add getNthUseInLimitTimestamp

will be used in a command that check the user limit

src/execution.ts

@@ -52,6 +52,39 @@ export async function getUserLimit(user: string | { id: string }, requestTimesta
   return {limit: userLimits.limit, remaining: userLimits.limit - usedLimit};
 }
 
+/**
+ * gets the timestamp of nth use inside time limit
+ * @param user the user or id to check
+ * @param requestTimestamp the timestamp of the request (message/interaction createdAt)
+ * @param nth which timestamp in time limit to get (orderedd from oldest to newest)
+ * @returns `false` if user is vip
+ * @returns `null` if there is no request
+ * @returns `Date` timestamp of the nth request
+ */
+export async function getNthUseInLimitTimestamp(user: string | { id: string }, requestTimestamp: Date, nth = 1) {
+  const userId: string = typeof user === "string" ? user : user.id;
+
+  const userLimits = await database.limits.findUnique({
+    where: { user: BigInt(userId)}
+  });
+
+  if (userLimits?.vip) return false;
+
+  const nthUseInLimit = await database.usage.findFirst({
+    where: {
+      user: BigInt(userId),
+      timestamp: {
+        gte: new Date(requestTimestamp.getTime() - 1000 * 60 * 60 * 24 /* 24 hours */)
+      }
+    },
+    orderBy: { timestamp: "asc" },
+    skip: nth - 1,
+  });
+
+  if (!nthUseInLimit) return null;
+  return nthUseInLimit.timestamp;
+}
+
 /**
  * Replies to a request
  * @param request the request to reply to