Connect bounded Reinforcements Battle Plan

game/reinforcements.ts

@@ -0,0 +1,31 @@
+import type { Card } from './cards';
+import { ecazTreacheryDefinition } from './ecaz-cards';
+
+export const REINFORCEMENTS_CARD = 'ecaz-reinforcements' as const;
+
+export class ReinforcementsError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'ReinforcementsError';
+  }
+}
+
+/** A matching id alone does not establish the physical variant card's identity. */
+export function isReinforcements(card: Card | undefined): boolean {
+  return !!card && card.id === REINFORCEMENTS_CARD &&
+    Object.keys(card).sort().join(',') === 'effect,id,kind,name' &&
+    ecazTreacheryDefinition(card)?.card.effect === 'reinforcements';
+}
+
+/** Spend exactly three own reserve counters, ordinary before elite; never dial them. */
+export function quoteReinforcements(
+  normalReserves: number,
+  eliteReserves: number,
+): { normal: number; elite: number; bonus: 2 } {
+  if (![normalReserves, eliteReserves].every(n => typeof n === 'number' && Number.isSafeInteger(n) && n >= 0))
+    throw new ReinforcementsError('Reinforcements needs valid nonnegative reserve counts.');
+  if (normalReserves < 3 && eliteReserves < 3 - normalReserves)
+    throw new ReinforcementsError('Reinforcements needs at least three own forces in reserves.');
+  const normal = Math.min(3, normalReserves);
+  return { normal, elite: 3 - normal, bonus: 2 };
+}