module MRI (
  flip_x,
  flip_y,
  mri_shape,
  mri_slice3d,
  read_word16s,
  round_array,
  swap_bytes,
  write_values_slice_to_bitmap,
  write_word16s,
  z_slice
  )
where

import Data.Word
import Data.Bits
import Data.Array.Repa                  as R
import Data.Array.Repa.IO.Binary        as R
import Data.Array.Repa.IO.ColorRamp     as R
import Data.Array.Repa.IO.BMP           as R (writeComponentsToBMP)

import Values

mri_depth :: Int
mri_depth = 109

mri_width :: Int
mri_width = 256

mri_height :: Int
mri_height = 256

mri_shape :: DIM3
mri_shape = (Z :. mri_depth :. mri_height :. mri_width)

mri_lower_threshold :: Double
mri_lower_threshold = 1400

mri_upper_threshold :: Double
mri_upper_threshold = 2500

mri_slice3d :: DIM3
mri_slice3d = (Z :. 1 :. mri_height  :. mri_width)

type RawData sh = Array sh Word16
type RawData3D = RawData DIM3

type RGB = (Word8, Word8, Word8)
type ColorData sh = Array sh RGB


read_word16s :: FilePath -> IO RawData3D
read_word16s path = do
  arr <- R.readArrayFromStorableFile path mri_shape
  arr `deepSeqArray` return ()
  return arr


bracket :: Double -> Word16
bracket x
        | x < mri_lower_threshold      = 0
        | x > mri_upper_threshold      = 255
        | otherwise                    = truncate (r * 255)
            where
              numerator = x - mri_lower_threshold
              denominator = mri_upper_threshold - mri_lower_threshold
              r = numerator/denominator


flip16 :: Word16 -> Word16
flip16 xx =
  shift xx 8 .|. (shift xx (-8) .&. 0x00ff)


swap_bytes :: (Shape sh) => (RawData sh) -> (RawData sh)
swap_bytes arr =
    R.force $ R.map flip16 arr


bracket_array :: (Shape sh) => (Values sh) -> (RawData sh)
bracket_array arr =
  R.force $ R.map bracket arr


round_array :: (Shape sh) => (Values sh) -> (RawData sh)
round_array arr =
  R.force $ R.map round arr


flip_y :: RawData3D -> RawData3D
flip_y arr =
  R.force $ R.traverse arr id
              (\get (Z :. z :. y :. x) ->
                   get (Z :. z :. (mri_height - 1) - y :. x))

flip_x :: RawData3D -> RawData3D
flip_x arr =
  R.force $ R.traverse arr id
              (\get (Z :. z :. y :. x) ->
                   get (Z :. z :. y :. (mri_width - 1) - x))

write_word16s :: (Shape sh) => FilePath -> (RawData sh) -> IO ()
write_word16s = R.writeArrayToStorableFile


values_to_colors :: (Shape sh) => (Values sh) -> (ColorData sh)
values_to_colors arr =
  R.force $ R.map (truncate_rgb . ramp_it) arr
  where
    ramp_it :: Double -> (Double, Double, Double)
    ramp_it x =
      if x == 0 then
        (0, 0, 0)
      else
        rampColorHotToCold 0 255 x

    truncate_rgb :: (Double, Double, Double) -> (Word8, Word8, Word8)
    truncate_rgb (r, g, b) =
      (r', g', b')
      where
        r' = truncate (r * 255)
        g' = truncate (g * 255)
        b' = truncate (b * 255)



z_slice :: Elt a => Int -> Array DIM3 a -> Array DIM2 a
z_slice n arr =
  slice arr (Any :. n :. All :. All)



write_values_slice_to_bitmap :: Values2D -> FilePath -> IO ()
write_values_slice_to_bitmap v3d path =
  R.writeComponentsToBMP path routput goutput boutput
  where
    arr_bracketed = bracket_array v3d
    colors = values_to_colors $ R.map fromIntegral arr_bracketed
    routput = R.map (\(red, _,     _)    -> red)   colors
    goutput = R.map (\(_,   green, _)    -> green) colors
    boutput = R.map (\(_,   _,     blue) -> blue)  colors