module Propellor.Property.Apt where

import Data.Maybe
import Control.Applicative
import Data.List
import System.IO
import Control.Monad
import System.Process (env)

import Propellor
import qualified Propellor.Property.File as File
import qualified Propellor.Property.Service as Service
import Propellor.Property.File (Line)

sourcesList :: FilePath
sourcesList = "/etc/apt/sources.list"

type Url = String
type Section = String

showSuite :: DebianSuite -> String
showSuite Stable = "stable"
showSuite Testing = "testing"
showSuite Unstable = "unstable"
showSuite Experimental = "experimental"
showSuite (DebianRelease r) = r

backportSuite :: String
backportSuite = showSuite stableRelease ++ "-backports"

debLine :: String -> Url -> [Section] -> Line
debLine suite mirror sections = unwords $
	["deb", mirror, suite] ++ sections

srcLine :: Line -> Line
srcLine l = case words l of
	("deb":rest) -> unwords $ "deb-src" : rest
	_ -> ""

stdSections :: [Section]
stdSections = ["main", "contrib", "non-free"]

binandsrc :: String -> DebianSuite -> [Line]
binandsrc url suite
	| isStable suite = [l, srcLine l, bl, srcLine bl]
	| otherwise = [l, srcLine l]
  where
	l = debLine (showSuite suite) url stdSections
	bl = debLine backportSuite url stdSections

debCdn :: DebianSuite -> [Line]
debCdn = binandsrc "http://cdn.debian.net/debian"

kernelOrg :: DebianSuite -> [Line]
kernelOrg = binandsrc "http://mirrors.kernel.org/debian"

-- | Only available for Stable and Testing
securityUpdates :: DebianSuite -> [Line]
securityUpdates suite
	| isStable suite || suite == Testing =
		let l = "deb http://security.debian.org/ " ++ showSuite suite ++ "/updates " ++ unwords stdSections
		in [l, srcLine l]
	| otherwise = []

-- | Makes sources.list have a standard content using the mirror CDN,
-- with a particular DebianSuite.
--
-- Since the CDN is sometimes unreliable, also adds backup lines using
-- kernel.org.
stdSourcesList :: DebianSuite -> Property
stdSourcesList suite = setSourcesList
	(concatMap (\gen -> gen suite) [debCdn, kernelOrg, securityUpdates])
	`describe` ("standard sources.list for " ++ show suite)

setSourcesList :: [Line] -> Property
setSourcesList ls = sourcesList `File.hasContent` ls `onChange` update

runApt :: [String] -> Property
runApt ps = cmdProperty' "apt-get" ps noninteractiveEnv

noninteractiveEnv :: [(String, String)]
noninteractiveEnv =
		[ ("DEBIAN_FRONTEND", "noninteractive")
		, ("APT_LISTCHANGES_FRONTEND", "none")
		]

update :: Property
update = runApt ["update"]
	`describe` "apt update"

upgrade :: Property
upgrade = runApt ["-y", "dist-upgrade"]
	`describe` "apt dist-upgrade"

type Package = String

installed :: [Package] -> Property
installed = installed' ["-y"]

installed' :: [String] -> [Package] -> Property
installed' params ps = robustly $ check (isInstallable ps) go
	`describe` (unwords $ "apt installed":ps)
  where
	go = runApt $ params ++ ["install"] ++ ps

installedBackport :: [Package] -> Property
installedBackport ps = trivial $ withOS desc $ \o -> case o of
	Nothing -> error "cannot install backports; os not declared"
	(Just (System (Debian suite) _))
		| isStable suite -> 
			ensureProperty $ runApt $ 
				["install", "-t", backportSuite, "-y"] ++ ps
	_ -> error $ "backports not supported on " ++ show o
  where
	desc = (unwords $ "apt installed backport":ps)

-- | Minimal install of package, without recommends.
installedMin :: [Package] -> Property
installedMin = installed' ["--no-install-recommends", "-y"]

removed :: [Package] -> Property
removed ps = check (or <$> isInstalled' ps) go
	`describe` (unwords $ "apt removed":ps)
  where
	go = runApt $ ["-y", "remove"] ++ ps

buildDep :: [Package] -> Property
buildDep ps = robustly go
	`describe` (unwords $ "apt build-dep":ps)
  where
	go = runApt $ ["-y", "build-dep"] ++ ps

-- | Installs the build deps for the source package unpacked
-- in the specifed directory, with a dummy package also
-- installed so that autoRemove won't remove them.
buildDepIn :: FilePath -> Property
buildDepIn dir = go `requires` installedMin ["devscripts", "equivs"]
  where
	go = cmdProperty' "sh" ["-c", "cd '" ++ dir ++ "' && mk-build-deps debian/control --install --tool 'apt-get -y --no-install-recommends' --remove"]
			noninteractiveEnv

-- | Package installation may fail becuse the archive has changed.
-- Run an update in that case and retry.
robustly :: Property -> Property
robustly p = Property (propertyDesc p) $ do
	r <- ensureProperty p
	if r == FailedChange
		then ensureProperty $ p `requires` update
		else return r

isInstallable :: [Package] -> IO Bool
isInstallable ps = do
	l <- isInstalled' ps
	return $ any (== False) l && not (null l)

isInstalled :: Package -> IO Bool
isInstalled p = (== [True]) <$> isInstalled' [p]

-- | Note that the order of the returned list will not always
-- correspond to the order of the input list. The number of items may
-- even vary. If apt does not know about a package at all, it will not
-- be included in the result list.
isInstalled' :: [Package] -> IO [Bool]
isInstalled' ps = catMaybes . map parse . lines
	<$> readProcess "apt-cache" ("policy":ps)
  where
	parse l
		| "Installed: (none)" `isInfixOf` l = Just False
		| "Installed: " `isInfixOf` l = Just True
		| otherwise = Nothing

autoRemove :: Property
autoRemove = runApt ["-y", "autoremove"]
	`describe` "apt autoremove"

-- | Enables unattended upgrades. Revert to disable.
unattendedUpgrades :: RevertableProperty
unattendedUpgrades = RevertableProperty enable disable
  where
	enable = setup True `before` Service.running "cron"
	disable = setup False

	setup enabled = (if enabled then installed else removed) ["unattended-upgrades"]
		`onChange` reConfigure "unattended-upgrades"
			[("unattended-upgrades/enable_auto_updates" , "boolean", v)]
		`describe` ("unattended upgrades " ++ v)
	  where
		v
			| enabled = "true"
			| otherwise = "false"

-- | Preseeds debconf values and reconfigures the package so it takes
-- effect.
reConfigure :: Package -> [(String, String, String)] -> Property
reConfigure package vals = reconfigure `requires` setselections
	`describe` ("reconfigure " ++ package)
  where
	setselections = Property "preseed" $ makeChange $
		withHandle StdinHandle createProcessSuccess p $ \h -> do
			forM_ vals $ \(tmpl, tmpltype, value) ->
				hPutStrLn h $ unwords [package, tmpl, tmpltype, value]
			hClose h
	reconfigure = cmdProperty "dpkg-reconfigure" ["-fnone", package]
	p = (proc "debconf-set-selections" [])
		{ env = Just noninteractiveEnv }

-- | Ensures that a service is installed and running.
--
-- Assumes that there is a 1:1 mapping between service names and apt
-- package names.
serviceInstalledRunning :: Package -> Property
serviceInstalledRunning svc = Service.running svc `requires` installed [svc]