module Graphics.GD (
                    -- * Types
                    Image, Size, Point, Color,
                    -- * Creating and copying images
                    newImage, copyImage,
                    -- * Loading images
                    -- ** JPEG
                    loadJpegFile, loadJpegData, 
                    -- ** PNG
                    loadPngFile, loadPngData, 
                    -- ** GIF
                    loadGifFile, loadGifData, 
                    -- * Saving images
                    -- ** JPEG
                    saveJpegFile,
                    -- ** PNG
                    savePngFile,
                    -- ** GIF
                    saveGifFile,
                    -- * Getting image information
                    imageSize,
                    -- * Manipulating images
                    resizeImage, rotateImage,
                    -- * Drawing
                    fillImage,
                    drawFilledRectangle,
                    drawFilledEllipse, 
                    antiAliased,
                    -- * Colors
                    rgb, rgba
                   ) where

import Control.Exception (bracket)
import Control.Monad (liftM)
import Foreign
import Foreign.C
import Foreign.ForeignPtr
import Foreign.Marshal.Error

data CFILE = CFILE

foreign import ccall "stdio.h fopen" c_fopen
    :: CString -> CString -> IO (Ptr CFILE)
foreign import ccall "stdio.h fclose" c_fclose
    :: Ptr CFILE -> IO CInt

fopen :: FilePath -> String -> IO (Ptr CFILE)
fopen file mode = 
    throwErrnoIfNull file $ withCString file $ 
                         \f -> withCString mode $ \m -> c_fopen f m

fclose :: Ptr CFILE -> IO ()
fclose p = throwErrnoIf_ (== #{const EOF}) "fclose" $ c_fclose p

withCFILE :: FilePath -> String -> (Ptr CFILE -> IO a) -> IO a
withCFILE file mode = bracket (fopen file mode) fclose

#include <gd.h>
#include "gd-extras.h"

data GDImage = GDImage

-- JPEG format

foreign import ccall "gd.h gdImageCreateFromJpeg" gdImageCreateFromJpeg
    :: Ptr CFILE -> IO (Ptr GDImage)

foreign import ccall "gd.h gdImageCreateFromJpegPtr" gdImageCreateFromJpegPtr
    :: CInt -> Ptr a -> IO (Ptr GDImage)

foreign import ccall "gd.h gdImageJpeg" gdImageJpeg
    :: Ptr GDImage -> Ptr CFILE -> CInt -> IO ()


-- PNG format

foreign import ccall "gd.h gdImageCreateFromPng" gdImageCreateFromPng
    :: Ptr CFILE -> IO (Ptr GDImage)

foreign import ccall "gd.h gdImageCreateFromPngPtr" gdImageCreateFromPngPtr
    :: CInt -> Ptr a -> IO (Ptr GDImage)

foreign import ccall "gd.h gdImagePng" gdImagePng
    :: Ptr GDImage -> Ptr CFILE -> IO ()


-- GIF format

foreign import ccall "gd.h gdImageCreateFromGif" gdImageCreateFromGif
    :: Ptr CFILE -> IO (Ptr GDImage)

foreign import ccall "gd.h gdImageCreateFromGifPtr" gdImageCreateFromGifPtr
    :: CInt -> Ptr a -> IO (Ptr GDImage)

foreign import ccall "gd.h gdImageGif" gdImageGif
    :: Ptr GDImage -> Ptr CFILE -> IO ()


-- Creating and destroying images

foreign import ccall "gd.h gdImageCreateTrueColor" gdImageCreateTrueColor 
    :: CInt -> CInt -> IO (Ptr GDImage)

foreign import ccall "gd.h &gdImageDestroy" ptr_gdImageDestroy 
    :: FunPtr (Ptr GDImage -> IO ())


-- Copying image parts

foreign import ccall "gd.h gdImageCopy" gdImageCopy
    :: Ptr GDImage -> Ptr GDImage 
    -> CInt -> CInt -> CInt -> CInt
    -> CInt -> CInt -> IO ()

foreign import ccall "gd.h gdImageCopyResampled" gdImageCopyResampled
    :: Ptr GDImage -> Ptr GDImage 
    -> CInt -> CInt -> CInt -> CInt
    -> CInt -> CInt -> CInt -> CInt -> IO ()

{-
foreign import ccall "gd.h gdImageCopyRotated" gdImageCopyRotated
    :: Ptr GDImage -> Ptr GDImage 
    -> CDouble -> CDouble -> CInt -> CInt
    -> CInt -> CInt -> CInt -> IO ()
-}

foreign import ccall "gd-extras.h gdImageCopyRotated90" gdImageCopyRotated90
    :: Ptr GDImage -> Ptr GDImage 
    -> CInt -> CInt -> CInt -> CInt
    -> CInt -> CInt -> CInt -> IO ()


-- Drawing functions

foreign import ccall "gd.h gdImageFilledRectangle" gdImageFilledRectangle
    :: Ptr GDImage -> CInt -> CInt -> CInt -> CInt -> CInt -> IO ()

foreign import ccall "gd.h gdImageFilledEllipse" gdImageFilledEllipse
    :: Ptr GDImage -> CInt -> CInt -> CInt -> CInt -> CInt -> IO ()

foreign import ccall "gd.h gdImageSetAntiAliased" gdImageSetAntiAliased
    :: Ptr GDImage -> CInt -> IO ()




type Image = ForeignPtr GDImage

type Size = (Int,Int)

type Point = (Int,Int)

type Color = CInt


-- | Call gd_free_image when the image is garbage collected.
mkImage :: Ptr GDImage -> IO Image
mkImage p = newForeignPtr ptr_gdImageDestroy p


withImage :: Image -> (Ptr GDImage -> IO a) -> IO a
withImage = withForeignPtr

-- | Create a new empty image.
newImage :: Size -> IO Image
newImage (w,h) = newImage_ (int w) (int h)

newImage_  :: CInt -> CInt -> IO Image
newImage_ w h = do p <- throwIfNull "gdImageCreateTrueColor" $
                        gdImageCreateTrueColor w h
                   mkImage p

-- | Create a new empty image and apply a function to it.
onNewImage :: CInt -> CInt -> (Ptr GDImage -> IO a) -> IO Image
onNewImage w h f = newImage_ w h >>= \i -> withImage i f >> return i

-- | Make a copy of an image.
copyImage :: Image -> IO Image
copyImage i = withImage i f
  where f p = do (w,h) <- imageSize_ p
                 onNewImage w h (\p' -> gdImageCopy p' p 0 0 0 0 w h)



--
-- * Loading images
--

-- | Load a JPEG image from a file.
loadJpegFile :: FilePath -> IO Image
loadJpegFile = loadImageFile gdImageCreateFromJpeg

-- | Load a JPEG image from a buffer.
loadJpegData :: Int -- ^ Buffer size.
             -> Ptr a -- ^ Buffer with image data.
             -> IO Image
loadJpegData = loadImageData gdImageCreateFromJpegPtr


-- | Load a PNG image from a file.
loadPngFile :: FilePath -> IO Image
loadPngFile = loadImageFile gdImageCreateFromPng

-- | Load a PNG image from a buffer.
loadPngData :: Int -- ^ Buffer size.
            -> Ptr a -- ^ Buffer with image data.
            -> IO Image
loadPngData = loadImageData gdImageCreateFromPngPtr


-- | Load a GIF image from a file.
loadGifFile :: FilePath -> IO Image
loadGifFile = loadImageFile gdImageCreateFromGif

-- | Load a GIF image from a buffer.
loadGifData :: Int -- ^ Buffer size.
            -> Ptr a -- ^ Buffer with image data.
            -> IO Image
loadGifData = loadImageData gdImageCreateFromGifPtr


loadImageFile :: (Ptr CFILE -> IO (Ptr GDImage)) -> FilePath -> IO Image
loadImageFile f file = 
    do p <- throwIfNull ("Loading image from " ++ file) $ withCFILE file "rb" f
       mkImage p

loadImageData :: (CInt -> Ptr a -> IO (Ptr GDImage)) -> Int -> Ptr a -> IO Image
loadImageData f sz buf =
    do p <- throwIfNull ("Loading image") $ f (fromIntegral sz) buf
       mkImage p

--
-- * Saving images
--

-- | Save an image as a JPEG file.
saveJpegFile :: Int -- ^ quality: 0-95, or negative for default quality.
             -> FilePath -> Image -> IO ()
saveJpegFile q = saveImageFile (\p h -> gdImageJpeg p h (fromIntegral q))

-- | Save an image as a PNG file.
savePngFile :: FilePath -> Image -> IO ()
savePngFile = saveImageFile gdImagePng

-- | Save an image as a GIF file.
saveGifFile :: FilePath -> Image -> IO ()
saveGifFile = saveImageFile gdImageGif

saveImageFile :: (Ptr GDImage -> Ptr CFILE -> IO ()) -> FilePath -> Image -> IO ()
saveImageFile f file i = withImage i (\p -> withCFILE file "wb" (f p))

--
-- * Getting information about images.
--

-- | Get the size of an image.
imageSize :: Image -> IO (Int,Int) -- ^ (width, height)
imageSize i = liftM f $ withImage i imageSize_
    where f = (\ (w,h) -> (fromIntegral w, fromIntegral h))

imageSize_ :: Ptr GDImage -> IO (CInt,CInt)
imageSize_ p = do w <- #{peek gdImage, sx} p
                  h <- #{peek gdImage, sy} p
                  return (w, h)

--
-- * Transforming images.
--

-- | Resize an image to a give size.
resizeImage :: Int -- ^ width in pixels of output image
            -> Int -- ^ height in pixels of output image
            -> Image 
            -> IO Image
resizeImage w h i = withImage i f
    where 
      f p = do let (outW,outH) = (fromIntegral w, fromIntegral h)
               (inW, inH) <- imageSize_ p
               onNewImage outW outH $ \p' -> 
                   gdImageCopyResampled p' p 0 0 0 0 outW outH inW inH

-- | Rotate an image by a multiple of 90 degrees counter-clockwise.
rotateImage :: Int -- ^ 1 for 90 degrees counter-clockwise, 
                   -- 2 for 180 degrees, etc.
            -> Image 
            -> IO Image
rotateImage r i = withImage i f
    where f p = do (inW,inH) <- imageSize_ p
                   let q = fromIntegral (r `mod` 4)
                       (outW,outH) | r `mod` 2 == 0 = (inW,inH) 
                                   | otherwise      = (inH,inW)
                       srcX = if q == 1 || q == 2 then inW-1 else 0;
                       srcY = if q == 2 || q == 3 then inH-1 else 0;
                   onNewImage outW outH (\p' ->
                       gdImageCopyRotated90 p' p 0 0 srcX srcY inW inH q)

--
-- * Drawing
--

-- | Fill the entire image with the given color.
fillImage :: Color -> Image -> IO ()
fillImage c i = do sz <- imageSize i
                   drawFilledRectangle (0,0) sz c i

drawFilledRectangle :: Point -- ^ Upper left corner
                    -> Point -- ^ Lower right corner
                    -> Color -> Image -> IO ()
drawFilledRectangle (x1,y1) (x2,y2) c i =
    withImage i $ \p -> 
        gdImageFilledRectangle p (int x1) (int y1) (int x2) (int y2) c

drawFilledEllipse :: Point -- ^ Center
                  -> Size  -- ^ Width and height
                  -> Color -> Image -> IO ()
drawFilledEllipse (cx,cy) (w,h) c i =
    withImage i $ \p -> 
        gdImageFilledEllipse p (int cx) (int cy) (int w) (int h) c

-- | Use anti-aliasing when performing the given drawing function.
--   This can cause a segault with some gd versions.
antiAliased :: (Color -> Image -> IO a) -> Color -> Image -> IO a
antiAliased f c i = 
    do withImage i (\p -> gdImageSetAntiAliased p c)
       f (#{const gdAntiAliased}) i

--
-- * Colors
--

rgb :: Int -- ^ Red (0-255)
         -> Int -- ^ Green (0-255)
         -> Int -- ^ Blue (0-255)
         -> Color
rgb r g b = rgba r g b 0

rgba :: Int -- ^ Red (0-255)
          -> Int -- ^ Green (0-255)
          -> Int -- ^ Blue (0-255)
          -> Int -- ^ Alpha (0-127), 0 is opaque, 127 is transparent
          -> Color
rgba r g b a = 
    (int a `shiftL` 24) .|.
    (int r `shiftL` 16) .|.
    (int g `shiftL` 8)  .|.
    int b


--
-- * Utilities
--

int :: (Integral a, Num b) => a -> b
int = fromIntegral