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module Xanthous.Game.Draw
  ( drawGame
  ) where
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import           Xanthous.Prelude
import           Brick hiding (loc)
import           Brick.Widgets.Border
import           Brick.Widgets.Border.Style
import           Brick.Widgets.Edit
import           Data.List.NonEmpty(NonEmpty((:|)))
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import           Xanthous.Data (Position(Position), x, y, loc)
import           Xanthous.Data.EntityMap (EntityMap, atPosition)
import qualified Xanthous.Data.EntityMap as EntityMap
import           Xanthous.Entities
import           Xanthous.Game
                 ( GameState(..)
                 , entities
                 , revealedPositions
                 , characterPosition
                 , MessageHistory(..)
                 , messageHistory
                 , GamePromptState(..)
                 , promptState
                 )
import           Xanthous.Game.Prompt
import           Xanthous.Resource (Name)
import qualified Xanthous.Resource as Resource
import           Xanthous.Orphans ()
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drawMessages :: MessageHistory -> Widget Name
drawMessages NoMessageHistory = emptyWidget
drawMessages (MessageHistory _ False) = str " "
drawMessages (MessageHistory (lastMessage :| _) True) = txt lastMessage

drawPromptState :: GamePromptState m -> Widget Name
drawPromptState NoPrompt = emptyWidget
drawPromptState (WaitingPrompt msg (Prompt _ pt ps _)) =
  case (pt, ps) of
    (SStringPrompt, StringPromptState edit) ->
      txt msg <+> renderEditor (txt . fold) True edit
    _ -> undefined

drawEntities
  :: Set Position
    -- ^ Positions the character has seen
    -- FIXME: this will break down as soon as creatures can walk around on their
    -- own, since we don't want to render things walking around when the
    -- character can't see them
  -> EntityMap SomeEntity -- ^ all entities
  -> Widget Name
drawEntities visiblePositions allEnts
  = vBox rows
  where
    entityPositions = EntityMap.positions allEnts
    maxY = fromMaybe 0 $ maximumOf (folded . y) entityPositions
    maxX = fromMaybe 0 $ maximumOf (folded . x) entityPositions
    rows = mkRow <$> [0..maxY]
    mkRow rowY = hBox $ renderEntityAt . flip Position rowY <$> [0..maxX]
    renderEntityAt pos
      | pos `member` visiblePositions
      = let neighbors = EntityMap.neighbors pos allEnts
        in maybe (str " ") (drawWithNeighbors neighbors)
           $ allEnts ^? atPosition pos . folded
      | otherwise = str " "

drawMap :: GameState -> Widget Name
drawMap game
  = viewport Resource.MapViewport Both
  . showCursor Resource.Character (game ^. characterPosition . loc)
  $ drawEntities
    (game ^. revealedPositions)
    (game ^. entities)

drawGame :: GameState -> [Widget Name]
drawGame game
  = pure
  . withBorderStyle unicode
  $   drawMessages (game ^. messageHistory)
  <=> drawPromptState (game ^. promptState)
  <=> border (drawMap game)