/************************TRICK HEADER*************************
PURPOSE:
    (This comment lists out the other object files that are not included from c++ headers)
LIBRARY DEPENDENCIES:
    (
    )
*************************************************************/

#include "sim_objects/default_trick_sys.sm"


##include <math.h>
##include "sim_services/Message/include/message_proto.h"
##include "sim_services/Integrator/include/Integrator.hh"
##include "sim_services/Integrator/include/integrator_c_intf.h"

/* base ball... get it? :) */
class ballSimObject : public Trick::SimObject {

    public:
        double mass;
        double input_position[2];
        double speed;
        double elevation;

        double output_position[2];
        double output_velocity[2];
        double output_acceleration[2];
        double output_external_force[2];

        double origin[2];
        double input_force;
        double output_force[2];


        int force_default_data () {

            origin[0] = 0.0 ;
            origin[1] = 2.0 ;
            input_force = 8.0 ;

            return(0) ;
        } ;

        int state_default_data () {
            mass = 10.0 ;
            speed = 3.5 ;
            elevation = 0.785398163 ;
            input_position[0] = 5.0 ;
            input_position[1] = 5.0 ;

            return(0) ;
        } ;

        int state_init() {
            /* TRANSFER INPUT POSITION STATES TO OUTPUT POSITION STATES */
            output_position[0] = input_position[0];  /* X state */
            output_position[1] = input_position[1];  /* Y state */

            /* TRANSFER INPUT SPEED AND ELEVATION INTO THE VELOCITY VECTOR */
            output_velocity[0] = speed * cos( elevation ); /* X velocity */
            output_velocity[1] = speed * sin( elevation ); /* Y velocity */

            return(0) ;
        } ;

        int force_field() {
            /* LOCAL VARIABLE DECLARATIONS */
            double mag;
            double rel_pos[2];
            double unit[2];

            /* GET RELATIVE VECTOR FROM BALL TO FORCE ORIGIN */
            rel_pos[0] = origin[0] - output_position[0];
            rel_pos[1] = origin[1] - output_position[1];

            /* GET UNIT VECTOR AND POSITION MAGNITUDE FROM BALL TO FORCE ORIGIN */
            /* Note sigularity when ball position = force origin. */
            mag = sqrt( rel_pos[0]*rel_pos[0] + rel_pos[1]*rel_pos[1] );
            unit[0] = rel_pos[0] / mag;
            unit[1] = rel_pos[1] / mag;

            /* COMPUTE EXTERNAL FORCE ON BALL IN THE DIRECTION OF THE UNIT VECTOR */
            output_force[0] = input_force * (unit[0]);
            output_force[1] = input_force * (unit[1]);

            return(0) ;
        } ;

        int state_deriv() {

            output_external_force[0] = output_force[0] ;
            output_external_force[1] = output_force[1] ;

            /* SOLVE FOR THE X AND Y ACCELERATIONS OF THE BALL */
            output_acceleration[0] = output_external_force[0] / mass;
            output_acceleration[1] = output_external_force[1] / mass;

            return(0) ;
        };

        int state_integ() {

            int ipass;

            /* LOAD THE POSITION AND VELOCITY STATES */
            load_state(
                &output_position[0] ,
                &output_position[1] ,
                &output_velocity[0] ,
                &output_velocity[1] ,
                NULL
            );

            /* LOAD THE POSITION AND VELOCITY STATE DERIVATIVES */
            load_deriv(
                &output_velocity[0] ,
                &output_velocity[1] ,
                &output_acceleration[0] ,
                &output_acceleration[1] ,
                NULL
            );

            /* CALL THE TRICK INTEGRATION SERVICE */
            ipass = integrate();

            /* UNLOAD THE NEW POSITION AND VELOCITY STATES */
            unload_state(
                &output_position[0] ,
                &output_position[1] ,
                &output_velocity[0] ,
                &output_velocity[1] ,
                NULL
            );

            /* RETURN */
            return( ipass );

        } ;

        int state_print() {
            message_publish(8, "time = %f , position = %f , %f\n" , exec_get_sim_time() , output_position[0] , output_position[1]) ;
            return 0 ;
        } ;

        ballSimObject() {
            ("default_data") force_default_data() ;
            ("default_data") state_default_data() ;

            ("initialization") state_init() ;

            ("derivative") force_field() ;
            ("derivative") state_deriv() ;
            ("integration") trick_ret = state_integ() ;

            (10.0, "scheduled") trick_ret = state_print() ;

            ("freeze") state_print() ;
        }

} ;

// Instantiations
ballSimObject ball ;

IntegLoop my_integ_loop (0.01) ball;


// Connect objects
void create_connections() {

    // Set the default termination time
    exec_set_terminate_time(300.0) ;
    exec_set_freeze_frame(0.10) ;

    my_integ_loop.getIntegrator(Runge_Kutta_2, 4);

}

