{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE AllowAmbiguousTypes #-}
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module Xanthous.Entities
  ( Draw(..)
  , DrawCharacter(..)
  , DrawStyledCharacter(..)
  , Entity(..)
  , SomeEntity(..)
  , downcastEntity
  , entityIs

  , Color(..)
  , KnownColor(..)

  , EntityChar(..)
  ) where
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import           Xanthous.Prelude
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import           Brick
import           Data.Typeable
import qualified Graphics.Vty.Attributes as Vty
import qualified Graphics.Vty.Image as Vty
import           Data.Aeson
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import           Xanthous.Data
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class (Show a, Eq a, Draw a) => Entity a where
  blocksVision :: a -> Bool

instance Entity a => Entity (Positioned a) where
  blocksVision (Positioned _ ent) = blocksVision ent

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data SomeEntity where
  SomeEntity :: forall a. (Entity a, Typeable a) => a -> SomeEntity

instance Show SomeEntity where
  show (SomeEntity e) = "SomeEntity (" <> show e <> ")"

instance Eq SomeEntity where
  (SomeEntity (a :: ea)) == (SomeEntity (b :: eb)) = case eqT @ea @eb of
    Just Refl -> a == b
    _ -> False

instance Draw SomeEntity where
  drawWithNeighbors ns (SomeEntity ent) = drawWithNeighbors ns ent

instance Entity SomeEntity where
  blocksVision (SomeEntity ent) = blocksVision ent

downcastEntity :: (Entity a, Typeable a) => SomeEntity -> Maybe a
downcastEntity (SomeEntity e) = cast e

entityIs :: forall a. (Entity a, Typeable a) => SomeEntity -> Bool
entityIs = isJust . downcastEntity @a
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class Draw a where
  drawWithNeighbors :: Neighbors (Vector SomeEntity) -> a -> Widget n
  drawWithNeighbors = const draw

  draw :: a -> Widget n
  draw = drawWithNeighbors $ pure mempty

instance Draw a => Draw (Positioned a) where
  drawWithNeighbors ns (Positioned _ a) = drawWithNeighbors ns a
  draw (Positioned _ a) = draw a

newtype DrawCharacter (char :: Symbol) (a :: Type) where
  DrawCharacter :: a -> DrawCharacter char a

instance KnownSymbol char => Draw (DrawCharacter char a) where
  draw _ = str $ symbolVal @char Proxy

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data Color = Black | Red | Green | Yellow | Blue | Magenta | Cyan | White

class KnownColor (color :: Color) where
  colorVal :: forall proxy. proxy color -> Vty.Color

instance KnownColor 'Black where colorVal _ = Vty.black
instance KnownColor 'Red where colorVal _ = Vty.red
instance KnownColor 'Green where colorVal _ = Vty.green
instance KnownColor 'Yellow where colorVal _ = Vty.yellow
instance KnownColor 'Blue where colorVal _ = Vty.blue
instance KnownColor 'Magenta where colorVal _ = Vty.magenta
instance KnownColor 'Cyan where colorVal _ = Vty.cyan
instance KnownColor 'White where colorVal _ = Vty.white

newtype DrawStyledCharacter (fg :: Color) (bg :: Color) (char :: Symbol) (a :: Type) where
  DrawStyledCharacter :: a -> DrawStyledCharacter fg bg char a

instance
  ( KnownColor fg
  , KnownColor bg
  , KnownSymbol char
  )
  => Draw (DrawStyledCharacter fg bg char a) where
  draw _ = raw $ Vty.string attr $ symbolVal @char Proxy
    where attr = Vty.Attr
            { Vty.attrStyle = Vty.Default
            , Vty.attrForeColor = Vty.SetTo $ colorVal @fg Proxy
            , Vty.attrBackColor = Vty.SetTo $ colorVal @bg Proxy
            , Vty.attrURL = Vty.Default
            }
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data EntityChar = EntityChar
  { _char :: Char
  , _style :: Vty.Attr
  }
  deriving stock (Show, Eq, Generic)
  deriving anyclass (NFData)

instance FromJSON EntityChar where
  parseJSON (String (chr :< Empty)) = pure $ EntityChar chr Vty.defAttr
  parseJSON (Object o) = do
    (EntityChar _char _) <- o .: "char"
    _style <- o .:? "style" >>= \case
      Just styleO -> do
        let attrStyle = Vty.Default -- TODO
            attrURL = Vty.Default
        attrForeColor <- styleO .:? "foreground" .!= Vty.Default
        attrBackColor <- styleO .:? "background" .!= Vty.Default
        pure Vty.Attr {..}
      Nothing -> pure Vty.defAttr
    pure EntityChar {..}
  parseJSON _ = fail "Invalid type, expected string or object"

instance Draw EntityChar where
  draw EntityChar{..} = raw $ Vty.string _style [_char]

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