-- TODO: collapse nodes when the node under them is removed.

local function attempt_collapse_at (pos)
	local below = pos + blockgame.vector.dirs.down
	if minetest.get_node(below).name ~= "air" then return end

	minetest.spawn_falling_node(pos)
end

local function place_loose_node (itemstack, placer, pointed)
	local result = minetest.item_place(itemstack, placer, pointed)
	attempt_collapse_at(pointed.above)
	return result
end

-- collapse nodes that somehow managed to stay in the air.
blockgame.register_abm({
	label = "collapse collapsible nodes",
	nodenames = {"group:loose"},
	neighbors = {"air"},
	interval = 15,
	chance = 1,
	action = attempt_collapse_at,
})

local function attempt_settle_at (pos)
	local below = pos + blockgame.vector.dirs.down
	if minetest.get_node(below).name == "air" then return end

	local def = minetest.registered_nodes[minetest.get_node(pos).name]
	minetest.set_node(pos, {name = def.stable_version})
end

-- settle nodes that are still (in the future, it will take some time for loose nodes that are still to settle).
blockgame.register_abm({
	label = "settle collapsible nodes",
	nodenames = {"group:loose"},
	interval = 30,
	chance = 10,
	action = attempt_settle_at,
})



function blockgame.register_loose_version (name)
	local def = minetest.registered_nodes[name]
	if not def then return false end

	local groups = {}
	for key, value in pairs(def.groups) do
		groups[key] = value
	end
	groups.loose = 1

	blockgame.register_node(name .. "_loose", {
		description = "Loose " .. def.description,
		tiles = def.tiles, -- temporary
		groups = groups,
		on_place = place_loose_node,
		stable_version = name,
	})
	return true
end