{- git-annex remote repositories -}

module Remotes (
	list,
	withKey,
	ensureGitConfigRead
) where

import Control.Monad.State (liftIO)
import qualified Data.Map as Map
import Data.String.Utils
import AbstractTypes
import qualified GitRepo as Git
import LocationLog
import Locations
import UUID
import List

{- Human visible list of remotes. -}
list :: [Git.Repo] -> String
list remotes = join " " $ map Git.repoDescribe remotes 

{- Cost ordered list of remotes that the LocationLog indicate may have a key. -}
withKey :: Key -> Annex [Git.Repo]
withKey key = do
	g <- gitAnnex
	uuids <- liftIO $ keyLocations g key
	allremotes <- remotesByCost
	remotes <- reposByUUID allremotes uuids
	if (0 == length remotes)
		then error $ "no configured git remotes have: " ++ (keyFile key) ++ "\n" ++
			"It has been seen before in these repositories:\n" ++
			prettyPrintUUIDs uuids
		else return remotes

{- Cost Ordered list of remotes. -}
remotesByCost :: Annex [Git.Repo]
remotesByCost = do
	g <- gitAnnex
	reposByCost $ Git.remotes g

{- Orders a list of git repos by cost. -}
reposByCost :: [Git.Repo] -> Annex [Git.Repo]
reposByCost l = do
	costpairs <- mapM costpair l
	return $ fst $ unzip $ sortBy bycost $ costpairs
	where
		costpair r = do
			cost <- repoCost r
			return (r, cost)
		bycost (_, c1) (_, c2) = compare c1 c2

{- Calculates cost for a repo.
 -
 - The default cost is 100 for local repositories, and 200 for remote
 - repositories; it can also be configured by remote.<name>.annex-cost
 -}
repoCost :: Git.Repo -> Annex Int
repoCost r = do
	g <- gitAnnex
	if ((length $ config g r) > 0)
		then return $ read $ config g r
		else if (Git.repoIsLocal r)
			then return 100
			else return 200
	where
		config g r = Git.configGet g (configkey r) ""
		configkey r = "remote." ++ (Git.repoRemoteName r) ++ ".annex-cost"

{- The git configs for the git repo's remotes is not read on startup
 - because reading it may be expensive. This function ensures that it is
 - read for a specified remote, and updates state. It returns the
 - updated git repo also. -}
ensureGitConfigRead :: Git.Repo -> Annex Git.Repo
ensureGitConfigRead r = do
	if (Map.null $ Git.configMap r)
		then do
			r' <- liftIO $ Git.configRead r
			g <- gitAnnex
			let l = Git.remotes g
			let g' = Git.remotesAdd g $ exchange l r'
			gitAnnexChange g'
			return r'
		else return r
	where 
		exchange [] new = []
		exchange (old:ls) new =
			if ((Git.repoRemoteName old) == (Git.repoRemoteName new))
				then new:(exchange ls new)
				else old:(exchange ls new)