Initial commit

game/distrans.ts

@@ -0,0 +1,67 @@
+import type { Card } from './cards';
+import { richeseCardDefinition } from './richese-cards';
+
+export type DistransParticipant = { id: string; hand: readonly Card[] };
+export type DistransTransfer = {
+  ownerHand: Card[];
+  recipientHand: Card[];
+  discarded: Card;
+  transferred: Card;
+};
+
+/**
+ * Physical custody only: transfer one other held card, then discard Distrans.
+ * The engine owns bid timing, committed cards, private projections and discard
+ * events. A returned receipt is not an extra physical copy or a public reveal.
+ */
+export function transferDistrans(
+  owner: DistransParticipant,
+  recipient: DistransParticipant,
+  activatingCardId: string,
+  transferredCardId: string,
+  recipientHandLimit: number,
+): DistransTransfer {
+  if (!owner.id || !recipient.id || owner.id === recipient.id)
+    throw new Error('Choose a different player to receive the card.');
+  if (!Number.isSafeInteger(recipientHandLimit) || recipientHandLimit < 0)
+    throw new RangeError(
+      'The recipient hand limit must be a nonnegative safe integer.',
+    );
+  const ids = new Set<string>();
+  // Array.from includes sparse slots so malformed restored custody cannot pass.
+  for (const card of [
+    ...Array.from(owner.hand),
+    ...Array.from(recipient.hand),
+  ]) {
+    if (!card || typeof card.id !== 'string' || !card.id || ids.has(card.id))
+      throw new Error(
+        'Both hands must contain unique physical card identities.',
+      );
+    ids.add(card.id);
+  }
+  const activation = owner.hand.find((card) => card.id === activatingCardId);
+  if (
+    !activation ||
+    richeseCardDefinition(activation)?.card.effect !== 'distrans'
+  )
+    throw new Error('Play the canonical Distrans physically in your hand.');
+  if (transferredCardId === activatingCardId)
+    throw new Error(
+      'Giving Distrans itself is unresolved; choose a different card.',
+    );
+  const given = owner.hand.find((card) => card.id === transferredCardId);
+  if (!given)
+    throw new Error('Choose another card physically in your own hand.');
+  if (recipient.hand.length >= recipientHandLimit)
+    throw new Error('The recipient’s Treachery hand is full.');
+  return {
+    ownerHand: structuredClone(
+      owner.hand.filter(
+        (card) => card.id !== activatingCardId && card.id !== transferredCardId,
+      ),
+    ),
+    recipientHand: structuredClone([...recipient.hand, given]),
+    discarded: structuredClone(activation),
+    transferred: structuredClone(given),
+  };
+}