New Plugin MarqueePipeReader

    Display a long text from a pipe with marquee. It wraps around
    with a given separator and the length may be specified as well
    as the delay in 10th seconds. See readme for an example.

3 files changed, 77 insertions, 1 deletions

diff --git a/readme.md b/readme.md
index 6209b44..3493e8b 100644
--- a/readme.md
+++ b/readme.md
@@ -1220,6 +1220,13 @@ can be used in the output template as `%mydate%`
 - Reads its displayed output from the given pipe.
 - Prefix an optional default text separated by a colon
 
+<font size="+1">**`MarqueePipeReader "default text:/path/to/pipe" (length, rate, sep) Alias`**</font>
+
+- Generally equivalent to PipeReader
+- Text is displayed as marquee with the specified length, rate in 10th seconds and separator when it wraps around
+
+        Run MarqueePipeReader "/tmp/testpipe" (10, 7, "+") "mpipe"
+
 <font size="+1">
 **`BufferedPipeReader Alias [(Timeout, Bool, "/path/to/pipe1"), ..]`**
 </font>
diff --git a/src/Config.hs b/src/Config.hs
index ed3e51a..bda8838 100644
--- a/src/Config.hs
+++ b/src/Config.hs
@@ -30,6 +30,7 @@ import Plugins.Monitors
 import Plugins.Date
 import Plugins.PipeReader
 import Plugins.BufferedPipeReader
+import Plugins.MarqueePipeReader
 import Plugins.CommandReader
 import Plugins.StdinReader
 import Plugins.XMonadLog
@@ -136,6 +137,6 @@ infixr :*:
 -- this function's type signature.
 runnableTypes :: Command :*: Monitors :*: Date :*: PipeReader :*: BufferedPipeReader :*: CommandReader :*: StdinReader :*: XMonadLog :*: EWMH :*: Kbd :*: Locks :*:
                  Mail :*: MBox :*:
-                 DateZone :*:
+                 DateZone :*: MarqueePipeReader :*:
                  ()
 runnableTypes = undefined
diff --git a/src/Plugins/MarqueePipeReader.hs b/src/Plugins/MarqueePipeReader.hs
new file mode 100644
index 0000000..babcfb6
--- /dev/null
+++ b/src/Plugins/MarqueePipeReader.hs
@@ -0,0 +1,68 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Plugins.MarqueePipeReader
+-- Copyright   :  (c) Reto Habluetzel
+-- License     :  BSD-style (see LICENSE)
+--
+-- Maintainer  :  Jose A. Ortega Ruiz <jao@gnu.org>
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- A plugin for reading from named pipes for long texts with marquee
+--
+-----------------------------------------------------------------------------
+
+module Plugins.MarqueePipeReader where
+
+import System.IO (openFile, IOMode(ReadWriteMode), Handle)
+import Plugins (tenthSeconds, Exec(alias, start), hGetLineSafe)
+import System.Posix.Files (getFileStatus, isNamedPipe)
+import Control.Concurrent(forkIO, threadDelay)
+import Control.Concurrent.STM (TChan, atomically, writeTChan, tryReadTChan, newTChan)
+import Control.Exception
+import Control.Monad(forever, unless)
+
+type Length = Int       -- length of the text to display
+type Rate = Int         -- delay in tenth seconds 
+type Seperator = String -- if text wraps around, use separator
+
+data MarqueePipeReader = MarqueePipeReader String (Length, Rate, Seperator) String
+    deriving (Read, Show)
+
+instance Exec MarqueePipeReader where
+    alias (MarqueePipeReader _ _ a)    = a
+    start (MarqueePipeReader p (len, rate, sep) _) cb = do
+        let (def, pipe) = split ':' p
+        unless (null def) (cb def)
+        checkPipe pipe
+        h <- openFile pipe ReadWriteMode
+        line <- hGetLineSafe h
+        chan <- atomically newTChan
+        forkIO $ writer (toInfTxt line sep) sep len rate chan cb
+        forever $ pipeToChan h chan
+      where
+        split c xs | c `elem` xs = let (pre, post) = span (c /=) xs
+                                   in (pre, dropWhile (c ==) post)
+                   | otherwise   = ([], xs)
+
+pipeToChan :: Handle -> TChan String -> IO ()
+pipeToChan h chan = do
+    line <- hGetLineSafe h 
+    atomically $ writeTChan chan line
+
+writer :: String -> Seperator -> Length -> Rate -> TChan String -> (String -> IO ()) -> IO ()
+writer txt sep len rate chan cb = do 
+    cb (take len txt)
+    mbnext <- atomically $ tryReadTChan chan
+    case mbnext of
+        Just new -> writer (toInfTxt new sep) sep len rate chan cb
+        Nothing -> tenthSeconds rate >> writer (drop 1 txt) sep len rate chan cb 
+
+toInfTxt :: String -> String -> String
+toInfTxt line sep = concat (repeat $ line ++ " " ++ sep ++ " ")
+
+checkPipe :: FilePath -> IO ()
+checkPipe file = handle (\(SomeException _) -> waitForPipe) $ do
+                    status <- getFileStatus file
+                    unless (isNamedPipe status) waitForPipe
+    where waitForPipe = threadDelay 1000 >> checkPipe file