Fancily write to file which song is playing in cmus (can be read from obs using textmonitor script)

cmus_now_playing.hs

#!/usr/bin/env stack
-- stack --resolver lts-15.7 script --package text --package process


{-# LANGUAGE OverloadedStrings #-}

import Control.Monad
import qualified Data.Text as T
import qualified Data.Text.IO as T
import System.Process
import Control.Exception
import Control.Concurrent


main :: IO ()
main = forever $ do
  run `catch` \(SomeException e) -> pure ()
  threadDelay 2000000

run :: IO ()
run = do
  current <- readTextFile
  text <- getSong

  unless (current == text) $ do
    deleteFromFile current
    threadDelay delay
    writeToFile "" =<< getSong

deleteFromFile :: T.Text -> IO ()
deleteFromFile current = do
  unless (T.null current) $ do
    let
      temp
        | T.drop (T.length current - 2) current == " " =
          T.take (T.length current - 2) current
        | otherwise =
          T.take (T.length current - 1) current
    T.writeFile file (prefix <> temp)
    threadDelay delay
    deleteFromFile temp

writeToFile :: T.Text -> T.Text -> IO ()
writeToFile current full = do
  unless (current == full) $ do
    let
      temp
        | T.drop (T.length current) full == " " =
          T.take (T.length current + 2) full
        | otherwise =
          T.take (T.length current + 1) full
    T.writeFile file (prefix <> temp)
    threadDelay delay
    writeToFile temp full

getSong :: IO T.Text
getSong =
  fmap
    (T.unwords . T.lines . T.pack)
    (readCreateProcess (shell "cmus-remote -C \"format_print %A - %t\"") "")

readTextFile :: IO T.Text
readTextFile =
  catch
    (T.drop (T.length prefix) <$> T.readFile file)
    (\(SomeException _) -> pure "") 

file :: FilePath
file = "/tmp/cmus_playing.txt"

prefix :: T.Text
prefix = "Now Playing: "

delay = 95000

I modified this script https://obsproject.com/forum/resources/text-monitor.825/ with:

This in the update function:

local function update(text)
	if debug then obs.script_log(obs.LOG_INFO, string.format("changed to %s", text)) end
	local source = obs.obs_get_source_by_name("playing now")
	if source ~= nil then
		local settings = obs.obs_data_create()
		obs.obs_data_set_string(settings, "text", text)
		obs.obs_source_update(source, settings)
		obs.obs_data_release(settings)
		obs.obs_source_release(source)
	end

end

and modified the checkFile function like this:

local function checkFile(id)
	-- if the script has reloaded then stop any old timers
	if id < activeId then
		obs.remove_current_callback()
		return
	end

	if debug then obs.script_log(obs.LOG_INFO, string.format("(%d) Checking text file...(%d)", id, interval)) end
	local f, err = io.open(textFile, "rb")
	if f then
		local line
		for line in f:lines() do
			if line then
				-- success : now check if the value has changed
				if current ~= line then
					current = line
					update(line)
				end
			end
		end
		f:close()
	else
		if debug then obs.script_log(obs.LOG_INFO, string.format("Error reading text file : ", err)) end
	end
end

And the intervals:

-- define properties that user can change
function script_properties()
	local props = obs.obs_properties_create()
	obs.obs_properties_add_path(props, "textFile", "Text File", obs.OBS_PATH_FILE, "", nil)
	obs.obs_properties_add_int(props, "interval", "Interval (ms)", 50, 2000, 10)
	obs.obs_properties_add_bool(props, "debug", "Debug")
	return props
end


-- set default values
function script_defaults(settings)
	obs.obs_data_set_default_string(settings, "textFile", "")
	obs.obs_data_set_default_int(settings, "interval", 100)
	obs.obs_data_set_default_bool(settings, "debug", false)
end

So that now I can update text faster than the default which is 1 second.