import {
  endEvent,
  Event,
  EventStream,
  EventStreamSeed,
  isEnd,
  Scope,
  ObservableSeed,
  Observer,
} from "./abstractions"
import { applyScopeMaybe } from "./applyscope"
import { fromSubscribe } from "./fromsubscribe"
import { nop, rename } from "./util"

export function repeat<V>(
  generator: (iteration: number) => ObservableSeed<V, any, any> | undefined
): EventStreamSeed<V>
export function repeat<V>(
  generator: (iteration: number) => ObservableSeed<V, any, any> | undefined,
  scope: Scope
): EventStream<V>

export function repeat<V>(
  generator: (iteration: number) => ObservableSeed<V, any, any> | undefined,
  scope?: Scope
): any {
  var index = 0

  return applyScopeMaybe(
    rename(
      "repeat(fn)",
      fromSubscribe<V>(function (
        onValue: Observer<V>,
        onEnd: Observer<void> = nop
      ) {
        var flag = false

        var unsub = function () {}

        function handleEnd() {
          if (!flag) {
            flag = true
          } else {
            subscribeNext()
          }
        }
        function subscribeNext() {
          var next: ObservableSeed<V, any, any> | undefined
          flag = true
          while (flag) {
            next = generator(index++)
            flag = false
            if (next) {
              unsub = next.consume().subscribe(onValue, handleEnd)
            } else {
              onEnd()
            }
          }
          flag = true
        }
        subscribeNext()
        return () => unsub()
      })
    ),
    scope
  )
}