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);
            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: {
                CODE: {
                    IDENT: func {
                        me.path = [];
                        me.device.display.updateSoftKeys();
                    },
                    BACK: func {
                        me.path = [];
                        me.device.display.updateSoftKeys();
                    },
                },
            },
        },
        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();
                },
            },
        },
    },
};