// m11 pong app: the same wiring as app.js (streams in, drawings out), reusing the course's modules.
import { initialPong, PongAction } from './model.js'
import { pongUpdate } from './rules.js'
import { pongView } from './view.js'
import { map as mapIO, randomSeed, drawScene } from '../io.js'
import { keyDowns, keyUps, interval, map, filterMap, merge, scan, startWith } from '../stream.js'

export const FRAME_MS_PONG = 30

const keys = {
  ArrowUp: 'Up', w: 'Up', W: 'Up',
  ArrowDown: 'Down', s: 'Down', S: 'Down',
}

// hasOwn, not `key in keys`: "constructor" and "toString" are inherited, not keys we mapped.
export const pongKey = (isDown, key) =>
  Object.hasOwn(keys, key) ? (isDown ? PongAction.Press : PongAction.Release)(keys[key])
    : (key === 'r' || key === 'R') && isDown ? PongAction.Restart
    : null

export const pongActions = merge(
  map(interval(FRAME_MS_PONG), () => PongAction.Frame),
  merge(
    filterMap(keyDowns, (key) => pongKey(true, key)),
    filterMap(keyUps, (key) => pongKey(false, key))))

export const pongStates = (seed, actions) =>
  startWith(scan(actions, pongUpdate, initialPong(seed)), initialPong(seed))

export const pongMain = mapIO(randomSeed, (seed) =>
  map(pongStates(seed, pongActions), (state) => drawScene(pongView(state))))