#if INTERACTIVE
#r @"nuget: Akka"
#r @"nuget: Akka.FSharp"
#endif


open System
open Akka.Actor
open Akka.Configuration
open Akka.FSharp

type CustomException() =
    inherit Exception()

type Message =
    | Echo of string
    | Crash

let system = System.create "system" (Configuration.defaultConfig())
    // create parent actor to watch over jobs delegated to it's child
let parent = 
    spawnOpt system "parent" 
        <| fun parentMailbox ->
            // define child actor
            let child = 
                    spawn parentMailbox "child" <| fun childMailbox ->
                        childMailbox.Defer (fun () -> printfn "Child stopping")
                        printfn "Child started"
                        let rec childLoop() = 
                            actor {
                                let! msg = childMailbox.Receive()
                                match msg with
                                | Echo info -> 
                                    // respond to original sender
                                    let response = "Child " + (childMailbox.Self.Path.ToStringWithAddress()) + " received: "  + info
                                    childMailbox.Sender() <! response
                                | Crash -> 
                                    // log crash request and crash
                                    //printfn "Child %A received crash order" (childMailbox.Self.Path)
                                    raise (CustomException())
                                return! childLoop()
                            }
                        childLoop()
            // define parent behavior
            let rec parentLoop() =
                actor {
                    let! (msg: Message) = parentMailbox.Receive()
                    child.Forward(msg)  // forward all messages through

                    //###########################################
                    //###### Notice this sender()

                    let sender = parentMailbox.Sender()
                    if sender <> null then
                        printfn "sender: %A" sender

                    //###########################################
                    return! parentLoop()
                }
            parentLoop()
        // define supervision strategy
        <| [ SpawnOption.SupervisorStrategy (
                // restart on Custom Exception, default behavior on all other exception types
                Strategy.OneForOne(fun e ->
                match e with
                | :? CustomException -> Directive.Restart 
                | _ -> SupervisorStrategy.DefaultDecider.Decide(e)
                //Directive.Restart
                )
        )  ]


parent <! Crash