Version of Lights.swift for dynamic linking

Lights.swift

import Foundation

let circle1 = 1
let circle2 = 2
let circle3 = 3

var time = 0.0
var step = 0

var updateProperty: (_ tag: Int, _ property: String, _ value: Any) -> Void
var addWidget: (_ widget: String, _ properties: [String: Any]) -> Void

@_cdecl("set_update_property_func")
public func setUpdatePropertyFunc(f: @escaping (_ tag: Int, _ property: String, _ value: Any) -> Void) {
    updateProperty = f
}

@_cdecl("set_add_widget_func")
public func setAddWidgetFunc(f: @escaping (_ widget: String, _ properties: [String: Any]) -> Void) {
    addWidget = f
}

@_cdecl("lights_tick")
public func tick(delta: TimeInterval) {
    time += delta
    if time >= 1.0 {
        time -= 1.0
        loopStep()
    }
}

@_cdecl("loop_step")
func loopStep() {
    switch step {
    case 0:
        updateProperty(circle1, "color", "#50ff0000")
        updateProperty(circle2, "color", "#ffffff00")
        updateProperty(circle3, "color", "#5000ff00")
        
    case 1:
        updateProperty(circle1, "color", "#50ff0000")
        updateProperty(circle2, "color", "#50ffff00")
        updateProperty(circle3, "color", "#ff00ff00")
        
    case 2:
        updateProperty(circle1, "color", "#ffff0000")
        updateProperty(circle2, "color", "#50ffff00")
        updateProperty(circle3, "color", "#5000ff00")
        
    default:
        break
    }
    step = (step + 1) % 3
}

@_cdecl("lights_start")
public func start(width: Double, height: Double) {
    let circleRadius = height / 10.0
    addWidget("Circle", [
        "tag": circle1,
        "x": width / 2,
        "y": circleRadius * 2,
        "radius": circleRadius,
        "color": "#ffff0000"
    ])
    addWidget("Circle", [
        "tag": circle2,
        "x": width / 2,
        "y": circleRadius * 5,
        "radius": circleRadius,
        "color": "#50ffff00"
    ])
    addWidget("Circle", [
        "tag": circle3,
        "x": width / 2,
        "y": circleRadius * 8,
        "radius": circleRadius,
        "color": "#5000ff00"
    ])
}