    {-# LANGUAGE DeriveDataTypeable #-}

    module Propellor.Property.Service where

    import Propellor.Base
    import Propellor.Types.Info
    import qualified Propellor.Property.File as File
    import Utility.FileMode

    type ServiceName = String

    -- | Ensures that a service is running. Does not ensure that
    -- any package providing that service is installed. See
    -- Apt.serviceInstalledRunning
    --
    -- Note that due to the general poor state of init scripts, the best
    -- we can do is try to start the service, and if it fails, assume
    -- this means it's already running.
    running :: ServiceName -> Property DebianLike
    running = signaled "start" "running"

    restarted :: ServiceName -> Property DebianLike
    restarted = signaled "restart" "restarted"

    reloaded :: ServiceName -> Property DebianLike
    reloaded = signaled "reload" "reloaded"

    signaled :: String -> Desc -> ServiceName -> Property DebianLike
    signaled cmd desc svc = check (not <$> servicesDisabled) $
    	tightenTargets $ p `describe` (desc ++ " " ++ svc)
      where
    	p = scriptProperty ["service " ++ shellEscape svc ++ " " ++ cmd ++ " >/dev/null 2>&1 || true"]
    		`assume` NoChange

    -- | This property prevents daemons and other services from being started,
    -- which is often something you want to prevent when building a chroot.
    --
    -- When this is set, `running` and `restarted` will not start services.
    --
    -- On Debian this installs a </usr/sbin/policy-rc.d> script to further
    -- prevent any packages that get installed from starting daemons.
    -- Reverting the property removes the script.
    noServices :: RevertableProperty (HasInfo + UnixLike) UnixLike
    noServices = (setup `setInfoProperty` toInfo (InfoVal NoServices)) <!> teardown
      where
    	f = "/usr/sbin/policy-rc.d"
    	script = [ "#!/bin/sh", "exit 101" ]
    	setup = combineProperties "no services started" $ toProps
    		[ File.hasContent f script
    		, File.mode f (combineModes (readModes ++ executeModes))
    		]
    	teardown = File.notPresent f

    -- | Check if the noServices property is in effect.
    servicesDisabled :: Propellor Bool
    servicesDisabled = isJust . fromInfoVal
    	<$> (askInfo :: Propellor (InfoVal NoServices))

    data NoServices = NoServices deriving (Eq, Show, Typeable)