flightgear/src/Main/options.cxx

// options.cxx -- class to handle command line options
//
// Written by Curtis Olson, started April 1998.
//
// Copyright (C) 1998  Curtis L. Olson  - http://www.flightgear.org/~curt
//
// 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// $Id$


#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <simgear/compiler.h>
#include <simgear/structure/exception.hxx>
#include <simgear/debug/logstream.hxx>
#include <simgear/timing/sg_time.hxx>
#include <simgear/misc/sg_dir.hxx>

#include <boost/foreach.hpp>

#include <math.h>		// rint()
#include <stdio.h>
#include <stdlib.h>		// atof(), atoi()
#include <string.h>		// strcmp()
#include <algorithm>

#include <iostream>
#include <string>

#include <simgear/math/sg_random.h>
#include <simgear/props/props_io.hxx>
#include <simgear/misc/sgstream.hxx>
#include <simgear/misc/sg_path.hxx>
#include <simgear/scene/material/mat.hxx>
#include <simgear/sound/soundmgr_openal.hxx>
#include <simgear/misc/strutils.hxx>
#include <Autopilot/route_mgr.hxx>
#include <GUI/gui.h>

#include "globals.hxx"
#include "fg_init.hxx"
#include "fg_props.hxx"
#include "options.hxx"
#include "util.hxx"
#include "main.hxx"
#include "locale.hxx"
#include <Viewer/viewer.hxx>
#include <Viewer/viewmgr.hxx>
#include <Environment/presets.hxx>

#include <osg/Version>

#if defined( HAVE_VERSION_H ) && HAVE_VERSION_H
#  include <Include/version.h>
#  include <simgear/version.h>
#else
#  include <Include/no_version.h>
#endif

#ifdef __APPLE__
#  include <CoreFoundation/CoreFoundation.h>
#endif

using std::string;
using std::sort;
using std::cout;
using std::cerr;
using std::endl;
using std::vector;
using std::cin;

#define NEW_DEFAULT_MODEL_HZ 120

enum
{
    FG_OPTIONS_OK = 0,
    FG_OPTIONS_HELP = 1,
    FG_OPTIONS_ERROR = 2,
    FG_OPTIONS_EXIT = 3,
    FG_OPTIONS_VERBOSE_HELP = 4,
    FG_OPTIONS_SHOW_AIRCRAFT = 5,
    FG_OPTIONS_SHOW_SOUND_DEVICES = 6
};

static flightgear::Options* shared_instance = NULL;

static double
atof( const string& str )
{
    return ::atof( str.c_str() );
}

static int
atoi( const string& str )
{
    return ::atoi( str.c_str() );
}

static int fgSetupProxy( const char *arg );

/**
 * Set a few fail-safe default property values.
 *
 * These should all be set in $FG_ROOT/preferences.xml, but just
 * in case, we provide some initial sane values here. This method
 * should be invoked *before* reading any init files.
 */
static void
fgSetDefaults ()
{

				// Position (deliberately out of range)
    fgSetDouble("/position/longitude-deg", 9999.0);
    fgSetDouble("/position/latitude-deg", 9999.0);
    fgSetDouble("/position/altitude-ft", -9999.0);

				// Orientation
    fgSetDouble("/orientation/heading-deg", 9999.0);
    fgSetDouble("/orientation/roll-deg", 0.0);
    fgSetDouble("/orientation/pitch-deg", 0.424);

				// Velocities
    fgSetDouble("/velocities/uBody-fps", 0.0);
    fgSetDouble("/velocities/vBody-fps", 0.0);
    fgSetDouble("/velocities/wBody-fps", 0.0);
    fgSetDouble("/velocities/speed-north-fps", 0.0);
    fgSetDouble("/velocities/speed-east-fps", 0.0);
    fgSetDouble("/velocities/speed-down-fps", 0.0);
    fgSetDouble("/velocities/airspeed-kt", 0.0);
    fgSetDouble("/velocities/mach", 0.0);

                                // Presets
    fgSetDouble("/sim/presets/longitude-deg", 9999.0);
    fgSetDouble("/sim/presets/latitude-deg", 9999.0);
    fgSetDouble("/sim/presets/altitude-ft", -9999.0);

    fgSetDouble("/sim/presets/heading-deg", 9999.0);
    fgSetDouble("/sim/presets/roll-deg", 0.0);
    fgSetDouble("/sim/presets/pitch-deg", 0.424);

    fgSetString("/sim/presets/speed-set", "knots");
    fgSetDouble("/sim/presets/airspeed-kt", 0.0);
    fgSetDouble("/sim/presets/mach", 0.0);
    fgSetDouble("/sim/presets/uBody-fps", 0.0);
    fgSetDouble("/sim/presets/vBody-fps", 0.0);
    fgSetDouble("/sim/presets/wBody-fps", 0.0);
    fgSetDouble("/sim/presets/speed-north-fps", 0.0);
    fgSetDouble("/sim/presets/speed-east-fps", 0.0);
    fgSetDouble("/sim/presets/speed-down-fps", 0.0);

    fgSetBool("/sim/presets/onground", true);
    fgSetBool("/sim/presets/trim", false);

				// Miscellaneous
    fgSetBool("/sim/startup/game-mode", false);
    fgSetBool("/sim/startup/splash-screen", true);
    fgSetBool("/sim/startup/intro-music", true);
    // we want mouse-pointer to have an undefined value if nothing is
    // specified so we can do the right thing for voodoo-1/2 cards.
    // fgSetString("/sim/startup/mouse-pointer", "disabled");
    fgSetString("/sim/control-mode", "joystick");
    fgSetBool("/controls/flight/auto-coordination", false);
    fgSetString("/sim/logging/priority", "alert");

				// Features
    fgSetBool("/sim/hud/color/antialiased", false);
    fgSetBool("/sim/hud/enable3d[1]", true);
    fgSetBool("/sim/hud/visibility[1]", false);
    fgSetBool("/sim/panel/visibility", true);
    fgSetBool("/sim/sound/enabled", true);
    fgSetBool("/sim/sound/working", true);

				// Flight Model options
    fgSetString("/sim/flight-model", "jsb");
    fgSetString("/sim/aero", "c172");
    fgSetInt("/sim/model-hz", NEW_DEFAULT_MODEL_HZ);
    fgSetInt("/sim/speed-up", 1);

				// Rendering options
    fgSetString("/sim/rendering/fog", "nicest");
    fgSetBool("/environment/clouds/status", true);
    fgSetBool("/sim/startup/fullscreen", false);
    fgSetBool("/sim/rendering/shading", true);
    fgSetBool("/sim/rendering/skyblend", true);
    fgSetBool("/sim/rendering/textures", true);
    fgTie( "/sim/rendering/filtering", SGGetTextureFilter, SGSetTextureFilter, false);
    fgSetInt("/sim/rendering/filtering", 1);
    fgSetBool("/sim/rendering/wireframe", false);
    fgSetBool("/sim/rendering/horizon-effect", false);
    fgSetBool("/sim/rendering/enhanced-lighting", false);
    fgSetBool("/sim/rendering/distance-attenuation", false);
    fgSetBool("/sim/rendering/specular-highlight", true);
    fgSetString("/sim/rendering/materials-file", "materials.xml");
    fgSetInt("/sim/startup/xsize", 800);
    fgSetInt("/sim/startup/ysize", 600);
    fgSetInt("/sim/rendering/bits-per-pixel", 16);
    fgSetString("/sim/view-mode", "pilot");
    fgSetDouble("/sim/current-view/heading-offset-deg", 0);

				// HUD options
    fgSetString("/sim/startup/units", "feet");
    fgSetString("/sim/hud/frame-stat-type", "tris");

				// Time options
    fgSetInt("/sim/startup/time-offset", 0);
    fgSetString("/sim/startup/time-offset-type", "system-offset");
    fgSetLong("/sim/time/cur-time-override", 0);

                                // Freeze options
    fgSetBool("/sim/freeze/master", false);
    fgSetBool("/sim/freeze/position", false);
    fgSetBool("/sim/freeze/clock", false);
    fgSetBool("/sim/freeze/fuel", false);

    fgSetString("/sim/multiplay/callsign", "callsign");
    fgSetString("/sim/multiplay/rxhost", "");
    fgSetString("/sim/multiplay/txhost", "");
    fgSetInt("/sim/multiplay/rxport", 0);
    fgSetInt("/sim/multiplay/txport", 0);
    
    fgSetString("/sim/version/flightgear", FLIGHTGEAR_VERSION);
    fgSetString("/sim/version/simgear", SG_STRINGIZE(SIMGEAR_VERSION));
    fgSetString("/sim/version/openscenegraph", osgGetVersion());
    fgSetString("/sim/version/revision", REVISION);
    fgSetInt("/sim/version/build-number", HUDSON_BUILD_NUMBER);
    fgSetString("/sim/version/build-id", HUDSON_BUILD_ID);
  
  char* envp = ::getenv( "http_proxy" );
    if( envp != NULL )
      fgSetupProxy( envp );
}

static bool
parse_wind (const string &wind, double * min_hdg, double * max_hdg,
	    double * speed, double * gust)
{
  string::size_type pos = wind.find('@');
  if (pos == string::npos)
    return false;
  string dir = wind.substr(0, pos);
  string spd = wind.substr(pos+1);
  pos = dir.find(':');
  if (pos == string::npos) {
    *min_hdg = *max_hdg = atof(dir.c_str());
  } else {
    *min_hdg = atof(dir.substr(0,pos).c_str());
    *max_hdg = atof(dir.substr(pos+1).c_str());
  }
  pos = spd.find(':');
  if (pos == string::npos) {
    *speed = *gust = atof(spd.c_str());
  } else {
    *speed = atof(spd.substr(0,pos).c_str());
    *gust = atof(spd.substr(pos+1).c_str());
  }
  return true;
}

static bool
parseIntValue(char** ppParserPos, int* pValue,int min, int max, const char* field, const char* argument)
{
    if ( !strlen(*ppParserPos) )
        return true;

    char num[256];
    int i = 0;

    while ( isdigit((*ppParserPos)[0]) && (i<255) )
    {
        num[i] = (*ppParserPos)[0];
        (*ppParserPos)++;
        i++;
    }
    num[i] = '\0';

    switch ((*ppParserPos)[0])
    {
        case 0:
            break;
        case ':':
            (*ppParserPos)++;
            break;
        default:
            SG_LOG(SG_GENERAL, SG_ALERT, "Illegal character in time string for " << field << ": '" <<
                    (*ppParserPos)[0] << "'.");
            // invalid field - skip rest of string to avoid further errors
            while ((*ppParserPos)[0])
                (*ppParserPos)++;
            return false;
    }

    if (i<=0)
        return true;

    int value = atoi(num);
    if ((value < min)||(value > max))
    {
        SG_LOG(SG_GENERAL, SG_ALERT, "Invalid " << field << " in '" << argument <<
               "'. Valid range is " << min << "-" << max << ".");
        return false;
    }
    else
    {
        *pValue = value;
        return true;
    }
}

// parse a time string ([+/-]%f[:%f[:%f]]) into hours
static double
parse_time(const string& time_in) {
    char *time_str, num[256];
    double hours, minutes, seconds;
    double result = 0.0;
    int sign = 1;
    int i;

    time_str = (char *)time_in.c_str();

    // printf("parse_time(): %s\n", time_str);

    // check for sign
    if ( strlen(time_str) ) {
	if ( time_str[0] == '+' ) {
	    sign = 1;
	    time_str++;
	} else if ( time_str[0] == '-' ) {
	    sign = -1;
	    time_str++;
	}
    }
    // printf("sign = %d\n", sign);

    // get hours
    if ( strlen(time_str) ) {
	i = 0;
	while ( (time_str[0] != ':') && (time_str[0] != '\0') ) {
	    num[i] = time_str[0];
	    time_str++;
	    i++;
	}
	if ( time_str[0] == ':' ) {
	    time_str++;
	}
	num[i] = '\0';
	hours = atof(num);
	// printf("hours = %.2lf\n", hours);

	result += hours;
    }

    // get minutes
    if ( strlen(time_str) ) {
	i = 0;
	while ( (time_str[0] != ':') && (time_str[0] != '\0') ) {
	    num[i] = time_str[0];
	    time_str++;
	    i++;
	}
	if ( time_str[0] == ':' ) {
	    time_str++;
	}
	num[i] = '\0';
	minutes = atof(num);
	// printf("minutes = %.2lf\n", minutes);

	result += minutes / 60.0;
    }

    // get seconds
    if ( strlen(time_str) ) {
	i = 0;
	while ( (time_str[0] != ':') && (time_str[0] != '\0') ) {
	    num[i] = time_str[0];
	    time_str++;
	    i++;
	}
	num[i] = '\0';
	seconds = atof(num);
	// printf("seconds = %.2lf\n", seconds);

	result += seconds / 3600.0;
    }

    SG_LOG( SG_GENERAL, SG_INFO, " parse_time() = " << sign * result );

    return(sign * result);
}

// parse a date string (yyyy:mm:dd:hh:mm:ss) into a time_t (seconds)
static long int
parse_date( const string& date, const char* timeType)
{
    struct tm gmt,*pCurrentTime;
    int year,month,day,hour,minute,second;
    char *argument, *date_str;

    SGTime CurrentTime;
    CurrentTime.update(SGGeod(),0,0);

    // FIXME This should obtain system/aircraft/GMT time depending on timeType
    pCurrentTime = CurrentTime.getGmt();

    // initialize all fields with current time
    year   = pCurrentTime->tm_year + 1900;
    month  = pCurrentTime->tm_mon + 1;
    day    = pCurrentTime->tm_mday;
    hour   = pCurrentTime->tm_hour;
    minute = pCurrentTime->tm_min;
    second = pCurrentTime->tm_sec;

    argument = (char *)date.c_str();
    date_str = argument;

    // start with parsing year
    if (!strlen(date_str) ||
        !parseIntValue(&date_str,&year,0,9999,"year",argument))
    {
        return -1;
    }

    if (year < 1970)
    {
        SG_LOG(SG_GENERAL, SG_ALERT, "Invalid year '" << year << "'. Use 1970 or later.");
        return -1;
    }

    parseIntValue(&date_str, &month,  1, 12, "month",  argument);
    parseIntValue(&date_str, &day,    1, 31, "day",    argument);
    parseIntValue(&date_str, &hour,   0, 23, "hour",   argument);
    parseIntValue(&date_str, &minute, 0, 59, "minute", argument);
    parseIntValue(&date_str, &second, 0, 59, "second", argument);

    gmt.tm_sec  = second;
    gmt.tm_min  = minute;
    gmt.tm_hour = hour;
    gmt.tm_mday = day;
    gmt.tm_mon  = month - 1;
    gmt.tm_year = year -1900;
    gmt.tm_isdst = 0; // ignore daylight savings time for the moment

    time_t theTime = sgTimeGetGMT( gmt.tm_year, gmt.tm_mon, gmt.tm_mday,
                                   gmt.tm_hour, gmt.tm_min, gmt.tm_sec );

    SG_LOG(SG_GENERAL, SG_INFO, "Configuring startup time to " << ctime(&theTime));

    return (theTime);
}


// parse angle in the form of [+/-]ddd:mm:ss into degrees
static double
parse_degree( const string& degree_str) {
    double result = parse_time( degree_str );

    // printf("Degree = %.4f\n", result);

    return(result);
}


// parse time offset string into seconds
static long int
parse_time_offset( const string& time_str) {
   long int result;

    // printf("time offset = %s\n", time_str);

#ifdef HAVE_RINT
    result = (int)rint(parse_time(time_str) * 3600.0);
#else
    result = (int)(parse_time(time_str) * 3600.0);
#endif

    // printf("parse_time_offset(): %d\n", result);

    return( result );
}


// Parse --fov=x.xx type option
static double
parse_fov( const string& arg ) {
    double fov = atof(arg);

    if ( fov < FG_FOV_MIN ) { fov = FG_FOV_MIN; }
    if ( fov > FG_FOV_MAX ) { fov = FG_FOV_MAX; }

    fgSetDouble("/sim/view[0]/config/default-field-of-view-deg", fov);

    // printf("parse_fov(): result = %.4f\n", fov);

    return fov;
}


// Parse I/O channel option
//
// Format is "--protocol=medium,direction,hz,medium_options,..."
//
//   protocol = { native, nmea, garmin, AV400, AV400Sim, fgfs, rul, pve, etc. }
//   medium = { serial, socket, file, etc. }
//   direction = { in, out, bi }
//   hz = number of times to process channel per second (floating
//        point values are ok.
//
// Serial example "--nmea=serial,dir,hz,device,baud" where
//
//  device = OS device name of serial line to be open()'ed
//  baud = {300, 1200, 2400, ..., 230400}
//
// Socket exacmple "--native=socket,dir,hz,machine,port,style" where
//
//  machine = machine name or ip address if client (leave empty if server)
//  port = port, leave empty to let system choose
//  style = tcp or udp
//
// File example "--garmin=file,dir,hz,filename" where
//
//  filename = file system file name

static bool
add_channel( const string& type, const string& channel_str ) {
    // This check is neccessary to prevent fgviewer from segfaulting when given
    // weird options. (It doesn't run the full initailization)
    if(!globals->get_channel_options_list())
    {
        SG_LOG(SG_GENERAL, SG_ALERT, "Option " << type << "=" << channel_str
                                     << " ignored.");
        return false;
    }
    SG_LOG(SG_GENERAL, SG_INFO, "Channel string = " << channel_str );
    globals->get_channel_options_list()->push_back( type + "," + channel_str );
    return true;
}

static void
clearLocation ()
{
    fgSetString("/sim/presets/airport-id", "");
    fgSetString("/sim/presets/vor-id", "");
    fgSetString("/sim/presets/ndb-id", "");
    fgSetString("/sim/presets/carrier", "");
    fgSetString("/sim/presets/parkpos", "");
    fgSetString("/sim/presets/fix", "");
}

static int
fgOptVOR( const char * arg )
{
    clearLocation();
    fgSetString("/sim/presets/vor-id", arg);
    return FG_OPTIONS_OK;
}

static int
fgOptNDB( const char * arg )
{
    clearLocation();
    fgSetString("/sim/presets/ndb-id", arg);
    return FG_OPTIONS_OK;
}

static int
fgOptCarrier( const char * arg )
{
    clearLocation();
    fgSetString("/sim/presets/carrier", arg);
    return FG_OPTIONS_OK;
}

static int
fgOptParkpos( const char * arg )
{
    fgSetString("/sim/presets/parkpos", arg);
    return FG_OPTIONS_OK;
}

static int
fgOptFIX( const char * arg )
{
    clearLocation();
    fgSetString("/sim/presets/fix", arg);
    return FG_OPTIONS_OK;
}

static int
fgOptLon( const char *arg )
{
    clearLocation();
    fgSetDouble("/sim/presets/longitude-deg", parse_degree( arg ));
    fgSetDouble("/position/longitude-deg", parse_degree( arg ));
    return FG_OPTIONS_OK;
}

static int
fgOptLat( const char *arg )
{
    clearLocation();
    fgSetDouble("/sim/presets/latitude-deg", parse_degree( arg ));
    fgSetDouble("/position/latitude-deg", parse_degree( arg ));
    return FG_OPTIONS_OK;
}

static int
fgOptAltitude( const char *arg )
{
    fgSetBool("/sim/presets/onground", false);
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
        fgSetDouble("/sim/presets/altitude-ft", atof( arg ));
    else
        fgSetDouble("/sim/presets/altitude-ft",
		    atof( arg ) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptUBody( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "UVW");
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
	fgSetDouble("/sim/presets/uBody-fps", atof( arg ));
    else
	fgSetDouble("/sim/presets/uBody-fps",
                    atof( arg ) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptVBody( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "UVW");
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
	fgSetDouble("/sim/presets/vBody-fps", atof( arg ));
    else
	fgSetDouble("/sim/presets/vBody-fps",
			    atof( arg ) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptWBody( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "UVW");
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
	fgSetDouble("/sim/presets/wBody-fps", atof(arg));
    else
	fgSetDouble("/sim/presets/wBody-fps",
			    atof(arg) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptVNorth( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "NED");
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
	fgSetDouble("/sim/presets/speed-north-fps", atof( arg ));
    else
	fgSetDouble("/sim/presets/speed-north-fps",
			    atof( arg ) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptVEast( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "NED");
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
	fgSetDouble("/sim/presets/speed-east-fps", atof(arg));
    else
	fgSetDouble("/sim/presets/speed-east-fps",
		    atof(arg) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptVDown( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "NED");
    if ( !strcmp(fgGetString("/sim/startup/units"), "feet") )
	fgSetDouble("/sim/presets/speed-down-fps", atof(arg));
    else
	fgSetDouble("/sim/presets/speed-down-fps",
			    atof(arg) * SG_METER_TO_FEET);
    return FG_OPTIONS_OK;
}

static int
fgOptVc( const char *arg )
{
    // fgSetString("/sim/presets/speed-set", "knots");
    // fgSetDouble("/velocities/airspeed-kt", atof(arg.substr(5)));
    fgSetString("/sim/presets/speed-set", "knots");
    fgSetDouble("/sim/presets/airspeed-kt", atof(arg));
    return FG_OPTIONS_OK;
}

static int
fgOptMach( const char *arg )
{
    fgSetString("/sim/presets/speed-set", "mach");
    fgSetDouble("/sim/presets/mach", atof(arg));
    return FG_OPTIONS_OK;
}

static int
fgOptRoc( const char *arg )
{
    fgSetDouble("/sim/presets/vertical-speed-fps", atof(arg)/60);
    return FG_OPTIONS_OK;
}

static int
fgOptFgScenery( const char *arg )
{
    globals->append_fg_scenery(arg);
    return FG_OPTIONS_OK;
}

static int
fgOptFov( const char *arg )
{
    parse_fov( arg );
    return FG_OPTIONS_OK;
}

static int
fgOptGeometry( const char *arg )
{
    bool geometry_ok = true;
    int xsize = 0, ysize = 0;
    string geometry = arg;
    string::size_type i = geometry.find('x');

    if (i != string::npos) {
        xsize = atoi(geometry.substr(0, i));
        ysize = atoi(geometry.substr(i+1));
    } else {
        geometry_ok = false;
    }

    if ( xsize <= 0 || ysize <= 0 ) {
        xsize = 640;
        ysize = 480;
        geometry_ok = false;
    }

    if ( !geometry_ok ) {
        SG_LOG( SG_GENERAL, SG_ALERT, "Unknown geometry: " << geometry );
        SG_LOG( SG_GENERAL, SG_ALERT,
 	        "Setting geometry to " << xsize << 'x' << ysize << '\n');
    } else {
        SG_LOG( SG_GENERAL, SG_INFO,
	        "Setting geometry to " << xsize << 'x' << ysize << '\n');
        fgSetInt("/sim/startup/xsize", xsize);
        fgSetInt("/sim/startup/ysize", ysize);
    }
    return FG_OPTIONS_OK;
}

static int
fgOptBpp( const char *arg )
{
    string bits_per_pix = arg;
    if ( bits_per_pix == "16" ) {
	fgSetInt("/sim/rendering/bits-per-pixel", 16);
    } else if ( bits_per_pix == "24" ) {
	fgSetInt("/sim/rendering/bits-per-pixel", 24);
    } else if ( bits_per_pix == "32" ) {
	fgSetInt("/sim/rendering/bits-per-pixel", 32);
    } else {
	SG_LOG(SG_GENERAL, SG_ALERT, "Unsupported bpp " << bits_per_pix);
    }
    return FG_OPTIONS_OK;
}

static int
fgOptTimeOffset( const char *arg )
{
    fgSetLong("/sim/startup/time-offset",
                parse_time_offset( arg ));
    fgSetString("/sim/startup/time-offset-type", "system-offset");
    return FG_OPTIONS_OK;
}

static int
fgOptStartDateSys( const char *arg )
{
    long int theTime = parse_date( arg, "system" );
    if (theTime>=0)
    {
        fgSetLong("/sim/startup/time-offset",  theTime);
        fgSetString("/sim/startup/time-offset-type", "system");
    }
    return FG_OPTIONS_OK;
}

static int
fgOptStartDateLat( const char *arg )
{
    long int theTime = parse_date( arg, "latitude" );
    if (theTime>=0)
    {
        fgSetLong("/sim/startup/time-offset", theTime);
        fgSetString("/sim/startup/time-offset-type", "latitude");
    }
    return FG_OPTIONS_OK;
}

static int
fgOptStartDateGmt( const char *arg )
{
    long int theTime = parse_date( arg, "gmt" );
    if (theTime>=0)
    {
        fgSetLong("/sim/startup/time-offset", theTime);
        fgSetString("/sim/startup/time-offset-type", "gmt");
    }
    return FG_OPTIONS_OK;
}

static int
fgSetupProxy( const char *arg )
{
    string options = simgear::strutils::strip( arg );
    string host, port, auth;
    string::size_type pos;

    // this is NURLP - NURLP is not an url parser
    if( simgear::strutils::starts_with( options, "http://" ) )
        options = options.substr( 7 );
    if( simgear::strutils::ends_with( options, "/" ) )
        options = options.substr( 0, options.length() - 1 );

    host = port = auth = "";
    if ((pos = options.find("@")) != string::npos)
        auth = options.substr(0, pos++);
    else
        pos = 0;

    host = options.substr(pos, options.size());
    if ((pos = host.find(":")) != string::npos) {
        port = host.substr(++pos, host.size());
        host.erase(--pos, host.size());
    }

    fgSetString("/sim/presets/proxy/host", host.c_str());
    fgSetString("/sim/presets/proxy/port", port.c_str());
    fgSetString("/sim/presets/proxy/authentication", auth.c_str());

    return FG_OPTIONS_OK;
}

static int
fgOptTraceRead( const char *arg )
{
    string name = arg;
    SG_LOG(SG_GENERAL, SG_INFO, "Tracing reads for property " << name);
    fgGetNode(name.c_str(), true)
	->setAttribute(SGPropertyNode::TRACE_READ, true);
    return FG_OPTIONS_OK;
}

static int
fgOptLogLevel( const char *arg )
{
    fgSetString("/sim/logging/priority", arg);
    setLoggingPriority(arg);

    return FG_OPTIONS_OK;
}

static int
fgOptLogClasses( const char *arg )
{
    fgSetString("/sim/logging/classes", arg);
    setLoggingClasses (arg);

    return FG_OPTIONS_OK;
}

static int
fgOptTraceWrite( const char *arg )
{
    string name = arg;
    SG_LOG(SG_GENERAL, SG_INFO, "Tracing writes for property " << name);
    fgGetNode(name.c_str(), true)
	->setAttribute(SGPropertyNode::TRACE_WRITE, true);
    return FG_OPTIONS_OK;
}

static int
fgOptViewOffset( const char *arg )
{
    // $$$ begin - added VS Renganathan, 14 Oct 2K
    // for multi-window outside window imagery
    string woffset = arg;
    double default_view_offset = 0.0;
    if ( woffset == "LEFT" ) {
	    default_view_offset = SGD_PI * 0.25;
    } else if ( woffset == "RIGHT" ) {
	default_view_offset = SGD_PI * 1.75;
    } else if ( woffset == "CENTER" ) {
	default_view_offset = 0.00;
    } else {
	default_view_offset = atof( woffset.c_str() ) * SGD_DEGREES_TO_RADIANS;
    }
    /* apparently not used (CLO, 11 Jun 2002)
        FGViewer *pilot_view =
	    (FGViewer *)globals->get_viewmgr()->get_view( 0 ); */
    // this will work without calls to the viewer...
    fgSetDouble( "/sim/current-view/heading-offset-deg",
                    default_view_offset  * SGD_RADIANS_TO_DEGREES );
    // $$$ end - added VS Renganathan, 14 Oct 2K
    return FG_OPTIONS_OK;
}

static int
fgOptVisibilityMeters( const char *arg )
{
    Environment::Presets::VisibilitySingleton::instance()->preset( atof( arg ) );
    return FG_OPTIONS_OK;
}

static int
fgOptVisibilityMiles( const char *arg )
{
    Environment::Presets::VisibilitySingleton::instance()->preset( atof( arg ) * 5280.0 * SG_FEET_TO_METER );
    return FG_OPTIONS_OK;
}

static int
fgOptRandomWind( const char *arg )
{
    double min_hdg = sg_random() * 360.0;
    double max_hdg = min_hdg + (20 - sqrt(sg_random() * 400));
    double speed = sg_random() * sg_random() * 40;
    double gust = speed + (10 - sqrt(sg_random() * 100));
    Environment::Presets::WindSingleton::instance()->preset(min_hdg, max_hdg, speed, gust);
    return FG_OPTIONS_OK;
}

static int
fgOptWind( const char *arg )
{
    double min_hdg = 0.0, max_hdg = 0.0, speed = 0.0, gust = 0.0;
    if (!parse_wind( arg, &min_hdg, &max_hdg, &speed, &gust)) {
	SG_LOG( SG_GENERAL, SG_ALERT, "bad wind value " << arg );
	return FG_OPTIONS_ERROR;
    }
    Environment::Presets::WindSingleton::instance()->preset(min_hdg, max_hdg, speed, gust);
    return FG_OPTIONS_OK;
}

static int
fgOptTurbulence( const char *arg )
{
    Environment::Presets::TurbulenceSingleton::instance()->preset( atof(arg) );
    return FG_OPTIONS_OK;
}

static int
fgOptCeiling( const char *arg )
{
    double elevation, thickness;
    string spec = arg;
    string::size_type pos = spec.find(':');
    if (pos == string::npos) {
        elevation = atof(spec.c_str());
        thickness = 2000;
    } else {
        elevation = atof(spec.substr(0, pos).c_str());
        thickness = atof(spec.substr(pos + 1).c_str());
    }
    Environment::Presets::CeilingSingleton::instance()->preset( elevation, thickness );
    return FG_OPTIONS_OK;
}

static int
fgOptWp( const char *arg )
{
    string_list *waypoints = globals->get_initial_waypoints();
    if (!waypoints) {
        waypoints = new string_list;
        globals->set_initial_waypoints(waypoints);
    }
    waypoints->push_back(arg);
    return FG_OPTIONS_OK;
}

static int
fgOptConfig( const char *arg )
{
    string file = arg;
    try {
	readProperties(file, globals->get_props());
    } catch (const sg_exception &e) {
	string message = "Error loading config file: ";
	message += e.getFormattedMessage() + e.getOrigin();
	SG_LOG(SG_INPUT, SG_ALERT, message);
	exit(2);
    }
    return FG_OPTIONS_OK;
}

static bool
parse_colon (const string &s, double * val1, double * val2)
{
    string::size_type pos = s.find(':');
    if (pos == string::npos) {
        *val2 = atof(s);
        return false;
    } else {
        *val1 = atof(s.substr(0, pos).c_str());
        *val2 = atof(s.substr(pos+1).c_str());
        return true;
    }
}


static int
fgOptFailure( const char * arg )
{
    string a = arg;
    if (a == "pitot") {
        fgSetBool("/systems/pitot/serviceable", false);
    } else if (a == "static") {
        fgSetBool("/systems/static/serviceable", false);
    } else if (a == "vacuum") {
        fgSetBool("/systems/vacuum/serviceable", false);
    } else if (a == "electrical") {
        fgSetBool("/systems/electrical/serviceable", false);
    } else {
        SG_LOG(SG_INPUT, SG_ALERT, "Unknown failure mode: " << a);
        return FG_OPTIONS_ERROR;
    }

    return FG_OPTIONS_OK;
}


static int
fgOptNAV1( const char * arg )
{
    double radial, freq;
    if (parse_colon(arg, &radial, &freq))
        fgSetDouble("/instrumentation/nav[0]/radials/selected-deg", radial);
    fgSetDouble("/instrumentation/nav[0]/frequencies/selected-mhz", freq);
    return FG_OPTIONS_OK;
}

static int
fgOptNAV2( const char * arg )
{
    double radial, freq;
    if (parse_colon(arg, &radial, &freq))
        fgSetDouble("/instrumentation/nav[1]/radials/selected-deg", radial);
    fgSetDouble("/instrumentation/nav[1]/frequencies/selected-mhz", freq);
    return FG_OPTIONS_OK;
}

static int
fgOptADF1( const char * arg )
{
    double rot, freq;
    if (parse_colon(arg, &rot, &freq))
        fgSetDouble("/instrumentation/adf[0]/rotation-deg", rot);
    fgSetDouble("/instrumentation/adf[0]/frequencies/selected-khz", freq);
    return FG_OPTIONS_OK;
}

static int
fgOptADF2( const char * arg )
{
    double rot, freq;
    if (parse_colon(arg, &rot, &freq))
        fgSetDouble("/instrumentation/adf[1]/rotation-deg", rot);
    fgSetDouble("/instrumentation/adf[1]/frequencies/selected-khz", freq);
    return FG_OPTIONS_OK;
}

static int
fgOptDME( const char *arg )
{
    string opt = arg;
    if (opt == "nav1") {
        fgSetInt("/instrumentation/dme/switch-position", 1);
        fgSetString("/instrumentation/dme/frequencies/source",
                    "/instrumentation/nav[0]/frequencies/selected-mhz");
    } else if (opt == "nav2") {
        fgSetInt("/instrumentation/dme/switch-position", 3);
        fgSetString("/instrumentation/dme/frequencies/source",
                    "/instrumentation/nav[1]/frequencies/selected-mhz");
    } else {
        double frequency = atof(arg);
        if (frequency==0.0)
        {
            SG_LOG(SG_INPUT, SG_ALERT, "Invalid DME frequency: '" << arg << "'.");
            return FG_OPTIONS_ERROR;
        }
        fgSetInt("/instrumentation/dme/switch-position", 2);
        fgSetString("/instrumentation/dme/frequencies/source",
                    "/instrumentation/dme/frequencies/selected-mhz");
        fgSetDouble("/instrumentation/dme/frequencies/selected-mhz", frequency);
    }
    return FG_OPTIONS_OK;
}

static int
fgOptLivery( const char *arg )
{
    string opt = arg;
    string livery_path = "livery/" + opt;
    fgSetString("/sim/model/texture-path", livery_path.c_str() );
    return FG_OPTIONS_OK;
}

static int
fgOptScenario( const char *arg )
{
    SGPropertyNode_ptr ai_node = fgGetNode( "/sim/ai", true );
    vector<SGPropertyNode_ptr> scenarii = ai_node->getChildren( "scenario" );
    int index = -1;
    for ( size_t i = 0; i < scenarii.size(); ++i ) {
        int ind = scenarii[i]->getIndex();
        if ( index < ind ) {
            index = ind;
        }
    }
    SGPropertyNode_ptr scenario = ai_node->getNode( "scenario", index + 1, true );
    scenario->setStringValue( arg );
    ai_node->setBoolValue( "scenarios-enabled", true );
    return FG_OPTIONS_OK;
}

static int
fgOptNoScenarios( const char *arg )
{
    SGPropertyNode_ptr ai_node = fgGetNode( "/sim/ai", true );
    ai_node->removeChildren("scenario",false);
    ai_node->setBoolValue( "scenarios-enabled", false );
    return FG_OPTIONS_OK;
}

static int
fgOptRunway( const char *arg )
{
    fgSetString("/sim/presets/runway", arg );
    fgSetBool("/sim/presets/runway-requested", true );
    return FG_OPTIONS_OK;
}

static int
fgOptParking( const char *arg )
{
    cerr << "Processing argument " << arg << endl;
    fgSetString("/sim/presets/parking", arg );
    fgSetBool  ("/sim/presets/parking-requested", true );
    return FG_OPTIONS_OK;
}

static int
fgOptVersion( const char *arg )
{
    cerr << "FlightGear version: " << FLIGHTGEAR_VERSION << endl;
    cerr << "Revision: " << REVISION << endl;
    cerr << "Build-Id: " << HUDSON_BUILD_ID << endl;
    cerr << "FG_ROOT=" << globals->get_fg_root() << endl;
    cerr << "FG_HOME=" << globals->get_fg_home() << endl;
    cerr << "FG_SCENERY=";

    int didsome = 0;
    string_list scn = globals->get_fg_scenery();
    for (string_list::const_iterator it = scn.begin(); it != scn.end(); it++)
    {
        if (didsome) cerr << ":";
        didsome++;
        cerr << *it;
    }
    cerr << endl;
    cerr << "SimGear version: " << SG_STRINGIZE(SIMGEAR_VERSION) << endl;
    cerr << "PLIB version: " << PLIB_VERSION << endl;
    return FG_OPTIONS_EXIT;
}

static int
fgOptCallSign(const char * arg)
{
    int i;
    char callsign[11];
    strncpy(callsign,arg,10);
    callsign[10]=0;
    for (i=0;callsign[i];i++)
    {
        char c = callsign[i];
        if (c >= 'A' && c <= 'Z') continue;
        if (c >= 'a' && c <= 'z') continue;
        if (c >= '0' && c <= '9') continue;
        if (c == '-' || c == '_') continue;
        // convert any other illegal characters
        callsign[i]='-';
    }
    fgSetString("sim/multiplay/callsign", callsign );
    return FG_OPTIONS_OK;
}


// Set a property for the --prop: option. Syntax: --prop:[<type>:]<name>=<value>
// <type> can be "double" etc. but also only the first letter "d".
// Examples:  --prop:alpha=1  --prop:bool:beta=true  --prop:d:gamma=0.123
static int
fgOptSetProperty(const char* raw)
{
  string arg(raw);
  string::size_type pos = arg.find('=');
  if (pos == arg.npos || pos == 0 || pos + 1 == arg.size())
    return FG_OPTIONS_ERROR;
  
  string name = arg.substr(0, pos);
  string value = arg.substr(pos + 1);
  string type;
  pos = name.find(':');
  
  if (pos != name.npos && pos != 0 && pos + 1 != name.size()) {
    type = name.substr(0, pos);
    name = name.substr(pos + 1);
  }
  SGPropertyNode *n = fgGetNode(name.c_str(), true);
  
  bool writable = n->getAttribute(SGPropertyNode::WRITE);
  if (!writable)
    n->setAttribute(SGPropertyNode::WRITE, true);
  
  bool ret = false;
  if (type.empty())
    ret = n->setUnspecifiedValue(value.c_str());
  else if (type == "s" || type == "string")
    ret = n->setStringValue(value.c_str());
  else if (type == "d" || type == "double")
    ret = n->setDoubleValue(strtod(value.c_str(), 0));
  else if (type == "f" || type == "float")
    ret = n->setFloatValue(atof(value.c_str()));
  else if (type == "l" || type == "long")
    ret =  n->setLongValue(strtol(value.c_str(), 0, 0));
  else if (type == "i" || type == "int")
    ret =  n->setIntValue(atoi(value.c_str()));
  else if (type == "b" || type == "bool")
    ret =  n->setBoolValue(value == "true" || atoi(value.c_str()) != 0);
  
  if (!writable)
    n->setAttribute(SGPropertyNode::WRITE, false);
  return ret ? FG_OPTIONS_OK : FG_OPTIONS_ERROR;
}



/*
   option       has_param type        property         b_param s_param  func

where:
 option    : name of the option
 has_param : option is --name=value if true or --name if false
 type      : OPTION_BOOL    - property is a boolean
             OPTION_STRING  - property is a string
             OPTION_DOUBLE  - property is a double
             OPTION_INT     - property is an integer
             OPTION_CHANNEL - name of option is the name of a channel
             OPTION_FUNC    - the option trigger a function
 b_param   : if type==OPTION_BOOL,
             value set to the property (has_param is false for boolean)
 s_param   : if type==OPTION_STRING,
             value set to the property if has_param is false
 func      : function called if type==OPTION_FUNC. if has_param is true,
             the value is passed to the function as a string, otherwise,
             s_param is passed.

    For OPTION_DOUBLE and OPTION_INT, the parameter value is converted into a
    double or an integer and set to the property.

    For OPTION_CHANNEL, add_channel is called with the parameter value as the
    argument.
*/

enum OptionType { OPTION_BOOL = 0, OPTION_STRING, OPTION_DOUBLE, OPTION_INT, OPTION_CHANNEL, OPTION_FUNC, OPTION_IGNORE };
const int OPTION_MULTI = 1 << 17;

struct OptionDesc {
    const char *option;
    bool has_param;
    int type;
    const char *property;
    bool b_param;
    const char *s_param;
    int (*func)( const char * );
    } fgOptionArray[] = {

    {"language",                     true,  OPTION_IGNORE, "", false, "", 0 },
    {"disable-rembrandt",            false, OPTION_BOOL,   "/sim/rendering/rembrandt/enabled", false, "", 0 },
    {"enable-rembrandt",             false, OPTION_BOOL,   "/sim/rendering/rembrandt/enabled", true, "", 0 },
    {"renderer",                     true,  OPTION_STRING, "/sim/rendering/rembrandt/renderer", false, "", 0 },
    {"disable-game-mode",            false, OPTION_BOOL,   "/sim/startup/game-mode", false, "", 0 },
    {"enable-game-mode",             false, OPTION_BOOL,   "/sim/startup/game-mode", true, "", 0 },
    {"disable-splash-screen",        false, OPTION_BOOL,   "/sim/startup/splash-screen", false, "", 0 },
    {"enable-splash-screen",         false, OPTION_BOOL,   "/sim/startup/splash-screen", true, "", 0 },
    {"disable-intro-music",          false, OPTION_BOOL,   "/sim/startup/intro-music", false, "", 0 },
    {"enable-intro-music",           false, OPTION_BOOL,   "/sim/startup/intro-music", true, "", 0 },
    {"disable-mouse-pointer",        false, OPTION_STRING, "/sim/startup/mouse-pointer", false, "disabled", 0 },
    {"enable-mouse-pointer",         false, OPTION_STRING, "/sim/startup/mouse-pointer", false, "enabled", 0 },
    {"disable-random-objects",       false, OPTION_BOOL,   "/sim/rendering/random-objects", false, "", 0 },
    {"enable-random-objects",        false, OPTION_BOOL,   "/sim/rendering/random-objects", true, "", 0 },
    {"disable-random-vegetation",    false, OPTION_BOOL,   "/sim/rendering/random-vegetation", false, "", 0 },
    {"enable-random-vegetation",     false, OPTION_BOOL,   "/sim/rendering/random-vegetation", true, "", 0 },
    {"disable-random-buildings",     false, OPTION_BOOL,   "/sim/rendering/random-buildings", false, "", 0 },
    {"enable-random-buildings",      false, OPTION_BOOL,   "/sim/rendering/random-buildings", true, "", 0 },
    {"disable-real-weather-fetch",   false, OPTION_BOOL,   "/environment/realwx/enabled", false, "", 0 },
    {"enable-real-weather-fetch",    false, OPTION_BOOL,   "/environment/realwx/enabled", true,  "", 0 },
    {"metar",                        true,  OPTION_STRING, "/environment/metar/data", false, "", 0 },
    {"disable-ai-models",            false, OPTION_BOOL,   "/sim/ai/enabled", false, "", 0 },
    {"enable-ai-models",             false, OPTION_BOOL,   "/sim/ai/enabled", true, "", 0 },
    {"disable-ai-traffic",           false, OPTION_BOOL,   "/sim/traffic-manager/enabled", false, "", 0 },
    {"enable-ai-traffic",            false, OPTION_BOOL,   "/sim/traffic-manager/enabled", true,  "", 0 },
    {"disable-freeze",               false, OPTION_BOOL,   "/sim/freeze/master", false, "", 0 },
    {"enable-freeze",                false, OPTION_BOOL,   "/sim/freeze/master", true, "", 0 },
    {"disable-fuel-freeze",          false, OPTION_BOOL,   "/sim/freeze/fuel", false, "", 0 },
    {"enable-fuel-freeze",           false, OPTION_BOOL,   "/sim/freeze/fuel", true, "", 0 },
    {"disable-clock-freeze",         false, OPTION_BOOL,   "/sim/freeze/clock", false, "", 0 },
    {"enable-clock-freeze",          false, OPTION_BOOL,   "/sim/freeze/clock", true, "", 0 },
    {"disable-hud-3d",               false, OPTION_BOOL,   "/sim/hud/enable3d[1]", false, "", 0 },
    {"enable-hud-3d",                false, OPTION_BOOL,   "/sim/hud/enable3d[1]", true, "", 0 },
    {"disable-anti-alias-hud",       false, OPTION_BOOL,   "/sim/hud/color/antialiased", false, "", 0 },
    {"enable-anti-alias-hud",        false, OPTION_BOOL,   "/sim/hud/color/antialiased", true, "", 0 },
    {"control",                      true,  OPTION_STRING, "/sim/control-mode", false, "", 0 },
    {"disable-auto-coordination",    false, OPTION_BOOL,   "/controls/flight/auto-coordination", false, "", 0 },
    {"enable-auto-coordination",     false, OPTION_BOOL,   "/controls/flight/auto-coordination", true, "", 0 },
    {"browser-app",                  true,  OPTION_STRING, "/sim/startup/browser-app", false, "", 0 },
    {"disable-hud",                  false, OPTION_BOOL,   "/sim/hud/visibility[1]", false, "", 0 },
    {"enable-hud",                   false, OPTION_BOOL,   "/sim/hud/visibility[1]", true, "", 0 },
    {"disable-panel",                false, OPTION_BOOL,   "/sim/panel/visibility", false, "", 0 },
    {"enable-panel",                 false, OPTION_BOOL,   "/sim/panel/visibility", true, "", 0 },
    {"disable-sound",                false, OPTION_BOOL,   "/sim/sound/working", false, "", 0 },
    {"enable-sound",                 false, OPTION_BOOL,   "/sim/sound/working", true, "", 0 },
    {"sound-device",                 true,  OPTION_STRING, "/sim/sound/device-name", false, "", 0 },
    {"airport",                      true,  OPTION_STRING, "/sim/presets/airport-id", false, "", 0 },
    {"runway",                       true,  OPTION_FUNC,   "", false, "", fgOptRunway },
    {"vor",                          true,  OPTION_FUNC,   "", false, "", fgOptVOR },
    {"vor-frequency",                true,  OPTION_DOUBLE, "/sim/presets/vor-freq", false, "", fgOptVOR },
    {"ndb",                          true,  OPTION_FUNC,   "", false, "", fgOptNDB },
    {"ndb-frequency",                true,  OPTION_DOUBLE, "/sim/presets/ndb-freq", false, "", fgOptVOR },
    {"carrier",                      true,  OPTION_FUNC,   "", false, "", fgOptCarrier },
    {"parkpos",                      true,  OPTION_FUNC,   "", false, "", fgOptParkpos },
    {"fix",                          true,  OPTION_FUNC,   "", false, "", fgOptFIX },
    {"offset-distance",              true,  OPTION_DOUBLE, "/sim/presets/offset-distance-nm", false, "", 0 },
    {"offset-azimuth",               true,  OPTION_DOUBLE, "/sim/presets/offset-azimuth-deg", false, "", 0 },
    {"lon",                          true,  OPTION_FUNC,   "", false, "", fgOptLon },
    {"lat",                          true,  OPTION_FUNC,   "", false, "", fgOptLat },
    {"altitude",                     true,  OPTION_FUNC,   "", false, "", fgOptAltitude },
    {"uBody",                        true,  OPTION_FUNC,   "", false, "", fgOptUBody },
    {"vBody",                        true,  OPTION_FUNC,   "", false, "", fgOptVBody },
    {"wBody",                        true,  OPTION_FUNC,   "", false, "", fgOptWBody },
    {"vNorth",                       true,  OPTION_FUNC,   "", false, "", fgOptVNorth },
    {"vEast",                        true,  OPTION_FUNC,   "", false, "", fgOptVEast },
    {"vDown",                        true,  OPTION_FUNC,   "", false, "", fgOptVDown },
    {"vc",                           true,  OPTION_FUNC,   "", false, "", fgOptVc },
    {"mach",                         true,  OPTION_FUNC,   "", false, "", fgOptMach },
    {"heading",                      true,  OPTION_DOUBLE, "/sim/presets/heading-deg", false, "", 0 },
    {"roll",                         true,  OPTION_DOUBLE, "/sim/presets/roll-deg", false, "", 0 },
    {"pitch",                        true,  OPTION_DOUBLE, "/sim/presets/pitch-deg", false, "", 0 },
    {"glideslope",                   true,  OPTION_DOUBLE, "/sim/presets/glideslope-deg", false, "", 0 },
    {"roc",                          true,  OPTION_FUNC,   "", false, "", fgOptRoc },
    {"fg-root",                      true,  OPTION_IGNORE,   "", false, "", 0 },
    {"fg-scenery",                   true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptFgScenery },
    {"fg-aircraft",                  true,  OPTION_IGNORE | OPTION_MULTI,   "", false, "", 0 },
    {"fdm",                          true,  OPTION_STRING, "/sim/flight-model", false, "", 0 },
    {"aero",                         true,  OPTION_STRING, "/sim/aero", false, "", 0 },
    {"aircraft-dir",                 true,  OPTION_IGNORE,   "", false, "", 0 },
    {"model-hz",                     true,  OPTION_INT,    "/sim/model-hz", false, "", 0 },
    {"max-fps",                      true,  OPTION_DOUBLE, "/sim/frame-rate-throttle-hz", false, "", 0 },
    {"speed",                        true,  OPTION_INT,    "/sim/speed-up", false, "", 0 },
    {"trim",                         false, OPTION_BOOL,   "/sim/presets/trim", true, "", 0 },
    {"notrim",                       false, OPTION_BOOL,   "/sim/presets/trim", false, "", 0 },
    {"on-ground",                    false, OPTION_BOOL,   "/sim/presets/onground", true, "", 0 },
    {"in-air",                       false, OPTION_BOOL,   "/sim/presets/onground", false, "", 0 },
    {"fog-disable",                  false, OPTION_STRING, "/sim/rendering/fog", false, "disabled", 0 },
    {"fog-fastest",                  false, OPTION_STRING, "/sim/rendering/fog", false, "fastest", 0 },
    {"fog-nicest",                   false, OPTION_STRING, "/sim/rendering/fog", false, "nicest", 0 },
    {"disable-horizon-effect",       false, OPTION_BOOL,   "/sim/rendering/horizon-effect", false, "", 0 },
    {"enable-horizon-effect",        false, OPTION_BOOL,   "/sim/rendering/horizon-effect", true, "", 0 },
    {"disable-enhanced-lighting",    false, OPTION_BOOL,   "/sim/rendering/enhanced-lighting", false, "", 0 },
    {"enable-enhanced-lighting",     false, OPTION_BOOL,   "/sim/rendering/enhanced-lighting", true, "", 0 },
    {"disable-distance-attenuation", false, OPTION_BOOL,   "/sim/rendering/distance-attenuation", false, "", 0 },
    {"enable-distance-attenuation",  false, OPTION_BOOL,   "/sim/rendering/distance-attenuation", true, "", 0 },
    {"disable-specular-highlight",   false, OPTION_BOOL,   "/sim/rendering/specular-highlight", false, "", 0 },
    {"enable-specular-highlight",    false, OPTION_BOOL,   "/sim/rendering/specular-highlight", true, "", 0 },
    {"disable-clouds",               false, OPTION_BOOL,   "/environment/clouds/status", false, "", 0 },
    {"enable-clouds",                false, OPTION_BOOL,   "/environment/clouds/status", true, "", 0 },
    {"disable-clouds3d",             false, OPTION_BOOL,   "/sim/rendering/clouds3d-enable", false, "", 0 },
    {"enable-clouds3d",              false, OPTION_BOOL,   "/sim/rendering/clouds3d-enable", true, "", 0 },
    {"fov",                          true,  OPTION_FUNC,   "", false, "", fgOptFov },
    {"aspect-ratio-multiplier",      true,  OPTION_DOUBLE, "/sim/current-view/aspect-ratio-multiplier", false, "", 0 },
    {"disable-fullscreen",           false, OPTION_BOOL,   "/sim/startup/fullscreen", false, "", 0 },
    {"enable-fullscreen",            false, OPTION_BOOL,   "/sim/startup/fullscreen", true, "", 0 },
    {"disable-save-on-exit",         false, OPTION_BOOL,   "/sim/startup/save-on-exit", false, "", 0 },
    {"enable-save-on-exit",          false, OPTION_BOOL,   "/sim/startup/save-on-exit", true, "", 0 },
    {"restore-defaults",             false, OPTION_BOOL,   "/sim/startup/restore-defaults", true, "", 0 },
    {"shading-flat",                 false, OPTION_BOOL,   "/sim/rendering/shading", false, "", 0 },
    {"shading-smooth",               false, OPTION_BOOL,   "/sim/rendering/shading", true, "", 0 },
    {"disable-skyblend",             false, OPTION_BOOL,   "/sim/rendering/skyblend", false, "", 0 },
    {"enable-skyblend",              false, OPTION_BOOL,   "/sim/rendering/skyblend", true, "", 0 },
    {"disable-textures",             false, OPTION_BOOL,   "/sim/rendering/textures", false, "", 0 },
    {"enable-textures",              false, OPTION_BOOL,   "/sim/rendering/textures", true, "", 0 },
    {"texture-filtering",            false, OPTION_INT,    "/sim/rendering/filtering", 1, "", 0 },
    {"disable-wireframe",            false, OPTION_BOOL,   "/sim/rendering/wireframe", false, "", 0 },
    {"enable-wireframe",             false, OPTION_BOOL,   "/sim/rendering/wireframe", true, "", 0 },
    {"materials-file",               true,  OPTION_STRING, "/sim/rendering/materials-file", false, "", 0 },
    {"disable-terrasync",            false, OPTION_BOOL,   "/sim/terrasync/enabled", false, "", 0 },
    {"enable-terrasync",             false, OPTION_BOOL,   "/sim/terrasync/enabled", true, "", 0 },
    {"terrasync-dir",                true,  OPTION_STRING, "/sim/terrasync/scenery-dir", false, "", 0 },
    {"geometry",                     true,  OPTION_FUNC,   "", false, "", fgOptGeometry },
    {"bpp",                          true,  OPTION_FUNC,   "", false, "", fgOptBpp },
    {"units-feet",                   false, OPTION_STRING, "/sim/startup/units", false, "feet", 0 },
    {"units-meters",                 false, OPTION_STRING, "/sim/startup/units", false, "meters", 0 },
    {"timeofday",                    true,  OPTION_STRING, "/sim/startup/time-offset-type", false, "noon", 0 },
    {"season",                       true,  OPTION_STRING, "/sim/startup/season", false, "summer", 0 },
    {"time-offset",                  true,  OPTION_FUNC,   "", false, "", fgOptTimeOffset },
    {"time-match-real",              false, OPTION_STRING, "/sim/startup/time-offset-type", false, "system-offset", 0 },
    {"time-match-local",             false, OPTION_STRING, "/sim/startup/time-offset-type", false, "latitude-offset", 0 },
    {"start-date-sys",               true,  OPTION_FUNC,   "", false, "", fgOptStartDateSys },
    {"start-date-lat",               true,  OPTION_FUNC,   "", false, "", fgOptStartDateLat },
    {"start-date-gmt",               true,  OPTION_FUNC,   "", false, "", fgOptStartDateGmt },
    {"hud-tris",                     false, OPTION_STRING, "/sim/hud/frame-stat-type", false, "tris", 0 },
    {"hud-culled",                   false, OPTION_STRING, "/sim/hud/frame-stat-type", false, "culled", 0 },
    {"atcsim",                       true,  OPTION_CHANNEL, "", false, "dummy", 0 },
    {"atlas",                        true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"httpd",                        true,  OPTION_CHANNEL, "", false, "", 0 },
#ifdef FG_JPEG_SERVER
    {"jpg-httpd",                    true,  OPTION_CHANNEL, "", false, "", 0 },
#endif
    {"native",                       true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"native-ctrls",                 true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"native-fdm",                   true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"native-gui",                   true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"opengc",                       true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"AV400",                        true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"AV400Sim",                     true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"AV400WSimA",                   true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"AV400WSimB",                   true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"garmin",                       true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"nmea",                         true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"generic",                      true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"props",                        true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"telnet",                       true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
    {"pve",                          true,  OPTION_CHANNEL, "", false, "", 0 },
    {"ray",                          true,  OPTION_CHANNEL, "", false, "", 0 },
    {"rul",                          true,  OPTION_CHANNEL, "", false, "", 0 },
    {"joyclient",                    true,  OPTION_CHANNEL, "", false, "", 0 },
    {"jsclient",                     true,  OPTION_CHANNEL, "", false, "", 0 },
    {"proxy",                        true,  OPTION_FUNC,    "", false, "", fgSetupProxy },
    {"callsign",                     true,  OPTION_FUNC,    "", false, "", fgOptCallSign},
    {"multiplay",                    true,  OPTION_CHANNEL | OPTION_MULTI, "", false, "", 0 },
#ifdef FG_HAVE_HLA
    {"hla",                          true,  OPTION_CHANNEL, "", false, "", 0 },
#endif
    {"trace-read",                   true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptTraceRead },
    {"trace-write",                  true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptTraceWrite },
    {"log-level",                    true,  OPTION_FUNC,   "", false, "", fgOptLogLevel },
    {"log-class",                    true,  OPTION_FUNC,   "", false, "", fgOptLogClasses },
    {"view-offset",                  true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptViewOffset },
    {"visibility",                   true,  OPTION_FUNC,   "", false, "", fgOptVisibilityMeters },
    {"visibility-miles",             true,  OPTION_FUNC,   "", false, "", fgOptVisibilityMiles },
    {"random-wind",                  false, OPTION_FUNC,   "", false, "", fgOptRandomWind },
    {"wind",                         true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptWind },
    {"turbulence",                   true,  OPTION_FUNC,   "", false, "", fgOptTurbulence },
    {"ceiling",                      true,  OPTION_FUNC,   "", false, "", fgOptCeiling },
    {"wp",                           true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptWp },
    {"flight-plan",                  true,  OPTION_STRING,   "/autopilot/route-manager/file-path", false, "", NULL },
    {"config",                       true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptConfig },
    {"aircraft",                     true,  OPTION_STRING, "/sim/aircraft", false, "", 0 },
    {"vehicle",                      true,  OPTION_STRING, "/sim/aircraft", false, "", 0 },
    {"failure",                      true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptFailure },
    {"com1",                         true,  OPTION_DOUBLE, "/instrumentation/comm[0]/frequencies/selected-mhz", false, "", 0 },
    {"com2",                         true,  OPTION_DOUBLE, "/instrumentation/comm[1]/frequencies/selected-mhz", false, "", 0 },
    {"nav1",                         true,  OPTION_FUNC,   "", false, "", fgOptNAV1 },
    {"nav2",                         true,  OPTION_FUNC,   "", false, "", fgOptNAV2 },
    {"adf", /*legacy*/               true,  OPTION_FUNC,   "", false, "", fgOptADF1 },
    {"adf1",                         true,  OPTION_FUNC,   "", false, "", fgOptADF1 },
    {"adf2",                         true,  OPTION_FUNC,   "", false, "", fgOptADF2 },
    {"dme",                          true,  OPTION_FUNC,   "", false, "", fgOptDME },
    {"min-status",                   true,  OPTION_STRING,  "/sim/aircraft-min-status", false, "all", 0 },
    {"livery",                       true,  OPTION_FUNC,   "", false, "", fgOptLivery },
    {"ai-scenario",                  true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptScenario },
    {"disable-ai-scenarios",         false, OPTION_FUNC,   "", false, "", fgOptNoScenarios},
    {"parking-id",                   true,  OPTION_FUNC,   "", false, "", fgOptParking  },
    {"version",                      false, OPTION_FUNC,   "", false, "", fgOptVersion },
    {"enable-fpe",                   false, OPTION_IGNORE,   "", false, "", 0},
    {"fgviewer",                     false, OPTION_IGNORE,   "", false, "", 0},
    {"prop",                         true,  OPTION_FUNC | OPTION_MULTI,   "", false, "", fgOptSetProperty},
    {0}
};


namespace flightgear
{

/**
 * internal storage of a value->option binding
 */
class OptionValue 
{
public:
  OptionValue(OptionDesc* d, const string& v) :
    desc(d), value(v)
  {;}
  
  OptionDesc* desc;
  string value;
};

typedef std::vector<OptionValue> OptionValueVec;
typedef std::map<string, OptionDesc*> OptionDescDict;
  
class Options::OptionsPrivate
{
public:
  
  OptionValueVec::const_iterator findValue(const string& key) const
  {
    OptionValueVec::const_iterator it = values.begin();
    for (; it != values.end(); ++it) {
      if (!it->desc) {
        continue; // ignore markers
      }
      
      if (it->desc->option == key) {
        return it;
      }
    } // of set values iteration
    
    return it; // not found
  }
  
  OptionDesc* findOption(const string& key) const
  {
    OptionDescDict::const_iterator it = options.find(key);
    if (it == options.end()) {
      return NULL;
    }
    
    return it->second;
  }
  
  int processOption(OptionDesc* desc, const string& arg_value)
  {
    if (!desc) {
      return FG_OPTIONS_OK; // tolerate marker options
    }
    
    switch ( desc->type & 0xffff ) {
      case OPTION_BOOL:
        fgSetBool( desc->property, desc->b_param );
        break;
      case OPTION_STRING:
        if ( desc->has_param && !arg_value.empty() ) {
          fgSetString( desc->property, arg_value.c_str() );
        } else if ( !desc->has_param && arg_value.empty() ) {
          fgSetString( desc->property, desc->s_param );
        } else if ( desc->has_param ) {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' needs a parameter" );
          return FG_OPTIONS_ERROR;
        } else {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' does not have a parameter" );
          return FG_OPTIONS_ERROR;
        }
        break;
      case OPTION_DOUBLE:
        if ( !arg_value.empty() ) {
          fgSetDouble( desc->property, atof( arg_value ) );
        } else {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' needs a parameter" );
          return FG_OPTIONS_ERROR;
        }
        break;
      case OPTION_INT:
        if ( !arg_value.empty() ) {
          fgSetInt( desc->property, atoi( arg_value ) );
        } else {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' needs a parameter" );
          return FG_OPTIONS_ERROR;
        }
        break;
      case OPTION_CHANNEL:
        // XXX return value of add_channel should be checked?
        if ( desc->has_param && !arg_value.empty() ) {
          add_channel( desc->option, arg_value );
        } else if ( !desc->has_param && arg_value.empty() ) {
          add_channel( desc->option, desc->s_param );
        } else if ( desc->has_param ) {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' needs a parameter" );
          return FG_OPTIONS_ERROR;
        } else {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' does not have a parameter" );
          return FG_OPTIONS_ERROR;
        }
        break;
      case OPTION_FUNC:
        if ( desc->has_param && !arg_value.empty() ) {
          return desc->func( arg_value.c_str() );
        } else if ( !desc->has_param && arg_value.empty() ) {
          return desc->func( desc->s_param );
        } else if ( desc->has_param ) {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' needs a parameter" );
          return FG_OPTIONS_ERROR;
        } else {
          SG_LOG( SG_GENERAL, SG_ALERT, "Option '" << desc->option << "' does not have a parameter" );
          return FG_OPTIONS_ERROR;
        }
        break;
        
      case OPTION_IGNORE:
        break;
    }
    
    return FG_OPTIONS_OK;
  }
    
  /**
   * insert a marker value into the values vector. This is necessary
   * when processing options, to ensure the correct ordering, where we scan
   * for marker values in reverse, and then forwards within each group.
   */
  void insertGroupMarker()
  {
    values.push_back(OptionValue(NULL, "-"));
  }
  
  /**
   * given a current iterator into the values, find the preceeding group marker,
   * or return the beginning of the value vector.
   */
  OptionValueVec::const_iterator rfindGroup(OptionValueVec::const_iterator pos) const
  {
    while (--pos != values.begin()) {
      if (pos->desc == NULL) {
        return pos; // found a marker, we're done
      }
    }
    
    return pos;
  }
  
  bool showHelp,
    verbose,
    showAircraft;
    
  OptionDescDict options;
  OptionValueVec values;
  simgear::PathList propertyFiles;
};
  
Options* Options::sharedInstance()
{
  if (shared_instance == NULL) {
    shared_instance = new Options;
  }
  
  return shared_instance;
}
  
Options::Options() :
  p(new OptionsPrivate())
{
  p->showHelp = false;
  p->verbose = false;
  p->showAircraft = false;
  
// build option map
  OptionDesc *desc = &fgOptionArray[ 0 ];
  while ( desc->option != 0 ) {
    p->options[ desc->option ] = desc;
    ++desc;
  }
}
  
Options::~Options()
{
}
  
void Options::init(int argc, char **argv, const SGPath& appDataPath)
{
  fgSetDefaults();
  
// first, process the command line
  bool inOptions = true;
  for (int i=1; i<argc; ++i) {
    if (inOptions && (argv[i][0] == '-')) {
      if (strcmp(argv[i], "--") == 0) { // end of options delimiter
        inOptions = true;
        continue;
      }
      
      int result = parseOption(argv[i]);
      processArgResult(result);
    } else {
    // XML properties file
      SGPath f(argv[i]);
      if (!f.exists()) {
        SG_LOG(SG_GENERAL, SG_ALERT, "config file not found:" << f.str());
        return;
      }
      
      p->propertyFiles.push_back(f);
    }
  } // of arguments iteration
  p->insertGroupMarker(); // command line is one group
  
  // establish log-level before anything else - otherwise it is not possible
  // to show extra (debug/info/warning) messages for the start-up phase.
  fgOptLogLevel(valueForOption("log-level", "alert").c_str());

// then config files
  SGPath config;
  
  if( homedir.size() && hostname.size() ) {
    // Check for ~/.fgfsrc.hostname
    config.set(homedir);
    config.append(".fgfsrc");
    config.concat( "." );
    config.concat( hostname );
    readConfig(config);
  }
  
// Check for ~/.fgfsrc
  if( homedir.size() ) {
    config.set(homedir);
    config.append(".fgfsrc");
    readConfig(config);
  }
  
// check for a config file in app data
  SGPath appDataConfig(appDataPath);
  appDataConfig.append("fgfsrc");
  if (appDataConfig.exists()) {
    readConfig(appDataConfig);
  }
  
// setup FG_ROOT
  setupRoot();
  
// system.fgfsrc handling
  if( hostname.size() > 0 ) {
    config.set(globals->get_fg_root());
    config.append( "system.fgfsrc" );
    config.concat( "." );
    config.concat( hostname );
    readConfig(config);
  }

  config.set(globals->get_fg_root());
  config.append( "system.fgfsrc" );
  readConfig(config);
}
  
void Options::initAircraft()
{
  BOOST_FOREACH(const string& paths, valuesForOption("fg-aircraft")) {
    globals->append_aircraft_paths(paths);
  }
  
  const char* envp = ::getenv("FG_AIRCRAFT");
  if (envp) {
    globals->append_aircraft_paths(envp);
  }

  string aircraft;
  if (isOptionSet("aircraft")) {
    aircraft = valueForOption("aircraft");
  } else if (isOptionSet("vehicle")) {
    aircraft = valueForOption("vehicle");
  }
    
  if (!aircraft.empty()) {
    SG_LOG(SG_INPUT, SG_INFO, "aircraft = " << aircraft );
    fgSetString("/sim/aircraft", aircraft.c_str() );
  } else {
    SG_LOG(SG_INPUT, SG_INFO, "No user specified aircraft, using default" );
  }
  
  if (p->showAircraft) {
    fgOptLogLevel( "alert" );
    SGPath path( globals->get_fg_root() );
    path.append("Aircraft");
    fgShowAircraft(path);
    exit(0);
  }
  
  if (isOptionSet("aircraft-dir")) {
    // set this now, so it's available in FindAndCacheAircraft
    fgSetString("/sim/aircraft-dir", valueForOption("aircraft-dir"));
  }
}
  
void Options::processArgResult(int result)
{
  if ((result == FG_OPTIONS_HELP) || (result == FG_OPTIONS_ERROR))
    p->showHelp = true;
  else if (result == FG_OPTIONS_VERBOSE_HELP)
    p->verbose = true;
  else if (result == FG_OPTIONS_SHOW_AIRCRAFT) {
    p->showAircraft = true;    
  } else if (result == FG_OPTIONS_SHOW_SOUND_DEVICES) {
    SGSoundMgr smgr;
    
    smgr.init();
    string vendor = smgr.get_vendor();
    string renderer = smgr.get_renderer();
    cout << renderer << " provided by " << vendor << endl;
    cout << endl << "No. Device" << endl;
    
    vector <const char*>devices = smgr.get_available_devices();
    for (vector <const char*>::size_type i=0; i<devices.size(); i++) {
      cout << i << ".  \"" << devices[i] << "\"" << endl;
    }
    devices.clear();
    smgr.stop();
    exit(0);
  } else if (result == FG_OPTIONS_EXIT) {
    exit(0);
  }
}
  
void Options::readConfig(const SGPath& path)
{
  sg_gzifstream in( path.str() );
  if ( !in.is_open() ) {
    return;
  }
  
  SG_LOG( SG_GENERAL, SG_INFO, "Processing config file: " << path.str() );
  
  in >> skipcomment;
  while ( ! in.eof() ) {
    string line;
    getline( in, line, '\n' );
    
    // catch extraneous (DOS) line ending character
    int i;
    for (i = line.length(); i > 0; i--)
      if (line[i - 1] > 32)
        break;
    line = line.substr( 0, i );
    
    if ( parseOption( line ) == FG_OPTIONS_ERROR ) {
      cerr << endl << "Config file parse error: " << path.str() << " '"
      << line << "'" << endl;
	    p->showHelp = true;
    }
    in >> skipcomment;
  }

  p->insertGroupMarker(); // each config file is a group
}
  
int Options::parseOption(const string& s)
{
  if ((s == "--help") || (s=="-h")) {
    return FG_OPTIONS_HELP;
  } else if ( (s == "--verbose") || (s == "-v") ) {
    // verbose help/usage request
    return FG_OPTIONS_VERBOSE_HELP;
  } else if (s.find("-psn") == 0) {
    // on Mac, when launched from the GUI, we are passed the ProcessSerialNumber
    // as an argument (and no others). Silently ignore the argument here.
    return FG_OPTIONS_OK;
  } else if ( s.find( "--show-aircraft") == 0) {
    return(FG_OPTIONS_SHOW_AIRCRAFT);
  } else if ( s.find( "--show-sound-devices") == 0) {
    return(FG_OPTIONS_SHOW_SOUND_DEVICES);
  } else if ( s.find( "--prop:") == 0) {
    // property setting has a slightly different syntax, so fudge things
    OptionDesc* desc = p->findOption("prop");
    if (s.find("=", 7) == string::npos) { // no equals token
      SG_LOG(SG_GENERAL, SG_ALERT, "malformed property option:" << s);
      return FG_OPTIONS_ERROR;
    }
    
    p->values.push_back(OptionValue(desc, s.substr(7)));
    return FG_OPTIONS_OK;
  } else if ( s.find( "--" ) == 0 ) {
    size_t eqPos = s.find( '=' );
    string key, value;
    if (eqPos == string::npos) {
      key = s.substr(2);
    } else {
      key = s.substr( 2, eqPos - 2 );
      value = s.substr( eqPos + 1);
    }
    
    return addOption(key, value);
  } else {
    SG_LOG(SG_GENERAL, SG_ALERT, "unknown option:" << s);
    return FG_OPTIONS_ERROR;
  }
}
  
int Options::addOption(const string &key, const string &value)
{
  OptionDesc* desc = p->findOption(key);
  if (!desc) {
    SG_LOG(SG_GENERAL, SG_ALERT, "unknown option:" << key);
    return FG_OPTIONS_ERROR;
  }
  
  if (!(desc->type & OPTION_MULTI)) {
    OptionValueVec::const_iterator it = p->findValue(key);
    if (it != p->values.end()) {
      SG_LOG(SG_GENERAL, SG_INFO, "multiple values forbidden for option:" << key << ", ignoring:" << value);
      return FG_OPTIONS_OK;
    }
  }
  
  p->values.push_back(OptionValue(desc, value));
  return FG_OPTIONS_OK;
}
  
bool Options::isOptionSet(const string &key) const
{
  OptionValueVec::const_iterator it = p->findValue(key);
  return (it != p->values.end());
}
  
string Options::valueForOption(const string& key, const string& defValue) const
{
  OptionValueVec::const_iterator it = p->findValue(key);
  if (it == p->values.end()) {
    return defValue;
  }
  
  return it->value;
}

string_list Options::valuesForOption(const std::string& key) const
{
  string_list result;
  OptionValueVec::const_iterator it = p->values.begin();
  for (; it != p->values.end(); ++it) {
    if (!it->desc) {
      continue; // ignore marker values
    }
    
    if (it->desc->option == key) {
      result.push_back(it->value);
    }
  }
  
  return result;
}

void Options::processOptions()
{
  // establish locale before showing help (this selects the default locale,
  // when no explicit option was set)
  globals->get_locale()->selectLanguage(valueForOption("language").c_str());

  // now FG_ROOT is setup, process various command line options that bail us
  // out quickly, but rely on aircraft / root settings
  if (p->showHelp) {
    showUsage();
    exit(0);
  }
  
  // processing order is complicated. We must process groups LIFO, but the
  // values *within* each group in FIFO order, to retain consistency with
  // older versions of FG, and existing user configs.
  // in practice this means system.fgfsrc must be *processed* before
  // .fgfsrc, which must be processed before the command line args, and so on.
  OptionValueVec::const_iterator groupEnd = p->values.end();

  while (groupEnd != p->values.begin()) {
    OptionValueVec::const_iterator groupBegin = p->rfindGroup(groupEnd);
  // run over the group in FIFO order
    OptionValueVec::const_iterator it;
    for (it = groupBegin; it != groupEnd; ++it) {      
      int result = p->processOption(it->desc, it->value);
      switch(result)
      {
          case FG_OPTIONS_ERROR:
              showUsage();
              exit(-1); // exit and return an error
          case FG_OPTIONS_EXIT:
              exit(0);  // clean exit
          default:
              break;
      }
    }
    
    groupEnd = groupBegin;
  }

  BOOST_FOREACH(const SGPath& file, p->propertyFiles) {
    if (!file.exists()) {
      SG_LOG(SG_GENERAL, SG_ALERT, "config file not found:" << file.str());
      continue;
    }
    
    SG_LOG(SG_GENERAL, SG_INFO,
           "Reading command-line property file " << file.str());
	  readProperties(file.str(), globals->get_props());
  }

// now options are process, do supplemental fixup
  const char *envp = ::getenv( "FG_SCENERY" );
  if (envp) {
    globals->append_fg_scenery(envp);
  }
    
// terrasync directory fixup
  if (fgGetBool("/sim/terrasync/enabled")) {
    string terrasyncDir = fgGetString("/sim/terrasync/scenery-dir");
    if (terrasyncDir.empty()) {
      SGPath p(globals->get_fg_home());
      p.append("TerraSync");
      if (!p.exists()) {
        simgear::Dir dd(p);
        dd.create(0700);
      }
      
      terrasyncDir = p.str();
      SG_LOG(SG_GENERAL, SG_INFO,
             "Using default TerraSync dir: " << terrasyncDir);
      fgSetString("/sim/terrasync/scenery-dir", terrasyncDir);
    }
    
    const string_list& scenery_paths(globals->get_fg_scenery());
    if (std::find(scenery_paths.begin(), scenery_paths.end(), terrasyncDir) == scenery_paths.end()) {
      // terrasync dir is not in the scenery paths, add it
      globals->append_fg_scenery(terrasyncDir);
    }
  }
  
  if (globals->get_fg_scenery().empty()) {
    // no scenery paths set *at all*, use the data in FG_ROOT
    SGPath root(globals->get_fg_root());
    root.append("Scenery");
    globals->append_fg_scenery(root.str());
  }
}
  
void Options::showUsage() const
{
  fgOptLogLevel( "alert" );
  
  FGLocale *locale = globals->get_locale();
  SGPropertyNode options_root;
  
  SG_LOG( SG_GENERAL, SG_ALERT, "" ); // To popup the console on Windows
  cout << endl;

  try {
    fgLoadProps("options.xml", &options_root);
  } catch (const sg_exception &) {
    cout << "Unable to read the help file." << endl;
    cout << "Make sure the file options.xml is located in the FlightGear base directory," << endl;
    cout << "and the location of the base directory is specified by setting $FG_ROOT or" << endl;
    cout << "by adding --fg-root=path as a program argument." << endl;
    
    exit(-1);
  }

  SGPropertyNode *options = options_root.getNode("options");
  if (!options) {
    SG_LOG( SG_GENERAL, SG_ALERT,
           "Error reading options.xml: <options> directive not found." );
    exit(-1);
  }

  if (!locale->loadResource("options"))
  {
      cout << "Unable to read the language resource." << endl;
      exit(-1);
  }

  const char* usage = locale->getLocalizedString(options->getStringValue("usage"), "options");
  if (usage) {
    cout << usage << endl;
  }
  
  vector<SGPropertyNode_ptr>section = options->getChildren("section");
  for (unsigned int j = 0; j < section.size(); j++) {
    string msg = "";
    
    vector<SGPropertyNode_ptr>option = section[j]->getChildren("option");
    for (unsigned int k = 0; k < option.size(); k++) {
      
      SGPropertyNode *name = option[k]->getNode("name");
      SGPropertyNode *short_name = option[k]->getNode("short");
      SGPropertyNode *key = option[k]->getNode("key");
      SGPropertyNode *arg = option[k]->getNode("arg");
      bool brief = option[k]->getNode("brief") != 0;
      
      if ((brief || p->verbose) && name) {
        string tmp = name->getStringValue();
        
        if (key){
          tmp.append(":");
          tmp.append(key->getStringValue());
        }
        if (arg) {
          tmp.append("=");
          tmp.append(arg->getStringValue());
        }
        if (short_name) {
          tmp.append(", -");
          tmp.append(short_name->getStringValue());
        }
        
        if (tmp.size() <= 25) {
          msg+= "   --";
          msg += tmp;
          msg.append( 27-tmp.size(), ' ');
        } else {
          msg += "\n   --";
          msg += tmp + '\n';
          msg.append(32, ' ');
        }
        // There may be more than one <description> tag associated
        // with one option
        
        vector<SGPropertyNode_ptr> desc;
        desc = option[k]->getChildren("description");
        if (desc.size() > 0) {
          for ( unsigned int l = 0; l < desc.size(); l++) {
            string t = desc[l]->getStringValue();

            // There may be more than one translation line.
            vector<SGPropertyNode_ptr>trans_desc = locale->getLocalizedStrings(t.c_str(),"options");
            for ( unsigned int m = 0; m < trans_desc.size(); m++ ) {
              string t_str = trans_desc[m]->getStringValue();
              
              if ((m > 0) || ((l > 0) && m == 0)) {
                msg.append( 32, ' ');
              }
              
              // If the string is too large to fit on the screen,
              // then split it up in several pieces.
              
              while ( t_str.size() > 47 ) {
                
                string::size_type m = t_str.rfind(' ', 47);
                msg += t_str.substr(0, m) + '\n';
                msg.append( 32, ' ');
                
                t_str.erase(t_str.begin(), t_str.begin() + m + 1);
              }
              msg += t_str + '\n';
            }
          }
        }
      }
    }
    
    const char* name = locale->getLocalizedString(section[j]->getStringValue("name"),"options");
    if (!msg.empty() && name) {
      cout << endl << name << ":" << endl;
      cout << msg;
      msg.erase();
    }
  }
  
  if ( !p->verbose ) {
    const char* verbose_help = locale->getLocalizedString(options->getStringValue("verbose-help"),"options");
    if (verbose_help)
        cout << endl << verbose_help << endl;
  }
#ifdef _MSC_VER
  std::cout << "Hit a key to continue..." << std::endl;
  std::cin.get();
#endif
}
  
#if defined(__CYGWIN__)
string Options::platformDefaultRoot() const
{
  return "../data";
}

#elif defined(_WIN32)
string Options::platformDefaultRoot() const
{
  return "..\\data";
}
#elif defined(__APPLE__)
string Options::platformDefaultRoot() const
{
  /*
   The following code looks for the base package inside the application 
   bundle, in the standard Contents/Resources location. 
   */
  CFURLRef resourcesUrl = CFBundleCopyResourcesDirectoryURL(CFBundleGetMainBundle());
  
  // look for a 'data' subdir
  CFURLRef dataDir = CFURLCreateCopyAppendingPathComponent(NULL, resourcesUrl, CFSTR("data"), true);
  
  // now convert down to a path, and the a c-string
  CFStringRef path = CFURLCopyFileSystemPath(dataDir, kCFURLPOSIXPathStyle);
  string root = CFStringGetCStringPtr(path, CFStringGetSystemEncoding());
  
  CFRelease(resourcesUrl);
  CFRelease(dataDir);
  CFRelease(path);
  
  return root;
}
#else
string Options::platformDefaultRoot() const
{
  return PKGLIBDIR;
}
#endif
  
void Options::setupRoot()
{
  string root;
  if (isOptionSet("fg-root")) {
    root = valueForOption("fg-root"); // easy!
  } else {
  // Next check if fg-root is set as an env variable
    char *envp = ::getenv( "FG_ROOT" );
    if ( envp != NULL ) {
      root = envp;
    } else {
      root = platformDefaultRoot();
    }
  } 
  
  SG_LOG(SG_INPUT, SG_INFO, "fg_root = " << root );
  globals->set_fg_root(root);
  
// validate it
  static char required_version[] = FLIGHTGEAR_VERSION;
  string base_version = fgBasePackageVersion();
  if ( !(base_version == required_version) ) {
    // tell the operator how to use this application
    
    SG_LOG( SG_GENERAL, SG_ALERT, "" ); // To popup the console on windows
    cerr << endl << "Base package check failed:" << endl \
    << "  Version " << base_version << " found at: " \
    << globals->get_fg_root() << endl \
    << "  Version " << required_version << " is required." << endl \
    << "Please upgrade/downgrade base package and set the path to your fgdata" << endl \
    << "with --fg-root=path_to_your_fgdata" << endl;
#ifdef _MSC_VER
    cerr << "Hit a key to continue..." << endl;
    cin.get();
#endif
    exit(-1);
  }
}
  
} // of namespace flightgear