{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE OverloadedStrings #-}

-- | Utility functions
module TestUtil where

import Control.Lens (Ixed (ix), to, use, (&), (.~), (^.), (^?))
import Control.Monad.Except
import Control.Monad.State
import Data.Text (Text)
import Data.Text qualified as T
import Swarm.Game.CESK
import Swarm.Game.Exception
import Swarm.Game.Robot
import Swarm.Game.State
import Swarm.Game.Step (gameTick, hypotheticalRobot, stepCESK)
import Swarm.Game.Value
import Swarm.Language.Context
import Swarm.Language.Pipeline (ProcessedTerm (..), processTerm)

eval :: GameState -> Text -> IO (GameState, Robot, Either Text (Value, Int))
eval g = either (return . (g,hypotheticalRobot undefined 0,) . Left) (evalPT g) . processTerm1

processTerm1 :: Text -> Either Text ProcessedTerm
processTerm1 txt = processTerm txt >>= maybe wsErr Right
 where
  wsErr = Left "expecting a term, but got only whitespace"

evalPT :: GameState -> ProcessedTerm -> IO (GameState, Robot, Either Text (Value, Int))
evalPT g t = evalCESK g (initMachine t empty emptyStore)

evalCESK :: GameState -> CESK -> IO (GameState, Robot, Either Text (Value, Int))
evalCESK g cesk =
  runCESK 0 cesk
    & flip runStateT r
    & flip runStateT (g & creativeMode .~ True)
    & fmap orderResult
 where
  r = hypotheticalRobot cesk 0
  orderResult ((res, rr), rg) = (rg, rr, res)

runCESK :: Int -> CESK -> StateT Robot (StateT GameState IO) (Either Text (Value, Int))
runCESK _ (Up exn _ []) = Left . flip formatExn exn <$> lift (use entityMap)
runCESK !steps cesk = case finalValue cesk of
  Just (v, _) -> return (Right (v, steps))
  Nothing -> stepCESK cesk >>= runCESK (steps + 1)

play :: GameState -> Text -> IO (Either Text (), GameState)
play g = either (return . (,g) . Left) playPT . processTerm1
 where
  playPT pt = runStateT (playUntilDone (hr ^. robotID)) gs
   where
    cesk = initMachine pt empty emptyStore
    hr = hypotheticalRobot cesk 0
    hid = hr ^. robotID
    gs =
      g
        & execState (addRobot hr)
        & viewCenterRule .~ VCRobot hid
        & creativeMode .~ True

playUntilDone :: RID -> StateT GameState IO (Either Text ())
playUntilDone rid = do
  w <- use robotMap
  case w ^? ix rid . to isActive of
    Just True -> do
      gameTick
      playUntilDone rid
    Just False -> return $ Right ()
    Nothing -> return $ Left . T.pack $ "The robot with ID " <> show rid <> " is nowhere to be found!"