-- LUALOCALS < ---------------------------------------------------------
local math, minetest, nodecore, pairs
    = math, minetest, nodecore, pairs
local math_random
    = math.random
-- LUALOCALS > ---------------------------------------------------------

local harden_to = {}
local harden_idx = {}
local soften_to = {}
minetest.after(0, function()
		for _, v in pairs(minetest.registered_nodes) do
			if v.strata then
				for i, n in pairs(v.strata) do
					harden_to[n] = v.strata[i + 1]
					soften_to[n] = v.strata[i - 1]
					harden_idx[n] = i
				end
			end
		end
	end)

minetest.register_abm({
		label = "stone hardening",
		nodenames = {"group:stone"},
		neighbors = {"group:lava"},
		neighbors_invert = true,
		interval = 10,
		chance = 50,
		action = function(pos)
			local water = #nodecore.find_nodes_around(pos, "group:water")
			local lux = #nodecore.find_nodes_around(pos, "group:lux_fluid")
			if water == lux then return end

			local node = minetest.get_node(pos)
			node.name = (water > lux and harden_to or soften_to)[node.name]
			if not node.name then return end

			local lava = #nodecore.find_nodes_around(pos, "group:lava")
			if lava < 1 then return end

			local fluid = water > lux and (water - lux) or (lux - water)
			local chance = harden_idx[node.name] - (fluid > lava and fluid or lava) / 8
			if (chance > 0) and (math_random() > (1/3) ^ chance) then return end
			nodecore.log("info", (water > lux and "hardened" or "softened")
				.. " to " .. node.name .. " at " .. minetest.pos_to_string(pos))
			nodecore.set_loud(pos, node)
			return nodecore.witness(pos, "stone " .. (water > lux and "hardened" or "softened"))
		end
	})