cis194:hw2

{-# OPTIONS_GHC -Wall #-}

module LogAnalysis where
import Log

-- ex 1
parseMessage :: String -> LogMessage
parseMessage line = 
    case words line of
      ("E":severity:timestamp:content) -> LogMessage (Error $ read severity) (read timestamp) (unwords content)
      ("W":timestamp:content) -> LogMessage Warning (read timestamp) (unwords content)
      ("I":timestamp:content) -> LogMessage Info (read timestamp) (unwords content)
      _ -> Unknown line

parse :: String -> [LogMessage]
parse = map parseMessage . lines

-- ex 2
insert :: LogMessage -> MessageTree -> MessageTree
insert (Unknown _) mt            = mt
insert _ (Node _ (Unknown _) _)  = Leaf
insert m@(LogMessage _ _ _) Leaf = Node Leaf m Leaf
insert m@(LogMessage _ t _) (Node left m'@(LogMessage _ t' _) right)
  | t < t' = Node (insert m left) m' right
  | otherwise = Node left m' (insert m right)

-- ex 3
build :: [LogMessage] -> MessageTree
build = foldl (\tree msg -> insert msg tree) Leaf

-- ex 4
inOrder :: MessageTree -> [LogMessage]
inOrder Leaf                = []
inOrder (Node left m right) = inOrder left ++ [m] ++ inOrder right

-- ex 5
whatWentWrong :: [LogMessage] -> [String]
whatWentWrong msgs = [s | LogMessage (Error severity) _ s <- inOrder $ build msgs, severity >= 50]