-- This makes sure the zombie is in our new state
function ZombieUpdate(zombie)

	-- check if the zombie's current state is lua state
	if zombie:getCurrentState() ~= LuaState:instance() then
		-- if not, then set it to that state. Zombie will therefore not be processing wander / pathfind code any more and
		-- we can override the behaviour.
		zombie:changeState(LuaState:instance());
		-- lock the zombie's state machine so the game code can't change it.
		zombie:setLockStates(true);	
	end
	
	local data = zombie:getModData();
	-- If we have no lua state selected then set the default to spin...
	if data.state == nil then
		data.state = "WalkInCircles";
		data.spinTimer = ZombRand(30); -- set timer randomly so zombies are all offset.
	end
end

-- Function to make zombie turn anticlockwise one compass direction per second, and walk forward.
function DoWalkInCircles(zombie, data) 
	
	data.spinTimer = data.spinTimer - 1;
	
	-- if timer ticks down to zero (one second, non frame comp)
	if data.spinTimer <= 0 then
		data.spinTimer = 30;		
		local dirIndex = zombie:getDir():index(); -- get the # index for the current direction.		
		zombie:setDir(dirIndex+1); -- set the current direction to the index + 1 (N -> NW, E -> NE etc)
	end

	local dirToMove = zombie:getVectorFromDirection();
	dirToMove:setLength(zombie:getPathSpeed());
	zombie:Move(dirToMove);

end

-- Called once per frame when zombie is in LuaState. Here we can call the relevant behaviour.
function AIStateExecute(zombie)
	local data = zombie:getModData();

	-- Check all possible states and call relevant function to deal with them.
	if data.state == "WalkInCircles" then
		DoWalkInCircles(zombie, data);
	elseif data.state == "SomethingElse" then
		--DoZombieSomethingElse(zombie);
	end

end

-- Since we're locking the state to force the zombie to stay in our state at all times,
-- we need to undo this if the zombie is knocked back or killed.
-- Here we check what state the zombie is in and unlock the state machine if we need to.
function ZombieStateChange(owner, newState, oldState)
	
	if newState == StaggerBackDieState:instance() or newState == StaggerBackState:instance() or newState == DieState:instance() or newState == BurntToDeath:instance() then
		if owner:getObjectName() == "Zombie" then
			owner:setLockStates(false);		
		end
	end

end


Events.OnAIStateChange.Add(ZombieStateChange);
Events.OnZombieUpdate.Add(ZombieUpdate);
Events.OnAIStateExecute.Add(AIStateExecute);