Clean up compiler warnings.

[dead/halcyon.git] / src / Mail.hs

diff --git a/src/Mail.hs b/src/Mail.hs
index c280f1e82d2f6324385d484b6c8570af7989e041..7f0fd8ba805049aa51371e0a0440fc12fb2523b5 100644 (file)
--- a/src/Mail.hs
+++ b/src/Mail.hs
@@ -1,16 +1,19 @@
+-- |Email functions and data types.
+
 module Mail
 where
 
 import Control.Concurrent
-import Control.Concurrent.MVar
 import Control.Exception (evaluate)
 import Data.List (intercalate)
 import System.Exit
 import System.Process
+import System.Time (CalendarTime(..), ClockTime, getClockTime, Month, toCalendarTime)
 import System.IO
 
 type Header = String
 
+-- |A crude model of an RFC821 email message.
 data Message = Message { headers :: [Header],
                          subject :: String,
                          body    :: String,
@@ -18,6 +21,13 @@ data Message = Message { headers :: [Header],
                          to      :: String }
              deriving (Eq)
 
+default_headers :: [Header]
+default_headers = ["MIME-Version: 1.0",
+                   "Content-type: text/plain; charset=UTF-8"]
+
+-- |Showing a message will print it in roughly RFC-compliant
+-- form. This form is sufficient for handing the message off to
+-- sendmail.
 instance Show Message where
     show m =
         concat [ if (length (headers m) == 0) then "" else (intercalate "\n" (headers m)) ++ "\n",
@@ -28,6 +38,75 @@ instance Show Message where
                  (body m) ]
 
 
+
+-- |Pad a string on the left with zeros until the entire string has
+-- length n.
+pad_left :: String -> Int -> String
+pad_left str n
+         | n < (length str) = str
+         | otherwise = (replicate num_zeros '0') ++ str
+    where num_zeros = n - (length str)
+
+
+
+-- |Formats a month name according to RFC822.
+format_month :: Month -> String
+format_month month = take 3 (show month)
+
+
+-- |Takes an offset from UTC (in seconds) and returns the four-digit
+-- offset as a 'String' in +hhmm format.
+format_timezone :: Int -> String
+format_timezone seconds =
+    sign ++ pad_hh ++ pad_mm
+    where
+      seconds_norm = abs seconds
+      hh = seconds_norm `div` 3600
+      mm = (seconds_norm - (hh*3600)) `div` 60
+      pad_hh = pad_left (show hh) 2
+      pad_mm = pad_left (show mm) 2
+      sign = if seconds < 0 then "-" else "+"
+
+
+-- |Takes a 'ClockTime' as an argument, and formats it as an RFC822 Date header.
+--
+-- See,
+--
+--   <http://cr.yp.to/immhf/date.html>
+--
+-- for information.
+format_clocktime :: ClockTime -> IO String
+format_clocktime ct = do
+  caltime <- (toCalendarTime ct)
+
+  let days = pad_left (show (ctDay caltime)) 2
+  let month = format_month (ctMonth caltime)
+  let year = show $ ctYear caltime
+  let hours = pad_left (show (ctHour caltime)) 2
+  let minutes = pad_left (show (ctMin caltime)) 2
+  let seconds = pad_left (show (ctSec caltime)) 2
+  let timezone = format_timezone (ctTZ caltime)
+
+  return $ concat [(show $ ctWDay caltime) ++ ", ",
+                   days ++ " ",
+                   month ++ " ",
+                   year ++ " ",
+                   hours ++ ":",
+                   minutes ++ ":",
+                   seconds ++ " ",
+                   timezone]
+
+
+-- |Constructs an RFC822 Date header with the current date/time.
+construct_date_header :: IO String
+construct_date_header = do
+  date <- getClockTime
+  format_clocktime date
+
+
+
+-- |Takes a message as an argument, and passes it to the system's
+-- sendmail binary.
 sendmail :: Message -> IO (String, String, ExitCode)
 sendmail message = do
   let sendmail_args = ["-f",
@@ -42,9 +121,9 @@ sendmail message = do
   errm <- newEmptyMVar
   errs <- hGetContents errh
 
-  forkIO $ hPutStr inh (show message) >> hClose inh
-  forkIO $ evaluate (length outs) >> putMVar outm ()
-  forkIO $ evaluate (length errs) >> putMVar errm ()
+  _ <- forkIO $ hPutStr inh (show message) >> hClose inh
+  _ <- forkIO $ evaluate (length outs) >> putMVar outm ()
+  _ <- forkIO $ evaluate (length errs) >> putMVar errm ()
 
   readMVar outm
   readMVar errm
@@ -53,6 +132,9 @@ sendmail message = do
   return (outs, errs, ec)
 
 
+-- |The 'sendmail' function returns a three-tuple of its outputs,
+-- errors, and exit codes.  This function pretty-prints one of those
+-- three-tuples.
 print_sendmail_result :: (String, String, ExitCode) -> IO ()
 print_sendmail_result (outs, errs, ec) = do
     case ec of