module Item where

import Data.Binary
import qualified Data.Set as S
import qualified Data.List as L
import qualified Data.Map as M
import Data.Maybe
import Data.Char
import Data.Function
import Data.Ord
import Control.Monad

import Utils.Assert
import Random
import Content.ItemKind
import qualified Color
import Flavour
import qualified Kind

data Item = Item
  { jkind   :: !(Kind.Id ItemKind)
  , jpower  :: !Int         -- TODO: see the TODO about jpower
  , jletter :: Maybe Char  -- ^ inventory identifier
  , jcount  :: !Int
  }
  deriving Show

instance Binary Item where
  put (Item ik ip il ic ) =
    put ik >> put ip >> put il >> put ic
  get = liftM4 Item get get get get

type FlavourMap = M.Map (Kind.Id ItemKind) Flavour  -- TODO: rewrite and move elsewhere

type Discoveries = S.Set (Kind.Id ItemKind)

-- | Assigns flavours to item kinds. Assures no flavor is repeated,
-- except for items with only one permitted flavour.
rollFlavourMap :: Kind.Id ItemKind -> ItemKind ->
              Rnd (FlavourMap, S.Set Flavour) ->
              Rnd (FlavourMap, S.Set Flavour)
rollFlavourMap key ik rnd =
  let flavours = iflavour ik
  in if L.length flavours == 1
     then rnd
     else do
       (assocs, available) <- rnd
       let proper = S.fromList flavours `S.intersection` available
       flavour <- oneOf (S.toList proper)
       return (M.insert key flavour assocs, S.delete flavour available)

-- | Randomly chooses flavour for all item kinds for this game.
dungeonFlavourMap :: Rnd FlavourMap
dungeonFlavourMap =
  liftM fst $ Kind.foldrWithKey rollFlavourMap (return (M.empty, S.fromList stdFlav))

getFlavour :: FlavourMap -> Kind.Id ItemKind -> Flavour
getFlavour assocs ik =
  let kind = Kind.getKind ik
  in  case iflavour kind of
        []  -> assert `failure` (assocs, ik, kind)
        [f] -> f
        _:_ -> assocs M.! ik

fistKindId :: Kind.Id ItemKind
fistKindId = Kind.getId ((== "fist") . iname)

viewItem :: Kind.Id ItemKind -> FlavourMap -> (Char, Color.Color)
viewItem ik assocs = (isymbol (Kind.getKind ik), flavourToColor $ getFlavour assocs ik)

itemLetter :: ItemKind -> Maybe Char
itemLetter ik = if isymbol ik == '$' then Just '$' else Nothing

-- | Generate an item.
newItem :: Int -> Rnd Item
newItem lvl = do
  (ikChosen, kind) <- frequency Kind.frequency
  count <- rollQuad lvl (icount kind)
  if count == 0
    then newItem lvl  -- Rare item; beware of inifite loops.
    else do
      power <- rollQuad lvl (ipower kind)
      return $ Item ikChosen power (itemLetter kind) count

-- | Assigns a letter to an item, for inclusion
-- in the inventory of a hero. Takes a remembered
-- letter and a starting letter.
assignLetter :: Maybe Char -> Char -> [Item] -> Maybe Char
assignLetter r c is =
    case r of
      Just l | l `L.elem` allowed -> Just l
      _ -> listToMaybe free
  where
    current    = S.fromList (mapMaybe jletter is)
    allLetters = ['a'..'z'] ++ ['A'..'Z']
    candidates = take (length allLetters) $
                   drop (fromJust (L.findIndex (==c) allLetters)) $
                     cycle allLetters
    free       = L.filter (\x -> not (x `S.member` current)) candidates
    allowed    = '$' : free

cmpLetter :: Char -> Char -> Ordering
cmpLetter x y = compare (isUpper x, toLower x) (isUpper y, toLower y)

cmpLetter' :: Maybe Char -> Maybe Char -> Ordering
cmpLetter' Nothing  Nothing   = EQ
cmpLetter' Nothing  (Just _)  = GT
cmpLetter' (Just _) Nothing   = LT
cmpLetter' (Just l) (Just l') = cmpLetter l l'

maxBy :: (a -> a -> Ordering) -> a -> a -> a
maxBy cmp x y = case cmp x y of
                  LT  ->  y
                  _   ->  x

maxLetter :: Char -> Char -> Char
maxLetter = maxBy cmpLetter

mergeLetter :: Maybe Char -> Maybe Char -> Maybe Char
mergeLetter = mplus

letterRange :: [Char] -> String
letterRange ls = sectionBy (L.sortBy cmpLetter ls) Nothing
  where
    succLetter c d = ord d - ord c == 1

    sectionBy []     Nothing      = ""
    sectionBy []     (Just (c,d)) = finish (c,d)
    sectionBy (x:xs) Nothing      = sectionBy xs (Just (x,x))
    sectionBy (x:xs) (Just (c,d))
      | succLetter d x            = sectionBy xs (Just (c,x))
      | otherwise                 = finish (c,d) ++ sectionBy xs (Just (x,x))

    finish (c,d) | c == d         = [c]
                 | succLetter c d = [c,d]
                 | otherwise      = [c,'-',d]

letterLabel :: Maybe Char -> String
letterLabel Nothing  = "    "
letterLabel (Just c) = c : " - "

-- | Adds an item to a list of items, joining equal items.
-- Also returns the joined item.
-- TODO: the resulting list can contain items with the same letter.
-- TODO: name [Item] Inventory and have some invariants, e.g. no equal letters.
joinItem :: Item -> [Item] -> (Item, [Item])
joinItem i is =
  case findItem (equalItemIdentity i) is of
    Nothing     -> (i, i : is)
    Just (j,js) -> let n = i { jcount = jcount i + jcount j,
                               jletter = mergeLetter (jletter j) (jletter i) }
                   in (n, n : js)

-- | Removes an item from a list of items.
-- Takes an equality function (i.e., by letter or ny kind) as an argument.
removeItemBy :: (Item -> Item -> Bool) -> Item -> [Item] -> [Item]
removeItemBy eq i = concatMap $ \ x ->
                    if eq i x
                      then let remaining = jcount x - jcount i
                           in if remaining > 0
                              then [x { jcount = remaining }]
                              else []
                      else [x]

equalItemIdentity :: Item -> Item -> Bool
equalItemIdentity i1 i2 = jpower i1 == jpower i2 && jkind i1 == jkind i2

removeItemByIdentity :: Item -> [Item] -> [Item]
removeItemByIdentity = removeItemBy equalItemIdentity

equalItemLetter :: Item -> Item -> Bool
equalItemLetter = (==) `on` jletter

removeItemByLetter :: Item -> [Item] -> [Item]
removeItemByLetter = removeItemBy equalItemLetter

-- | Finds an item in a list of items.
findItem :: (Item -> Bool) -> [Item] -> Maybe (Item, [Item])
findItem p = findItem' []
  where
    findItem' _   []     = Nothing
    findItem' acc (i:is)
      | p i              = Just (i, reverse acc ++ is)
      | otherwise        = findItem' (i:acc) is

strongestItem :: [Item] -> String -> Maybe Item
strongestItem is groupName =
  let cmp = comparing jpower
      igs = L.filter (\ i -> iname (Kind.getKind (jkind i)) == groupName) is
  in  case igs of
        [] -> Nothing
        _  -> Just $ L.maximumBy cmp igs

itemPrice :: Item -> Int
itemPrice i =
  case iname (Kind.getKind (jkind i)) of
    "gold piece" -> jcount i
    "gem" -> jcount i * 100
    _ -> 0