Restrict users from multiple failed login attempts

I'm not resetting the failed LoginAttempt count, which is a low priority for
now, but necessary eventually.

src/LoginAttempts.hs

@@ -0,0 +1,29 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+--------------------------------------------------------------------------------
+module LoginAttempts where
+--------------------------------------------------------------------------------
+import Database.SQLite.Simple
+
+import qualified Types as T
+--------------------------------------------------------------------------------
+
+reset :: FilePath -> T.Username -> IO ()
+reset dbFile username = withConnection dbFile $ \conn ->
+  execute conn "UPDATE LoginAttempts SET numAttempts = 0 WHERE username = ?"
+    (Only username)
+
+-- | Attempt to return the number of failed login attempts for
+-- `username`. Returns a Maybe in case `username` doesn't exist.
+forUsername :: FilePath -> T.Username -> IO (Maybe Integer)
+forUsername dbFile username = withConnection dbFile $ \conn -> do
+  res <- query conn "SELECT (numAttempts) FROM LoginAttempts WHERE username = ?"
+    (Only username)
+  case res of
+    [T.LoginAttempt{..}] -> pure (Just loginAttemptNumAttempts)
+    _  -> pure Nothing
+
+increment :: FilePath -> T.Username -> IO ()
+increment dbFile username = withConnection dbFile $ \conn ->
+  execute conn "UPDATE LoginAttempts SET numAttempts = numAttempts + 1 WHERE username = ?"
+    (Only username)