
	if (argc < 1)
		usage("missing command");

	if (!strcmp(argv[1], "start")) {

		if (thread_running) {
			printf("fixedwing_pos_control already running\n");
			/* this is not an error */
			exit(0);
		}

		thread_should_exit = false;
		deamon_task = task_spawn("fixedwing_pos_control",
					 SCHED_DEFAULT,
					 SCHED_PRIORITY_MAX - 20,
					 2048,
					 fixedwing_pos_control_thread_main,
					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
		thread_running = true;
		exit(0);
	}

	if (!strcmp(argv[1], "stop")) {
		thread_should_exit = true;
		exit(0);
	}

	if (!strcmp(argv[1], "status")) {
		if (thread_running) {
			printf("\tfixedwing_pos_control is running\n");

		} else {
			printf("\tfixedwing_pos_control not started\n");
		}

		exit(0);
	}

	usage("unrecognized command");
	exit(1);
}
