var softkeysClass = {
    new : func (device, node, role) {
        var m = { parents: [ softkeysClass ] };
        m.node = node;
        m.device = device;
        m.role = role;
        m.path = [];
        return m;
    },

    clean : func {
        # deletes unsed bindings
        foreach (var b; keys(me.bindings))
            if (b != me.role)
                delete(me.bindings, b);
    },

    SoftKey : func (n, a) {
        # released key not yet managed
        if (a == 1)
            return;

        var key = me.device.display.screenElements[sprintf("SoftKey%02i-text",n)].get('text');
        if (key == '' or key == nil)
            return;

        var path = keyMap[me.role];
        foreach(var p; me.path) {
            if (contains(path, p))
                path = path[p];
            else
                break;
        }

        var bindings = me.bindings[me.role];
        foreach(var p; me.path) {
            if (contains(bindings, p))
                bindings = bindings[p];
            else
                break;
        }

        if (contains(path, key)) {
            append(me.path, key);
            if (contains(bindings[key], 'hook'))
                call(bindings[key].hook, [], me);
            me.device.display.updateSoftKeys();
        }
        elsif (contains(bindings, key)) {
            call(bindings[key], [], me);
        }
        elsif (key == 'BACK') {
            pop(me.path);
            me.device.display.updateSoftKeys();
        }
        else
            print(me.device.role ~ '/' ~ key ~ ' : not yet implemented');
    },

    bindings : {
        PFD : {
            INSET: {
                OFF: func {
                    pop(me.path);
                    me.device.display.updateSoftKeys();
                },
            },
            PFD: {
                'STD BARO': func {
                    pop(me.path);
                    me.device.display.updateSoftKeys();
                },
                'AOA/WIND' : {
                    WIND : {
                        OPTN1 : func {
                            me.device.display._winddata_optn = 1;
                            me.device.display.screenElements['WindData'].show();
                            me.device.display.screenElements['WindData-OPTN1'].show();
                            me.device.display.screenElements['WindData-OPTN1-HDG'].show();
                            me.device.display.screenElements['WindData-OPTN2'].hide();
                            me.device.display.updateWindData();
                        },
                        OPTN2 : func {
                            me.device.display._winddata_optn = 2;
                            me.device.display.screenElements['WindData'].show();
                            me.device.display.screenElements['WindData-OPTN1'].hide();
                            me.device.display.screenElements['WindData-OPTN2'].show();
                            me.device.display.screenElements['WindData-OPTN2-symbol'].show();
                            me.device.display.screenElements['WindData-OPTN2-headwind'].show();
                            me.device.display.screenElements['WindData-OPTN2-crosswind'].show();
                            me.device.display.updateWindData();
                        },
                        OFF : func {
                            me.device.display._winddata_optn = 0;
                            me.device.display.screenElements['WindData'].hide();
                            me.device.display.screenElements['WindData-OPTN1'].hide();
                            me.device.display.screenElements['WindData-OPTN2'].hide();
                        },
                    },
                },
                BRG1 : func (brg = 1){
                    var source = 'brg' ~ brg ~ '-source';
                    var list = ['NAV' ~ brg, 'GPS', 'ADF', 'OFF'];
                    var index = std.Vector
                                   .new(list)
                                   .index(radios.getNode(source).getValue());
                    var next = (index == size(list) -1) ?  0 : index + 1;
                    radios.getNode(source).setValue(list[next]);
                },
                BRG2 : func {
                    call(me.bindings.PFD.PFD.BRG1, [ 2 ], me);
                },
            },
            XPDR: {
                STBY : func {
                    me.bindings.PFD.XPDR.inactivity.restart(45);
                    setprop('/instrumentation/transponder/ident', 0);
                    setprop('/instrumentation/transponder/knob-mode', 1);
                    setprop('/instrumentation/zkv1000/radio/xpdr-mode', 'STBY');
                    me.device.display.updateXPDR();
                },
                ON : func {
                    me.bindings.PFD.XPDR.inactivity.restart(45);
                    setprop('/instrumentation/transponder/ident', 1);
                    setprop('/instrumentation/transponder/knob-mode', 4);
                    setprop('/instrumentation/zkv1000/radio/xpdr-mode', 'ON');
                    me.device.display.updateXPDR();
                },
                ALT : func {
                    me.bindings.PFD.XPDR.inactivity.restart(45);
                    setprop('/instrumentation/transponder/ident', 1);
                    setprop('/instrumentation/transponder/knob-mode', 5);
                    setprop('/instrumentation/zkv1000/radio/xpdr-mode', 'ALT');
                    me.device.display.updateXPDR();
                },
                VFR : func {
                    me.bindings.PFD.XPDR.inactivity.restart(45);
                    setprop('/instrumentation/transponder/id-code', '1200');
                    me.device.display.updateXPDR();
                },
                IDENT : func {
                    me.bindings.PFD.XPDR.inactivity.restart(45);
                    call(me.bindings.PFD.IDENT, [], me);
                },
                CODE : {
                    '0' : func (n = 0) {
                        me.bindings.PFD.XPDR.inactivity.restart(45);
                        var tuning = radios.getNode('xpdr-tuning-digit');
                        var d = tuning.getValue();
                        setprop('/instrumentation/transponder/inputs/digit[' ~ d ~ ']', n);
                        d += (d > 0) ? -1 : 3;
                        tuning.setValue(d);
                        me.device.display.updateXPDR();
                    },
                    '1' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 1 ], me);
                    },
                    '2' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 2 ], me);
                    },
                    '3' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 3 ], me);
                    },
                    '4' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 4 ], me);
                    },
                    '5' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 5 ], me);
                    },
                    '6' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 6 ], me);
                    },
                    '7' : func {
                        call(me.bindings.PFD.XPDR.CODE['0'], [ 7 ], me);
                    },
                    IDENT: func {
                        me.bindings.PFD.XPDR.inactivity.restart(45);
                        call(me.bindings.PFD.IDENT, [], me);
                    },
                    BKSP: func {
                        me.bindings.PFD.XPDR.inactivity.restart(45);
                        var tuning = radios.getNode('xpdr-tuning-digit');
                        var d = tuning.getValue();
                        d += (d < 3) ? 1 : -3;
                        tuning.setValue(d);
                        me.device.display.updateXPDR();
                    },
                    BACK : func (inactive = 0) {
                        var code = sprintf('%i', getprop('/instrumentation/zkv1000/radios/xpdr-backup-code'));
                        for (var i = 0; i < 4; i += 1)
                            setprop('/instrumentation/transponder/inputs/digit[' ~ (3 - i) ~ ']',
                                    substr(code, i, 1));
                        pop(me.path);
                        call(me.bindings.PFD.XPDR.CODE.exit, inactive ? [[]] : [me.path], me);
                    },
                    exit : func (p) {
                        if (contains(me.bindings.PFD.XPDR, 'inactivity')) # does not exists if IDENT pressed from top-level
                            me.bindings.PFD.XPDR.inactivity.stop();
                        radios.removeChild('xpdr-tuning-digit', 0);
                        radios.removeChild('xpdr-backup-code', 0);
                        me.path = p;
                        me.device.display.updateXPDR();
                        me.device.display.updateSoftKeys();
                    },
                    hook : func {
                        me.bindings.PFD.XPDR.inactivity.restart(45);
                        var tuning = getprop('/instrument/zkv1000/radios/xpdr-tuning-digit');
                        if (tuning == nil) {
                            radios.getNode('xpdr-tuning-digit', 1).setValue(3);
                            radios.getNode('xpdr-backup-code', 1).setValue(getprop('/instrumentation/transponder/id-code'));
                            me.device.display.updateXPDR();
                        }
                    },
                },
                hook : func {
                    me.bindings.PFD.XPDR.inactivity = maketimer(45,
                        func call(me.bindings.PFD.XPDR.CODE.BACK, [1], me));
                    me.bindings.PFD.XPDR.inactivity.singleShot = 1;
                    me.bindings.PFD.XPDR.inactivity.start();
                },
            },
            IDENT : func {
                if (getprop('/instrumentation/zkv1000/radio/xpdr-mode') == 'STBY')
                    return;
                setprop('/instrumentation/transponder/ident', 1);
                me.bindings.PFD.XPDR.ident = maketimer(18,
                        func {
                            setprop('/instrumentation/transponder/ident', 0);
                            me.device.display.updateXPDR();
                        });
                me.bindings.PFD.XPDR.ident.singleShot = 1;
                me.bindings.PFD.XPDR.ident.start();
                call(me.bindings.PFD.XPDR.CODE.exit, [[]], me);
            },
        },
        MFD : {
            ENGINE: {
                FUEL: {
                    UNDO: func {
                        pop(me.path);
                        me.device.display.updateSoftKeys();
                    },
                    ENTER: func {
                        pop(me.path);
                        me.device.display.updateSoftKeys();
                    },
                },
                ENGINE: func {
                    me.path = [];
                    me.device.display.updateSoftKeys();
                },
            },
        },
    },
};