{-# LANGUAGE CPP #-}
{- arch-tag: Sendmail utility
Copyright (C) 2004-2005 John Goerzen <jgoerzen@complete.org>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-}

{- |
   Module     : Network.Email.Sendmail
   Copyright  : Copyright (C) 2004-2005 John Goerzen
   License    : GNU GPL, version 2 or above

   Maintainer : John Goerzen <jgoerzen@complete.org> 
   Stability  : provisional
   Portability: portable

This Haskell module provides an interface to transmitting a mail message.

This is not compatible with Windows at this time.

Written by John Goerzen, jgoerzen\@complete.org
-}

#ifdef mingw32_HOST_OS
module Network.Email.Sendmail
where
#else
module Network.Email.Sendmail(sendmail)
where

import System.Cmd.Utils
import System.Directory
import System.IO
import System.IO.Error

sendmails = ["/usr/sbin/sendmail",
             "/usr/local/sbin/sendmail",
             "/usr/local/bin/sendmail",
             "/usr/bin/sendmail",
             "/etc/sendmail",
             "/usr/etc/sendmail"]

findsendmail :: IO String
findsendmail =
    let worker [] = return "sendmail"
        worker (this:next) =
            do
            e <- doesFileExist this
            if e then
               do
               p <- getPermissions this
               if executable p then
                  return this
                  else worker next
               else worker next
        in
        worker sendmails

{- | Transmits an e-mail message using the system's mail transport agent.

This function takes a message, a list of recipients, and an optional sender,
and transmits it using the system's MTA, sendmail.

If @sendmail@ is on the @PATH@, it will be used; otherwise, a list of system
default locations will be searched.

A failure will be logged, since this function uses 'System.Cmd.Utils.safeSystem'
internally.

This function will first try @sendmail@.  If it does not exist, an error is
logged under @System.Cmd.Utils.pOpen3@ and various default @sendmail@ locations
are tried.  If that still fails, an error is logged and an exception raised.

 -}
sendmail :: Maybe String                -- ^ The envelope from address.  If not specified, takes the system's default, which is usually based on the effective userid of the current process.  This is not necessarily what you want, so I recommend specifying it.
         -> [String]                    -- ^ A list of recipients for your message.  An empty list is an error.
         -> String                      -- ^ The message itself.
         -> IO ()
sendmail _ [] _ = fail "sendmail: no recipients specified"
sendmail Nothing recipients msg = sendmail_worker recipients msg
sendmail (Just from) recipients msg = 
    sendmail_worker (("-f" ++ from) : recipients) msg
    
sendmail_worker :: [String] -> String -> IO ()
sendmail_worker args msg =
    let func h = hPutStr h msg 
        in
        do
        --pOpen WriteToPipe "/usr/sbin/sendmail" args func
        rv <- try (pOpen WriteToPipe "sendmail" args func)
        case rv of
            Right x -> return x
            Left _ -> do
                      sn <- findsendmail
                      rv <- pOpen WriteToPipe sn args func
                      return $! rv
                         
#endif