feat(helper): add rate limiter to control command usage

- Implemented `RateLimiter` class to manage rate limiting of commands.
- Added `rateLimits` map to track command usage per user.
- Introduced `COMMAND_LIMIT` and `TIME_FRAME` for rate limiting constraints.
- Implemented `initCleanup` method for periodic cleanup of old rate limit entries.
- Added `limit` method to enforce rate limiting based on user command count and time frame.
- Set up periodic cleanup task with `CLEANUP_INTERVAL` to remove outdated entries.

Author: bitsgenix

src/helper/RateLimiter.ts

@@ -0,0 +1,60 @@
+interface RateLimitEntry {
+  lastCommandTime: number;
+  commandCount: number;
+}
+
+export class RateLimiter {
+  private static rateLimits: Map<number, RateLimitEntry> = new Map();
+  private static COMMAND_LIMIT = 5; // Max commands allowed
+  private static TIME_FRAME = 10000; // Time frame in milliseconds (10 seconds)
+  private static CLEANUP_INTERVAL = 60000; // Cleanup interval in milliseconds (1 minute)
+
+  // Initializes the cleanup task
+  static initCleanup() {
+    setInterval(() => {
+      const currentTime = Date.now();
+      for (const [userId, entry] of this.rateLimits.entries()) {
+        if (currentTime - entry.lastCommandTime > this.TIME_FRAME) {
+          this.rateLimits.delete(userId);
+        }
+      }
+    }, this.CLEANUP_INTERVAL);
+  }
+
+  // Rate limit checking logic
+  static limit(userId: number): boolean {
+    const currentTime = Date.now();
+    const entry = this.rateLimits.get(userId);
+
+    if (entry) {
+      if (currentTime - entry.lastCommandTime > this.TIME_FRAME) {
+        // Reset if the time frame has passed
+        this.rateLimits.set(userId, {
+          lastCommandTime: currentTime,
+          commandCount: 1,
+        });
+        return true;
+      }
+
+      if (entry.commandCount < this.COMMAND_LIMIT) {
+        // Increment the command count
+        entry.commandCount += 1;
+        this.rateLimits.set(userId, entry);
+        return true;
+      } else {
+        // Rate limit exceeded, silently return false
+        return false;
+      }
+    } else {
+      // First command from the user
+      this.rateLimits.set(userId, {
+        lastCommandTime: currentTime,
+        commandCount: 1,
+      });
+      return true;
+    }
+  }
+}
+
+// Initialize the cleanup task
+RateLimiter.initCleanup();