72 lines
2.3 KiB
JavaScript
72 lines
2.3 KiB
JavaScript
// @ts-check
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/**
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* Layer 1 — owns lifecycle, the (injected) clock, and the move log; delegates all
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* game meaning to an injected `rules` object. This is where timing authority
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* lives: on the client `clock` is `Date.now` (cosmetic); on a server it is the
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* server's clock (authoritative). The session never calls a wall clock itself.
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* Future home: @cozy-games/game-session.
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*
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* @typedef {{ init: Function, apply: Function, status: Function, project: Function }} Rules
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*/
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export class GameSession {
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/**
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* @param {Rules} rules
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* @param {{ seed: number, config: object, clock?: () => number }} opts
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*/
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constructor(rules, { seed, config, clock = () => 0 }) {
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this.rules = rules
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this.clock = clock
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this.state = rules.init(seed, config)
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/** @type {Array<{ move: object, t: number }>} */
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this._log = []
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this._t0 = null
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this._tEnd = null
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}
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/**
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* Apply a move: stamp it, fold it through the rules, and return the projected
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* view + events + authoritative elapsed time.
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* @param {object} move
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*/
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applyMove(move) {
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const t = this.clock()
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const before = this.rules.status(this.state)
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const { state, events } = this.rules.apply(this.state, move)
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this.state = state
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this._log.push({ move, t })
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const after = this.rules.status(state)
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// Timer starts on the first move that leaves 'fresh' (the opening reveal).
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if (before === 'fresh' && after !== 'fresh' && this._t0 === null) this._t0 = t
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if ((after === 'won' || after === 'lost') && this._tEnd === null) this._tEnd = t
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return { events, view: this.rules.project(state), time: this.elapsed() }
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}
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status() {
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return this.rules.status(this.state)
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}
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view() {
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return this.rules.project(this.state)
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}
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log() {
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return this._log.slice()
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}
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/** Authoritative elapsed ms: first move → terminal move (or → now if ongoing). */
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elapsed() {
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if (this._t0 === null) return 0
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const end = this._tEnd !== null ? this._tEnd : this.clock()
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return end - this._t0
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}
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/** The signed-off result, or null while the game is still in progress. */
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result() {
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const status = this.status()
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if (status !== 'won' && status !== 'lost') return null
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return { status, time: this.elapsed(), seed: this.state.seed, config: this.state.config, log: this.log() }
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}
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}
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