From 261a4d864e0f85ebcf8cb54252a51426dcc967d7 Mon Sep 17 00:00:00 2001
From: tiennm99 <tiennm99@outlook.com>
Date: Tue, 7 Apr 2026 20:51:36 +0700
Subject: [PATCH] feat: add emoji pool and difficulty-based selection

---
 superpowers/src/game/emoji.ts        | 17 +++++++++++++++
 superpowers/tests/game/emoji.test.ts | 32 ++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 superpowers/src/game/emoji.ts
 create mode 100644 superpowers/tests/game/emoji.test.ts

diff --git a/superpowers/src/game/emoji.ts b/superpowers/src/game/emoji.ts
new file mode 100644
index 0000000..f465639
--- /dev/null
+++ b/superpowers/src/game/emoji.ts
@@ -0,0 +1,17 @@
+import { Difficulty } from "../types";
+import { DIFFICULTY_CONFIGS } from "./constants";
+
+export const EMOJI_POOL: string[] = [
+  "🐶", "🐱", "🐭", "🐹", "🐰", "🦊", "🐻", "🐼",
+  "🐨", "🐯", "🦁", "🐮", "🐷", "🐸", "🐵", "🐔",
+  "🐧", "🐦", "🦆", "🦅", "🦉", "🦇", "🐺", "🐗",
+  "🐴", "🦄", "🐝", "🐛", "🦋", "🐌", "🐞", "🐢",
+  "🐍", "🦎", "🐙", "🦑", "🦐", "🦀", "🐡", "🐠",
+  "🐟", "🐬", "🐳", "🐊",
+];
+
+export function getEmojisForDifficulty(difficulty: Difficulty): string[] {
+  const count = DIFFICULTY_CONFIGS[difficulty].pairCount;
+  const shuffled = [...EMOJI_POOL].sort(() => Math.random() - 0.5);
+  return shuffled.slice(0, count);
+}
diff --git a/superpowers/tests/game/emoji.test.ts b/superpowers/tests/game/emoji.test.ts
new file mode 100644
index 0000000..cdbbad5
--- /dev/null
+++ b/superpowers/tests/game/emoji.test.ts
@@ -0,0 +1,32 @@
+import { describe, it, expect } from "vitest";
+import { EMOJI_POOL, getEmojisForDifficulty } from "../../src/game/emoji";
+
+describe("emoji", () => {
+  it("pool has at least 40 unique emoji", () => {
+    expect(EMOJI_POOL.length).toBeGreaterThanOrEqual(40);
+    expect(new Set(EMOJI_POOL).size).toBe(EMOJI_POOL.length);
+  });
+
+  it("returns correct count for easy", () => {
+    const emojis = getEmojisForDifficulty("easy");
+    expect(emojis.length).toBe(12);
+    expect(new Set(emojis).size).toBe(12);
+  });
+
+  it("returns correct count for medium", () => {
+    const emojis = getEmojisForDifficulty("medium");
+    expect(emojis.length).toBe(24);
+  });
+
+  it("returns correct count for hard", () => {
+    const emojis = getEmojisForDifficulty("hard");
+    expect(emojis.length).toBe(40);
+  });
+
+  it("returned emojis are a subset of the pool", () => {
+    const emojis = getEmojisForDifficulty("hard");
+    for (const e of emojis) {
+      expect(EMOJI_POOL).toContain(e);
+    }
+  });
+});