diff --git a/apache2-log-parser.cabal b/apache2-log-parser.cabal
index 15565322038420c1681b028066b083610b42912b..9a6ef87fc039f109b3e7f3a7cb0ccf73284e3364 100644
--- a/apache2-log-parser.cabal
+++ b/apache2-log-parser.cabal
@@ -20,3 +20,5 @@ executable a2p
                       ,attoparsec
                       ,MissingH
                       ,bytestring
+                      ,optparse-applicative
+                      ,time
diff --git a/src/Main.hs b/src/Main.hs
index 0f6ae39190663b26051670c83f4db7c328de5eb2..8358dd87e6e9a702e7ef6ba145a5c7c467f3cfd8 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -6,9 +6,14 @@ module Main where
 -- represented using an 8-bit character set, e.g. ASCII or ISO-8859-15.
 import Data.Attoparsec.ByteString.Char8
 import Data.Word
-import Data.ByteString
+import qualified Data.ByteString as B
+import Data.ByteString (ByteString)
 
-import Data.Bits.Utils (c2w8)
+import Options.Applicative hiding (Parser)
+import qualified Options.Applicative as O
+
+import Data.Time.Clock (getCurrentTime, diffUTCTime)
+import Text.Printf (printf)
 
 data AccessLog = AccessLog { clientIp :: ByteString
                            , datetime :: ByteString
@@ -18,6 +23,10 @@ data AccessLog = AccessLog { clientIp :: ByteString
                            , browser :: ByteString
                            , responseTime :: Int} deriving (Show)
 
+---------------
+-- log parsing
+---------------
+
 tillChar :: Char -> Parser ByteString
 tillChar c = takeTill (== c)
 
@@ -34,7 +43,7 @@ parseDate = do
   char ' '
   timezone <- tillChar ']'
   char ']'
-  return $ Data.ByteString.concat [date, " ", timezone]
+  return $ B.concat [date, " ", timezone]
 
 parseRequest :: Parser (ByteString, ByteString)
 parseRequest = do
@@ -76,6 +85,49 @@ parseLine = do
                      ,browser=browser
                      ,responseTime=responseTime}
 
+logParser :: Parser [AccessLog]
+logParser = many $ parseLine <* endOfLine
+
+----------------------------------
+-- command line argument handling
+----------------------------------
+
+data AppArguments = AppArguments { inputFile :: String }
+
+argumentParser :: O.Parser AppArguments
+argumentParser = AppArguments
+                 <$> strOption
+                     (long "input"
+                      <> short 'i'
+                      <> metavar "ACCESS_LOG_FILE"
+                      <> help "the access filename to parse")
+
+parseArguments :: IO AppArguments
+parseArguments = execParser opts
+    where
+      opts = info (helper <*> argumentParser)
+             ( fullDesc
+               <> progDesc "parse apache2 access log"
+               <> header "a2p - parse apache2 access log")
+
+parseFile :: AppArguments -> IO ()
+parseFile args = do
+  let filename = inputFile args
+  putStrLn $ "parsing file " ++ filename
+  startTime <- getCurrentTime
+  bytes <- B.readFile filename
+  case (parseOnly logParser) bytes of
+    Left msg -> putStrLn "parse failed"
+    Right logs -> do
+      let linesParsed = length logs
+      finishTime <- getCurrentTime
+      -- duration in seconds
+      let duration = (round . toRational) (diffUTCTime startTime finishTime)
+      if duration == 0 then
+          printf "parsed %d lines instantly.\n" linesParsed
+      else
+          printf "parsed %d lines in %d seconds. (%d line/s)\n"
+                 linesParsed duration (linesParsed `div` duration)
+
 main :: IO ()
-main = do
-  print $ parseOnly parseLine "10.21.176.7 - - [06/Sep/2015:06:26:02 +0800] \"GET /v3/auth/tokens HTTP/1.1\" 200 3997 \"-\" \"-\" 1011068"
+main = parseArguments >>= parseFile