#include <psemek/gfx/pixmap.hpp>
#include <psemek/gfx/detail/stb_image.h>
#include <psemek/util/exception.hpp>

namespace psemek::gfx
{

	template <typename Pixel>
	basic_pixmap<Pixel> read_image(io::istream && is)
	{
		stbi_io_callbacks callbacks;

		callbacks.read = [](void * user, char * data, int size) -> int
		{
			return reinterpret_cast<io::istream *>(user)->read(data, size);
		};

		callbacks.skip = [](void * user, int count)
		{
			if (count < 0)
				throw util::exception("unget is not supported in stb_image skip callback");

			char buffer[1024];
			while (count > 0)
			{
				int read_count = std::min(1024, count);
				count -= reinterpret_cast<io::istream *>(user)->read(buffer, read_count);
			}
		};

		callbacks.eof = [](void * user)
		{
			return reinterpret_cast<io::istream *>(user)->finished() ? 1 : 0;
		};

		int width, height, channels;
		auto data = stbi_load_from_callbacks(&callbacks, &is, &width, &height, &channels, sizeof(Pixel));

		if (!data)
			throw util::exception(stbi_failure_reason());

		basic_pixmap<Pixel> result({width, height});
		std::copy(data, data + width * height * sizeof(Pixel), reinterpret_cast<stbi_uc *>(result.data()));

		stbi_image_free(data);

		return result;
	}

	template pixmap_monochrome read_image<std::uint8_t>(io::istream && is);
	template pixmap_rgb read_image<color_rgb>(io::istream && is);
	template pixmap_rgba read_image<color_rgba>(io::istream && is);

}