import { Action } from './model.js'
import { update } from './game.js'
import { newGame } from './spawn.js'
import { view, CELL } from './view.js'
import { map as mapIO, flatMap as flatMapIO, sequence, randomSeed, drawScene, loadBest, saveBest, trace } from './io.js'
import { keyDowns, interval, map, filterMap, merge, scan, startWith, clampTime, run } from './stream.js'
import { keyToAction } from './input.js'
/** @import { GameState, Session, Scene, IO, Stream, Input, Op, Program } from './types' */

export const TICK_MS = 150
export const FRAME_MS = 25
// m10: the longest step of time the game accepts at once; a longer silence (a background tab) counts as this much.
export const MAX_GAP_MS = 250

// Everything that can happen to the game: a Tick every TICK_MS, and a Turn for each steering key.
/** @type {Stream<Action>} */
export const classicActions = merge(
  map(interval(TICK_MS), () => Action.Tick),
  filterMap(keyDowns, keyToAction))

// m10: a Frame every FRAME_MS instead of a Tick; the game itself decides (movesEvery) which frames take a step.
/** @type {Stream<Action>} */
export const speedActions = merge(
  map(interval(FRAME_MS), () => Action.Frame),
  filterMap(keyDowns, keyToAction))

// Actions folded into game states. startWith puts the initial state first so it is drawn right away.
/** @type {(seed: number, actions: Stream<Action>) => Stream<GameState>} */
export const states = (seed, actions) =>
  startWith(scan(actions, update, newGame(seed)), newGame(seed))

/** @type {(state: GameState) => IO<undefined>} */
export const render = (state) => drawScene(view(state))

// m10: a session wraps the game with the best score so far. GameState, update and view do not know about it.
// `improved` says whether the action that produced this session raised the best, which is when it must be saved.
/** @type {(session: Session, action: Action) => Session} */
export const sessionUpdate = (session, action) => {
  const game = update(session.game, action)
  const best = Math.max(session.best, game.score)
  return { game, best, improved: best > session.best }
}

// The same running fold as `states`, one level up.
/** @type {(seed: number, best: number, actions: Stream<Action>) => Stream<Session>} */
export const sessions = (seed, best, actions) => {
  const s0 = { game: newGame(seed), best, improved: false }
  return startWith(scan(actions, sessionUpdate, s0), s0)
}

// The game's picture with the best score at the top right, level with the score on the left.
/** @type {(session: Session) => Scene} */
export const sessionView = (session) => [
  ...view(session.game),
  { tag: 'Text', x: session.game.width * CELL - 6, y: 18, text: `Best: ${session.best}`, color: '#ffffff', size: 16, align: 'right' },
]

// Draw, and save the best only on the action that raised it.
/** @type {(session: Session) => IO<undefined>} */
export const renderSession = (session) =>
  session.improved
    ? sequence([drawScene(sessionView(session)), saveBest(session.best)])
    : drawScene(sessionView(session))

// The whole program as a value: get a seed, then the stored best, then turn the stream of sessions into a stream
// of drawings. clampTime wraps the whole stream, so everything inside it sees the clamped clock.
// Nothing runs here; runtime.js interprets it.
/** @type {Program} */
export const main = flatMapIO(randomSeed, (seed) =>
  mapIO(loadBest, (best) => clampTime(map(sessions(seed, best, speedActions), renderSession), MAX_GAP_MS)))

// m09: the whole program in one equality. For each drawing that `main` emits while fed `events`, the ops it
// performs, answered by the pure interpreter (`seed` for RandomSeed, and from m10 `best` for LoadBest).
/** @type {(main: Program, seed: number, events: Input[], best?: number) => Op[][]} */
export const play = (main, seed, events, best = 0) =>
  run(trace(main, seed, best).result, events).map((io) => trace(io, seed, best).ops)