{-# LANGUAGE OverloadedStrings #-}

module Init where

import SDL (($=))
import qualified SDL

import qualified Graphics.Rendering.OpenGL as GL
import qualified Graphics.GLUtil as GLU

import Data.List.Split (chunksOf)
import qualified Data.ByteString as BS

import Physics.Bullet.Raw

import Codec.Wavefront

import Linear as L

import SpatialMath

import Foreign

import Util
import Types

load :: IO StateData
load = do
  _ <- SDL.setMouseLocationMode SDL.RelativeLocation
  GL.depthFunc $= Just GL.Less

  (shipBO, sobj, stl) <- genVertBufObject "assets/ships/jaeger/jaeger.obj"

  (vectHandleBO, hobj, vhtl) <- genVertBufObject "assets/spheres/vertHandle.obj"

  texture <- GL.genObjectName
  GL.bindBuffer GL.ArrayBuffer $= Just texture
  maybe (return ()) (\a -> withArray a $ \ptr ->
    GL.bufferData GL.ArrayBuffer $=
      ( fromIntegral $ length a * 2 * sizeOf (0 :: Double)
      , ptr
      , GL.StaticDraw
      )) (loTexTri sobj)
  GL.vertexAttribPointer (GL.AttribLocation 1) $=
    ( GL.ToFloat
    , GL.VertexArrayDescriptor 2 GL.Float 0 (plusPtr nullPtr 0)
    )
  GL.vertexAttribArray (GL.AttribLocation 1) $= GL.Enabled

  GL.texture GL.Texture2D $= GL.Enabled
  GL.activeTexture $= GL.TextureUnit 0
  t <- loadTex "assets/ships/jaeger/jaeger.texture.tga"
  GL.textureBinding GL.Texture2D $= Just t

  let vertexShader = foldl BS.append BS.empty
        [ "attribute vec3 coord3d;"
        , "attribute vec2 texcoord;"
        , "uniform mat4 mvp;"
        , "varying vec2 f_texcoord;"
        , "void main(void) {"
        , "  gl_Position = mvp * vec4(coord3d, 1.0);"
        , "  f_texcoord = texcoord;"
        , "}"
        ]
      fragmentShaderShip = foldl BS.append BS.empty
        [ "varying vec2 f_texcoord;"
        , "uniform sampler2D texture;"
        , "void main(void) {"
        , "  vec2 flip = vec2(f_texcoord.x, 1.0 - f_texcoord.y);"
        , "  gl_FragColor = texture2D(texture, flip);"
        , "}"
        ]
      fragmentShaderHandle = foldl BS.append BS.empty
        [ "varying vec2 f_texcoord;"
        , "void main(void) {"
        , "  gl_FragColor = vec4(0,0,0,0.5);"
        , "}"
        ]

  handleProgram <- GLU.simpleShaderProgramBS vertexShader fragmentShaderHandle
  shipProgram   <- GLU.simpleShaderProgramBS vertexShader fragmentShaderShip

  phys <- initPhysics

  po <- initPhysicsObjects

  -- mapM_ (addRigidBody (pWorld phys)) (map bodyRigidBody (poBalls po))
  addRigidBody (pWorld phys) (bodyRigidBody $ poBall po)

  return StateData
    { ship = Ship shipBO stl
      (V3 0 0 0)
      (Quaternion 1 (V3 0 0 0))
      (Just t)
    , vertHandles = createHandles vectHandleBO vhtl (loPoints sobj)
    , proj = perspective (pi/2) (1600 / 900) 1 (-1)
    , camera = Camera
      { cameraFocus = V3 0 0 0
      , cameraRot = Euler 0 0 0
      , cameraDist = -10
      }
    , physics = phys
    , physicsObjects = po
    , shipProgram = shipProgram
    , handleProgram = handleProgram
    }

initPhysics :: IO Physics
initPhysics = do
  bp <- newDbvtBroadphase
  config <- newDefaultCollisionConfiguration
  disp <- newCollisionDispatcher config
  solver <- newSequentialImpulseConstraintSolver
  world <- newDiscreteDynamicsWorld disp bp solver config
  setGravity world (V3 0 0 0)
  return $ Physics bp config disp solver world

initPhysicsObjects :: IO PhysicsObjects
initPhysicsObjects = do
  -- ground <- newStaticPlaneShape (V3 0 1 0) 1
  ball <- newSphereShape 3

  -- groundMotionState <- newDefaultMotionState (Quaternion 1 (V3 0 0 0)) (V3 0 (-51) 0)
  -- groundBody <- newRigidBody 0 groundMotionState 0.9 0.5 ground (V3 0 0 0)

  -- balls <- mapM (\pos -> do
  ballMotionState <- newDefaultMotionState (Quaternion 1 (V3 0 0 0))
    (V3 0 0 0)
  localInertia <- calculateLocalInertia ball 1 (V3 0 0 0)
  ballBody <- newRigidBody 1 ballMotionState 0 0 ball localInertia
  setSleepingThresholds ballBody 0 0
  -- ) poss

  return PhysicsObjects
    -- { poGround = PhysBody ground groundMotionState groundBody
    { poBall  = PhysBody ball ballMotionState ballBody
    }

genVertBufObject :: FilePath -> IO (GL.VertexArrayObject, LoadedObject, Int)
genVertBufObject path = do
  eobj <- fromFile path
  let obj = case eobj of
        Right o -> o
        Left err -> error err
      lobj = loadObj obj

  shipBO <- GL.genObjectName
  GL.bindVertexArrayObject $= Just shipBO

  verts <- GL.genObjectName
  GL.bindBuffer GL.ArrayBuffer $= Just verts
  withArray (loTriangles lobj) $ \ptr ->
    GL.bufferData GL.ArrayBuffer $=
      ( fromIntegral $ length (loTriangles lobj) * 3 * sizeOf (0 :: Double)
      , ptr
      , GL.StaticDraw
      )
  GL.vertexAttribPointer (GL.AttribLocation 0) $=
    ( GL.ToFloat
    , GL.VertexArrayDescriptor 4 GL.Float 0 (plusPtr nullPtr 0)
    )
  GL.vertexAttribArray (GL.AttribLocation 0) $= GL.Enabled
  return (shipBO, lobj, length (loTriangles lobj))

createHandles :: GL.VertexArrayObject -> Int -> [Float] -> [Ship]
createHandles bo len ps =
  map (\p -> Ship bo len (toPos p) (Quaternion 1 (V3 0 0 0)) Nothing) tris
  where
    tris            = chunksOf 3 ps
    toPos [x, y, z] = V3 x y z
    toPos _         = error "not triangular"