Data.hs

module Angel.Data ( GroupConfig(..)
                  , SpecKey
                  , RunKey
                  , ProgramId
                  , FileRequest
                  , Program(..)
                  , Spec
                  , defaultProgram
                  , defaultDelay
                  , defaultStdout
                  , defaultStderr
                  ) where

import qualified Data.Map as M
import System.Process ( createProcess
                      , proc
                      , waitForProcess
                      , ProcessHandle )
import System.Process ( terminateProcess
                      , CreateProcess(..)
                      , StdStream(..) )
import Control.Concurrent.STM.TChan (TChan)
import System.IO (Handle)

-- |the whole shared state of the program; spec is what _should_
-- |be running, while running is what actually _is_ running_ currently
data GroupConfig = GroupConfig {
    spec :: SpecKey,
    running :: RunKey,
    fileRequest :: TChan FileRequest
}

-- |map program ids to relevant structure
type SpecKey = M.Map ProgramId Program
type RunKey = M.Map ProgramId (Program, Maybe ProcessHandle)
type ProgramId = String
type FileRequest = (String, TChan (Maybe Handle))

-- |the representation of a program is these 6 values, 
-- |read from the config file
data Program = Program {
    name :: String,
    exec :: Maybe String,
    delay :: Maybe Int,
    stdout :: Maybe String,
    stderr :: Maybe String,
    workingDir :: Maybe FilePath,
    logExec :: Maybe String,
    pidFile :: Maybe FilePath,
    env     :: [(String, String)]
} deriving (Show, Eq, Ord)

-- |Lower-level atoms in the configuration process
type Spec = [Program]

-- |a template for an empty program; the variable set to ""
-- |are required, and must be overridden in the config file
defaultProgram :: Program
defaultProgram = Program "" Nothing Nothing Nothing Nothing Nothing Nothing Nothing []

defaultDelay :: Int
defaultDelay = 5

defaultStdout :: FilePath
defaultStdout = "/dev/null"

defaultStderr :: FilePath
defaultStderr = "/dev/null"