local mod_player_monoids = minetest.get_modpath("player_monoids") ~= nil
local mod_playerphysics = minetest.get_modpath("playerphysics") ~= nil

local utility = {}

function utility.rangelim(value, min, max)
	return math.min(math.max(value, min), max)
end

-- from https://stackoverflow.com/a/29133654
-- merges two tables together
-- if in conflict, b will override values of a
function utility.merge_tables(a, b)
	if type(a) == "table" and type(b) == "table" then
		for k,v in pairs(b) do
			if type(v)=="table" and type(a[k] or false)=="table" then
				merge(a[k],v)
			else a[k]=v end
		end
	end
	return a
end

-- see https://en.wikipedia.org/wiki/Logistic_function
function utility.logistic_growth(value, max, growth, midpoint)
	return max / (1 + math.exp(-growth * (value - midpoint)))
end

-- generates a wave of cycle length 1
-- maps parameters to values between 0 and 1
-- 0 is mapped to 0 and 0.5 to 1
function utility.normalized_cycle(value)
	return math.cos((2 * value + 1) * math.pi) / 2 + 0.5
end

-- override player physics
-- use utility mod if possible to avoid conflict
function utility.add_physics(id, player, effect, value)
	if mod_player_monoids then
		player_monoids[effect]:add_change(player, value, id)
	elseif mod_playerphysics then
		playerphysics.add_physics_factor(player, effect, id, value)
	else
		local override = {}
		override[effect] = value
		player:set_physics_override(override)
	end
end

-- reset player phsysics to normal
function utility.remove_physics(id, player, effect)
	if mod_player_monoids then
		player_monoids[effect]:del_change(player, id)
	elseif mod_playerphysics then
		playerphysics.remove_physics_factor(player, effect, id)
	else
		local override = {}
		override[effect] = 1
		player:set_physics_override(override)
	end
end

return utility