Initial commit

game/nullentropy-box.ts

@@ -0,0 +1,78 @@
+import type { Card } from './cards';
+import { richeseCardDefinition } from './richese-cards';
+
+export type NullentropyBoxResult = {
+  ownerHand: Card[];
+  discard: Card[];
+  selected: Card;
+};
+
+function validatePhysicalCards(cards: readonly Card[]) {
+  const ids = new Set<string>();
+  for (const card of Array.from(cards)) {
+    if (!card || typeof card.id !== 'string' || !card.id || ids.has(card.id))
+      throw new Error('Cards must have unique physical identities.');
+    ids.add(card.id);
+  }
+}
+
+const isAnyBox = (card: Card) =>
+  card.effect === 'nullentropyBox' || card.name === 'Nullentropy Box';
+
+/** Pure filtering does not grant a viewer permission to inspect the discard. */
+export function eligibleNullentropyCards(discard: readonly Card[]): Card[] {
+  validatePhysicalCards(discard);
+  return structuredClone(discard.filter((card) => !isAnyBox(card)));
+}
+
+/**
+ * The caller supplies the server-shuffled order after authorizing and charging
+ * the private search. This helper neither shuffles nor spends spice. Last is top.
+ * The selected receipt is independently cloned, not a second physical copy.
+ */
+export function resolveNullentropyBox(
+  ownerHand: readonly Card[],
+  activatingBoxId: string,
+  discard: readonly Card[],
+  selectedId: string,
+  remainingOrderIds: readonly string[],
+  handLimit: number,
+): NullentropyBoxResult {
+  if (!Number.isSafeInteger(handLimit) || handLimit < 0)
+    throw new RangeError('The hand limit must be a nonnegative safe integer.');
+  validatePhysicalCards([...Array.from(ownerHand), ...Array.from(discard)]);
+  const box = ownerHand.find((card) => card.id === activatingBoxId);
+  if (!box || richeseCardDefinition(box)?.card.effect !== 'nullentropyBox')
+    throw new Error(
+      'Use the canonical Nullentropy Box physically in your hand.',
+    );
+  if (ownerHand.length >= handLimit)
+    throw new Error(
+      'Full-hand Nullentropy Box use is unresolved; a pre-existing free hand slot is required by the current guard.',
+    );
+  const selected = discard.find((card) => card.id === selectedId);
+  if (!selected || isAnyBox(selected))
+    throw new Error('Choose a discard card other than any Nullentropy Box.');
+  const remaining = new Map(
+    discard
+      .filter((card) => card.id !== selectedId)
+      .map((card) => [card.id, card]),
+  );
+  const order = Array.from(remainingOrderIds);
+  if (
+    order.length !== remaining.size ||
+    new Set(order).size !== order.length ||
+    order.some((id) => typeof id !== 'string' || !remaining.has(id))
+  )
+    throw new Error(
+      'The remaining discard order must be an exact permutation.',
+    );
+  return {
+    ownerHand: structuredClone([
+      ...ownerHand.filter((card) => card.id !== activatingBoxId),
+      selected,
+    ]),
+    discard: structuredClone([...order.map((id) => remaining.get(id)!), box]),
+    selected: structuredClone(selected),
+  };
+}