Improve user check

scrape.py

@@ -11,6 +11,7 @@
 
 import base64
 import json
+import re
 import requests
 from lxml import html
 from typing import Optional, Iterable, Dict, Tuple
@@ -205,8 +206,16 @@ def get_user_info(username):
     return _get_user_info(username)
 
 
+username_regex = re.compile(r'^[a-z][\w-]{1,14}$', flags=re.ASCII)
+
+
 def username_exists(username):
-    if get_user_info(username):
+    ''' From last.fm sign up page:
+    "Your username should be between 2 and 15 characters, begin with a letter and contain only letters, numbers, '_' or '-'"
+    Check username first locally for this format, and then remote for existence.
+    '''
+    username = username.lower()
+    if (username == 'last.hq' or re.match(username_regex, username)) and get_user_info(username):
         return True
 
 

tests.py

@@ -0,0 +1,26 @@
+import unittest
+import re
+
+from scrape import username_regex
+
+
+class TestUserName(unittest.TestCase):
+    def test_username_regex(self):
+        username_list = [
+            ('a1', True),
+            ('a1234567890', True),
+            ('a1234567890-_', True),
+            ('a12345678912345', True),
+            ('a', False),
+            ('a()', False),
+            ('aa ', False),
+            ('123', False),
+            ('a123456789123456', False),
+        ]
+        for username, valid in username_list:
+            with self.subTest(username=username):
+                self.assertEqual(re.match(username_regex, username) is not None, valid)
+
+
+if __name__ == '__main__':
+    unittest.main()

util.py

@@ -66,7 +66,7 @@ def get_recent_users():
         with open(RECENT_USERS_FILE) as f:
             return f.read()
     except FileNotFoundError:
-        return ""
+        return "last.hq"
 
 
 def add_recent_user(username):

utils/api.py

@@ -68,7 +68,7 @@ def _get_user_info(username):
     print("Getting " + url.replace(API_KEY, 'SECRET'))
     from scrape import TIMEOUT
     resp = session.get(url, timeout=TIMEOUT)
-    if resp.status_code == 404:
+    if resp.status_code != 200:
         return ''
     # Dump json as text so we can cache it to disk
     return resp.text