module RPGEngine.Render.Core
( Renderer

, getRender
, setRenderPos
, overlay
) where

import RPGEngine.Config

import Data.Maybe
import Graphics.Gloss
import GHC.IO
import Graphics.Gloss.Juicy

----------------------------- Constants ------------------------------

type Renderer a = a -> Picture

unknownImage :: FilePath
unknownImage = "unknown.png"

allEntities :: [(String, FilePath)]
allEntities = [
    ("player", "player.png"),
    ("door", "door.png")
    ]

allEnvironment :: [(String, FilePath)]
allEnvironment = [
    ("void",     "void.png"),
    ("overlay",  "overlay.png"),
    ("tile",     "tile.png"),
    ("wall",     "wall.png"),
    ("entrance", "entrance.png"),
    ("exit",     "exit.png")
    ]

allItems :: [(String, FilePath)]
allItems = [
    ("dagger", "dagger.png"),
    ("key",    "key.png"   )
    ]

allGui :: [(String, FilePath)]
allGui = [
    ("main", "main.png"),
    ("health", "health.png")
    ]

-- Map of all renders
library :: [(String, Picture)]
library = unknown:entities ++ environment ++ gui ++ items
    where unknown     = ("unknown", renderPNG (assetsFolder ++ unknownImage))
          entities    = map (\(f, s) -> (f, renderPNG (assetsFolder ++ "entities/"    ++ s))) allEntities
          environment = map (\(f, s) -> (f, renderPNG (assetsFolder ++ "environment/" ++ s))) allEnvironment
          gui         = map (\(f, s) -> (f, renderPNG (assetsFolder ++ "gui/"         ++ s))) allGui
          items       = map (\(f, s) -> (f, renderPNG (assetsFolder ++ "items/"       ++ s))) allItems

------------------------------ Exported ------------------------------

-- Retrieve an image from the library. If the library does not contain
-- the requested image, a default is returned.
getRender :: String -> Picture
getRender id = get filtered
    where filtered         = filter ((== id) . fst) library
          get []           = snd $ head library
          get ((_, res):_) = res

-- Move a picture by game coordinates
setRenderPos :: Int -> Int -> Picture -> Picture
setRenderPos x y = translate floatX floatY
    where floatX = fromIntegral x * zoom * resolution
          floatY = fromIntegral y * zoom * resolution

overlay :: Picture
overlay = setRenderPos offX offY $ pictures voids
    where voids = [setRenderPos x y void | x <- [0 .. width], y <- [0 .. height]]
          void  = getRender "overlay"
          intZoom = round zoom :: Int
          height = round $ 4320 / resolution / zoom
          width  = round $ 7680 / resolution / zoom
          offX   = negate (width `div` 2)
          offY   = negate (height `div` 2)

----------------------------------------------------------------------

-- Turn a path to a .png file into a Picture.
renderPNG :: FilePath -> Picture
renderPNG path = scale zoom zoom $ fromJust $ unsafePerformIO $ loadJuicyPNG path