getAdjacentTargets.lua

--[[
For complete API reference see
https://github.com/VladimirMakeev/D2ModdingToolset/blob/master/luaApi.md

If the script is used as SEL_SCRIPT, no unit is selected yet (selected.position == -1).

Unit positions on a battlefield are mirrored.
Frontline positions are even, backline - odd.
1 0    0 1
3 2 vs 2 3
5 4    4 5
--]]

function getTargets(attacker, selected, allies, targets, targetsAreAllies)
	-- If targets are enemies and the attacker stands on the backline (position % 2 ~= 0)
	if not targetsAreAllies and attacker.backline then
		for i = 1, #allies do
			-- If any ally stands on the frontline (position % 2 == 0)
			if allies[i].frontline then
				-- Ally prevents us to reach adjacent targets
				return {}
			end
		end
	end

	-- Determine closest distance to adjacent target (excluding self)
	local closestDistance = 99
	for i = 1, #targets do
		local target = targets[i]
		if target ~= attacker then
			local distance = target:distance(attacker)
			if closestDistance > distance then
				closestDistance = distance
			end
		end
	end

	-- Allow closest targets only (including self)
	local result = {}
	for i = 1, #targets do
		local target = targets[i]
		if target == attacker or target:distance(attacker) == closestDistance then
			if target == selected then
				-- Ensure first target in case of custom damage ratio
				table.insert(result, 1, target)
			else
				table.insert(result, target)
			end
		end
	end
	return result
end