namespace Logger

open System.Collections.Generic

open Logger.Types

type internal Listeners () =
    let monitor = obj ()

    let listeners = List<IListener> ()

    member this.Add (listener : IListener) =
        lock monitor (
            fun () ->
                if not <| listeners.Contains listener then
                    listeners.Add listener
        )

    member this.Remove (listener : IListener) =
        lock monitor (
            fun () ->
                listeners.Remove listener |> ignore
        )

    member this.NewEntry (message : Message) =
        lock monitor (
            fun () ->
                if listeners.Count > 0 then
                    let header = Utils.formatHeader message
                    for listener in listeners do
                        listener.NewEntry message.Severity header message.Message
        )