// Reference: https://en.wikipedia.org/wiki/GIF#Example_GIF_file
// Reference: https://giflib.sourceforge.net/whatsinagif/bits_and_bytes.html
bool hasGlobalColorTable(string filename) {
	jjSTREAM dat(filename);
	if (dat.getSize() < 13) {
		return false;
	}
	
	string magic;
	dat.get(magic, 6);
	if (magic != "GIF89a") {
		return false;
	}
	dat.discard(2); // discard logical screen width
	dat.discard(2); // discard logical screen height
	uint8 gctFlags;
	dat.pop(gctFlags);
	if (gctFlags & 0x80 != 0) { // "the highest true bit means that the GCT is present"
		return true;
	}
	return false;
}

void onLevelBegin() {
	jjConsole("Test GIFs by typing a filename in chat");
}

bool onLocalChat(string &in stringReceived, CHAT::Type) {
	bool res1 = jjPAL().load(stringReceived);
	bool res2 = hasGlobalColorTable(stringReceived);
	if (res1 != res2) {
		jjAlert("jjPAL().load(...) != hasGlobalColorTable(...)");
		jjAlert("    " + res1 + " != " + res2);
	}
	return true;
}