import type { StructuredCombatEvent } from "../game/combatEvents";

export const PARTY_HEAL_POPUP_LIFETIME_MS = 1_500;
export const MAX_PARTY_HEAL_POPUPS = 20;

export interface PartyHealPopup {
  readonly key: string;
  readonly targetActorId: string;
  readonly amount: number;
  readonly critical: boolean;
  readonly horizontalOffset: number;
}

function eventKey(event: StructuredCombatEvent): string {
  return `${event.occurredAt}:${event.id}`;
}

/** Convert only newly committed, effective in-combat heals into party-frame UI events. */
export function addedPartyHealPopups(
  previousEvents: readonly StructuredCombatEvent[],
  nextEvents: readonly StructuredCombatEvent[],
  inCombat: boolean,
): PartyHealPopup[] {
  if (!inCombat || previousEvents === nextEvents) return [];
  const previousKeys = new Set(previousEvents.map(eventKey));
  return nextEvents
    .filter((event) => (
      event.kind === "healing"
      && event.effectiveAmount > 0
      && !previousKeys.has(eventKey(event))
    ))
    .map((event) => ({
      key: eventKey(event),
      targetActorId: event.targetActorId,
      amount: Math.max(1, Math.round(event.effectiveAmount)),
      critical: event.critical,
      horizontalOffset: ((event.id % 3) - 1) * 14,
    }));
}

export function appendPartyHealPopups(
  current: readonly PartyHealPopup[],
  added: readonly PartyHealPopup[],
): PartyHealPopup[] {
  if (added.length === 0) return [...current];
  const addedKeys = new Set(added.map((popup) => popup.key));
  return [...current.filter((popup) => !addedKeys.has(popup.key)), ...added]
    .slice(-MAX_PARTY_HEAL_POPUPS);
}