{-# LANGUAGE CPP, MultiParamTypeClasses, FlexibleInstances, Safe, DeriveGeneric, RecordWildCards #-}
module Game.Hanabi(
              -- * Functions for Dealing Games
              main, selfplay, start, createGame, startFromCards, createGameFromCards, run, createDeck,
              prettyEndGame, isMoveValid, checkEndGame, help,
              -- * Datatypes
              -- ** The Class of Strategies
              Strategies, Strategy(..), StrategyDict(..), mkSD, DynamicStrategy, mkDS, mkDS', Verbose(..), STDIO, stdio, Blind, ViaHandles(..), Verbosity(..), verbose, quiet,
              -- ** Audience
              Peeker, peek,
              -- ** The Game Specification
              GameSpec(..), defaultGS, Rule(..), defaultRule, isRuleValid, colors, handSize, setHandSize,
              -- ** The Game State and Interaction History
              Move(..), Index, State(..), PrivateView(..), PublicInfo(..), Result(..), EndGame(..),
              -- ** The Cards
              Card(..), Color(..), Number(..), Marks, Possibilities, cardToInt, intToCard, readsColorChar, readsNumberChar,
              -- * Utilities
              -- ** Hints
              isCritical, isUseless, bestPossibleRank, achievedRank, isPlayable, isHinted, currentScore, achievableScore,
              isMoreObviouslyUseless, isObviouslyUseless, isDefinitelyUseless, isMoreObviouslyPlayable, isObviouslyPlayable, isDefinitelyPlayable, obviousChopss, definiteChopss, isDoubleDrop,
              tryMove, (|||), ifA,
              -- ** Minor ones
              what'sUp, what'sUp1, ithPlayer, recentEvents, prettyPI, prettySt, ithPlayerFromTheLast, view, replaceNth, shuffle, showPossibilities, showColorPossibilities, showNumberPossibilities, showTrial) where
-- module Hanabi where
import qualified Data.IntMap as IM
import System.Random
import Control.Applicative((<*>))
import Control.Monad(when)
import Control.Monad.IO.Class(MonadIO, liftIO)
import Data.Char(isSpace, isAlpha, isAlphaNum, toLower, toUpper)
import Data.Maybe(fromJust)
import Data.List(isPrefixOf, group, zipWith4)
import System.IO
import Data.Dynamic
import Data.Bits hiding (rotate)

import GHC.Generics hiding (K1)

data Number  = Empty | K1 | K2 | K3 | K4 | K5 deriving (Eq, Ord, Show, Read, Enum, Bounded, Generic)
data Color = White | Yellow | Red | Green | Blue | Multicolor
  deriving (Eq, Show, Read, Enum, Bounded, Generic)
readsColorChar :: ReadS Color
readsColorChar (c:str)
  | isSpace c = readsColorChar str
  | otherwise = case lookup (toUpper c) [(head $ show i, i) | i <- [White .. Multicolor]] of
                           Nothing -> []
                           Just i  -> [(i, str)]
readsColorChar [] = []
readsNumberChar :: ReadS Number
readsNumberChar ('0':rest) = [(Empty,rest)]
readsNumberChar str = reads ('K':str)

data Card = C {color :: Color, number :: Number} deriving (Eq, Generic)
instance Show Card where
  showsPrec _ (C color number) = (head (show color) :) . (show (fromEnum number) ++)
instance Read Card where
  readsPrec _ str = [(C i k, rest) | (i, xs) <- readsColorChar str, (k, rest) <- readsNumberChar xs]
cardToInt :: Card -> Int
cardToInt c = fromEnum (color c) * (succ $ fromEnum (maxBound::Number)) + fromEnum (number c)
intToCard :: Int -> Card
intToCard i = case i `divMod` (succ $ fromEnum (maxBound::Number)) of (c,k) -> C (toEnum c) (toEnum k)
type Index = Int -- starts from 0

data Move = Drop {index::Index}            -- ^ drop the card (0-origin)
          | Play {index::Index}            -- ^ play the card (0-origin)
          | Hint Int (Either Color Number) -- ^ give hint to the ith next player
            deriving (Eq, Generic)
instance Show Move where
    showsPrec _ (Drop i) = ("Drop"++) . shows i
    showsPrec _ (Play i) = ("Play"++) . shows i
    showsPrec _ (Hint i eith) = ("Hint"++) . shows i . (either (\c -> (take 1 (show c) ++)) (\k -> tail . shows k) eith)
instance Read Move where
    readsPrec _ str
      = let (cmd,other) = span (not.isSpace) str'
            str' = dropWhile isSpace str
        in case span (not . (`elem` "dDpP")) cmd of
          (tk, d:dr) | all (not.isAlphaNum) tkdr && null (drop 1 $ group tkdr) -> [((if toLower d == 'd' then Drop else Play) $ length tk, other)]
                    where tkdr = tk++dr
          _ -> case span isAlpha str' of
                        (kw, xs)  | kwl `isPrefixOf` "hint" -> parseHint xs  -- Since kwl can be "", "11" parses as "Hint11".
                                  | kwl `isPrefixOf` "drop" -> [(Drop i, rest) | (i, rest) <- reads xs]
                                  | kwl `isPrefixOf` "play" -> [(Play i, rest) | (i, rest) <- reads xs]
                                  where kwl = map toLower kw
                        _         -> []
                 where parseHint xs = [(Hint i eith, rest) | let (istr, ys) = splitAt 1 $ dropWhile isSpace xs -- These two lines is similar to @(i, ys) <- reads xs@,
                                                           , (i, _) <- reads istr                              -- but additionally accepts something like "hint12".
                                                           , let ys' = dropWhile isSpace ys
                                                           , (eith, rest) <- [ (Left c, zs) | (c,zs) <- readsColorChar ys' ] ++ [ (Right c, zs) | (c,zs) <- readsNumberChar ys' ] ]

-- | The help text.
help :: String
help = "`Play0',  `play0',   `P0', `p0', etc.        ... play the 0th card from the left (0-origin).\n"
     ++"`Drop1',  `drop1',   `D1', `d1', etc.        ... drop the 1st card from the left (0-origin).\n"
     ++"`Hint2W', `hint2w', `h2w', `H2W', `2w', etc. ... tell the White card(s) of the 2nd next player.\n"
     ++"`Hint14',           `h14', `H14', `14', etc. ... tell the Rank-4 card(s) of the next player.\n"
     ++"`---P-',  `@@@p@', `___P', `...p', etc.      ... play the 3rd card from the left (0-origin). Letters other than p or P must not be alphanumeric. Also note that just `p' or `P' means playing the 0th card.\n"
     ++"`D////',  `d~~~~', `D',    `d',    etc.      ... drop the 0th card from the left (0-origin). Letters other than d or D must not be alphanumeric.\n"

-- | 'Rule' is the datatype representing the game variants.
--
--   [Minor remark] When adopting Variant 4, that is, the rule of continuing even after a round after the pile is exhausted, there can be a situation where a player cannot choose any valid move, because she has no card and there is no hint token.
--   This can happen, after one player (who has no critical card) repeats discarding, and other players repeat hinting each other, consuming hint tokens.
--   Seemingly, the rule book does not state what happens in such a case, but I (Susumu) believe the game should end as failure, then, because
--
--   * This situation can easily be made, and easily be avoided;
--
--   * If deadline is set up, this should cause time out;
--
--   * When Variant 4 is adopted, the game must end with either the perfect game or failure.
--
--   See also the definition of 'checkEndGame'.
data Rule = R { numBlackTokens :: Int    -- ^ E.g., if this is 3, the third failure ends the game with failure.
              , funPlayerHand  :: [Int]  -- ^ memoized function taking the number of players; the default is [5,5,4,4,4,4,4,4,4,4]
              , numColors      :: Int    -- ^ number of colors. 5 for the normal rule, and 6 for Variant 1-3 of the rule book.
              , prolong        :: Bool   -- ^ continue even after a round after the pile is exhausted. @True@ for Variant 4 of the rule book.
              , earlyQuit      :: Bool   -- ^ quit the game when the best possible score is achieved. 
              , numMulticolors :: [Int]  -- ^ number of each of multicolor cards. @[3,2,2,2,1]@ for Variant 1 (and Variant 3?), and @[1,1,1,1,1]@ for Variant 2.

--          x , multicolor     :: Bool   -- ^ multicolor play, or Variant 3
              } deriving (Show, Read, Eq, Generic)
isRuleValid :: Rule -> Bool
isRuleValid rl@R{..} = numBlackTokens > 0 && and [ h>0 && h<=mh | (h,mh) <- zip funPlayerHand maxPlayerHand ] && numColors>0 && numColors <=6 && (numColors < 6 || all (>0) numMulticolors)
  where maxPlayerHand = [ succ (numberOfCards rl) `div` numP | numP <- [2..]]
        -- This makes sure that there is at least one card on the deck.

-- | @defaultRule@ is the normal rule from the rule book of the original card game Hanabi.
defaultRule :: Rule
defaultRule = R { numBlackTokens = 3
                , funPlayerHand  = [5,5]++take 8 (repeat 4)
                , numColors      = 5
                , prolong        = False
                , earlyQuit      = False
                , numMulticolors = replicate 5 0
--          x , multicolor     = False
              }
defaultGS :: GameSpec
defaultGS = GS{numPlayers=2, rule=defaultRule}
numberOfCards :: Rule -> Int
numberOfCards rl = sum (take (numColors rl) $  [10,10,10,10,10]++[sum (numMulticolors rl)])
initialPileNum :: GameSpec -> Int
initialPileNum gs = numberOfCards (rule gs)
                    - handSize gs * numPlayers gs
handSize :: GameSpec -> Int
handSize GS{..} = (funPlayerHand rule ++ repeat 1) !! (numPlayers - 2)
setHandSize :: GameSpec -> Int -> Rule
setHandSize GS{..} n = rule{funPlayerHand = snd $ replaceNth (numPlayers - 2) n $ funPlayerHand rule}
data GameSpec = GS {numPlayers :: Int, rule :: Rule} deriving (Read, Show, Eq, Generic)

-- | State consists of all the information of the current game state, including public info, private info, and the hidden deck.
data State = St { publicState :: PublicInfo
                , pile :: [Card]    -- ^ invisible card pile or deck.
                , hands :: [[Card]] -- ^ partly invisible list of each player's hand.
                                    --   In the current implementation (arguably), this represents [current player's hand, next player's hand, second next player's hand, ...]
                                    --   and this is rotated every turn.
                } deriving (Read, Show, Eq, Generic)

-- | PublicInfo is the info that is available to all players.
data PublicInfo = PI { gameSpec  :: GameSpec
                     , pileNum   :: Int               -- ^ The number of cards at the pile.
                     , played    :: IM.IntMap Number  -- ^ @'Color' -> 'Number'@. The maximum number of successfully played cards of etch number.

                                                      -- Just a list with length 5 or 6 could do the job.
                     , discarded :: IM.IntMap Int     -- ^ @'Card' -> Int@. The multiset of discarded cards.

                     , nonPublic :: IM.IntMap Int     -- ^ @'Card' -> Int@. The multiset of Cards that have not been revealed to the public.
                                                      --   This does not include cards whose Color and Number are both revealed.
                                                      --
                                                      --   This is redundant information that can be computed from 'played' and 'discarded'.
                     , turn      :: Int               -- ^ How many turns have been completed since the game started. This can be computed from 'pileNum', 'deadline', and @map length 'givenHints'@.
                     , lives      :: Int              -- ^ The number of black tokens. decreases at each failure
                     , hintTokens :: Int              -- ^ The number of remaining hint tokens.

--                 , numHandCards :: [Int]  -- the number of cards each player has. This was used by isMoveValid, but now abolished because @numHandCards == map length . givenHints@.
                     , deadline   :: Maybe Int        -- ^ The number of turns until the endgame, after the pile exhausted. @Nothing@ when @pileNum > 0@.
                     , givenHints :: [[Marks]]
                                                      -- ^ The Number and Color hints given to each card in each player's hand.

                                                      -- Negative hints should also be implemented, but they should be kept separate from givenHints,
                                                      -- in order to guess the behavior of algorithms that do not use such information.
                     , possibilities :: [[Possibilities]]
                     , result :: Result               -- ^ The result of the last move. This info may be separated from 'PublicInfo' in future.
                     } deriving (Read, Show, Eq, Generic)

-- | 'Marks' is the type synonym representing the hint trace of a card.
type Marks = (Maybe Color, Maybe Number)

type Possibilities = (Int, Int)

-- | the best achievable rank for each color.
bestPossibleRank :: PublicInfo -> Color -> Number
bestPossibleRank pub iro = toEnum $ length $ takeWhile (/=0) $ zipWith subtract (numEachCard (gameSpec pub) iro)
                                                                                (map ((discarded pub IM.!) . cardToInt . C iro) [K1 .. K5])
numEachCard :: GameSpec -> Color -> [Int]
numEachCard gs iro = if iro==Multicolor then numMulticolors $ rule gs else [3,2,2,2,1]
-- | isUseless pi card means either the card is already played or it is above the bestPossibleRank.
isUseless :: PublicInfo -> Card -> Bool
isUseless pub card =  number card <= achievedRank pub (color card) -- the card is already played
                   || number card > bestPossibleRank pub (color card)
-- | A critical card is a useful card and the last card that has not been dropped.
--
--   Unmarked critical card on the chop should be marked.
isCritical :: PublicInfo -> Card -> Bool
isCritical pub card = not (isUseless pub card)
                      && succ (discarded pub IM.! cardToInt card) == (numEachCard (gameSpec pub) (color card) !! (pred $ fromEnum $ number card))

isPlayable :: PublicInfo -> Card -> Bool
isPlayable pub card = pred (number card) == achievedRank pub (color card)

isHinted :: Marks -> Bool
isHinted = not . (==(Nothing, Nothing))

-- | 'isMostObviouslyPlayable' only looks at the current hint marks (and the played piles) and decides if the card is surely playable.
--   This is useful only for predicting the behaviors of beginner players.
isMostObviouslyPlayable :: PublicInfo -> Marks -> Bool
isMostObviouslyPlayable pub (Just c, Just n) = isPlayable pub $ C c n
isMostObviouslyPlayable _   _                = False

-- | 'isMoreObviouslyPlayable' looks at the publicly available current info and decides if the card is surely playable.
isMoreObviouslyPlayable :: PublicInfo -> Marks -> Bool
isMoreObviouslyPlayable pub = iOP (nonPublic pub) pub

-- | In addition to 'isMoreObviouslyPlayable', 'isObviouslyPlayable' also looks into the color/number possibilities of the card and decides if the card is surely playable.
isObviouslyPlayable :: PublicInfo -> Possibilities -> Bool
isObviouslyPlayable pub (pc,pn) = all (\card -> (nonPublic pub IM.! cardToInt card) == 0 || isPlayable pub card)
                                      [ C color number | color <- colorPossibilities pc, number <- numberPossibilities pn ]

-- | In addition to 'isObviouslyPlayable', 'isDefinitelyPlayable' also looks at other players' hand and decides if the card is surely playable.
{- This is a weaker version not looking into the possibilities.
isDefinitelyPlayable :: PrivateView -> Marks -> Bool
isDefinitelyPlayable pv = iOP (invisibleBag pv) (publicView pv)
-}
isDefinitelyPlayable :: PrivateView -> Marks -> Possibilities -> Bool
isDefinitelyPlayable pv (Just c, Just n) _       = isPlayable (publicView pv) $ C c n -- The condition is indispensable, because now invisibleBag considers fully-marked cards visible.
isDefinitelyPlayable pv _                (pc,pn) = all (\card -> (invisibleBag pv IM.! cardToInt card) == 0 || isPlayable (publicView pv) card)
                                                       [ C color number | color <- colorPossibilities pc, number <- numberPossibilities pn ]


iOP :: IM.IntMap Int -> PublicInfo -> (Maybe Color, Maybe Number) -> Bool
iOP _   pub (Just c, Just n) = isPlayable pub $ C c n
iOP bag pub (Nothing,Just n) = all (\card -> (bag IM.! cardToInt card) == 0 || isPlayable pub card) [ C color n | color <- colors pub ]
iOP _   _   _                = False

-- | 'isMoreObviouslyUseless' looks at the publicly available current info and decides if the card is surely useless.
isMoreObviouslyUseless :: PublicInfo -> Marks -> Bool
isMoreObviouslyUseless pub (Just c,  Just n)  = isUseless pub $ C c n
isMoreObviouslyUseless pub (Just c,  Nothing) = bestPossibleRank pub c == achievedRank pub c
isMoreObviouslyUseless pub (Nothing, Just n)  = all (\c -> n <= achievedRank pub c || bestPossibleRank pub c < n) $ colors pub
isMoreObviouslyUseless _   (Nothing, Nothing) = False

isObviouslyUseless :: PublicInfo -> Possibilities -> Bool
isObviouslyUseless pub (pc,pn) = all (\card@(C c n) -> n <= achievedRank pub c || bestPossibleRank pub c < n || (nonPublic pub IM.! cardToInt card) == 0 )
                                     [ C color number | color <- colorPossibilities pc, number <- numberPossibilities pn ]

isDefinitelyUseless :: PrivateView -> Marks -> Possibilities -> Bool
isDefinitelyUseless pv (Just c, Just n) _       = isUseless (publicView pv) $ C c n -- The condition is indispensable, because now invisibleBag considers fully-marked cards visible.
isDefinitelyUseless pv _                (pc,pn) = all (\card@(C c n) -> n <= achievedRank pub c || bestPossibleRank pub c < n || (invisibleBag pv IM.! cardToInt card) == 0 )
                                                      [ C color number | color <- colorPossibilities pc, number <- numberPossibilities pn ]
                            where pub = publicView pv

{- This is a weaker version not looking into the possibilities.
isDefinitelyUseless :: PrivateView -> Marks -> Bool
isDefinitelyUseless pv (Just c,  Just n)  = isUseless (publicView pv) $ C c n
isDefinitelyUseless pv (Just c,  Nothing) = all ((==0) . (invisibleBag pv IM.!) . cardToInt . C c . toEnum) [ succ $ fromEnum $ achievedRank (publicView pv) c .. fromEnum $ bestPossibleRank (publicView pv) c ] 
isDefinitelyUseless pv (Nothing, Just n)  = all (\c -> n <= achievedRank (publicView pv) c || bestPossibleRank (publicView pv) c < n || (invisibleBag pv IM.! cardToInt (C c n)) == 0 ) $ colors $ publicView pv
isDefinitelyUseless pv (Nothing, Nothing) = all (\c -> all ((==0) . (invisibleBag pv IM.!) . cardToInt . C c . toEnum) [ succ $ fromEnum $ achievedRank (publicView pv) c .. fromEnum $ bestPossibleRank (publicView pv) c ]) $ colors $ publicView pv
-}
-- In fact, invisibleBag should be included in PrivateView for efficiency of isDefinitelyUseless, etc., but should not be sent via WebSocket. This is the matter of Read and Show (or ToJSON and FromJSON).


-- | @'choppiri' marks@ = [unmarked last, unmarked second last, ...]. This is "beginner players' idea of chops". 
choppiri :: [Marks] -> [(Index, Marks)]
choppiri = reverse . filter (not . isHinted . snd) . zip [0..]

-- | In addition to 'choppiri', 'definiteChopss' and 'obviousChopss' consider 'isDefinitelyUseless' and 'isObviouslyUseless' respectively. Since "from which card to drop among obviously-useless cards" depends on conventions, cards with the same uselessness are wrapped in a list within the ordered list.
definiteChopss :: PrivateView -> [Marks] -> [Possibilities] -> [[Index]]
definiteChopss pv hls ps = (if null useless then id else (useless :)) $ map ((:[]) . fst) (choppiri hls)
   where useless = map fst $ filter (uncurry (isDefinitelyUseless pv) . snd) (zip [0..] $ zip hls ps)
obviousChopss :: PublicInfo -> [Marks] -> [Possibilities] -> [[Index]]
obviousChopss pub hls ps = (if null useless then id else (useless :)) $ map ((:[]) . fst) (choppiri hls)
   where useless = map fst $ filter (isObviouslyUseless pub . snd) (zip [0..] ps)
-- | 'chops' is the flattened version of 'obviousChopss'
chops :: PublicInfo -> [Marks] -> [Possibilities] -> [Index]
chops pub hls ps = concat $ map reverse $ obviousChopss pub hls ps

isDoubleDrop :: PrivateView -> Result -> [Index] -> (Int, Int) -> Bool
isDoubleDrop pv@PV{publicView=pub} (Discard c@C{..}) [_i] (pc,pn) = not (any (==(Just color, Just number)) myHints) &&  -- This pattern captures: the last player discards B1; I have a card which is hinted as B and 1; I don't know where the third B1 is.
                                                                                                                        -- This can be improved to check whether any card other than the chop is obviously the just-dropped card or not, by looking at the Possibilities.
                                                                    isCritical pub c &&
                                                                    color  `elem` colorPossibilities pc &&
                                                                    number `elem` numberPossibilities pn &&
                                                                    (invisibleBag pv IM.! cardToInt c) > 0
                                         where myHints = head $ givenHints pub
isDoubleDrop _pv _lastresult _chopset _ps = False

colors :: PublicInfo -> [Color]
colors pub = take (numColors $ rule $ gameSpec pub) [minBound .. maxBound]

achievedRank :: PublicInfo -> Color -> Number
achievedRank pub k = case IM.lookup (fromEnum k) (played pub) of
                            Just n  -> n
#ifdef DEBUG
                            Nothing | numColors (rule $ gameSpec pub) <= k -> error "requesting invalid color."
                                    | otherwise                            -> error "PublicInfo is not initialized."
#else
                            Nothing -> Empty
#endif
currentScore :: PublicInfo -> Int
currentScore pub = sum [ fromEnum $ achievedRank pub k | k <- colors pub ]
achievableScore :: PublicInfo -> Int
achievableScore pub = sum [ fromEnum $ bestPossibleRank pub k | k <- colors pub ]

tryMove :: PrivateView -> Move -> Move -> Move
tryMove pv m alt | isMoveValid pv m = m
                 | otherwise        = alt
(|||) :: (PrivateView -> Move) -> (PrivateView -> Move) -> PrivateView -> Move
a ||| b = tryMove <*> a <*> b
ifA :: (PrivateView -> Bool) -> (PrivateView -> Move) -> (PrivateView -> Move) -> PrivateView -> Move
ifA pred at af = (\pv t f -> if pred pv then t else f) <*> at <*> af

-- | 'Result' is the result of the last move.
data Result = None -- ^ Hinted or at the beginning of the game
            | Discard Card | Success Card | Fail Card deriving (Read, Show, Eq, Generic)

-- The view history [PrivateView] records the memory of what has been visible `as is'. That is, the info of the cards in the history is not updated by revealing them.
-- I guess, sometimes, ignorance of other players might also be an important knowledge.
-- Algorithms that want updated info could implement the functionality for themselves.


-- | PrivateView is the info that is available to the player that has @head 'hands'@.
data PrivateView = PV { publicView :: PublicInfo
                      , handsPV :: [[Card]]           -- ^ Other players' hands. [next player's hand, second next player's hand, ...]
                                                      --   This is based on the viewer's viewpoint (unlike 'hands' which is based on the current player's viewpoint),
                                                      --   and the view history @[PrivateView]@ must be from the same player's viewpoint (as the matter of course).
                      , invisibleBag :: IM.IntMap Int -- ^ @'Card' -> Int@. 'invisibleBag' is the bag of unknown cards (which are either in the pile or in the player's hand and not fully hinted).
                      } deriving (Generic) -- ToDo: Instance for Generic should also be specialized for efficiency.
instance Show PrivateView where
  showsPrec p (PV pub h _) = showsPrec p (pub,h)
instance Read PrivateView where
  readsPrec p str = [ (mkPV pub hs, rest) | ((pub,hs), rest) <- readsPrec p str ]
instance Eq PrivateView where
  PV pub1 hs1 _ == PV pub2 hs2 _ = (pub1,hs1) == (pub2,hs2)

-- | 'mkPV' is the constructor of PrivateView.
mkPV :: PublicInfo -> [[Card]] -> PrivateView
mkPV pub hs = PV pub hs $ foldr (IM.update (Just . pred)) (nonPublic pub) $ map cardToInt $ concat $ [ C c n | (Just c, Just n) <- head $ givenHints pub ] : hs

prettyPV :: Verbosity -> PrivateView -> String
prettyPV v pv@PV{publicView=pub} = prettyPI pub ++ "\nMy hand:\n"
                                              ++ concat (replicate (length myHand) $ wrap "+--+") ++ "\n"
--                                              ++ concat [ if markObviouslyPlayable v && isDefinitelyPlayable pv h then " _^" else " __" | h <- myHand ] ++"\n"
                                              ++ concat (replicate (length myHand) $ wrap "|**|") ++ "\n"
                                              ++ (if markHints v then showHintLine wrap myHand else "")
                                     -- x         ++ concat (replicate (length myHand) " ~~") ++ "\n"
-- x                                             ++ concat [ '+':shows d "-" | d <- [0 .. pred $ length myHand] ]
                                              ++ concat [ wrap $
                                                          '+':(if warnDoubleDrop v && isDoubleDrop pv (result pub) chopSet p && d `elem` chopSet then ('D':) else
                                                               if markChops v && d `elem` chopSet then ('X':) else shows d)
                                                                      (if markObviouslyUseless  v && isDefinitelyUseless pv h p then ".+" else
                                                                       if markObviouslyPlayable v && isDefinitelyPlayable pv h p then "^+" else "-+") | (d,h,p) <- zip3 [0..] myHand myPos ]

                                              ++"\n"
                                              ++ (if markPossibilities v then showPosLines $ head $ possibilities pub else "")
                                              ++ concat (zipWith4 (prettyHand v pub (ithPlayer $ numPlayers $ gameSpec pub)) [1..] (handsPV pv) (tail $ givenHints pub) (tail $ possibilities pub))++"\n"
  where myHand = head (givenHints pub)
        myPos  = head (possibilities pub)
        wrap xs | markPossibilities v = "  "++xs++" "
                | otherwise           = xs
        chopSet = concat $ take 1 $ definiteChopss pv myHand myPos
prettySt :: (Int -> Int -> String) -> State -> String
prettySt ithP st@St{publicState=pub} = prettyPI pub ++ concat (zipWith4 (prettyHand verbose pub (ithP $ numPlayers $ gameSpec pub)) [0..] (hands st) (givenHints pub) (possibilities pub))
verbose, quiet :: Verbosity
verbose = V{warnCritical=True, markUseless=True, markPlayable=True, markObviouslyUseless=True, markObviouslyPlayable=True, markHints=True, markPossibilities=True, markChops=True, warnDoubleDrop=True}
quiet   = V{warnCritical=False,markUseless=False,markPlayable=False,markObviouslyUseless=False,markObviouslyPlayable=False,markHints=False,markPossibilities=False,markChops=False,warnDoubleDrop=False}
prettyHand :: Verbosity -> PublicInfo -> (Int->String) -> Int -> [Card] -> [Marks] -> [Possibilities] -> String
prettyHand v pub ithPnumP i cards hl ps = "\n\n" ++ ithPnumP i ++ " hand:\n"
--                          ++ concat (replicate (length cards) " __") ++ " \n"
                          ++ concat [ wrap $
                                      if markUseless v && isUseless pub card then "+..+"
                                      else case (warnCritical v && tup==(Nothing,Nothing) && isCritical pub card, markPlayable v && isPlayable pub card) of
                                             (True, True)  -> "+!^+"
                                             (True, False) -> "+!!+"
                                             (False,True)  -> "+-^+"
                                             (False,False) -> "+--+"
                                    | (card, tup) <- zip cards hl ] ++"\n"
                          ++ concat [ wrap $ '|':shows card "|" | card <- cards ] ++"\n"
                          ++ (if markHints v then showHintLine wrap hl else "")
-- x                          ++ concat (replicate (length cards) "+--")
                          ++ concat [ wrap $
                                      '+':(if markChops v && d `elem` (concat $ take 1 $ obviousChopss pub hl ps) then ('X':) else ('-':))
                                             (if markObviouslyUseless  v && isObviouslyUseless  pub h then ".+" else
                                              if markObviouslyPlayable v && isObviouslyPlayable pub h then "^+" else "-+") | (d,h) <- zip [0..] ps ]++"\n"
                          ++ (if markPossibilities v then showPosLines ps else "")
                    where wrap xs | markPossibilities v = "  "++xs++" "
                                  | otherwise           = {- take 3 -} xs


showHintLine :: (String -> String) -> [Marks] -> String
showHintLine wrapper hl = concat [ wrapper $ '|' : maybe ' ' (head . show) mc : maybe ' ' (head . show . fromEnum) mk : "|" | (mc,mk) <- hl] ++ "\n"
showPosLines :: [Possibilities] -> String
showPosLines ps = concat [ ' ' : showColorPossibilities  cs | (cs,_) <- ps] ++ "\n"
               ++ concat [ showNumberPossibilities ns ++" " | (_,ns) <- ps]

showColorPossibilities, showNumberPossibilities :: Int -> String
showColorPossibilities  = reverse . showPossibilities ' ' colorkeys
showNumberPossibilities = reverse . showPossibilities ' ' "54321 "
colorkeys :: String
colorkeys = map (head . show) [maxBound, pred maxBound .. minBound::Color] -- colorkeys == "MBGRYW", but I just prefer to make this robust to changes in the order.
showPossibilities :: a -> [a] -> Int -> [a]
showPossibilities _     []     _   = []
showPossibilities blank (x:xs) pos = (if odd pos then x else blank) : showPossibilities blank xs (pos `div` 2)

colorPossibilities  :: Int -> [Color] -- The result is in the reverse order but I do not care.
colorPossibilities  = concat . showPossibilities [] (map (:[]) [maxBound, pred maxBound .. minBound])
numberPossibilities :: Int -> [Number] -- The result is in the reverse order but I do not care.
numberPossibilities = concat . showPossibilities [] (map (:[]) [K5,K4 .. K1])



-- | 'Verbosity' is the set of options used by verbose 'Strategy's
data Verbosity = V { warnCritical :: Bool -- ^ mark unhinted critical cards with "!!" ("!^" if it is playable and markPlayable==True.)
                   , markUseless  :: Bool -- ^ mark useless  cards with "..".
                   , markPlayable :: Bool -- ^ mark playable cards with "_^". ("!^" if it is unhinted critical and warnCritical==True.)
                   , markObviouslyUseless  :: Bool -- ^ mark useless  cards with "_." based on the hint marks.
                   , markObviouslyPlayable :: Bool -- ^ mark playable cards with "_^" based on the hint marks.
                   , markChops     :: Bool -- ^ mark the chop card(s) with "X". All obviously-useless cards will be marked, if any.
                   , warnDoubleDrop:: Bool -- ^ mark the chop card with "D" when dropping it is double-dropping.
                   , markHints     :: Bool -- ^ mark hints.
                   , markPossibilities :: Bool -- ^ mark more detailed hints based on the positive/negative hint history.
                                               --   markPossibilities == True && markHints == False is a reasonable choice, though markHints should still be informative for guessing other players' behavior.
                   } deriving (Read, Show, Eq, Generic)


prettyPI :: PublicInfo -> String
prettyPI pub
{- This was too verbose
  = let
      showDeck 0 = "no card at the deck (the game will end in " ++ shows (fromJust $ deadline pub) " turn(s)), "
      showDeck 1 = "1 card at the deck, "
      showDeck n = shows n " cards at the deck, "
    in  "Turn "++ shows (turn pub) ": " ++ showDeck (pileNum pub) ++ shows (lives pub) " live(s) left, " ++ shows (hintTokens pub) " hint tokens;\n\n"
-}
  = let
      showDeck 0 = if prolong $ rule $ gameSpec pub then "Deck: 0,  " else "Deck: 0 (" ++ shows (fromJust $ deadline pub) " turn(s) left),  "
      showDeck 1 = "Deck: 1,  "
      showDeck n = "Deck: " ++ shows n ",  "
    in  "Turn: "++ shows (turn pub) ",  " ++ showDeck (pileNum pub) ++ "Lives: " ++ shows (lives pub) ",  Hints: " ++ shows (hintTokens pub) ";\n\n"
            ++ "played (" ++ shows (currentScore pub) " / " ++ shows (achievableScore pub) "):"
                         ++ concat [ "  " ++ concat ( [ show $ C c k | k <- [K1 .. achievedRank pub c] ] ++ replicate (possible - fromEnum playedMax) "__" ++ replicate (5 - possible) "XX")
                                   | c <- colors pub
                                   , let playedMax = achievedRank pub c
                                         possible  = fromEnum $ bestPossibleRank pub c
                                   ]
            ++ "\ndropped: " ++ concat [ '|' : concat (replicate n $ show $ intToCard ci) | (ci,n) <- IM.toList $ discarded pub ] ++"|\n"

view :: State -> PrivateView
view st = mkPV (publicState st) (tail $ hands st)

main :: IO ()
main = selfplay defaultGS

-- | 'selfplay' starts selfplay with yourself:)
--
--   Also,
--
-- > selfplay defaultGS{numPlayers=n}
--
--  (where 1<n<10) starts selfplay with youselves:D
selfplay :: GameSpec -> IO ()
selfplay gs
     = do g <- newStdGen
          ((finalSituation,_),_) <- start gs [] [stdio] g
          putStrLn $ prettyEndGame finalSituation

-- | 'prettyEndGame' can be used to pretty print the final situation.
prettyEndGame :: (EndGame, [State], [Move]) -> String
prettyEndGame (eg,sts@(st:_),mvs)
   = unlines $ recentEvents ithPlayerFromTheLast (map view sts) mvs :
               replicate 80 '!' :
               surround (replicate 40 '!') (show eg) :
               replicate 80 '!' :
               map (surround $ replicate 38 ' ' ++"!!") (lines $ prettySt ithPlayerFromTheLast st) ++
             [ replicate 80 '!' ]
surround :: [a] -> [a] -> [a]
surround ys xs = let len  = length xs
                     len2 =len `div` 2
                 in reverse (drop len2 ys) ++ xs ++ drop (len - len2) ys

type Peeker m = State -> [Move] -> m ()
peek :: Peeker IO
peek st []     = putStrLn $ prettySt ithPlayerFromTheLast st
peek st (mv:_) = putStrLn $ replicate 20 '-' ++ '\n' :
                            showTrial (const "") undefined (view st) mv ++ '\n' :
                            replicate 20 '-' ++ '\n' : prettySt ithPlayerFromTheLast st

-- | 'start' creates and runs a game. This is just the composition of 'createGame' and 'run'.
start :: (RandomGen g, Monad m, Strategies ps m) =>
       GameSpec -> [Peeker m] -> ps -> g -> m (((EndGame, [State], [Move]), ps), g)
start gs audience players gen = let
                         (st, g) = createGame gs gen
                       in fmap (\e -> (e,g)) $ run audience [st] [] players
startFromCards :: (Monad m, Strategies ps m) =>
       GameSpec -> [Peeker m] -> ps -> [Card] -> m ((EndGame, [State], [Move]), ps)
startFromCards gs audience players shuffled = let
                         st = createGameFromCards gs shuffled
                       in run audience [st] [] players
run :: (Monad m, Strategies ps m) => [Peeker m] -> [State] -> [Move] -> ps -> m ((EndGame, [State], [Move]), ps)
run audience states moves players = do
                              ((mbeg, sts, mvs), ps) <- runARound (\sts@(st:_) mvs -> let myOffset = turn (publicState st) in mapM_ (\p -> p st mvs) audience >> broadcast (zipWith rotate [-myOffset, 1-myOffset ..] sts) mvs players (myOffset `mod` numPlayers (gameSpec $ publicState st)) >> return ()) states moves players
                              case mbeg of Nothing -> run audience sts mvs ps
                                           Just eg -> return ((eg, sts, mvs), ps)

-- | The 'Strategy' class is exactly the interface that
--   AI researchers defining their algorithms have to care about.
class Monad m => Strategy p m where
      -- | 'strategyName' is just the name of the strategy. The designer of the instance should choose one.
      strategyName :: m p -> m String

      -- | 'move' is the heart of the strategy. It takes the history of observations and moves, and selects a 'Move'.
      --   Because the full history is available, your algorithm can be stateless, but still there is the option to design it in the stateful manner.
      move :: [PrivateView] -- ^ The history of 'PrivateView's, new to old.
                   -> [Move]     -- ^ The history of 'Move's, new to old.
                   -> p          -- ^ The strategy's current state. This can be isomorphic to @()@ if the strategy does not have any parameter.
                   -> m (Move, p) -- ^ 'move' returns the pair of the Move and the next state, wrapped with monad m that is usually either IO or Identity.
                                  --   The next state can be the same as the current one unless the algorithm is learning on-line during the game.

      -- | 'observe' is called during other players' turns. It allows (mainly) human players to think while waiting.
      --
      --   It is arguable whether algorithms running on the same machine may think during other players' turn, especially when the game is timed.
      observe :: [PrivateView] -- ^ The history of 'PrivateView's, new to old.
                 -> [Move]     -- ^ The history of 'Move's, new to old.
                 -> p          -- ^ The strategy's current state. This can be isomorphic to @()@ if the strategy does not have any parameter.
                 -> m ()
      observe _pvs _moves _st = return () -- The default does nothing.
{-
                 -> m ((), p)  -- ^ 'observe' returns the next state, wrapped with monad m that is usually either IO or Identity.
                               --   The next state can be the same as the current one unless the algorithm is learning on-line during the game.
      observe _pvs _moves st = return ((),st) -- The default does nothing.
-}


-- StrategyDict should be used instead of class Strategy, maybe.

-- | 'StrategyDict' is a dictionary implementation of class 'Strategy'. It can be used instead if you like.
data StrategyDict m s = SD{sdName :: String, sdMove :: Mover s m, sdObserve :: Observer s m, sdState :: s}
type Mover    s m = [PrivateView] -> [Move] -> s -> m (Move, s)
type Observer s m = [PrivateView] -> [Move] -> s -> m ()
mkSD :: (Monad m, Typeable s, Strategy s m) => String -> s -> StrategyDict m s
mkSD name s = SD{sdName=name, sdMove=move, sdObserve=observe, sdState=s}
instance Monad m => Strategy (StrategyDict m s) m where
  strategyName mp = do p <- mp
                       return $ sdName p
  move    pvs mvs s = sdMove s pvs mvs (sdState s) >>= \ (m, nexts) -> return (m, s{sdState=nexts})
  observe pvs mvs s = sdObserve s pvs mvs $ sdState s


-- Should DynamicStrategy be limited to IO?
type DynamicStrategy m = StrategyDict m Dynamic
mkDS :: (Monad m, Typeable s, Strategy s m) => String -> s -> DynamicStrategy m
mkDS name s = mkDS' $ mkSD name s
mkDS' :: (Monad m, Typeable s) => StrategyDict m s -> DynamicStrategy m
mkDS' gs = SD{sdName    = sdName gs,
              sdMove    = \pvs mvs dyn -> fmap (\(m,p)->(m, toDyn p)) $ sdMove gs pvs mvs (fromDyn dyn (error "mkDS': impossible")),
              sdObserve = \pvs mvs dyn -> sdObserve gs pvs mvs (fromDyn dyn (error "mkDS': impossible")),
              sdState   = toDyn $ sdState gs}


-- | The 'Strategies' class defines the list of 'Strategy's. If all the strategies have the same type, one can use the list instance.
--   I (Susumu) guess that in most cases one can use 'Dynamic' in order to force the same type, but just in case, the tuple instance is also provided. (Also, the tuple instance should be more handy.)
--
--   The strategies are used in order, cyclically.
--   The number of strategies need not be the same as 'numPlayers', though the latter should be a divisor of the former.
--   For normal play, they should be the same. 
--   If only one strategy is provided, that means selfplay, though this is not desired because all the hidden info can be memorized. (In order to avoid such cheating, the same strategy should be repeated.)
--   If there are twice as many strategies as 'numPlayers', the game will be "Pair Hanabi", like "Pair Go" or "Pair Golf" or whatever. (Maybe this is also interesting.)
class Strategies ps m where
   runARound :: ([State] -> [Move] -> m ()) -> [State] -> [Move] -> ps -> m ((Maybe EndGame, [State], [Move]), ps)
   broadcast :: [State] -> [Move] -> ps -> Int -> m ([State], Int)
{- Abolished in order to avoid confusion due to overlapping instances. When necessary, use a singleton list instead.
instance {-# OVERLAPS #-} (Strategy p1 m, Monad m) => Strategies p1 m where
   runARound states moves p = runATurn states moves p
-}
instance (Strategies p1 m, Strategies p2 m, Monad m) => Strategies (p1,p2) m where
   runARound hook states moves (p,ps) = runARound hook states moves p >>= \(tup@(mbeg,sts,mvs), p') -> case mbeg of
                                                               Nothing -> do (tups,ps') <- runARound hook sts mvs ps
                                                                             return (tups, (p',ps'))
                                                               _       -> return (tup, (p',ps))
   broadcast states moves (p1,p2) offset = do (sts, ofs) <- broadcast states moves p1 offset
                                              broadcast sts moves p2 ofs
instance (Strategy p m, Monad m) => Strategies [p] m where
--   runARound hook states moves []     = return ((Nothing, states, moves), [])
   runARound _    _      _     []     = error "It takes at least one algorithm to play Hanabi!"
   runARound hook states moves [p]    = hook states moves >> runATurn states moves p >>= \(tup, p') -> return (tup, [p'])
   runARound hook states moves (p:ps) = hook states moves >> runATurn states moves p >>= \(tup@(mbeg,sts,mvs), p') -> case mbeg of
                                                               Nothing -> do (tups,ps') <- runARound hook sts mvs ps
                                                                             return (tups, (p':ps'))
                                                               _       -> return (tup, (p':ps))
   broadcast _      _     []     _   = error "It takes at least one algorithm to play Hanabi!"
   broadcast states moves [p]    ofs = when (ofs/=0) (observe (map view states) moves p) >> return (map (rotate 1) states, pred ofs)
   broadcast states moves (p:ps) ofs = when (ofs/=0) (observe (map view states) moves p) >> broadcast (map (rotate 1) states) moves ps (pred ofs)

runATurn :: (Strategy p m, Monad m) => [State] -> [Move] -> p -> m ((Maybe EndGame, [State], [Move]), p)
runATurn states moves p = let alg = move (map view $ zipWith rotate [0..] states) moves p in
                                     do (mov, p') <- alg
                                        case proceed (head states) mov of
                                          Nothing -> do name <- strategyName (fmap snd alg)
                                                        error $ show mov ++ " by " ++ name ++ ": invalid move!"  -- 'strategyName' exists in order to blame stupid algorithms:) 
                                                                                                                 -- (but seriously, this could end with failure. There is a safety net for human players.)
                                          Just st -> let nxt = rotate 1 st
                                                     in return ((checkEndGame $ publicState nxt, nxt:states, mov:moves), p')

-- | Verbose makes a player verbose. It is useful to monitor the viewpoint of a specific player.
data Verbose p = Verbose {unV :: p, verbV :: Verbosity} deriving (Read, Show)
instance (Strategy p m, MonadIO m) => Strategy (Verbose p) m where
    strategyName mp = do name <- strategyName $ fmap unV mp
                         return $ if name == "Blind" then "STDIO" else "Verbose " ++ name
    move views@(_:_) moves (Verbose p verb) = let alg = move views moves p in
                                              do name <- strategyName (fmap (\a -> Verbose (snd a) verb) alg)
                                                 liftIO $ putStrLn $ what'sUp verb name views moves
                                                 (mv,p') <- alg
                                                 -- liftIO $ putStrLn $ "Move is " ++ show mv -- This is redundant because of echo back.
                                                 return (mv, Verbose p' verb)
    observe _     []    _ = return ()
    observe (v:_) (m:_) (Verbose _ verb) = liftIO $ putStrLn $ what'sUp1 verb v m

what'sUp :: Verbosity -> String -> [PrivateView] -> [Move] -> String
what'sUp verb name views@(v:_) moves = replicate 20 '-' ++ '\n' :
                                  recentEvents ithPlayer views moves ++ '\n' :
                                  replicate 20 '-' ++ '\n' :
                                  "Algorithm: " ++ name ++ '\n' :
                                  prettyPV verb v ++ "\nYour turn.\n"
what'sUp1 :: Verbosity -> PrivateView -> Move -> String
what'sUp1 verb v m = replicate 20 '-' ++ '\n' :
                showTrial (const "") undefined v m ++ '\n' :
                replicate 20 '-' ++ '\n' :
                prettyPV verb v

recentEvents :: (Int -> Int -> String) -> [PrivateView] -> [Move] -> String
recentEvents ithP vs@(v:_) ms = unlines $ reverse $ zipWith3 (showTrial $ ithP nump) [pred nump, nump-2..0] vs ms
   where nump = numPlayers $ gameSpec $ publicView v

showTrial :: (Int -> String) -> Int -> PrivateView -> Move -> String
showTrial ithP i v m = ithP i ++ " move: " ++ replicate (length (ithP 2) - length (ithP i)) ' ' ++ show m ++
                                                        case result $ publicView v of Discard c -> ", which revealed "++shows c "."
                                                                                      Success c -> ", which succeeded revealing "++shows c "."
                                                                                      Fail    c -> ", which failed revealing " ++ shows c "."
                                                                                      _         -> "."

ithPlayer :: Int -> Int -> String
ithPlayer _ 0 = "My"
ithPlayer _ i = "The " ++ ith i ++"next player's"
ith :: Int -> String
ith 1 = ""
ith 2 = "2nd "
ith 3 = "3rd "
ith i = shows i "th "
ithPlayerFromTheLast :: Int -> Int -> String
ithPlayerFromTheLast nump j = "The " ++ ith (nump-j) ++"last player's"

type STDIO = Verbose Blind
stdio :: Verbose Blind
stdio = Verbose Blind verbose
data Blind = Blind
instance (MonadIO m) => Strategy Blind m where
    strategyName _ = return "Blind"
    move (v:_) _ _ = do mov <- liftIO $ repeatReadingAMoveUntilSuccess stdin stdout v
                        return (mov, Blind)
data ViaHandles = VH {hin :: Handle, hout :: Handle, verbVH :: Verbosity}
instance (MonadIO m) => Strategy ViaHandles m where
    strategyName _ = return "via handles"
    move views@(v:_) moves vh = liftIO $ do hPutStrLn (hout vh) $ what'sUp (verbVH vh) "via handles" views moves
                                            mov <- repeatReadingAMoveUntilSuccess (hin vh) (hout vh) v
                                            return (mov, vh)

repeatReadingAMoveUntilSuccess :: Handle -> Handle -> PrivateView -> IO Move
repeatReadingAMoveUntilSuccess hin hout v = do
    str <- hGetLine hin
    case reads str of [(mv, rest)] | all isSpace rest -> if isMoveValid v mv then return mv else hPutStrLn hout "Invalid Move" >> repeatReadingAMoveUntilSuccess hin hout v
                      _            -> hPutStr hout ("Parse error.\n"++help) >> repeatReadingAMoveUntilSuccess hin hout v

-- | 'createGameFromCards' deals cards and creates the initial state.
createGameFromCards :: GameSpec -> [Card] -> State
createGameFromCards gs = splitCons (numPlayers gs) []
           where splitCons 0 hnds stack
                   = St {publicState = PI {gameSpec   = gs,
                                            pileNum    = initialPileNum gs,
                                            played     = IM.fromAscList [ (i,            Empty) | i <- [0 .. pred $ numColors $ rule gs] ],
                                            discarded  = IM.fromList    [ (cardToInt $ C i k, 0) | i <- take (numColors $ rule gs) [White .. Multicolor],
                                                                                                   k <- [K1 ..K5] ],
                                            nonPublic  = cardMap $ rule gs,
                                            turn       = 0,
                                            lives      = numBlackTokens $ rule gs,
                                            hintTokens = 8,
                                            deadline   = Nothing,
                                            givenHints = replicate (numPlayers gs) $ replicate (handSize gs) (Nothing, Nothing),
                                            possibilities = replicate (numPlayers gs) $ replicate (handSize gs) (unknown gs),
                                            result     = None
                                           },
                           pile  = stack,
                           hands = hnds
                          }
                 splitCons n hnds stack = case splitAt (handSize gs) stack of (tk,dr) -> splitCons (pred n) (tk:hnds) dr
createGame :: RandomGen g => GameSpec -> g -> (State, g) -- Also returns the new RNG state, in order not to require safe 'split' for collecting statistics. RNG is only used for initial shuffling.
createGame gs gen = (createGameFromCards gs shuffled, g) where
                 (shuffled, g) = createDeck (rule gs) gen
createDeck :: RandomGen g => Rule -> g -> ([Card], g)
createDeck r gen = shuffle (cardBag r) gen


numAssoc :: [(Number, Int)]
numAssoc = zip [K1 ..K5] [3,2,2,2,1]
cardAssoc :: Rule -> [(Card,Int)]
cardAssoc rule = take (5 * numColors rule) $
               [ (C i k, n) | i <- [White .. pred Multicolor], (k,n) <- numAssoc ] ++ [ (C Multicolor k, n) | (k, n) <- zip [K1 ..K5] (numMulticolors rule) ]
cardBag :: Rule -> [Card]
cardBag rule = concat         [ replicate n c | (c,n) <- cardAssoc rule ]
cardMap :: Rule -> IM.IntMap Int
cardMap rule = IM.fromList [ (cardToInt c, n) | (c,n) <- cardAssoc rule ]
unknown :: GameSpec -> Possibilities
unknown gs = (64 - bit (6 - numColors (rule gs)),  31)

shuffle :: RandomGen g => [a] -> g -> ([a], g)
shuffle xs = shuf [] xs $ length xs
shuf :: RandomGen g => [a] -> [a] -> Int -> g -> ([a], g)
shuf result _  0 gen  = (result, gen)
shuf result xs n gen  = let (i,  g)    = randomR (0, pred n) gen
                            (nth,rest) = pickNth i xs
                        in shuf (nth:result) rest (pred n) g

-- | 'isMoveValid' can be used to check if the candidate Move is compliant to the rule under the current situation. Each player can decide it based on the current 'PrivateView' (without knowing the full state).
isMoveValid :: PrivateView -> Move -> Bool
isMoveValid PV{publicView=pub} (Drop ix) = hintTokens pub < 8 && length (head $ givenHints pub) > ix && ix >= 0
isMoveValid PV{publicView=pub} (Play ix) = length (head $ givenHints pub) > ix && ix >= 0
isMoveValid PV{publicView=pub,handsPV=tlHands} (Hint hintedpl eck)
                                         = hintTokens pub > 0 &&
                                           hintedpl > 0 && hintedpl < numPlayers (gameSpec pub) &&    -- existing player other than the current
                                           not (null $ filter willBeHinted (tlHands !! pred hintedpl))
    where willBeHinted :: Card -> Bool
          willBeHinted = either (\c -> (==c).color) (\k -> (==k).number) eck
pickNth :: Int -> [a] -> (a, [a])
pickNth    n   xs = case splitAt n xs of (tk,nth:dr) -> (nth,tk++dr)
replaceNth :: Int -> a -> [a] -> (a, [a])
replaceNth n x xs = case splitAt n xs of (tk,nth:dr) -> (nth,tk++x:dr)    -- = updateNth n (const x) xs
updateNth :: Int -> (a -> a) -> [a] -> (a, [a])
updateNth  n f xs = case splitAt n xs of (tk,nth:dr) -> (nth,tk++f nth:dr)

-- | 'proceed' updates the state based on the current player's Move, without rotating.
proceed :: State -> Move -> Maybe State
proceed st@(St{publicState=pub@PI{gameSpec=gS}}) mv = if (isMoveValid (view st) mv) then return (prc mv) else Nothing where

  -- only used by Drop and Play
  (nth, droppedHand) = pickNth (index mv) playersHand where playersHand = head $ hands st
  (_  , droppedHint) = pickNth (index mv) playersHint where playersHint = head $ givenHints pub
  (_  , droppedPos)  = pickNth (index mv) playersPos  where playersPos  = head $ possibilities pub
  (nextHand,nextHint,nextPos,nextPile, nextPileNum) = case pile st of []   -> (droppedHand,   droppedHint,                   droppedPos,              [], 0)
                                                                      d:ps -> (d:droppedHand, (Nothing,Nothing):droppedHint, unknown gS : droppedPos, ps, pred $ pileNum pub)
  nextHands = nextHand : tail (hands st)
  nextHints = nextHint : tail (givenHints pub)
  nextPoss  = nextPos  : tail (possibilities pub)
  nextDeadline = case deadline pub of Nothing | nextPileNum==0 && not (prolong $ rule $ gameSpec pub) -> Just $ numPlayers gS
                                              | otherwise                                             -> Nothing
                                      Just i  -> Just $ pred i
  prc (Drop _) = st{pile = nextPile,
                    hands = nextHands,
                    publicState = pub{pileNum = nextPileNum,
                                      discarded = IM.update (Just . succ) (cardToInt nth) $ discarded pub,
                                      nonPublic = IM.update (Just . pred) (cardToInt nth) $ nonPublic pub,
                                      turn       = succ $ turn pub,
                                      hintTokens = succ $ hintTokens pub,
                                      givenHints = nextHints,
                                      possibilities = nextPoss,
                                      deadline   = nextDeadline,
                                      result     = Discard nth}}
  prc (Play i) | failure   = let newst@St{publicState=newpub} = prc (Drop i) in newst{publicState=newpub{hintTokens = hintTokens pub, lives = pred $ lives pub, result = Fail nth}}
               | otherwise = st{pile = nextPile,
                                hands = nextHands,
                                publicState = pub{pileNum = nextPileNum,
                                                  played = IM.update (Just . succ) (fromEnum $ color nth) (played pub),
                                                  nonPublic = IM.update (Just . pred) (cardToInt nth) $ nonPublic pub,
                                                  turn       = succ $ turn pub,
                                                  hintTokens = if hintTokens pub < 8 && number nth == K5 then succ $ hintTokens pub else hintTokens pub,
                                                  givenHints = nextHints,
                                                  possibilities = nextPoss,
                                                  deadline   = nextDeadline,
                                                  result = Success nth}}
    where failure = not $ isPlayable pub nth
  prc (Hint hintedpl eik) = st{publicState = pub{hintTokens = pred $ hintTokens pub,
                                                 turn       = succ $ turn pub,
                                                 givenHints = snd $ updateNth hintedpl newHints (givenHints pub),
                                                 possibilities = snd $ updateNth hintedpl newPoss (possibilities pub),
                                                 deadline   = case deadline pub of Nothing -> Nothing
                                                                                   Just i  -> Just $ pred i,
                                                 result     = None}}
    where newHints hs = zipWith zipper (hands st !! hintedpl) hs
          zipper (C ir ka) (mi,mk) = case eik of Left  i | i==ir -> (Just i, mk)
                                                 Right k | k==ka -> (mi, Just k)
                                                 _               -> (mi,     mk)
          newPoss  hs = zipWith zipperPos (hands st !! hintedpl) hs
          zipperPos (C ir ka) (c,n) = case eik of Left i  | i == ir -> (bit ibit,        n)
                                                          |otherwise-> (clearBit c ibit, n)
                                                       where ibit = 5 - fromEnum i
                                                  Right k | k == ka -> (c, bit kbit)
                                                          |otherwise-> (c, clearBit n kbit)
                                                       where kbit = 5 - fromEnum k


-- | @'rotate' num@ rotates the first person by @num@ (modulo the number of players).
rotate :: Int -> State -> State
rotate num st@(St{publicState=pub@PI{gameSpec=gS}}) = st{hands       = rotateList $ hands st,
                                                         publicState = pub{givenHints = rotateList $ givenHints pub, possibilities = rotateList $ possibilities pub}}
    where rotateList xs = case splitAt (num `mod` numPlayers gS) xs of (tk,dr) -> dr++tk

-- | 'EndGame' represents the game score, along with the info of how the game ended.
--   It is not just @Int@ in order to distinguish 'Failure' (disaster / no life) from @'Soso' 0@ (not playing any card), though @'Soso' 0@ does not look more attractive than 'Failure'.
data EndGame = Failure | Soso Int | Perfect deriving (Show,Read,Eq,Generic)

checkEndGame :: PublicInfo -> Maybe EndGame
checkEndGame pub | lives pub == 0                                      = Just Failure
                 | all (==K5) [ achievedRank pub k | k <- colors pub ] = Just Perfect
                 | deadline pub == Just 0 ||
                   (earlyQuit (rule $ gameSpec pub) && currentScore pub == achievableScore pub)
                                                                       = Just $ Soso $ IM.foldr (+) 0 $ fmap fromEnum $ played pub
                 | hintTokens pub == 0 && null (head $ givenHints pub) = Just Failure -- No valid play is possible for the next player. This can happen when prolong==True.
                 | otherwise                                           = Nothing