회원 탈퇴와 덱 일괄 삭제 추가

api/src/services/accountDeletion.js

@@ -0,0 +1,33 @@
+import { deleteAvatarImage } from './avatarImage.js';
+
+/**
+ * 사용자 계정과 개인 데이터를 영구 삭제하고 저장 덱은 익명으로 보존한다.
+ * @param {import('better-sqlite3').Database} db
+ * @param {number} userId
+ * @returns {{deleted: boolean, retainedDeckCount: number, avatarDeleted: boolean}}
+ */
+export function deleteUserAccount(db, userId) {
+    const user = db.prepare('SELECT id FROM users WHERE id = ?').get(userId);
+    if (!user) {
+        return {
+            deleted: false,
+            retainedDeckCount: 0,
+            avatarDeleted: false,
+        };
+    }
+
+    const retainedDeckCount = db.prepare(`
+        SELECT COUNT(*) AS count
+        FROM decks
+        WHERE user_id = ?
+    `).get(userId).count;
+
+    db.prepare('DELETE FROM users WHERE id = ?').run(userId);
+    const avatarDeleted = deleteAvatarImage(userId);
+
+    return {
+        deleted: true,
+        retainedDeckCount,
+        avatarDeleted,
+    };
+}