{-# LANGUAGE TemplateHaskell #-}
{- |
Datatypes used to setup and pass data to shaders.
-}
module Shader.Data
    ( VAO (..)
    , VBO (..)
    , FullShader (..)
    , VShader (..)
    , ShaderTexture (..)
    , EPrimitiveMode (..)
    , PicShads (..)
-- | Lens functions
    , vao
    , vaoVBO

    , shaderProgram
    , shaderVAO
    , shaderPokeStrategy
    , shaderDrawPrimitive
    , shaderTexture
    , shaderCustomUnis

    , vshaderProgram
    , vshaderVAO
    , vshaderDrawPrimitive
    , vshaderTexture
    , vshaderCustomUnis
    , vshaderPokeTest

    , psPoly 
    , psPolyz
    , psBez  
    , psText 
    , psArc  
    , psEll  

-- TODO make lenses for VBO object
--    , textureObject 
    ) where
import Picture.Data

import Graphics.Rendering.OpenGL
import Foreign
import Control.Lens
--import Graphics.GL.Types
{- | Vertex array object: contains the reference to the object,
and its buffer targets.  -}
data VAO = VAO
    { _vao :: VertexArrayObject
    , _vaoVBO :: VBO
    }
{- | Vertex buffer object: contains the reference to the object,
a pointer to a location with space that can be written to the buffer,
and a list of attribute pointer sizes.
Vertex attributes are interleaved within the vbo. -}
data VBO = VBO
    { _vbo      :: BufferObject
    , _vboPointer :: Ptr Float
    , _vboAttribSizes :: [Int]  -- ^ It is not clear to me if this is necessary to store or not
    , _vboStride :: Int
    }
data VShader = VShader
    { _vshaderProgram :: Program
    , _vshaderVAO :: VAO
    , _vshaderDrawPrimitive :: EPrimitiveMode
    , _vshaderTexture :: Maybe ShaderTexture
    , _vshaderCustomUnis :: [UniformLocation]
    , _vshaderPokeTest :: VertexType -> Bool
    }
data PicShads a = PicShads
    { _psPoly   :: a
    , _psPolyz  :: a
    , _psBez    :: a
    , _psText   :: a
    , _psArc    :: a
    , _psEll    :: a
    }
-- boilerplate folows
instance Functor PicShads where
    fmap f PicShads
        { _psPoly  = thePoly 
        , _psPolyz = thePolyz
        , _psBez   = theBez  
        , _psText  = theText 
        , _psArc   = theArc  
        , _psEll   = theEll  
        }
        = PicShads
        { _psPoly  = f thePoly 
        , _psPolyz = f thePolyz
        , _psBez   = f theBez  
        , _psText  = f theText 
        , _psArc   = f theArc  
        , _psEll   = f theEll  
        }
instance Applicative PicShads where
    pure a = PicShads a a a a a a
    (<*>) PicShads
        { _psPoly  = fPoly 
        , _psPolyz = fPolyz
        , _psBez   = fBez  
        , _psText  = fText 
        , _psArc   = fArc  
        , _psEll   = fEll  
        }
        PicShads
        { _psPoly  = thePoly 
        , _psPolyz = thePolyz
        , _psBez   = theBez  
        , _psText  = theText 
        , _psArc   = theArc  
        , _psEll   = theEll  
        }
        = PicShads
        { _psPoly  = fPoly  thePoly 
        , _psPolyz = fPolyz thePolyz
        , _psBez   = fBez   theBez  
        , _psText  = fText  theText 
        , _psArc   = fArc   theArc  
        , _psEll   = fEll   theEll  
        }
instance Foldable PicShads where
    foldr f x PicShads
        { _psPoly  = thePoly 
        , _psPolyz = thePolyz
        , _psBez   = theBez  
        , _psText  = theText 
        , _psArc   = theArc  
        , _psEll   = theEll  
        }
        = f thePoly . f thePolyz . f theBez . f theText . f theArc $ f theEll x


{- | Datatype containing the necessary information for a single shader.  -}
data FullShader = FullShader
    { _shaderProgram :: Program
    , _shaderVAO :: VAO
    , _shaderPokeStrategy :: RenderType -> [[Float]]-- -> F.FoldM IO RenderType Int
    , _shaderDrawPrimitive :: EPrimitiveMode
    , _shaderTexture :: Maybe ShaderTexture
    , _shaderCustomUnis :: [UniformLocation]
    }
{- | Datatype containing the reference to a texture object.  -}
newtype ShaderTexture = ShaderTexture
    { _textureObject :: TextureObject }

data EPrimitiveMode
    = EPoints
    | ELines
    | ELinesAdjacency
    | ELineLoop
    | ELineStrip
    | ETriangles
    | ETriangleStrip
    | ETriangleFan
    | EQuads
    | EQuadStrip
    | EPolygon
    | EPatches

makeLenses ''VAO
makeLenses ''FullShader
makeLenses ''VShader
makeLenses ''PicShads