import { assertEquals, test } from "Test"
import { Just, Nothing } from "Maybe"
import String from "String"

import { loop, maybeLoop } from "./Control"

// loop
test("loop - doubling", () => {
  expected = 16
  actual = loop(1, (x) => x < 10, (x) => x * 2)
  return assertEquals(actual, expected)
})

test("loop - count to 100", () => assertEquals(
  loop(0, (x) => x < 100, (x) => x + 1),
  100,
))

test("loop - immediate false", () => assertEquals(
  loop(42, (_) => false, (x) => x + 1),
  42,
))

test("loop - string building", () => assertEquals(
  loop("", (s) => String.length(s) < 5, (s) => s ++ "a"),
  "aaaaa",
))

// maybeLoop
test("maybeLoop - doubling", () => {
  expected = 16
  actual = maybeLoop(1, (x) => x < 10 ? Just(x * 2) : Nothing)
  return assertEquals(actual, expected)
})

test("maybeLoop - immediate Nothing", () => assertEquals(
  maybeLoop(42, (_) => Nothing),
  42,
))

test("maybeLoop - count up", () => assertEquals(
  maybeLoop(0, (x) => x < 5 ? Just(x + 1) : Nothing),
  5,
))

test("maybeLoop - accumulate list", () => assertEquals(
  maybeLoop(
    #[0, []],
    (pair) => where(pair) {
      #[n, acc] =>
        n < 4 ? Just(#[n + 1, [...acc, n]]) : Nothing
    },
  ),
  #[4, [0, 1, 2, 3]],
))