{-# LANGUAGE CPP #-}

{-# LANGUAGE FlexibleContexts #-}

{-# LANGUAGE GADTs #-}

module Persistence.DatabaseConnection (getConnection) where

import Persistence.DBConfig

import qualified Persistence.SQLite as SQLite

#ifdef MYSQL

-- NOTE: MySQL support requires users to install MySQL even if they want to use

-- SQLite or PostgreSQL.

import qualified Persistence.MySQL as MySQL

#endif

#ifndef UNI_PACKAGE

import qualified Persistence.PostgreSQL as PSQL

#endif

import Control.Monad.IO.Class

import Control.Monad.Trans.Control

import Control.Monad.Logger

import Data.Maybe (fromMaybe)

import Data.Pool (Pool)

import Database.Persist.Sql

defaultPoolSize :: Int

defaultPoolSize = 4

getConnection :: ( BaseBackend backend ~ SqlBackend

, IsPersistBackend backend

, MonadIO m

, MonadBaseControl IO m

, MonadLogger m

)

=> DBConfig -> IO ((Pool backend -> m a) -> m a)

getConnection dbConfig = case adapter dbConfig of

#ifdef MYSQL

Just "mysql" -> fail mySQLErrorMessage

Just "mysql2" -> fail mySQLErrorMessage

Just "mysql" -> return $ MySQL.connection dbConfig $

fromMaybe defaultPoolSize $ pool dbConfig

Just "mysql" -> return $ MySQL.connection dbConfig $

fromMaybe defaultPoolSize $ pool dbConfig

#endif

#ifdef UNI_PACKAGE

Just "postgresql" -> fail postgreSQLErrorMessage

#else

Just "postgresql" -> return $ PSQL.connection dbConfig $

fromMaybe defaultPoolSize $ pool dbConfig

#endif

Just "sqlite" -> return $ SQLite.connection dbConfig $

fromMaybe defaultPoolSize $ pool dbConfig

Just "sqlite3" -> return $ SQLite.connection dbConfig $

fromMaybe defaultPoolSize $ pool dbConfig

_ -> fail ("Persistence.Database: No database adapter specified "

++ "or adapter unsupported.")

where

#ifdef MYSQL

mySQLErrorMessage = "MySQL support is deactivated. If you need it, please use a hets-server package compiled with the mysql flag instead of hets-desktop."

#endif

#ifdef UNI_PACKAGE

postgreSQLErrorMessage = "PostgreSQL support is deactivated. If you need it, please use the package hets-server instead of hets-desktop."

#endif