// A switch flipped on and off, and a `never` property that counts how often it went on.
//
// After on-then-off the world is exactly as it started, so a search that merges states by
// the world alone never tries "on" a second time, and wrongly says it never happens. What
// the property remembers of the path (here: how often it went on) is part of the state.
//
// Expected: `onOnce` breaks in 3 steps (on, off, on).
import { defineActor, defineProperty, defineScenario, defineSpec, defineZone } from "@leostera/feynman";

export function lightSwitch() {
  const zone = defineZone({ name: "Room" });
  const Switch = defineActor({
    name: "Switch",
    zone,
    singleton: true,
    initialState: () => ({ on: false }),
    display: { icon: "plug", status: (s) => (s.on ? "on" : "off"), mood: (s) => (s.on ? "ok" : "off") },
    transitions: {
      up: { description: "Goes on.", when: (s) => !s.on, run: (s) => void (s.on = true) },
      down: { description: "Goes off.", when: (s) => s.on, run: (s) => void (s.on = false) },
    },
  });

  const onOnce = defineProperty("onOnce", { description: "The switch never goes on twice.", never: (t) => t.count((e) => e.is(Switch, "up")) >= 2 });

  const onAndOff = defineScenario("On and off", {
    description: "The switch goes on, then off: back where it started.",
    run(s) {
      s.step(s.the(Switch), "up");
      s.step(s.the(Switch), "down");
    },
  });

  const onAgain = defineScenario("On again", {
    description: "On, off, and on again: the world is as it was after the first, but the switch has gone on twice.",
    run(s) {
      s.step(s.the(Switch), "up");
      s.step(s.the(Switch), "down");
      s.step(s.the(Switch), "up");
    },
  });

  return defineSpec({
    name: "Switch",
    actors: [Switch],
    properties: [onOnce],
    scenarios: [onAndOff, onAgain],
  });
}

export default lightSwitch();