{- Tests the system and generates Build.SysConfig.hs. -}

module Build.TestConfig where

import Utility.Path
import Utility.Monad
import Utility.SafeCommand

import System.IO
import System.Cmd
import System.Exit
import System.FilePath
import System.Directory

type ConfigKey = String
data ConfigValue =
	BoolConfig Bool |
	StringConfig String |
	MaybeStringConfig (Maybe String) |
	MaybeBoolConfig (Maybe Bool)
data Config = Config ConfigKey ConfigValue

type Test = IO Config
type TestName = String
data TestCase = TestCase TestName Test

instance Show ConfigValue where
	show (BoolConfig b) = show b
	show (StringConfig s) = show s
	show (MaybeStringConfig s) = show s
	show (MaybeBoolConfig s) = show s

instance Show Config where
	show (Config key value) = unlines
		[ key ++ " :: " ++ valuetype value
		, key ++ " = " ++ show value
		]
	  where
		valuetype (BoolConfig _) = "Bool"
		valuetype (StringConfig _) = "String"
		valuetype (MaybeStringConfig _) = "Maybe String"
		valuetype (MaybeBoolConfig _) = "Maybe Bool"

writeSysConfig :: [Config] -> IO ()
writeSysConfig config = writeFile "Build/SysConfig.hs" body
  where
	body = unlines $ header ++ map show config ++ footer
	header = [
		  "{- Automatically generated. -}"
		, "module Build.SysConfig where"
		, ""
		]
	footer = []

runTests :: [TestCase] -> IO [Config]
runTests [] = return []
runTests (TestCase tname t : ts) = do
	testStart tname
	c <- t
	testEnd c
	rest <- runTests ts
	return $ c:rest

{- Tests that a command is available, aborting if not. -}
requireCmd :: ConfigKey -> String -> Test
requireCmd k cmdline = do
	ret <- testCmd k cmdline
	handle ret
  where
	handle r@(Config _ (BoolConfig True)) = return r
	handle r = do
		testEnd r
		error $ "** the " ++ c ++ " command is required"
	c = head $ words cmdline

{- Checks if a command is available by running a command line. -}
testCmd :: ConfigKey -> String -> Test
testCmd k cmdline = do
	ok <- boolSystem "sh" [ Param "-c", Param $ quiet cmdline ]
	return $ Config k (BoolConfig ok)

{- Ensures that one of a set of commands is available by running each in
 - turn. The Config is set to the first one found. -}
selectCmd :: ConfigKey -> [(String, String)] -> Test
selectCmd k = searchCmd
		(return . Config k . StringConfig)
		(\cmds -> do
			testEnd $ Config k $ BoolConfig False
			error $ "* need one of these commands, but none are available: " ++ show cmds
		)

maybeSelectCmd :: ConfigKey -> [(String, String)] -> Test
maybeSelectCmd k = searchCmd
		(return . Config k . MaybeStringConfig . Just)
		(\_ -> return $ Config k $ MaybeStringConfig Nothing)

searchCmd :: (String -> Test) -> ([String] -> Test) -> [(String, String)] -> Test
searchCmd success failure cmdsparams = search cmdsparams
  where
	search [] = failure $ fst $ unzip cmdsparams
	search ((c, params):cs) = do
		ok <- boolSystem "sh" [ Param "-c", Param $ quiet $ c ++ " " ++ params ]
		if ok
			then success c
			else search cs

{- Finds a command, either in PATH or perhaps in a sbin directory not in
 - PATH. If it's in PATH the config is set to just the command name,
 - but if it's found outside PATH, the config is set to the full path to
 - the command. -}
findCmdPath :: ConfigKey -> String -> Test
findCmdPath k command = do
	ifM (inPath command)
		( return $ Config k $ MaybeStringConfig $ Just command
		, do
			r <- getM find ["/usr/sbin", "/sbin", "/usr/local/sbin"]
			return $ Config k $ MaybeStringConfig r
		)
  where
	find d =
		let f = d </> command
		in ifM (doesFileExist f) ( return (Just f), return Nothing )

quiet :: String -> String
quiet s = s ++ " >/dev/null 2>&1"

testStart :: TestName -> IO ()
testStart s = do
	putStr $ "  checking " ++ s ++ "..."
	hFlush stdout

testEnd :: Config -> IO ()
testEnd (Config _ (BoolConfig True)) = status "yes"
testEnd (Config _ (BoolConfig False)) = status "no"
testEnd (Config _ (StringConfig s)) = status s
testEnd (Config _ (MaybeStringConfig (Just s))) = status s
testEnd (Config _ (MaybeStringConfig Nothing)) = status "not available"
testEnd (Config _ (MaybeBoolConfig (Just True))) = status "yes"
testEnd (Config _ (MaybeBoolConfig (Just False))) = status "no"
testEnd (Config _ (MaybeBoolConfig Nothing)) = status "unknown"

status :: String -> IO ()
status s = putStrLn $ ' ':s
