//

// Timers.swift

// JavaScriptCoreBrowserObjectModel

//

// Created by Connor Grady on 10/7/17.

// Copyright © 2017 Connor Grady. All rights reserved.

//

import Foundation

import JavaScriptCore

//@objc protocol TimerJSExport : JSExport {

// func setTimeout(_ callback: JSValue, _ ms: Double) -> String

// func clearTimeout(_ identifier: String)

// func setInterval(_ callback: JSValue, _ ms: Double) -> String

// func clearInterval(_ identifier: String)

//}

@objc open class Timers: NSObject {

//

// General

//

//public class var count: Int { return timers.count }

//public class func destroy() {

// // TODO: iterate all `timers` & invalidate each

//}

// @usage:

// let context = JSContext()!

// Timers.extend(context)

// context.evaluateScript("setTimeout(done, 5 * 1000)") // `done()` is called after 5s

open class func extend(_ jsContext: JSContext) {

jsContext.setObject(setTimeout, forKeyedSubscript: "setTimeout" as (NSCopying & NSObjectProtocol))

jsContext.setObject(clearTimeout, forKeyedSubscript: "clearTimeout" as (NSCopying & NSObjectProtocol))

jsContext.setObject(setInterval, forKeyedSubscript: "setInterval" as (NSCopying & NSObjectProtocol))

jsContext.setObject(clearInterval, forKeyedSubscript: "clearInterval" as (NSCopying & NSObjectProtocol))

}

//

// JS Methods

//

// Timeout

public static let setTimeout: @convention(block) (JSValue, Double) -> UInt = { (callback, delay) in

return createTimer(callback: callback, delay: delay, repeats: false)

}

public static let clearTimeout: @convention(block) (UInt) -> Void = { (identifier) in

invalidateTimer(identifier)

}

// Interval

public static let setInterval: @convention(block) (JSValue, Double) -> UInt = { (callback, delay) in

return createTimer(callback: callback, delay: delay, repeats: true)

}

public static let clearInterval: @convention(block) (UInt) -> Void = { (identifier) in

invalidateTimer(identifier)

}

//

// Internals

//

internal static var timers = [UInt: Timer]()

internal static var prevTimerId: UInt = 0

fileprivate struct TimerData {

var id: UInt

var callbackManagedValue: JSManagedValue

var repeats: Bool

}

internal class func createTimer(callback: JSValue, delay: Double, repeats: Bool) -> UInt {

let callbackManagedValue = JSManagedValue(value: callback)!

let timerId = prevTimerId + 1

prevTimerId = timerId

let timer = Timer.scheduledTimer(

timeInterval: delay/1000.0,

target: self,

selector: #selector(fireTimer(timer:)),

userInfo: TimerData(id: timerId, callbackManagedValue: callbackManagedValue, repeats: repeats),

repeats: repeats

)

/*

// NOTE: the following implementation requires iOS 10, so we'll switch to it eventually

let timer = Timer.scheduledTimer(withTimeInterval: delay/1000.0, repeats: repeats) { timer in

let callback = callbackManagedValue.value

guard callback?.call(withArguments: []) != nil else {

// INFO: callback no-longer exists, or is not a function

timer.invalidate()

timers.removeValue(forKey: timerId)

return

}

if !repeats {

timers.removeValue(forKey: timerId)

}

}

*/

callback.context.virtualMachine.addManagedReference(callbackManagedValue, withOwner: timer)

timers[timerId] = timer

return timerId

}

@objc internal class func fireTimer(timer: Timer) {

let userInfo = timer.userInfo as! TimerData

let callback = userInfo.callbackManagedValue.value

guard callback?.call(withArguments: []) != nil else {

// INFO: callback no-longer exists, or is not a function

timer.invalidate()

timers.removeValue(forKey: userInfo.id)

return

}

if !userInfo.repeats {

timers.removeValue(forKey: userInfo.id)

}

}

internal class func invalidateTimer(_ identifier: UInt) {

if let timer = timers.removeValue(forKey: identifier) {

let userInfo = timer.userInfo as! TimerData

let callbackManagedValue = userInfo.callbackManagedValue

let callback = callbackManagedValue.value

callback?.context.virtualMachine.removeManagedReference(callbackManagedValue, withOwner: timer)

timer.invalidate()

}

}

}