{- git-annex special remote configuration
 -
 - Copyright 2019 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU AGPL version 3 or higher.
 -}

module Annex.SpecialRemote.Config where

import Common
import Types.Remote (RemoteConfigField, RemoteConfig)
import Types.UUID

import qualified Data.Map as M
import qualified Data.Set as S

newtype Sameas t = Sameas t
	deriving (Show)

newtype ConfigFrom t = ConfigFrom t
	deriving (Show)

{- The name of a configured remote is stored in its config using this key. -}
nameField :: RemoteConfigField
nameField = "name"

{- The name of a sameas remote is stored using this key instead. 
 - This prevents old versions of git-annex getting confused. -}
sameasNameField :: RemoteConfigField
sameasNameField = "sameas-name"

lookupName :: RemoteConfig -> Maybe String
lookupName c = M.lookup nameField c <|> M.lookup sameasNameField c

{- The uuid that a sameas remote is the same as is stored in this key. -}
sameasUUIDField :: RemoteConfigField
sameasUUIDField = "sameas-uuid"

{- The type of a remote is stored in its config using this key. -}
typeField :: RemoteConfigField
typeField = "type"

autoEnableField :: RemoteConfigField
autoEnableField = "autoenable"

encryptionField :: RemoteConfigField
encryptionField = "encryption"

macField :: RemoteConfigField
macField = "mac"

cipherField :: RemoteConfigField
cipherField = "cipher"

cipherkeysField :: RemoteConfigField
cipherkeysField = "cipherkeys"

pubkeysField :: RemoteConfigField
pubkeysField = "pubkeys"

chunksizeField :: RemoteConfigField
chunksizeField = "chunksize"

{- A remote with sameas-uuid set will inherit these values from the config
 - of that uuid. These values cannot be overridden in the remote's config. -}
sameasInherits :: S.Set RemoteConfigField
sameasInherits = S.fromList
	-- encryption configuration is necessarily the same for two
	-- remotes that access the same data store
	[ encryptionField
	, macField
	, cipherField
	, cipherkeysField
	, pubkeysField
	-- legacy chunking was either enabled or not, so has to be the same
	-- across configs for remotes that access the same data
	-- (new-style chunking does not have that limitation)
	, chunksizeField
	]

{- Each RemoteConfig that has a sameas-uuid inherits some fields
 - from it. Such fields can only be set by inheritance; the RemoteConfig
 - cannot provide values from them. -}
addSameasInherited :: M.Map UUID RemoteConfig -> RemoteConfig -> RemoteConfig
addSameasInherited m c = case findSameasUUID c of
	Nothing -> c
	Just (Sameas sameasuuid) -> case M.lookup sameasuuid m of
		Nothing -> c
		Just parentc -> 
			M.withoutKeys c sameasInherits			
				`M.union`
			M.restrictKeys parentc sameasInherits

findSameasUUID :: RemoteConfig -> Maybe (Sameas UUID)
findSameasUUID c = Sameas . toUUID <$> M.lookup sameasUUIDField c

{- Remove any fields inherited from a sameas-uuid. When storing a
 - RemoteConfig, those fields don't get stored, since they were already
 - inherited. -}
removeSameasInherited :: RemoteConfig -> RemoteConfig
removeSameasInherited c = case M.lookup sameasUUIDField c of
	Nothing -> c
	Just _ -> M.withoutKeys c sameasInherits