    -- | Maintainer: Félix Sipma <felix+propellor@gueux.org>
    --
    -- Support for the Attic backup tool <https://attic-backup.org/>
    --
    -- This module is deprecated because Attic is not available in debian
    -- stable any longer (so the installed property no longer works), and it
    -- appears to have been mostly supersceded by Borg.

    module Propellor.Property.Attic {-# DEPRECATED "Use Borg instead" #-}
    	( installed
    	, repoExists
    	, init
    	, restored
    	, backup
    	, KeepPolicy (..)
    	) where

    import Propellor.Base hiding (init)
    import Prelude hiding (init)
    import qualified Propellor.Property.Apt as Apt
    import qualified Propellor.Property.Cron as Cron
    import Data.List (intercalate)

    type AtticParam = String

    type AtticRepo = FilePath

    installed :: Property DebianLike
    installed = Apt.installed ["attic"]

    repoExists :: AtticRepo -> IO Bool
    repoExists repo = boolSystem "attic" [Param "list", File repo]

    -- | Inits a new attic repository
    init :: AtticRepo -> Property DebianLike
    init backupdir = check (not <$> repoExists backupdir) (cmdProperty "attic" initargs)
    	`requires` installed
      where
    	initargs =
    		[ "init"
    		, backupdir
    		]

    -- | Restores a directory from an attic backup.
    --
    -- Only does anything if the directory does not exist, or exists,
    -- but is completely empty.
    --
    -- The restore is performed atomically; restoring to a temp directory
    -- and then moving it to the directory.
    restored :: FilePath -> AtticRepo -> Property DebianLike
    restored dir backupdir = go `requires` installed
      where
    	go :: Property DebianLike
    	go = property (dir ++ " restored by attic") $ ifM (liftIO needsRestore)
    		( do
    			warningMessage $ dir ++ " is empty/missing; restoring from backup ..."
    			liftIO restore
    		, noChange
    		)

    	needsRestore = isUnpopulated dir

    	restore = withTmpDirIn (takeDirectory dir) "attic-restore" $ \tmpdir -> do
    		ok <- boolSystem "attic" $
    			[ Param "extract"
    			, Param backupdir
    			, Param tmpdir
    			]
    		let restoreddir = tmpdir ++ "/" ++ dir
    		ifM (pure ok <&&> doesDirectoryExist restoreddir)
    			( do
    				void $ tryIO $ removeDirectory dir
    				renameDirectory restoreddir dir
    				return MadeChange
    			, return FailedChange
    			)

    -- | Installs a cron job that causes a given directory to be backed
    -- up, by running attic with some parameters.
    --
    -- If the directory does not exist, or exists but is completely empty,
    -- this Property will immediately restore it from an existing backup.
    --
    -- So, this property can be used to deploy a directory of content
    -- to a host, while also ensuring any changes made to it get backed up.
    -- For example:
    --
    -- >	& Attic.backup "/srv/git" "root@myserver:/mnt/backup/git.attic" Cron.Daily
    -- >		["--exclude=/srv/git/tobeignored"]
    -- >		[Attic.KeepDays 7, Attic.KeepWeeks 4, Attic.KeepMonths 6, Attic.KeepYears 1]
    --
    -- Note that this property does not make attic encrypt the backup
    -- repository.
    --
    -- Since attic uses a fair amount of system resources, only one attic
    -- backup job will be run at a time. Other jobs will wait their turns to
    -- run.
    backup :: FilePath -> AtticRepo -> Cron.Times -> [AtticParam] -> [KeepPolicy] -> Property DebianLike
    backup dir backupdir crontimes extraargs kp = backup' dir backupdir crontimes extraargs kp
    	`requires` restored dir backupdir

    -- | Does a backup, but does not automatically restore.
    backup' :: FilePath -> AtticRepo -> Cron.Times -> [AtticParam] -> [KeepPolicy] -> Property DebianLike
    backup' dir backupdir crontimes extraargs kp = cronjob
    	`describe` desc
    	`requires` installed
      where
    	desc = backupdir ++ " attic backup"
    	cronjob = Cron.niceJob ("attic_backup" ++ dir) crontimes (User "root") "/" $
    		"flock " ++ shellEscape lockfile ++ " sh -c " ++ shellEscape backupcmd
    	lockfile = "/var/lock/propellor-attic.lock"
    	backupcmd = intercalate ";" $
    		createCommand
    		: if null kp then [] else [pruneCommand]
    	createCommand = unwords $
    		[ "attic"
    		, "create"
    		, "--stats"
    		]
    		++ map shellEscape extraargs ++
    		[ shellEscape backupdir ++ "::" ++ "$(date --iso-8601=ns --utc)"
    		, shellEscape dir
    		]
    	pruneCommand = unwords $
    		[ "attic"
    		, "prune"
    		, shellEscape backupdir
    		]
    		++
    		map keepParam kp

    -- | Constructs an AtticParam that specifies which old backup generations to
    -- keep. By default, all generations are kept. However, when this parameter is
    -- passed to the `backup` property, they will run attic prune to clean out
    -- generations not specified here.
    keepParam :: KeepPolicy -> AtticParam
    keepParam (KeepHours n) = "--keep-hourly=" ++ val n
    keepParam (KeepDays n) = "--keep-daily=" ++ val n
    keepParam (KeepWeeks n) = "--keep-daily=" ++ val n
    keepParam (KeepMonths n) = "--keep-monthly=" ++ val n
    keepParam (KeepYears n) = "--keep-yearly=" ++ val n

    -- | Policy for backup generations to keep. For example, KeepDays 30 will
    -- keep the latest backup for each day when a backup was made, and keep the
    -- last 30 such backups. When multiple KeepPolicies are combined together,
    -- backups meeting any policy are kept. See attic's man page for details.
    data KeepPolicy
    	= KeepHours Int
    	| KeepDays Int
    	| KeepWeeks Int
    	| KeepMonths Int
    	| KeepYears Int