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{-# LANGUAGE OverloadedStrings #-}
module Logstat.Main (main) where
import Control.Exception (catchJust)
import Control.Monad (filterM,foldM)
import System.Directory (doesFileExist,getHomeDirectory)
import System.Exit
import System.FilePath ((</>))
import System.IO (hPutStrLn,stderr)
import System.IO.Error (isEOFError)
import Options.Applicative
import Data.Semigroup ((<>))
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as C
import qualified Data.Map.Strict as Map
import Logstat.Types
import Logstat.Parse
import Logstat.Value
import Logstat.Eval
-- Extract the final 'show' statement or provide a default expression to display.
-- Returns an error if there is a non-last 'show' statement.
extractShow :: [Stmt] -> Either String ([Expr], [Stmt])
extractShow proc = f [] ["msg"] proc
where
f l v [] = Right (map (\v' -> Loc Nothing (EField v')) v, reverse l)
f l _ ((Loc _ (SShow e)):[]) = Right (e, reverse l)
f _ _ ((Loc pos (SShow _)):_) = Left $ "Error: show at " ++ show pos ++ " must not be followed by other statements"
f l _ (x@(Loc _ (SGroup v)):xs) = f (x:l) v xs
f l v (x:xs) = f (x:l) v xs
run :: [State] -> [Event -> Either EvalError Val] -> Step -> ([State] -> [Either EvalError Event]) -> IO ()
run st sh stp fnl = loop st
where
loop state = do
r <- catchJust
(\e -> if isEOFError e then Just () else Nothing)
(Just <$> line state)
(const (Nothing <$ finalize state))
case r of
Nothing -> return ()
Just state' -> loop state'
eval ev =
case mapM (\f -> f ev) sh of
Left e -> hPutStrLn stderr $ show e
Right v -> C.putStrLn $ B.intercalate ", " $ map asBS v
line state = do
l <- B.getLine
let event = Map.fromList [("msg", bs l)]
(state', r) = stp state event
case r of
Left (Loc _ Filtered) -> return ()
Left e -> hPutStrLn stderr $ show e ++ " with input: " ++ show l
Right v -> eval v
return state'
finalize state = mapM_
(\r ->
case r of
Left e -> hPutStrLn stderr $ show e
Right l -> eval l)
(fnl state)
data Options = Options
{ optConfig :: [String]
, optEval :: [String]
, optNoRC :: Bool
} deriving(Show)
main :: IO ()
main = do
o <- execParser opts
home <- getHomeDirectory
c <- loadCfg
(if optNoRC o then [] else ["/etc/logstat.conf", home </> ".logstat.conf", "logstat.conf"])
(optConfig o)
stmts' <- concat <$> mapM (parseStmtsIO c "-e") (optEval o)
(sh, stmts) <- case extractShow stmts' of
Left e -> hPutStrLn stderr e >> exitFailure
Right r -> return r
run (newState stmts) (map evalExpr sh) (stepL stmts) (finalL stmts)
where
opts = info (optparse <**> helper) fullDesc
optparse = Options
<$> many (strOption (long "config" <> short 'c' <> metavar "FILE" <> help "Config file"))
<*> some (strOption (long "eval" <> short 'e' <> metavar "CODE" <> help "Code to evaluate"))
<*> switch (long "norc" <> short 'X' <> help "Don't load default config files")
loadCfg :: [String] -> [String] -> IO Config
loadCfg def conf = do
def' <- filterM doesFileExist def
foldM
parseFileIO
(Config mempty mempty [])
(def' ++ conf)
|
