Recover precheck logic to prevent reclaim (#148)

src/packtPublishingFreeEbook.py

@@ -145,15 +145,19 @@ def grab_ebook(self, api_client):
         [user_data] = user_response.json().get('data')
         user_id = user_data.get('id')
 
+        product_response = api_client.get(PACKT_PRODUCT_SUMMARY_URL.format(product_id=product_id))
+        self.book_data = {'id': product_id, 'title': product_response.json()['title']}\
+            if product_response.status_code == 200 else None
+
+        if any(product_id == book['id'] for book in self.get_all_books_data(api_client)):
+            logger.info('You have already claimed Packt Free Learning "{}" offer.'.format(self.book_data['title']))
+            return
+
         claim_response = api_client.put(
             PACKT_API_FREE_LEARNING_CLAIM_URL.format(user_id=user_id, offer_id=offer_id),
             json={'recaptcha': self.solve_packt_recapcha()}
         )
 
-        product_response = api_client.get(PACKT_PRODUCT_SUMMARY_URL.format(product_id=product_id))
-        self.book_data = {'id': product_id, 'title': product_response.json()['title']}\
-            if product_response.status_code == 200 else None
-
         if claim_response.status_code == 200:
             logger.info('A new Packt Free Learning ebook "{}" has been grabbed!'.format(self.book_data['title']))
         elif claim_response.status_code == 409: