{-# OPTIONS_GHC -Wall #-}
module LogAnalysis where

import Log

-- Exercise 1

nthWord :: Int -> String -> String
nthWord n = (!! n) . words

firstWord :: String -> String
firstWord = nthWord 0

nthWordInt :: Int -> String -> Int
nthWordInt n = read . nthWord n

timeStamp :: String -> Int
timeStamp s
    | firstWord s == "E" = nthWordInt 2 s
    | otherwise = nthWordInt 1 s

restOfMessage :: String -> String
restOfMessage s
    | firstWord s == "E" = (unwords . drop 3 . words) s
    | otherwise = (unwords . drop 2 . words) s

parseMessage :: String -> LogMessage
parseMessage s
    | firstWord s == "I" = LogMessage Info (timeStamp s) (restOfMessage s)
    | firstWord s == "W" = LogMessage Warning (timeStamp s) (restOfMessage s)
    | firstWord s == "E" = LogMessage (Error (nthWordInt 1 s)) (timeStamp s) (restOfMessage s)
    | otherwise = Unknown s

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

-- Exercise 2

insert :: LogMessage -> MessageTree -> MessageTree
insert (Unknown _) t = t
insert _ t@(Node _ (Unknown _) _) = t -- should never happen
insert m Leaf = Node Leaf m Leaf
insert m1@(LogMessage _ newTime _) (Node tl m2@(LogMessage _ time _) tr)
    | newTime < time = Node (insert m1 tl) m2 tr
    | otherwise = Node tl m2 (insert m1 tr)

-- Exercise 3

build :: [LogMessage] -> MessageTree
build [] = Leaf
build (m:ms) = insert m (build ms)

-- Exercise 4

inOrder :: MessageTree -> [LogMessage]
inOrder Leaf = []
inOrder (Node tl m tr) = inOrder tl ++ [m] ++ inOrder tr

-- Exercise 5

logText :: LogMessage -> String
logText (Unknown _) = ""
logText (LogMessage _ _ text) = text

isRelevant :: LogMessage -> Bool
isRelevant (Unknown _) = False
isRelevant (LogMessage (Error s) _ _)
    | s >= 50 = True
    | otherwise = False
isRelevant (LogMessage _ _ _) = False

whatWentWrong :: [LogMessage] -> [String]
whatWentWrong [] = []
whatWentWrong ((Unknown _):ms) = whatWentWrong ms
whatWentWrong ms = map logText (filter isRelevant ((inOrder . build) ms))