first commit

src/games/onecard/rules.ts

@@ -0,0 +1,42 @@
+import type { Card, CardColor, CardValue } from './types'
+
+export function getEffectiveColor(card: Card, activeColor: CardColor | null): CardColor {
+  if (card.color !== 'wild' && card.color) return card.color
+  return activeColor ?? 'wild'
+}
+
+export function canPlayCard(
+  card: Card,
+  topCard: Card,
+  activeColor: CardColor | null,
+  drawPenalty: number,
+): boolean {
+  if (drawPenalty > 0) {
+    return card.value === 'draw2' || card.value === 'wild4'
+  }
+
+  if (card.color === 'wild') return true
+
+  const topColor = getEffectiveColor(topCard, activeColor)
+  if (card.color === topColor) return true
+  if (card.value === topCard.value) return true
+
+  return false
+}
+
+export function getPlayableCards(
+  hand: Card[],
+  topCard: Card,
+  activeColor: CardColor | null,
+  drawPenalty: number,
+): Card[] {
+  return hand.filter((c) => canPlayCard(c, topCard, activeColor, drawPenalty))
+}
+
+export function isActionCard(value: CardValue): boolean {
+  return value === 'skip' || value === 'reverse' || value === 'draw2' || value === 'wild' || value === 'wild4'
+}
+
+export function cardNeedsColorChoice(card: Card): boolean {
+  return card.color === 'wild'
+}