mutally exclusive layers in group with title 'exclusive'

layers.js

// LINE 146
case CHANGE_LAYER_PROPERTIES: {
        const flatLayers = (state.flat || []);
        let isBackground = flatLayers.reduce(
            (background, layer) => background || (layer.id === action.layer && layer.group === 'background'),
            false);
        const newLayers = flatLayers.map((layer) => {
            if ( includes(castArray(action.layer), layer.id )) {
                return assign(
                    {},
                    layer,
                    action.newProperties,
                    action.params
                        ? {
                            params: assign({}, layer.params, action.params)
                        }
                        : {});
            } else if (layer.group === 'background' && isBackground && action.newProperties && action.newProperties.visibility) {
                // TODO remove
                return assign({}, layer, {visibility: false});
            }
            // check if layer shall be exclusive
            const groups = (state.groups);
            for (let i in groups) {
                const group = groups[i];
                if (group.id === layer.group) {
                    // get group of layer
                    if (group.title === 'exclusive') {
                        if (action.newProperties && action.newProperties.visibility) {
                            console.log(layer.title + " should not be visible anymore");
                            return assign({}, layer, {visibility: false});
                        }
                    }
                }
            }
            return assign({}, layer);
        });

        return assign({}, state, {flat: newLayers});
    }