// Technique 1: a fixed seed.
// Every track's glue asks the browser for its seed the same way: it makes a Uint32Array of length 1 and hands it to
// crypto.getRandomValues (JS: `new Uint32Array(1)`; Scala: `new Uint32Array(1)`; F#: `Array.zeroCreate<uint32> 1`,
// which Fable compiles to a Uint32Array). This init script replaces `getRandomValues` before any page script runs,
// writes the seed into such an array, and logs every call so a test can prove the page asked exactly once, in exactly
// that shape. Any other request (none of the pages makes one) falls through to the real generator and is logged too.

/** The seed every test uses unless it says otherwise. Above 2^31 on purpose: a track that read the seed as a signed
 * 32-bit number would start a different game and every comparison with the model would fail. */
export const SEED = 0xdeadbeef

/** Runs in the page (Playwright serialises it), so it may use only its argument. */
const seedScript = (seed) => {
  const real = Crypto.prototype.getRandomValues
  const calls = []
  Object.defineProperty(window, '__e2eSeedCalls', { value: calls })
  Crypto.prototype.getRandomValues = function (array) {
    const type = array?.constructor?.name
    calls.push({ type, length: array?.length })
    if (type === 'Uint32Array' && array.length === 1) {
      array[0] = seed
      return array
    }
    return real.call(this, array)
  }
}

/** Install the fixed seed for every document the page loads from now on. */
export const fixSeed = (page, seed = SEED) => page.addInitScript(seedScript, seed)

/** The calls the current document made to crypto.getRandomValues: [{type, length}]. */
export const seedCalls = (page) => page.evaluate(() => window.__e2eSeedCalls ?? null)