{-# LANGUAGE PatternGuards #-}

module Distribution.Server.Features.Upload.Backup (
    maintainerBackup,
    maintToExport,
    maintToCSV
  ) where

import Distribution.Server.Features.Upload.State

import Distribution.Server.Users.Group (UserList(..))
import Distribution.Server.Framework.BackupRestore
import Distribution.Server.Framework.BackupDump

import Distribution.Package
import Distribution.Text
import Data.Version
import Text.CSV (CSV, Record)

import Data.Map (Map)
import qualified Data.Map as Map
import qualified Data.IntSet as IntSet

-------------------------------------------------------------------------------
-- Maintainer groups backup
maintainerBackup :: RestoreBackup PackageMaintainers
maintainerBackup = updateMaintainers Map.empty

updateMaintainers :: Map PackageName UserList -> RestoreBackup PackageMaintainers
updateMaintainers mains = RestoreBackup {
    restoreEntry = \entry -> do
      case entry of
        BackupByteString ["maintainers.csv"] bs -> do
          csv    <- importCSV "maintainers.csv" bs
          mains' <- importMaintainers csv mains
          return (updateMaintainers mains')
        _ ->
          return (updateMaintainers mains)
  , restoreFinalize =
      return $ PackageMaintainers (mains)
  }

importMaintainers :: CSV -> Map PackageName UserList -> Restore (Map PackageName UserList)
importMaintainers = concatM . map fromRecord . drop 2
  where
    fromRecord :: Record -> Map PackageName UserList -> Restore (Map PackageName UserList)
    fromRecord (packageStr:idStr) mains = do
        pkgname <- parseText "package name" packageStr
        ids <- mapM (parseRead "user id") idStr
        return (Map.insert pkgname (UserList $ IntSet.fromList ids) mains)
    fromRecord x _ = fail $ "Invalid package maintainer record: " ++ show x

maintToExport :: Map PackageName UserList -> BackupEntry
maintToExport pkgmap = csvToBackup ["maintainers.csv"] (maintToCSV assocUsers)
  where assocUsers = map (\(name, UserList ul) -> (name, IntSet.toList ul))
                   $ Map.toList pkgmap

maintToCSV :: [(PackageName, [Int])] -> CSV
maintToCSV users = [showVersion pkgCSVVer]:pkgCSVKey:
    map (\(name, ids) -> display name:map show ids) users
  where
    pkgCSVKey = ["package", "maintainers"]
    pkgCSVVer = Version [0,1] ["unstable"]