X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FMain.hs;h=293f953ac8b82a5952d759ee85c1a07dab13ca61;hb=8096b134a33ace33ea23368353c011e9f68549c7;hp=bd3cc45f5ff741e936243c9de0cf5baa84f0e1ce;hpb=c9c873eead8a45dd7df8e8ef1f5861a5aa741d9e;p=email-validator.git

diff --git a/src/Main.hs b/src/Main.hs
index bd3cc45..293f953 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,9 +1,11 @@
 {-# LANGUAGE DoAndIfThenElse #-}
+{-# LANGUAGE RecordWildCards #-}
 
 module Main
 where
 
 import Control.Concurrent.ParallelIO.Global (parallel, stopGlobalPool)
+import Control.Monad (when)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.UTF8 as BSU
 import Network.DNS (
@@ -14,9 +16,21 @@ import Network.DNS (
   makeResolvSeed,
   withResolver)
 import Network.DNS.Lookup (lookupMX)
-import System.IO (hGetContents, hFlush, hPutStrLn, stdin, stdout)
+import System.Directory (doesFileExist)
+import System.Exit (exitWith, ExitCode(..))
+import System.IO (
+  Handle,
+  IOMode( WriteMode ),
+  hClose,
+  hFlush,
+  openFile,
+  stdin,
+  stdout)
 import Text.Regex.PCRE.Light (compile, match, utf8)
 
+import CommandLine (Args(..), apply_args)
+import ExitCodes (exit_input_file_doesnt_exist)
+
 type Address = BSU.ByteString
 
 -- | Resolver parameters. We increase the default timeout from 3 to 5
@@ -34,6 +48,8 @@ common_domains = map BSU.fromString [ "aol.com",
                                       "yahoo.com",
                                       "verizon.net" ]
 
+
+-- | Check whether the given domain has a valid MX record.
 validate_mx :: Resolver -> Domain -> IO Bool
 validate_mx resolver domain
   | domain `elem` common_domains = return True
@@ -96,19 +112,53 @@ validate resolver address = do
   else do
     return (address, False)
 
+
+-- | Append a ByteString to a file Handle, followed by a newline.
+append_handle_with_newline :: Handle -> BS.ByteString -> IO ()
+append_handle_with_newline h bs = do
+  BS.hPutStr h bs
+  BS.hPutStr h newline
+  where
+    newline = BSU.fromString "\n"
+
+
 main :: IO ()
 main = do
-  input <- hGetContents stdin
-
-  let addresses = BSU.lines $ BSU.fromString input
+  Args{..} <- apply_args
+
+  -- Get the input from either stdin, or the file given on the command
+  -- line.
+  input <- case input_file of
+             Nothing   -> BS.hGetContents stdin
+             Just path -> do
+               is_file <- doesFileExist path
+               when (not is_file) $ do
+                 exitWith (ExitFailure exit_input_file_doesnt_exist)
+               BS.readFile path
+
+  -- Do the same for the output handle and stdout.
+  output_handle <- case output_file of
+                     Nothing -> return stdout
+                     Just path -> openFile path WriteMode
+
+  -- Split the input into lines.
+  let addresses = BSU.lines input
+
+  -- And remove the empty ones.
   let nonempty_addresses = filter (not . BS.null) addresses
 
   rs <- makeResolvSeed resolv_conf
   withResolver rs $ \resolver -> do
+    -- Construst a list of [IO (Address, Bool)]
     let actions = map (validate resolver) nonempty_addresses
+    -- And compute them in parallel.
     results <- parallel actions
+    stopGlobalPool
+    -- Find the pairs with a True in the second position.
     let good_pairs = filter snd results
-    mapM_ ((hPutStrLn stdout) . BSU.toString . fst) good_pairs
+    -- And output the results.
+    mapM_ ((append_handle_with_newline output_handle) . fst) good_pairs
 
-  stopGlobalPool
-  hFlush stdout
+  -- Clean up. It's safe to try to close stdout.
+  hFlush output_handle
+  hClose output_handle