module GoalTransform (
	Goal (..),
	moveGoal,
	evalMoves,
	subgoals,
	satGoal,
	satGoals,
) where

import Eval
import Lambda

import System.IO
import qualified Data.Array.IO as A

type Goal = (Maybe Int, Term)

type Goals = [(Int, Term)]

applyMove :: Term -> Move -> Term
applyMove t (MoveLeft Card_Zero _) = Prim Card_I
applyMove t (MoveLeft Card_I _) = t
applyMove (Const n) (MoveLeft Card_Succ _) = Const (n+1)
applyMove (Const n) (MoveLeft Card_Dbl _) = Const (n*2)
applyMove (Prim Card_I) (MoveRight _ Card_Zero) = Const 0
applyMove (Prim Card_I) (MoveRight _ c) = Prim c
applyMove (Prim Card_Succ) (MoveRight _ Card_Zero) = Const 1
applyMove (Prim Card_Dbl) (MoveRight _ Card_Zero) = Const 0
applyMove t (MoveLeft c _) = Apply (Prim c) t
applyMove t (MoveRight _ c) = Apply t (Prim c)

evalMoves :: Goals -> Int -> Maybe Term -> [Move] -> [(Goals, Move)]
evalMoves current pos = _eval where
	_eval _ [] = []
	_eval Nothing moves = ((pos, Prim Card_I):current, MoveLeft Card_Zero pos):_eval (Just $ Prim Card_I) moves
	_eval (Just t) (m:xm) = let t' = (applyMove t m) in ((pos, t'):current, m):_eval (Just t') xm

copyTo :: Goals -> Int -> Int -> Term -> [(Goals, Move)]
copyTo current src dst t = if (src == dst) then [] else evalMoves current dst Nothing (storeInt dst src) ++ [((dst, t):current,MoveLeft Card_Get dst)]

_subgoals current pos (Const n) = evalMoves current pos Nothing (storeInt pos n)
_subgoals current pos (Apply (Prim c) t) = let m = MoveLeft c pos in _subgoals current pos t ++ [((pos, applyMove t m):current, m)]
_subgoals current pos (Apply (Const 0) t) = let m = MoveLeft Card_Zero pos in _subgoals current pos t ++ [((pos, applyMove t m):current, m)]
_subgoals current pos (Apply t (Prim c)) = let m = MoveRight pos c in _subgoals current pos t ++ [((pos, applyMove t m):current, m)]
_subgoals current pos (Apply t (Const 0)) = let m = MoveRight pos Card_Zero in _subgoals current pos t ++ [((pos, applyMove t m):current, m)]
_subgoals current pos (Prim c) = evalMoves current pos Nothing [MoveRight pos c]
_subgoals current 0 (Apply a b) = _subgoals current 1 (Apply a b) ++ copyTo ((1, Apply a b):current) 1 0 (Apply a b)
_subgoals current pos (Apply a b) = _subgoals current pos a ++ _subgoals ((pos,a):current) (pos+1) b ++ copyTo ((pos,a):(pos+1, b):current) (pos+1) 0 b ++ evalMoves ((0, b):current) pos (Just a) [MoveLeft Card_K pos, MoveLeft Card_S pos, MoveRight pos Card_Get] ++ [((pos, Apply a b):current, MoveRight pos Card_Zero)]

subgoals pos t = reverse $ _subgoals [] pos t

termEqVal :: Term -> Value -> Bool
termEqVal (Const a) (ValInt b) = (a == b)
termEqVal (Prim Card_Zero) (ValInt 0) = True
termEqVal t (ValFunction s _) = (show t) == s
termEqVal _ _ = False

satGoal :: (Int, Term) -> Turn Bool
satGoal (pos, t) = do
	game <- getGame
	(val, vit) <- liftIO $ A.readArray (fields $ proponent game) pos
	return (vit > 0 && termEqVal t val)

satGoals :: Goals -> Turn Bool
satGoals [] = return True
satGoals (g:xg) = satGoal g >>= \r -> if (r) then satGoals xg else return False

_pickMove :: [(Goals, Move)] -> Turn (Maybe Move)
_pickMove [] = return Nothing
_pickMove ((g,m):xs) = do
	found <- satGoals g
	if (found) then return Nothing else do
		r <- _pickMove xs
		case r of Nothing -> return $ Just m; _ -> return r

pickMove :: [(Goals, Move)] -> Turn (Move, Bool)
pickMove l@((_,m):_) = do
	r <- _pickMove l
	case r of Nothing -> return (m, True); Just m -> return (m, False)

moveGoal :: Goal -> Turn Move
moveGoal (Nothing, t) = moveGoal (Just 0, t)
moveGoal (Just pos, t) = do
	let subs = subgoals pos t
	(move, finished) <- pickMove subs
	liftIO $ hPutStrLn stderr $ "Trying to reach Goal " ++ show (pos, t)
	liftIO $ hPutStrLn stderr $ "Next step: " ++ show move
	return move