{-# LANGUAGE PackageImports #-}

-- | This module lets you construct Properties by running commands and
-- scripts. To get from an `UncheckedProperty` to a `Property`, it's
-- up to the user to check if the command made a change to the system. 
--
-- The best approach is to `check` a property, so that the command is only
-- run when it needs to be. With this method, you avoid running the
-- `cmdProperty` unnecessarily.
--
-- > check (not <$> userExists "bob")
-- > 	(cmdProperty "useradd" ["bob"])
--
-- Sometimes it's just as expensive to check a property as it would be to
-- run the command that ensures the property. So you can let the command
-- run every time, and use `changesFile` or `checkResult` to determine if
-- anything changed:
--
-- > cmdProperty "chmod" ["600", "/etc/secret"]
-- > 	`changesFile` "/etc/secret"
--
-- Or you can punt and `assume` a change was made, but then propellor will
-- always say it make a change, and `onChange` will always fire.
--
-- > cmdProperty "service" ["foo", "reload"]
-- > 	`assume` MadeChange

module Propellor.Property.Cmd (
	-- * Constricting properties running commands and scripts
	cmdProperty,
	cmdProperty',
	cmdPropertyEnv,
	Script,
	scriptProperty,
	userScriptProperty,
	cmdResult,
	-- * Lower-level interface for running commands
	CommandParam(..),
	boolSystem,
	boolSystemEnv,
	safeSystem,
	safeSystemEnv,
	shellEscape,
	createProcess,
	waitForProcess,
) where

import Data.List
import "mtl" Control.Monad.Reader
import Control.Applicative
import Prelude

import Propellor.Types
import Propellor.Property
import Utility.SafeCommand
import Utility.Env
import Utility.Process (createProcess, CreateProcess, waitForProcess)

-- | A property that can be satisfied by running a command.
--
-- The command must exit 0 on success.
cmdProperty :: String -> [String] -> UncheckedProperty UnixLike
cmdProperty :: String -> [String] -> UncheckedProperty UnixLike
cmdProperty String
cmd [String]
params = String
-> [String]
-> (CreateProcess -> CreateProcess)
-> UncheckedProperty UnixLike
cmdProperty' String
cmd [String]
params forall a. a -> a
id

cmdProperty' :: String -> [String] -> (CreateProcess -> CreateProcess) -> UncheckedProperty UnixLike
cmdProperty' :: String
-> [String]
-> (CreateProcess -> CreateProcess)
-> UncheckedProperty UnixLike
cmdProperty' String
cmd [String]
params CreateProcess -> CreateProcess
mkprocess = forall i. Property i -> UncheckedProperty i
unchecked forall a b. (a -> b) -> a -> b
$ forall {k} (metatypes :: k).
SingI metatypes =>
String -> Propellor Result -> Property (MetaTypes metatypes)
property String
desc forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$
	Bool -> Result
cmdResult forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> String
-> [CommandParam] -> (CreateProcess -> CreateProcess) -> IO Bool
boolSystem' String
cmd (forall a b. (a -> b) -> [a] -> [b]
map String -> CommandParam
Param [String]
params) CreateProcess -> CreateProcess
mkprocess
  where
	desc :: String
desc = [String] -> String
unwords forall a b. (a -> b) -> a -> b
$ String
cmd forall a. a -> [a] -> [a]
: [String]
params

cmdResult :: Bool -> Result
cmdResult :: Bool -> Result
cmdResult Bool
False = Result
FailedChange
cmdResult Bool
True = Result
NoChange

-- | A property that can be satisfied by running a command,
-- with added environment variables in addition to the standard
-- environment.
cmdPropertyEnv :: String -> [String] -> [(String, String)] -> UncheckedProperty UnixLike
cmdPropertyEnv :: String
-> [String] -> [(String, String)] -> UncheckedProperty UnixLike
cmdPropertyEnv String
cmd [String]
params [(String, String)]
env = forall i. Property i -> UncheckedProperty i
unchecked forall a b. (a -> b) -> a -> b
$ forall {k} (metatypes :: k).
SingI metatypes =>
String -> Propellor Result -> Property (MetaTypes metatypes)
property String
desc forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ do
	[(String, String)]
env' <- forall k v. Eq k => [(k, v)] -> [(k, v)] -> [(k, v)]
addEntries [(String, String)]
env forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> IO [(String, String)]
getEnvironment
	Bool -> Result
cmdResult forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> String -> [CommandParam] -> Maybe [(String, String)] -> IO Bool
boolSystemEnv String
cmd (forall a b. (a -> b) -> [a] -> [b]
map String -> CommandParam
Param [String]
params) (forall a. a -> Maybe a
Just [(String, String)]
env')
  where
	desc :: String
desc = [String] -> String
unwords forall a b. (a -> b) -> a -> b
$ String
cmd forall a. a -> [a] -> [a]
: [String]
params

-- | A series of shell commands. (Without a leading hashbang.)
type Script = [String]

-- | A property that can be satisfied by running a script.
scriptProperty :: Script -> UncheckedProperty UnixLike
scriptProperty :: [String] -> UncheckedProperty UnixLike
scriptProperty [String]
script = String -> [String] -> UncheckedProperty UnixLike
cmdProperty String
"sh" [String
"-c", String
shellcmd]
  where
	shellcmd :: String
shellcmd = forall a. [a] -> [[a]] -> [a]
intercalate String
" ; " (String
"set -e" forall a. a -> [a] -> [a]
: [String]
script)

-- | A property that can satisfied by running a script
-- as user (cd'd to their home directory).
userScriptProperty :: User -> Script -> UncheckedProperty UnixLike
userScriptProperty :: User -> [String] -> UncheckedProperty UnixLike
userScriptProperty (User String
user) [String]
script = String -> [String] -> UncheckedProperty UnixLike
cmdProperty String
"su"
	[String
"--login", String
"--shell", String
"/bin/sh", String
"-c", String
shellcmd, String
user]
  where
	shellcmd :: String
shellcmd = forall a. [a] -> [[a]] -> [a]
intercalate String
" ; " (String
"set -e" forall a. a -> [a] -> [a]
: String
"cd" forall a. a -> [a] -> [a]
: [String]
script)