#include "texture_util.h"

#include <cstdlib>
#include <cstring>

#include <godot_cpp/classes/os.hpp>
#include <godot_cpp/core/class_db.hpp>
#include <godot_cpp/variant/packed_byte_array.hpp>
#include <godot_cpp/variant/utility_functions.hpp>

using namespace godot;

namespace mtgodot {
namespace {

int g_state = -1; // -1 = uninit, 0 = off, 1 = on
bool g_warned = false;

void lazy_init() {
	if (g_state != -1) {
		return;
	}
	if (const char *e = std::getenv("MTGODOT_TEXCOMP")) {
		g_state = (e[0] == '1') ? 1 : 0;
		return;
	}
	// No explicit override: on for mobile targets, off for desktop (keeps the
	// Phase-1 parity path byte-identical).
	OS *os = OS::get_singleton();
	g_state = (os && os->has_feature("mobile")) ? 1 : 0;
}

} // namespace

bool texcomp_enabled() {
	lazy_init();
	return g_state == 1;
}

void texcomp_set_enabled(bool on) {
	g_state = on ? 1 : 0;
}

Ref<ImageTexture> make_color_texture(int w, int h, const uint8_t *rgba, size_t len,
		bool mipmaps, TexUse use) {
	if (w <= 0 || h <= 0 || rgba == nullptr || len < size_t(w) * size_t(h) * 4) {
		return Ref<ImageTexture>();
	}

	PackedByteArray bytes;
	bytes.resize(int64_t(w) * h * 4);
	std::memcpy(bytes.ptrw(), rgba, size_t(w) * size_t(h) * 4);

	Ref<Image> img = Image::create_from_data(w, h, false, Image::FORMAT_RGBA8, bytes);
	if (img.is_null()) {
		return Ref<ImageTexture>();
	}
	if (mipmaps) {
		img->generate_mipmaps();
	}

	if (use == TexUse::COLOR && texcomp_enabled()) {
		// ASTC 8x8: ~2 bpp vs 32 for RGBA8. GENERIC source hint (sRGB colour).
		Error err = img->compress(Image::COMPRESS_ASTC, Image::COMPRESS_SOURCE_GENERIC,
				Image::ASTC_FORMAT_8x8);
		if (err != OK && !g_warned) {
			g_warned = true;
			UtilityFunctions::push_warning(
					"mtgodot: runtime ASTC compression unavailable, using RGBA8");
		}
	}

	return ImageTexture::create_from_image(img);
}

} // namespace mtgodot