/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/*
  simulator connection for JSBSim - https://github.com/JSBSim-Team/jsbsim
*/

#pragma once

#include <AP_HAL/utility/Socket.h>

#include "SIM_Aircraft.h"

namespace SITL {

/*
  a Jsbsim simulator
 */
class JSBSim : public Aircraft {
public:
    JSBSim(const char *frame_str);

    /* update model by one time step */
    void update(const struct sitl_input &input) override;

    /* static object creator */
    static Aircraft *create(const char *frame_str) {
        return new JSBSim(frame_str);
    }

private:
    // tcp input control socket to JSBSIm
    SocketAPM sock_control;

    // UDP packets from JSBSim in fgFDM format
    SocketAPM sock_fgfdm;

    bool initialised;

    uint16_t control_port;
    uint16_t fdm_port;
    char *jsbsim_script;
    char *jsbsim_fgout;
    int jsbsim_stdout;

    // default JSBSim model
    const char *jsbsim_model = "Rascal";

    bool created_templates;
    bool started_jsbsim;
    bool opened_control_socket;
    bool opened_fdm_socket;

    enum {
        FRAME_NORMAL,
        FRAME_ELEVON,
        FRAME_VTAIL
    } frame;

    bool create_templates(void);
    bool start_JSBSim(void);
    bool open_control_socket(void);
    bool open_fdm_socket(void);
    void send_servos(const struct sitl_input &input);
    void recv_fdm(const struct sitl_input &input);
    void check_stdout(void) const;
    bool expect(const char *str) const;

    void drain_control_socket();
};

/*
  FGNetFDM class from JSBSim
 */
class FGNetFDM {
public:

    enum {
        FG_MAX_ENGINES = 4,
        FG_MAX_WHEELS = 3,
        FG_MAX_TANKS = 4
    };

    uint32_t version;		// increment when data values change
    uint32_t padding;		// padding

    // Positions
    double longitude;		// geodetic (radians)
    double latitude;		// geodetic (radians)
    double altitude;		// above sea level (meters)
    float agl;			    // above ground level (meters)
    float phi;			    // roll (radians)
    float theta;		    // pitch (radians)
    float psi;			    // yaw or true heading (radians)
    float alpha;        // angle of attack (radians)
    float beta;         // side slip angle (radians)

    // Velocities
    float phidot;		     // roll rate (radians/sec)
    float thetadot;		   // pitch rate (radians/sec)
    float psidot;		     // yaw rate (radians/sec)
    float vcas;          // calibrated airspeed
    float climb_rate;		 // feet per second
    float v_north;       // north velocity in local/body frame, fps
    float v_east;        // east velocity in local/body frame, fps
    float v_down;        // down/vertical velocity in local/body frame, fps
    float v_body_u;      // ECEF velocity in body axis
    float v_body_v;      // ECEF velocity in body axis
    float v_body_w;      // ECEF velocity in body axis

    // Accelerations
    float A_X_pilot;		// X accel in body frame ft/sec^2
    float A_Y_pilot;		// Y accel in body frame ft/sec^2
    float A_Z_pilot;		// Z accel in body frame ft/sec^2

    // Stall
    float stall_warning;  // 0.0 - 1.0 indicating the amount of stall
    float slip_deg;		    // slip ball deflection

    // Pressure

    // Engine status
    uint32_t num_engines;               // Number of valid engines
    uint32_t eng_state[FG_MAX_ENGINES]; // Engine state (off, cranking, running)
    float rpm[FG_MAX_ENGINES];          // Engine RPM rev/min
    float fuel_flow[FG_MAX_ENGINES];    // Fuel flow gallons/hr
    float fuel_px[FG_MAX_ENGINES];      // Fuel pressure psi
    float egt[FG_MAX_ENGINES];          // Exhuast gas temp deg F
    float cht[FG_MAX_ENGINES];          // Cylinder head temp deg F
    float mp_osi[FG_MAX_ENGINES];       // Manifold pressure
    float tit[FG_MAX_ENGINES];          // Turbine Inlet Temperature
    float oil_temp[FG_MAX_ENGINES];     // Oil temp deg F
    float oil_px[FG_MAX_ENGINES];       // Oil pressure psi

    // Consumables
    uint32_t num_tanks;		              // Max number of fuel tanks
    float fuel_quantity[FG_MAX_TANKS];

    // Gear status
    uint32_t num_wheels;
    uint32_t wow[FG_MAX_WHEELS];
    float gear_pos[FG_MAX_WHEELS];
    float gear_steer[FG_MAX_WHEELS];
    float gear_compression[FG_MAX_WHEELS];

    // Environment
    uint32_t cur_time;           // current simulation time of JSBSim
    int32_t warp;                // offset in seconds to unix time
    float visibility;            // visibility in meters (for env. effects)

    // Control surface positions (normalized values)
    float elevator;
    float elevator_trim_tab;
    float left_flap;
    float right_flap;
    float left_aileron;
    float right_aileron;
    float rudder;
    float nose_wheel;
    float speedbrake;
    float spoilers;

    // nasty hack .... JSBSim sends in little-endian
    void ByteSwap(void);
};

} // namespace SITL