-- | Saving and restoring game state, used by both server and clients.
module Game.LambdaHack.Common.Save
  ( ChanSave, saveToChan, wrapInSaves, restoreGame
  , compatibleVersion, delayPrint
  , saveNameCli, saveNameSer, bkpAllSaves
#ifdef EXPOSE_INTERNAL
    -- * Internal operations
  , loopSave
#endif
  ) where

import Prelude ()

import Game.LambdaHack.Core.Prelude

import           Control.Concurrent
import           Control.Concurrent.Async
import qualified Control.Exception as Ex
import           Data.Binary
import qualified Data.Text as T
import qualified Data.Text.IO as T
import           Data.Version
import           System.FilePath
import           System.IO (hFlush, stdout)
import qualified System.Random.SplitMix32 as SM

import Game.LambdaHack.Common.ClientOptions
import Game.LambdaHack.Common.File
import Game.LambdaHack.Common.Kind
import Game.LambdaHack.Common.Misc
import Game.LambdaHack.Common.Types
import Game.LambdaHack.Content.RuleKind
import Game.LambdaHack.Core.Random

type ChanSave a = MVar (Maybe a)

saveToChan :: ChanSave a -> a -> IO ()
saveToChan :: forall a. ChanSave a -> a -> IO ()
saveToChan ChanSave a
toSave a
s = do
  -- Wipe out previous candidates for saving.
  IO (Maybe (Maybe a)) -> IO ()
forall (f :: * -> *) a. Functor f => f a -> f ()
void (IO (Maybe (Maybe a)) -> IO ()) -> IO (Maybe (Maybe a)) -> IO ()
forall a b. (a -> b) -> a -> b
$ ChanSave a -> IO (Maybe (Maybe a))
forall a. MVar a -> IO (Maybe a)
tryTakeMVar ChanSave a
toSave
  ChanSave a -> Maybe a -> IO ()
forall a. MVar a -> a -> IO ()
putMVar ChanSave a
toSave (Maybe a -> IO ()) -> Maybe a -> IO ()
forall a b. (a -> b) -> a -> b
$ a -> Maybe a
forall a. a -> Maybe a
Just a
s

-- | Repeatedly save serialized snapshots of current state.
--
-- Running with @-N2@ ca reduce @Max pause@ from 0.2s to 0.01s
-- and @bytes copied during GC@ 10-fold, but framerate nor the frequency
-- of not making a backup save are unaffected (at standard backup settings),
-- even with null frontend, because saving takes so few resources.
-- So, generally, backup save settings are relevant only due to latency
-- impact on very slow computers or in JS.
loopSave :: Binary a => COps -> (a -> FilePath) -> ChanSave a -> IO ()
loopSave :: forall a. Binary a => COps -> (a -> String) -> ChanSave a -> IO ()
loopSave COps
cops a -> String
stateToFileName ChanSave a
toSave =
  IO ()
loop
 where
  loop :: IO ()
loop = do
    -- Wait until anyting to save.
    ms <- ChanSave a -> IO (Maybe a)
forall a. MVar a -> IO a
takeMVar ChanSave a
toSave
    case ms of
      Just a
s -> do
        dataDir <- IO String
appDataDir
        tryCreateDir (dataDir </> "saves")
        let fileName = a -> String
stateToFileName a
s
        yield  -- minimize UI lag due to saving
        encodeEOF (dataDir </> "saves" </> fileName)
                  (rexeVersion $ corule cops)
                  s
        -- Wait until the save finished. During that time, the mvar
        -- is continually updated to newest state values.
        loop
      Maybe a
Nothing -> () -> IO ()
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return ()  -- exit

wrapInSaves :: Binary a
            => COps -> (a -> FilePath) -> (ChanSave a -> IO ()) -> IO ()
{-# INLINE wrapInSaves #-}
wrapInSaves :: forall a.
Binary a =>
COps -> (a -> String) -> (ChanSave a -> IO ()) -> IO ()
wrapInSaves COps
cops a -> String
stateToFileName ChanSave a -> IO ()
exe = do
  -- We don't merge this with the other calls to waitForChildren,
  -- because, e.g., for server, we don't want to wait for clients to exit,
  -- if the server crashes (but we wait for the save to finish).
  toSave <- IO (ChanSave a)
forall a. IO (MVar a)
newEmptyMVar
  a <- async $ loopSave cops stateToFileName toSave
  link a
  let fin = do
        -- Wait until the last save (if any) starts
        -- and tell the save thread to end.
        ChanSave a -> Maybe a -> IO ()
forall a. MVar a -> a -> IO ()
putMVar ChanSave a
toSave Maybe a
forall a. Maybe a
Nothing
        -- Wait 0.5s to flush debug and then until the save thread ends.
        Int -> IO ()
threadDelay Int
500000
        Async () -> IO ()
forall a. Async a -> IO a
wait Async ()
a
  exe toSave `Ex.finally` fin
  -- The creation of, e.g., the initial client state, is outside the 'finally'
  -- clause, but this is OK, since no saves are ordered until 'runActionCli'.
  -- We save often, not only in the 'finally' section, in case of
  -- power outages, kill -9, GHC runtime crashes, etc. For internal game
  -- crashes, C-c, etc., the finalizer would be enough.
  -- If we implement incremental saves, saving often will help
  -- to spread the cost, to avoid a long pause at game exit.

-- | Restore a saved game, if it exists. Initialize directory structure
-- and copy over data files, if needed.
restoreGame :: Binary a
            => RuleContent -> ClientOptions -> FilePath -> IO (Maybe a)
restoreGame :: forall a.
Binary a =>
RuleContent -> ClientOptions -> String -> IO (Maybe a)
restoreGame RuleContent
corule ClientOptions
clientOptions String
fileName = do
  -- Create user data directory and copy files, if not already there.
  dataDir <- IO String
appDataDir
  tryCreateDir dataDir
  let path = String
dataDir String -> String -> String
</> String
"saves" String -> String -> String
</> String
fileName
  saveExists <- doesFileExist path
  -- If the savefile exists but we get IO or decoding errors,
  -- we show them and start a new game. If the savefile was randomly
  -- corrupted or made read-only, that should solve the problem.
  -- OTOH, serious IO problems (e.g. failure to create a user data directory)
  -- terminate the program with an exception.
  res <- Ex.try $
    if saveExists then do
      let vExe1 = RuleContent -> Version
rexeVersion RuleContent
corule
      (vExe2, s) <- strictDecodeEOF path
      if compatibleVersion vExe1 vExe2
      then return $! s `seq` Just s
      else do
        let msg = Text
"Savefile" Text -> Text -> Text
<+> String -> Text
T.pack String
path
                  Text -> Text -> Text
<+> Text
"from an incompatible version"
                  Text -> Text -> Text
<+> String -> Text
T.pack (Version -> String
showVersion Version
vExe2)
                  Text -> Text -> Text
<+> Text
"detected while trying to restore"
                  Text -> Text -> Text
<+> String -> Text
T.pack (Version -> String
showVersion Version
vExe1)
                  Text -> Text -> Text
<+> Text
"game."
        fail $ T.unpack msg
    else return Nothing
  let handler :: Ex.SomeException -> IO (Maybe a)
      handler SomeException
e = do
        moveAside <- RuleContent -> ClientOptions -> IO Bool
bkpAllSaves RuleContent
corule ClientOptions
clientOptions
        let msg = Text
"Restore failed."
                  Text -> Text -> Text
<+> (if Bool
moveAside
                      then Text
"The wrong file has been moved aside."
                      else Text
"")
                  Text -> Text -> Text
<+> Text
"The error message is:"
                  Text -> Text -> Text
<+> ([Text] -> Text
T.unwords ([Text] -> Text) -> (Text -> [Text]) -> Text -> Text
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Text -> [Text]
T.lines) (SomeException -> Text
forall a. Show a => a -> Text
tshow SomeException
e)
        delayPrint msg
        return Nothing
  either handler return res

-- Minor version discrepancy permitted.
compatibleVersion :: Version -> Version -> Bool
compatibleVersion :: Version -> Version -> Bool
compatibleVersion Version
v1 Version
v2 = Int -> [Int] -> [Int]
forall a. Int -> [a] -> [a]
take Int
3 (Version -> [Int]
versionBranch Version
v1) [Int] -> [Int] -> Bool
forall a. Eq a => a -> a -> Bool
== Int -> [Int] -> [Int]
forall a. Int -> [a] -> [a]
take Int
3 (Version -> [Int]
versionBranch Version
v2)

delayPrint :: Text -> IO ()
delayPrint :: Text -> IO ()
delayPrint Text
t = do
  smgen <- IO SMGen
SM.newSMGen
  let (delay, _) = nextRandom 10000 smgen
  threadDelay $ 100 * delay  -- try not to interleave saves with other clients
  T.hPutStr stdout $! t <> "\n"  -- hPutStrLn not atomic enough
  hFlush stdout

saveNameCli :: RuleContent -> FactionId -> String
saveNameCli :: RuleContent -> FactionId -> String
saveNameCli RuleContent
corule FactionId
side =
  let gameShortName :: String
gameShortName =
        case String -> [String]
words (String -> [String]) -> String -> [String]
forall a b. (a -> b) -> a -> b
$ RuleContent -> String
rtitle RuleContent
corule of
          String
w : [String]
_ -> String
w
          [String]
_ -> String
"Game"
  in String
gameShortName
     String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
".team_" String -> String -> String
forall a. [a] -> [a] -> [a]
++ Int -> String
forall a. Show a => a -> String
show (FactionId -> Int
forall a. Enum a => a -> Int
fromEnum FactionId
side)
     String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
".sav"

saveNameSer :: RuleContent -> String
saveNameSer :: RuleContent -> String
saveNameSer RuleContent
corule =
  let gameShortName :: String
gameShortName =
        case String -> [String]
words (String -> [String]) -> String -> [String]
forall a b. (a -> b) -> a -> b
$ RuleContent -> String
rtitle RuleContent
corule of
          String
w : [String]
_ -> String
w
          [String]
_ -> String
"Game"
  in String
gameShortName String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
".server.sav"

bkpAllSaves :: RuleContent -> ClientOptions -> IO Bool
bkpAllSaves :: RuleContent -> ClientOptions -> IO Bool
bkpAllSaves RuleContent
corule ClientOptions
clientOptions = do
  dataDir <- IO String
appDataDir
  let benchmark = ClientOptions -> Bool
sbenchmark ClientOptions
clientOptions
      defPrefix = ClientOptions -> String
ssavePrefixCli ClientOptions
defClientOptions
      moveAside = Bool -> Bool
not Bool
benchmark Bool -> Bool -> Bool
&& ClientOptions -> String
ssavePrefixCli ClientOptions
clientOptions String -> String -> Bool
forall a. Eq a => a -> a -> Bool
== String
defPrefix
      bkpOneSave String
name = do
        let pathSave :: String -> String
pathSave String
bkp = String
dataDir String -> String -> String
</> String
"saves" String -> String -> String
</> String
bkp String -> String -> String
forall a. Semigroup a => a -> a -> a
<> String
defPrefix String -> String -> String
forall a. Semigroup a => a -> a -> a
<> String
name
        b <- String -> IO Bool
doesFileExist (String -> String
pathSave String
"")
        when b $ renameFile (pathSave "") (pathSave "bkp.")
      bkpAll = do
        String -> IO ()
bkpOneSave (String -> IO ()) -> String -> IO ()
forall a b. (a -> b) -> a -> b
$ RuleContent -> String
saveNameSer RuleContent
corule
        [Int] -> (Int -> IO ()) -> IO ()
forall (t :: * -> *) (m :: * -> *) a.
(Foldable t, Monad m) =>
t a -> (a -> m ()) -> m ()
forM_ [-Int
199..Int
199] ((Int -> IO ()) -> IO ()) -> (Int -> IO ()) -> IO ()
forall a b. (a -> b) -> a -> b
$ \Int
n ->
          String -> IO ()
bkpOneSave (String -> IO ()) -> String -> IO ()
forall a b. (a -> b) -> a -> b
$ RuleContent -> FactionId -> String
saveNameCli RuleContent
corule (Int -> FactionId
forall a. Enum a => Int -> a
toEnum Int
n)
  when moveAside bkpAll
  return moveAside