import type { PartyMon } from "./pokemon";

/** The happiness a Pokémon has just after hatching (HatchEggs: `ld [hl], $78`),
 * which replaces the Egg's remaining cycles. */
export const HATCHED_HAPPINESS = 0x78;

/** The counters CountStep keeps in work RAM (wStepCount,
 * wPoisonStepCount) and StepHappiness's toggle (wHappinessStepCount). */
export interface StepCounters {
  stepCount: number;
  poisonStepCount: number;
  happinessStepCount: number;
}

/** StepHappiness (engine/events/happiness_egg.asm): called each time
 * wStepCount wraps (every 256 steps), it raises the happiness of every
 * Pokémon that is not an Egg by one on every other call, so once per 512
 * steps, up to 255. It does not go through ChangeHappiness: no bonus and
 * no cap other than the byte's, and a Pokémon already at 255 stays there. */
export function stepHappiness(
  counters: Pick<StepCounters, "happinessStepCount">,
  party: PartyMon[],
) {
  counters.happinessStepCount = (counters.happinessStepCount + 1) & 1;
  if (counters.happinessStepCount) return;
  for (const mon of party)
    if (!mon.egg) mon.happiness = Math.min(0xff, mon.happiness + 1);
}

/** DoEggStep (engine/pokemon/breeding.asm): from the first slot, each Egg's
 * cycles (kept in its happiness byte) drop by one until one reaches zero,
 * which ends the loop and reports that an Egg is ready to hatch; the Eggs
 * after it are not counted down on that step. A byte already at zero
 * wraps to 255 (`dec [hl]` has no floor) and does not hatch. */
export function doEggStep(party: PartyMon[]): boolean {
  for (const mon of party) {
    if (!mon.egg) continue;
    mon.happiness = (mon.happiness - 1) & 0xff;
    if (!mon.happiness) return true;
  }
  return false;
}