travelers_adventure/mods/eg_prospector/pick.lua

local modname = minetest.get_current_modname()
local S = minetest.get_translator(modname)

local get_prospect = _G[modname].get_prospect

reading_message_chart =
{
	{-3, "Found traces of traces of @1."},
	{-2, "Found traces of @1."},
	{-0.3, "Found large traces of @1."},
	{0, "Found @1."},
}
local function get_message_from_reading(strength)
	local ret
	for k, v in ipairs(reading_message_chart)
	do
		print(k, type(k))
		if strength >= v[1]
		then
			ret = v[2]
		end
	end
	return ret
end

minetest.register_tool(modname .. ":pick",
	{
		description = S("Prospector pick"),
		inventory_image = modname .. "_pick.png",
		on_use = function(itemstack, user, pointed_thing)
			if pointed_thing.type == "node"
			then
				local prospect = get_prospect(pointed_thing.under)
				local highest_name
				local highest_val = -math.huge
				for k, v in pairs(prospect)
				do
					if v > highest_val
					then
						highest_name = k
						highest_val = v
					end
				end
				if highest_name
				then
					local msg =
						highest_val < -3 and S("Found nothing.") or
						S(get_message_from_reading(highest_val), highest_name)
					minetest.chat_send_player(user:get_player_name(), msg)
				else
					minetest.chat_send_player(user:get_player_name(), S("Found nothing.") )
				end
			end
		end,
	})