module Graphics.LambdaCube.Compositor where

import Data.Maybe
import Data.Word
import Data.IntMap (IntMap)

import Graphics.LambdaCube.Types
import Graphics.LambdaCube.Common
import Graphics.LambdaCube.PixelFormat
import Graphics.LambdaCube.RenderSystem
import Graphics.LambdaCube.Material
import Graphics.LambdaCube.GpuProgram
import Graphics.LambdaCube.Texture

-- | Enumeration that enumerates the various composition pass types.
data PassType
    = PT_CLEAR          -- ^ Clear target to one colour
    | PT_STENCIL        -- ^ Set stencil operation
    | PT_RENDERSCENE    -- ^ Render the scene or part of it
    | PT_RENDERQUAD     -- ^ Render a full screen quad

-- | Input mode of a TargetPass
data InputMode
    = IM_NONE       -- ^ No input
    | IM_PREVIOUS   -- ^ Output of previous Composition in chain
    deriving Eq
    
{-| Class representing a Compositor object. Compositors provide the means 
    to flexibly "composite" the final rendering result from multiple scene renders
    and intermediate operations like rendering fullscreen quads. This makes 
    it possible to apply postfilter effects, HDRI postprocessing, and shadow 
    effects to a Viewport. -}
data (Texture t, LinkedGpuProgram lp) => Compositor t lp
    = Compositor
    { cmpName                   :: String
    , cmpTechniques             :: [CompositionTechnique t lp]
    , cmpSupportedTechniques    :: Maybe [CompositionTechnique t lp]
	}

-- | Local texture definition
data Texture t => TextureDefinition t
    = TextureDefinition
    { tdName            :: String
    , tdWidth           :: Maybe Int        -- Nothing means adapt to target width
    , tdHeight          :: Maybe Int        -- Nothing means adapt to target height
    , tdWidthFactor     :: FloatType        -- multiple of target width to use (if width = Nothing)
    , tdHeightFactor    :: FloatType        -- multiple of target height to use (if height = Nothing)
    , tdFormatList      :: [PixelFormat]    -- more than one means MRT
    , tdFsaa            :: Bool             -- FSAA enabled; true = determine from main target (if render_scene), false = disable
    , tdHwGammaWrite    :: Bool             -- Do sRGB gamma correction on write (only 8-bit per channel formats) 
    , tdShared          :: Bool             -- whether to use shared textures for this one
    , tdTexture         :: Maybe t
    }

data InputTex
    = InputTex
    { itName        :: String   -- ^ Name (local) of the input texture
    , itMrtIndex    :: Int      -- ^ MRT surface index if applicable
    }

data (Texture t, LinkedGpuProgram lp) => CompositionTechnique t lp
    = CompositionTechnique
    { ctTextureDefinitions  :: [TextureDefinition t]        -- ^ Local texture definitions
    , ctTargetPasses        :: [CompositionTargetPass t lp] -- ^ Intermediate target passes
    , ctOutputTarget        :: CompositionTargetPass t lp   -- ^ Output target pass (can be only one)
    , ctSchemeName          :: String                       -- ^ Optional scheme name
    }

-- | Object representing one render to a RenderTarget or Viewport in the Ogre Composition framework.
data (Texture t, LinkedGpuProgram lp) => CompositionTargetPass t lp
    = CompositionTargetPass
    { ctpInputMode      :: InputMode                    -- ^ Input name
    , ctpOutputName     :: String                       -- ^ (local) output texture
    , ctpOutput         :: Maybe (TextureDefinition t)
    , ctpPasses         :: [CompositionPass t lp]       -- ^ Passes
    , ctpOnlyInitial    :: Bool                         -- ^ This target pass is only executed initially after the effect has been enabled.
    , ctpVisibilityMask :: Word32                       -- ^ Visibility mask for this render
    , ctpLodBias        :: FloatType                    -- ^ LOD bias of this render
    , ctpMaterialScheme :: String                       -- ^ Material scheme name
    , ctpShadowsEnabled :: Bool                         -- ^ Shadows option
    }

{-| Object representing one pass or operation in a composition sequence. This provides a 
    method to conveniently interleave RenderSystem commands between Render Queues. -}
data (Texture t, LinkedGpuProgram lp) => CompositionPass t lp
    = CompositionPass
    { cpType                        :: PassType         -- ^ Type of composition pass
    , cpIdentifier                  :: Word32           -- ^ Identifier for this pass
    , cpMaterialName                :: String           -- ^ Material used for rendering
    , cpMaterial                    :: Maybe (Material t lp)
    , cpFirstRenderQueue            :: Int              -- ^ [first,last] render queue to render this pass (in case of PT_RENDERSCENE)
    , cpLastRenderQueue             :: Int
    , cpClearBuffers                :: (Bool,Bool,Bool) -- ^ Clear buffers (in case of PT_CLEAR), hint: [colour] [depth] [stencil]
    , cpClearColour                 :: ColourValue      -- ^ Clear colour (in case of PT_CLEAR)
    , cpClearDepth                  :: FloatType        -- ^ Clear depth (in case of PT_CLEAR)
    , cpClearStencil                :: Word32           -- ^ Clear stencil value (in case of PT_CLEAR)
    , cpInputs                      :: IntMap InputTex  -- ^ Inputs (for material used for rendering the quad)
    , cpStencilCheck                :: Bool             -- ^ Stencil operation parameters
    , cpStencilFunc                 :: CompareFunction
    , cpStencilRefValue             :: Word32
    , cpStencilMask                 :: Word32
    , cpStencilFailOp               :: StencilOperation
    , cpStencilDepthFailOp          :: StencilOperation
    , cpStencilPassOp               :: StencilOperation
    , cpStencilTwoSidedOperation    :: Bool
    , cpQuadCornerModified          :: Bool             -- ^ true if quad should not cover whole screen
    , cpQuadLeft                    :: FloatType        -- ^ quad positions in normalised coordinates [-1;1]x[-1;1] (in case of PT_RENDERQUAD)
    , cpQuadTop                     :: FloatType
    , cpQuadRight                   :: FloatType
    , cpQuadBottom                  :: FloatType
    , cpQuadFarCorners              :: Bool
    , cpQuadFarCornersViewSpace     :: Bool
    }
{-        
data CompositionPass
    = CompositionRenderQuadPass
    , rqInput    :: (Int, String, Int)
    }
-}
--compileCompositor