// heading_indicator_dg.cxx - a Directional Gyro (DG) compass.
// Based on the vacuum driven Heading Indicator Written by David Megginson,
// started 2002.
//
// Written by Vivian Meazza, started 2005.
//
// This file is in the Public Domain and comes with no warranty.

#include <simgear/compiler.h>
#include <iostream>
#include <string>
#include <sstream>

#include <Main/fg_props.hxx>
#include <Main/util.hxx>

#include "heading_indicator_dg.hxx"


HeadingIndicatorDG::HeadingIndicatorDG ( SGPropertyNode *node ) :
    name("heading-indicator-dg"),
    num(0)
{
    int i;
    for ( i = 0; i < node->nChildren(); ++i ) {
        SGPropertyNode *child = node->getChild(i);
        string cname = child->getName();
        string cval = child->getStringValue();
        if ( cname == "name" ) {
            name = cval;
        } else if ( cname == "number" ) {
            num = child->getIntValue();
        } else {
            SG_LOG( SG_INSTR, SG_WARN, "Error in DG heading-indicator config logic" );
            if ( name.length() ) {
                SG_LOG( SG_INSTR, SG_WARN, "Section = " << name );
            }
        }
    }
}

HeadingIndicatorDG::HeadingIndicatorDG ()
{
}

HeadingIndicatorDG::~HeadingIndicatorDG ()
{
}

void
HeadingIndicatorDG::init ()
{
    string branch;
    branch = "/instrumentation/" + name;

    _heading_in_node = fgGetNode("/orientation/heading-deg", true);
    SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
    _offset_node = node->getChild("offset-deg", 0, true);
    _serviceable_node = node->getChild("serviceable", 0, true);
    _error_node = node->getChild("heading-bug-error-deg", 0, true);
    _nav1_error_node = node->getChild("nav1-course-error-deg", 0, true);
    _heading_out_node = node->getChild("indicated-heading-deg", 0, true);
    _last_heading_deg = (_heading_in_node->getDoubleValue() +
                         _offset_node->getDoubleValue());
    _electrical_node = fgGetNode("/systems/electrical/outputs/DG", true);
}

void
HeadingIndicatorDG::bind ()
{
    std::ostringstream temp;
    string branch;
    temp << num;
    branch = "/instrumentation/" + name + "[" + temp.str() + "]";

    fgTie((branch + "/serviceable").c_str(),
          &_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
    fgTie((branch + "/spin").c_str(),
          &_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
}

void
HeadingIndicatorDG::unbind ()
{
    std::ostringstream temp;
    string branch;
    temp << num;
    branch = "/instrumentation/" + name + "[" + temp.str() + "]";

    fgUntie((branch + "/serviceable").c_str());
    fgUntie((branch + "/spin").c_str());
}

void
HeadingIndicatorDG::update (double dt)
{
                                // Get the spin from the gyro
    _gyro.set_power_norm(_electrical_node->getDoubleValue());

    _gyro.update(dt);
    double spin = _gyro.get_spin_norm();

                                // No time-based precession	for a flux gate compass
                                // No magvar
    double offset = 0;

                                // TODO: movement-induced error

                                // Next, calculate the indicated heading,
                                // introducing errors.
    double factor = 0.01 / (spin * spin * spin * spin * spin * spin);
    double heading = _heading_in_node->getDoubleValue();

                                // Now, we have to get the current
                                // heading and the last heading into
                                // the same range.
    while ((heading - _last_heading_deg) > 180)
        _last_heading_deg += 360;
    while ((heading - _last_heading_deg) < -180)
        _last_heading_deg -= 360;

    heading = fgGetLowPass(_last_heading_deg, heading, dt/factor);
    _last_heading_deg = heading;

    heading += offset;
    while (heading < 0)
        heading += 360;
    while (heading > 360)
        heading -= 360;

    _heading_out_node->setDoubleValue(heading);

                                 // calculate the difference between the indicacted heading
                                 // and the selected heading for use with an autopilot
    static SGPropertyNode *bnode
        = fgGetNode( "/autopilot/settings/heading-bug-deg", false );
    if ( bnode ) {
        double diff = bnode->getDoubleValue() - heading;
        if ( diff < -180.0 ) { diff += 360.0; }
        if ( diff > 180.0 ) { diff -= 360.0; }
        _error_node->setDoubleValue( diff );
    }
                                 // calculate the difference between the indicated heading
                                 // and the selected nav1 radial for use with an autopilot
    SGPropertyNode *nnode
        = fgGetNode( "/instrumentation/nav/radials/selected-deg", false );
    if ( nnode ) {
        double diff = nnode->getDoubleValue() - heading;
        if ( diff < -180.0 ) { diff += 360.0; }
        if ( diff > 180.0 ) { diff -= 360.0; }
        _nav1_error_node->setDoubleValue( diff );
    }
}

// end of heading_indicator_fg.cxx
