// environment_ctrl.cxx -- manager for natural environment information.
//
// Written by David Megginson, started February 2002.
//
// Copyright (C) 2002  David Megginson - david@megginson.com
//
// 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 2 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, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$

#include <simgear/debug/logstream.hxx>

#include <stdlib.h>
#include <Main/fg_props.hxx>

#include "environment_ctrl.hxx"



////////////////////////////////////////////////////////////////////////
// Implementation of FGEnvironmentCtrl abstract base class.
////////////////////////////////////////////////////////////////////////

FGEnvironmentCtrl::FGEnvironmentCtrl ()
  : _environment(0),
    _lon_deg(0),
    _lat_deg(0),
    _elev_ft(0)
{
}

FGEnvironmentCtrl::~FGEnvironmentCtrl ()
{
}

void
FGEnvironmentCtrl::setEnvironment (FGEnvironment * environment)
{
  _environment = environment;
}

void
FGEnvironmentCtrl::setLongitudeDeg (double lon_deg)
{
  _lon_deg = lon_deg;
}

void
FGEnvironmentCtrl::setLatitudeDeg (double lat_deg)
{
  _lat_deg = lat_deg;
}

void
FGEnvironmentCtrl::setElevationFt (double elev_ft)
{
  _elev_ft = elev_ft;
}

void
FGEnvironmentCtrl::setPosition (double lon_deg, double lat_deg, double elev_ft)
{
  _lon_deg = lon_deg;
  _lat_deg = lat_deg;
  _elev_ft = elev_ft;
}



////////////////////////////////////////////////////////////////////////
// Implementation of FGUserDefEnvironmentCtrl.
////////////////////////////////////////////////////////////////////////

FGUserDefEnvironmentCtrl::FGUserDefEnvironmentCtrl ()
  : _base_wind_speed_node(0),
    _gust_wind_speed_node(0),
    _current_wind_speed_kt(0),
    _delta_wind_speed_kt(0)
{
}

FGUserDefEnvironmentCtrl::~FGUserDefEnvironmentCtrl ()
{
}

void
FGUserDefEnvironmentCtrl::init ()
{
				// Fill in some defaults.
  if (!fgHasNode("/environment/params/base-wind-speed-kt"))
    fgSetDouble("/environment/params/base-wind-speed-kt",
		fgGetDouble("/environment/wind-speed-kt"));
  if (!fgHasNode("/environment/params/gust-wind-speed-kt"))
    fgSetDouble("/environment/params/gust-wind-speed-kt",
		fgGetDouble("/environment/params/base-wind-speed-kt"));

  _base_wind_speed_node =
    fgGetNode("/environment/params/base-wind-speed-kt", true);
  _gust_wind_speed_node =
    fgGetNode("/environment/params/gust-wind-speed-kt", true);

  _current_wind_speed_kt = _base_wind_speed_node->getDoubleValue();
  _delta_wind_speed_kt = 0.1;
}

void
FGUserDefEnvironmentCtrl::update (int dt)
{
  double base_wind_speed = _base_wind_speed_node->getDoubleValue();
  double gust_wind_speed = _gust_wind_speed_node->getDoubleValue();

  if (base_wind_speed == gust_wind_speed) {
    _current_wind_speed_kt = base_wind_speed;
  } else {
    int rn = rand() % 128;
    int sign = (_delta_wind_speed_kt < 0 ? -1 : 1);
    double gust = _current_wind_speed_kt - base_wind_speed;
    double incr = gust / 50;

    if (rn == 0)
      _delta_wind_speed_kt = - _delta_wind_speed_kt;
    else if (rn < 4)
      _delta_wind_speed_kt -= incr * sign;
    else if (rn < 16)
      _delta_wind_speed_kt += incr * sign;

    _current_wind_speed_kt += _delta_wind_speed_kt;

    if (_current_wind_speed_kt < base_wind_speed) {
      _current_wind_speed_kt = base_wind_speed;
      _delta_wind_speed_kt = 0.01;
    } else if (_current_wind_speed_kt > gust_wind_speed) {
      _current_wind_speed_kt = gust_wind_speed;
      _delta_wind_speed_kt = -0.01;
    }
  }
  
  if (_environment != 0)
    _environment->set_wind_speed_kt(_current_wind_speed_kt);
}

// end of environment_ctrl.cxx