// rng.ts provides seeded, reproducible pseudo-randomness, so a whole game
// replays exactly from its seed.

// mulberry32: small, fast, good-enough distribution for game-flavoured
// randomness (home base placement, bot tie-breaking). Not cryptographic --
// nothing here needs to be.
export const seeded = (seed: number): (() => number) => {
  let state = seed >>> 0;
  return (): number => {
    state = (state + 0x6d2b79f5) >>> 0;
    let t = state;
    t = Math.imul(t ^ (t >>> 15), t | 1);
    t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
};

// The one impure function in this module, called exactly once by main.ts
// when no seed was pinned. Mirrors the convention game.ts's
// generateHomeBases already set: game.ts and bot code never reach for
// Math.random themselves -- the caller supplies the randomness, which is
// what makes a whole game (home bases, every bot decision) replayable from
// a single recorded seed.
export const randomSeed = (): number => Math.floor(Math.random() * 2 ** 32);