ffi = require "ffi"
requireffi = require "requireffi.requireffi"
bff = require "ILL.IMG.buffer.buffer"

has_loaded, JPG = pcall requireffi, "ILL.IMG.turbojpeg.turbojpeg.turbojpeg"

ffi.cdef [[
	typedef void *tjhandle;
	typedef enum {
		TJPF_RGB = 0,
		TJPF_BGR = 1,
		TJPF_RGBX = 2,
		TJPF_BGRX = 3,
		TJPF_XBGR = 4,
		TJPF_XRGB = 5,
		TJPF_GRAY = 6,
		TJPF_RGBA = 7,
		TJPF_BGRA = 8,
		TJPF_ABGR = 9,
		TJPF_ARGB = 10,
		TJPF_CMYK = 11,
		TJPF_UNKNOWN = -1,
	} TJPF;
	typedef enum {
		TJSAMP_444 = 0,
		TJSAMP_422,
		TJSAMP_420,
		TJSAMP_GRAY,
		TJSAMP_440,
		TJSAMP_411
	} TJPF;
	int tjDestroy(tjhandle handle);
	tjhandle tjInitDecompress(void);
	int tjDecompressHeader3(tjhandle handle, const unsigned char *jpegBuf, unsigned long jpegSize, int *width, int *height, int *jpegSubsamp, int *jpegColorspace);
	int tjDecompress2(tjhandle handle, const unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf, int width, int pitch, int height, int pixelFormat, int flags);
]]

-- https://github.com/koreader/koreader-base/tree/master/ffi
class LIBJPG

	new: (@filename = filename) =>

	read: =>
		file = io.open @filename, "rb"
		assert file, "Couldn't open JPEG file"

		@rawData = file\read "*a"
		file\close!

	setArguments: =>
		@width       = ffi.new "int[1]"
		@height      = ffi.new "int[1]"
		@jpegSubsamp = ffi.new "int[1]"
		@colorSpace  = ffi.new "int[1]"

	decode: (gray) =>
		@read!

		handle = JPG.tjInitDecompress!
		assert handle, "no TurboJPEG API decompressor handle"

		@setArguments!

		JPG.tjDecompressHeader3 handle, ffi.cast("const unsigned char*", @rawData), #@rawData, @width, @height, @jpegSubsamp, @colorSpace
		assert @width[0] > 0 and @height[0] > 0, "Image dimensions"

		buffer = gray and bff.BUFFER(@width[0], @height[0], 1) or bff.BUFFER @width[0], @height[0], 4
		format = gray and JPG.TJPF_GRAY or JPG.TJPF_RGB

		err = JPG.tjDecompress2(handle, ffi.cast("unsigned char*", @rawData), #@rawData, ffi.cast("unsigned char*", buffer.data), @width[0], buffer.pitch, @height[0], format, 0) == -1
		assert not err, "Decoding error"

		JPG.tjDestroy handle

		@rawData = buffer
		@width = buffer\get_width!
		@height = buffer\get_height!
		@bit_depth = buffer\get_bpp!

		@getPixel = (x, y) => buffer\get_pixel x, y

		@getData = =>
			@data = ffi.new "color_RGBA[?]", @width * @height

			for y = 0, @height - 1
				for x = 0, @width - 1
					i = y * @width + x
					with @getPixel(x, y)\get_color_32!
						@data[i].r = .r
						@data[i].g = .g
						@data[i].b = .b
						@data[i].a = .alpha

			return @data

		return @

{:LIBJPG}