import { todo } from './todo.js'

/**
 * The single impure place in the course (with browser.js and main.js): everything else only builds values.
 * A Platform is `{ fillRect(x,y,w,h,color), fillText(x,y,text,color,size,align), randomSeed() -> number,
 * startClock(onTime: t => void), onKeyDown(cb: key => void), onKeyUp(cb: key => void) }`.
 * Here `let`, loops and mutation are allowed. Keep it tiny.
 */

/**
 * Interpret an IO against a platform and return its final value.
 * `Draw` of a Rect -> `platform.fillRect(x, y, w, h, color)`; of a Text -> `platform.fillText(x, y, text, color, size, align)`;
 * `RandomSeed` -> `platform.randomSeed()`. The result of each op is passed to `io.k`.
 * Must be a loop, not recursion: a long sequence of draws must not overflow the stack.
 */
export const runIO = (io, platform) => todo('m09')

/**
 * Run the program: `runIO(main)` gives the stream; keep the current stream in the one mutable variable.
 * Register `platform.onKeyDown` / `onKeyUp` / `startClock` so that each event steps the stream with the matching
 * input (`{tag:'KeyDown', key}`, `{tag:'KeyUp', key}`, `{tag:'Time', t}`), stores the next stream,
 * and runs every IO the step emitted, in order.
 */
export const runApp = (main, platform) => todo('m09')