.{Color, Surface, new_surface, put_surface} := @use("../lib.hb");
.{log, memory} := @use("../../../stn/src/lib.hb")

BitmapFileHeader := packed struct {
	magic: u16,
	size: u32,
	reserved_1: u16,
	reserved_2: u16,
	offset: u32,
}

BitmapInfoHeader := packed struct {
	size: u32,
	width: i32,
	height: i32,
	planes: u16,
	bits: u16,
	compression: u32,
	image_size: u32,
	x_resolution: i32,
	y_resolution: i32,
	n_colours: u32,
	important_colours: u32,
}

BitmapColorHeader := packed struct {
	red_mask: u32,
	green_mask: u32,
	blue_mask: u32,
	alpha_mask: u32,
	color_space_type: u32,
	unused: u32,
}

from := fn(bmp: ^u8): ?Surface {
	file_header := @as(^BitmapFileHeader, @bitcast(bmp))
	info_header := @as(^BitmapInfoHeader, @bitcast(bmp + @sizeof(BitmapFileHeader)))
	bmp += file_header.offset

	if file_header.magic != 0x4D42 | info_header.width == 0 | info_header.height == 0 {
		log.error("Invalid BMP image.\0")
		return null
	}

	width := @as(uint, info_header.width)
	height := @as(uint, info_header.height)
	lhs := Surface.(@bitcast(bmp), width, height)
	rhs := new_surface(width, height)
	put_surface(rhs, lhs, .(0, 0), true)

	return rhs
}