module Render (
    createLightMap,
    renderLayer,
    pingPongBetween,
    bindFBO,
) where

import Control.Lens
import Control.Monad.Primitive
import Data.Preload.Render
import qualified Data.Vector.Fusion.Stream.Monadic as VFSM
import qualified Data.Vector.Mutable as MV
import qualified Data.Vector.Unboxed.Mutable as UMV
import Dodge.Data.Config
import Foreign hiding (rotate)
import Geometry.Data
import Graphics.GL.Core45
import Picture.Data
import Shader
import Shader.Data

{- | Determine where light is shining in the world.
 think of the produced texture as showing what RGB values should be "taken
 away" from the shape colors.
-}
createLightMap ::
    Config ->
    -- | number of walls
    GLsizei ->
    -- | number of silhoutte lines to draw
    Int ->
    -- | number of "caps" to attempt to draw
    Int ->
    -- | the texture object giving positions
    TO ->
    -- | the texture object giving normals
    TO ->
    [(Point3, Float, Point3)] -> -- Lights
    RenderData ->
    IO ()
createLightMap cfig = case shadrendertype of
    NoShadows -> const . const . const renderLightingNoShadows
    NoLighting -> const . const . const . const . const . const renderFlatLighting
    _ -> renderShadows shadrendertype
  where
    shadrendertype = cfig ^. gr_shadow_rendering

renderLightingNoShadows ::
    TO ->
    TO ->
    [(V3 GLfloat, GLfloat, V3 GLfloat)] ->
    RenderData ->
    IO ()
renderLightingNoShadows positiontexture normaltexture lightPoints pdata = do
    glBindFramebuffer GL_FRAMEBUFFER (_unFBO (fst (_fboLighting pdata)))
    let ltextShad = _lightingTextureShader pdata
    -- we assume that the renderbuffer's depth has been correctly set elsewhere
    -- we will not be changing that here
    glDepthMask GL_FALSE
    -- clearColor is specified differently in preloadRender
    -- the colors are inverted
    withArray [1, 1, 1, 1] $ \ptr ->
        glClearNamedFramebufferfv
            (pdata ^. fboLighting . _1 . unFBO)
            GL_COLOR
            0
            ptr
    glBlendFunc GL_ZERO GL_ONE_MINUS_SRC_COLOR
    glEnable GL_STENCIL_TEST
    glStencilOpSeparate GL_FRONT GL_KEEP GL_KEEP GL_INCR_WRAP
    glStencilOpSeparate GL_BACK GL_KEEP GL_KEEP GL_DECR_WRAP
    flip VFSM.mapM_ (VFSM.fromList lightPoints) $ \(V3 x y z, rad, V3 r g b) -> do
        glDepthFunc GL_LESS
        -- setup stencil
        glColorMask GL_FALSE GL_FALSE GL_FALSE GL_FALSE
        with 0 $ \ptr ->
            glClearNamedFramebufferiv
                (pdata ^. fboLighting . _1 . unFBO)
                GL_STENCIL
                0
                ptr
        glDisable GL_CULL_FACE
        glStencilFunc GL_ALWAYS 0 255
        --draw lightmap itself
        glDepthFunc GL_ALWAYS
        -- bind world position texture
        glBindTextureUnit 0 (positiontexture ^. unTO)
        glBindTextureUnit 1 (normaltexture ^. unTO)
        glColorMask GL_TRUE GL_TRUE GL_TRUE GL_TRUE
        glStencilFunc GL_EQUAL 0 255
        glUseProgram (ltextShad ^. shaderUINT)
        glUniform3f 0 x y z
        glUniform4f 1 r g b rad
        glBindVertexArray $ ltextShad ^. shaderVAO . vaoName
        glDrawArrays
            (_unPrimitiveMode (_shaderPrimitive ltextShad))
            0
            (fromIntegral (4 :: Int))
    --cleanup: may not be necessary, depending on what comes after...
    glDisable GL_CULL_FACE
    glStencilFunc GL_NOTEQUAL 128 255
    glStencilOp GL_KEEP GL_KEEP GL_KEEP
    glColorMask GL_TRUE GL_TRUE GL_TRUE GL_TRUE
--    glDisable GL_STENCIL_TEST


renderFlatLighting :: RenderData -> IO ()
renderFlatLighting pdata = do
    glBindFramebuffer GL_FRAMEBUFFER (_unFBO (fst (_fboLighting pdata)))
    withArray [0, 0, 0, 1] $ \ptr ->
        glClearNamedFramebufferfv
            (pdata ^. fboLighting . _1 . unFBO)
            GL_COLOR
            0
            ptr
    glDisable GL_CULL_FACE
    glDepthFunc GL_ALWAYS
    glDepthMask GL_FALSE
    glStencilFunc GL_NOTEQUAL 128 255
    glStencilOp GL_KEEP GL_KEEP GL_KEEP

renderShadows ::
    ShadowRendering ->
    GLsizei ->
    Int ->
    Int ->
    TO ->
    TO ->
    [(Point3, Float, Point3)] ->
    RenderData ->
    IO ()
renderShadows shadrendertype nWalls nSils nCaps positiontexture normaltexture lightPoints pdata = do
    glBindFramebuffer GL_FRAMEBUFFER $ pdata ^. fboLighting . _1 . unFBO
    let llinesShad = _lightingLineShadowShader pdata
        lcapShad = _lightingCapShader pdata
        lwallShad = _lightingWallShadShader pdata
        ltextShad = _lightingTextureShader pdata
    -- we assume that the renderbuffer's depth has been correctly set elsewhere
    -- we will not be changing that here
    glDepthMask GL_FALSE
    -- clearColor is specified differently in preloadRender
    -- the colors are inverted
    withArray [1, 1, 1, 1] $ \ptr ->
        glClearNamedFramebufferfv
            (pdata ^. fboLighting . _1 . unFBO)
            GL_COLOR
            0
            ptr
    -- setup stencil and blending
    glBlendFunc GL_ZERO GL_ONE_MINUS_SRC_COLOR
    glStencilOpSeparate GL_FRONT GL_KEEP GL_KEEP GL_INCR_WRAP
    glStencilOpSeparate GL_BACK GL_KEEP GL_KEEP GL_DECR_WRAP
    -- bind world position texture-- these will be used by the lighting shader
    glBindTextureUnit 0 (positiontexture ^. unTO)
    glBindTextureUnit 1 (normaltexture ^. unTO)
    -- for each of the lights:
    -- 1. stencil out the shadows from this light's point of view
    -- 2. calculate lighting based on each fragment's position and normal
    flip VFSM.mapM_ (VFSM.fromList lightPoints) $ \(V3 x y z, rad, V3 r g b) -> do
        -- note that the stencil shadows rely on the depth buffer
        glDepthFunc GL_LESS
        glColorMask GL_FALSE GL_FALSE GL_FALSE GL_FALSE
        -- setup stencil
        with 0 $
            glClearNamedFramebufferiv
                (pdata ^. fboLighting . _1 . unFBO)
                GL_STENCIL
                0
        glDisable GL_CULL_FACE
        -- the first bit has been used to stencil out "ceilings" under which we never draw
        glStencilFunc GL_NOTEQUAL 128 255 
        --draw wall shadows
        glUseProgram (_shaderUINT lwallShad)
        glUniform3f 0 x y z
        glUniform1f 1 rad
        --glBindVertexArray $ lwallShad ^. shaderVAO . vaoName -- Just (_vao $ _shadVAO lwallShad)
        glBindVertexArray $ pdata ^. dummyVAO . vaoName -- Just (_vao $ _shadVAO lwallShad)
        glDrawArrays
            (_unPrimitiveMode $ _shaderPrimitive lwallShad)
            0
            (nWalls * 18)
        case shadrendertype of
            GeoObjShads -> do
                --draw silhouette shadows
                glEnable GL_DEPTH_CLAMP
                glUseProgram (_shaderUINT llinesShad)
                glUniform3f 0 x y z
                glUniform1f 1 rad
                --glBindVertexArray (_vaoName $ _shaderVAO llinesShad)
                glBindVertexArray (pdata ^. dummyVAO . vaoName)
                glDrawArrays
                    GL_TRIANGLES
                    0
                    ((fromIntegral nSils * 6) `div` 4)
                --glDrawElements
                --    (_unPrimitiveMode $ _shaderPrimitive llinesShad)
                --    (fromIntegral nSils)
                --    GL_UNSIGNED_INT
                --    nullPtr
                --draw caps on the near plane as required
                glEnable GL_CULL_FACE
                glCullFace GL_FRONT
                glUseProgram (_shaderUINT lcapShad)
                glUniform3f 0 x y z
                glUniform4f 1 r g b rad
                --glBindVertexArray $ lcapShad ^. shaderVAO . vaoName --Just (_vao $ _shadVAO lcapShad)
                glBindVertexArray $ pdata ^. dummyVAO . vaoName
                glFrontFace(GL_CW)
                glDrawArrays
                    GL_TRIANGLES
                    0
                    --3
                    (fromIntegral nCaps)
                glFrontFace(GL_CCW)
                --glDrawElements
                --    (_unPrimitiveMode $ _shaderPrimitive lcapShad)
                --    (fromIntegral nCaps)
                --    GL_UNSIGNED_SHORT
                --    nullPtr
                glDisable GL_DEPTH_CLAMP
            _ -> return ()
        --draw lightmap itself
        glDepthFunc GL_ALWAYS
        glDisable GL_CULL_FACE
        glColorMask GL_TRUE GL_TRUE GL_TRUE GL_FALSE
        glStencilFunc GL_EQUAL 0 255
        glUseProgram (ltextShad ^. shaderUINT)
        glUniform3f 0 x y z
        glUniform4f 1 r g b rad
        glBindVertexArray $ ltextShad ^. shaderVAO . vaoName
        glDrawArrays
            (_unPrimitiveMode (_shaderPrimitive ltextShad))
            0
            (fromIntegral (4 :: Int))
    --cleanup: may not be necessary, depending on what comes after...
--    glDisable GL_STENCIL_TEST
    glStencilFunc GL_NOTEQUAL 128 255
    glStencilOp GL_KEEP GL_KEEP GL_KEEP
    glColorMask GL_TRUE GL_TRUE GL_TRUE GL_TRUE

-- assumes that vertices have already been sent to the shader
pingPongBetween ::
    (FBO, TO) ->
    (FBO, TO) ->
    Shader ->
    IO ()
pingPongBetween (fb1, to1) (fb2, to2) fs = do
    glBindFramebuffer GL_FRAMEBUFFER (_unFBO fb2)
    glBindTextureUnit 0 (_unTO to1)
    drawShader fs 4
    glBindFramebuffer GL_FRAMEBUFFER (_unFBO fb1)
    glBindTextureUnit 0 (_unTO to2)
    drawShader fs 4

renderLayer ::
    Layer ->
    MV.MVector (PrimState IO) (Shader, VBO) ->
    UMV.MVector (PrimState IO) Int ->
    IO ()
renderLayer layer shads counts = do
    let layerCounts = UMV.slice (ln * numLayers) numShads counts
    MV.imapM_ (drawShaderLay ln layerCounts) shads
  where
    ln = fromEnum layer

bindFBO :: FBO -> IO ()
bindFBO fb =
    --bindFramebuffer Framebuffer $= fb
    glBindFramebuffer GL_FRAMEBUFFER (_unFBO fb)