var APClass = {

    new : func {

        var m = { parents: [ APClass ] };

        m.system = 'none';

        var ap_systems = { # described AP systems to search, if it returns true system is set

            STEC55X: func contains(stec55x, 'ITAF'),

        };

        foreach (var s; sort(keys(ap_systems), func(a,b) cmp(a,b))) {

            call(ap_systems[s], [], nil, nil, var errors = []);

            if (!size(errors)) {

                msg('found autopilot system: ' ~ s);

                m.system = s;

                break;

            }

        }

        m.engaged = 0;

        if (! contains(data.timers, 'updateAP')) {

            data.timers.updateAP = maketimer(1, m, m.systems[m.system].updateDisplay);

            data.timers.updateAP.start();

        }

        var ap_annun = [

            'LATMOD-Armed-text',  'LATMOD-Active-text',

            'AP-Status-text',     'YD-Status-text',

            'VERMOD-Active-text', 'VERMOD-Reference-text', 'VERMOD-Armed-text'

        ];

        foreach (var elem; ap_annun) {

            var color = (elem == 'LATMOD-Armed-text' or elem == 'VERMOD-Armed-text') ? 'white' : 'green';

            flightdeck.PFD.display.screenElements[elem]

                .setColor(flightdeck.PFD.display.colors[color])

                .setVisible(0);

        }

        foreach (var ap; [ 'AP', 'YD' ])

            flightdeck.PFD.display.screenElements[ap ~ '-Status-text']

                .setText(ap);

        ap_annun = nil;

        ap_systems = nil;

        # delete unused systems

        foreach (var e; keys(m.systems))

            if (e != m.system)

                delete(m.systems, e);

        if (contains(m.systems[m.system], 'hook') and typeof(m.systems[m.system].hook) == 'func')

                m.systems[m.system].hook();

        return m;

    },

    softkey: func (side, row, a) {

        if (a)

            return;

        var _system = me.systems[me.system];

        var _side = _system[side];

        _side[row]();

    },

    systems : {

        # L: AP FD  NAV ALT VS FLC

        # R: YD HDG APR VNV UP DN

        none: {

            updateDisplay: func,

            hook: func,

            L: [ func, func, func, func, func, func ],

            R: [ func, func, func, func, func, func ],

        },

        STEC55X: {

            _aliases: {

                hdg:          afcs.getNode('heading-bug-deg'),

                alt:          afcs.getNode('selected-alt-ft'),

                NAVCourse:    cdi.getNode('course'),

                OBSNAVNeedle: cdi.getNode('course-deflection'),

            },

            hook : func {

                me.trimTarget = 0;

                foreach (var a; keys(me._aliases)) stec55x[a].alias(me._aliases[a]);

                setprop('/it-stec55x/input/ap-master-sw', 1);

            },

            updateDisplay: func {

                var se = flightdeck.PFD.display.screenElements;

                se['AP-Status-text'].setVisible(stec55x.rollMode  != -1 or stec55x.pitchMode != -1);

                se['YD-Status-text'].setVisible(stec55x.yaw.getValue() != -1);

                if (stec55x.rollMode  != -1) {

                    se['LATMOD-Active-text'].setVisible(1).setText('ROL');

                    var armed = '';

                    foreach (var m; [ 'NAV', 'CNAV', 'REV', 'CREV' ])

                        if (stec55x[m]) armed = m;

                    if (stec55x.roll.getValue() == 0) armed = 'HDG';

                    elsif (stec55x.roll.getValue() == 2) armed = 'GPS';

                    elsif (stec55x.APR_annun.getValue()) armed = 'APR';

                    se['LATMOD-Armed-text']

                        .setVisible(size(armed))

                        .setText(armed);

                }

                else {

                    se['LATMOD-Active-text'].setVisible(0);

                    se['LATMOD-Armed-text'].setVisible(0);

                }

                if (stec55x.pitchMode != 1) {

                    var armed     = '';

                    var active    = '';

                    var reference = '';

                    if (stec55x.ALT_annun.getBoolValue()) {

                        if (abs(data.alt - afcs.getValue('selected-alt-ft')) < 150) {

                            active    = 'ALT';

                            reference = sprintf('%5d ft', afcs.getValue('selected-alt-ft'));

                            armed     = 'ALTS'

                        }

                        else {

                            active    = 'ALT';

                            reference = sprintf('%5d ft', math.round(data.alt, 10));

                            armed     = 'ALT';

                        }

                    }

                    elsif (stec55x.VS_annun.getBoolValue()) {

                        active    = 'VS';

                        reference = sprintf('%s%4d fpm',

                                        utf8.chstr(stec55x.vs.getValue() > 0 ? 9650 : 9660),

                                        math.abs(math.round(stec55x.vs.getValue(), 10)));

                    }

                    elsif (stec55x.GSArmed.getBoolValue()) {

                        armed  = 'VPATH';

                        active = 'GS';

                    }

# TODO: ask Octal450 which prop or variable can be used here

#                    elsif (stec55x.???) {

#                        armed  = 'PIT';

#                        active = 'ALT';

#                        reference = sprintf("%d°", autopilot.systems.STEC55X.trim);

#                    }

                    se['VERMOD-Active-text'].setVisible(size(active)).setText(active);

                    se['VERMOD-Armed-text'].setVisible(size(armed)).setText(armed);

                    se['VERMOD-Reference-text'].setVisible(size(reference)).setText(reference);

                }

            },

            L: [

                func,

                func {

#                    var apfd_master_sw = '/it-stec55x/input/apfd-master-sw';

#                    setprop(apfd_master_sw, !getprop(apfd_master_sw));

                },

                func {

                    var _roll = stec55x.roll.getValue();

                    if (_roll == 1 or _roll == 2 or _roll == 4)

                        stec55x.roll.setValue(-1);

                    else {

                        stec55x.roll.setValue(1);

                        call(stec55x.button.NAV, [], nil, stec55x);

                    }

                },

                func {

#                    call(stec55x.button.ALT, [], nil, stec55x);

                },

                func {

#                    stec55x.vs.setValue(math.round(data.vsi, 100));

#                    call(stec55x.button.VS, [], nil, stec55x);

                },

                func,

            ],

            R: [

                func {

#                    var yaw_dumper_sw = '/it-stec55x/input/yaw-damper-sw';

#                    setprop(yaw_dumper_sw, !getprop(yaw_dumper_sw));

                },

                func {

                    if (stec55x.roll.getValue() == 0)

                        stec55x.roll.setValue(-1);

                    else

                        call(stec55x.button.HDG, [], nil, stec55x);

                },

                func {

#                    call(stec55x.button.APR, [], nil, stec55x);

                },

                func,

                func { # UP (trim)

#                    if (autopilot.systems.STEC55X.trimTarget > -15)

#                        autopilot.systems.STEC55X.trimTarget -= 1;

#                    fgcommand('property-assign', {property: '/it-stec55x/input/man-trim', value: -1});

#                    fgcommand('property-assign', {property: '/it-stec55x/input/man-trim', value:  0});

                },

                func { # DN (trim)

#                    if (autopilot.systems.STEC55X.trimTarget < 20)

#                        autopilot.systems.STEC55X.trimTarget += 1;

#                    fgcommand('property-assign', {property: '/it-stec55x/input/man-trim', value: 1});

#                    fgcommand('property-assign', {property: '/it-stec55x/input/man-trim', value: 0});

                },

            ],

        }

    }

};