--- Makes an associative table of node_name => weight into a list of node ids.
-- Node names with a heigher weight are repeated more times.
function worldeditadditions.make_weighted(tbl)
	local result = {}
	for node_name, weight in pairs(tbl) do
		local next_id = minetest.get_content_id(node_name)
		print("[make_weighted] seen "..node_name.." @ weight "..weight.." → id "..next_id)
		for i = 1, weight do
			table.insert(result, next_id)
		end
	end
	return result, #result
end

--- Unwinds a list of { node = string, weight = number } tables into a list of node ids.
-- The node ids will be repeated multiple times according to their weights
-- (e.g. an entry with a weight of 2 will be repeated twice).
-- @param	list		table[]		The list to unwind.
-- @return	number[],number			The unwound list of node ids, follows by the number of node ids in total.
function worldeditadditions.unwind_node_list(list)
	local result = {}
	for i,item in ipairs(list) do
		local node_id = minetest.get_content_id(item.node)
		for i = 1, item.weight do
			table.insert(result, node_id)
		end
	end
	return result, #result
end

local node_id_air = minetest.get_content_id("air")
local node_id_ignore = minetest.get_content_id("ignore")

--- Determines whether the given node/content id is an airlike node or not.
-- It is recommended that the result of this function be cached.
-- @param	id		number	The content/node id to check.
-- @return	bool	Whether the given node/content id is an airlike node or not.
function worldeditadditions.is_airlike(id)
	--  Do a fast check against air and ignore
	if id == node_id_air then
		return true
	elseif id == node_id_ignore then -- ignore = not loaded yet IIRC (so it could be anything)
		return false
	end
	
	-- If the node isn't registered, then it might not be an air node
	if not minetest.registered_nodes[id] then return false end
	if minetest.registered_nodes[id].sunlight_propagates == true then
		return true
	end
	-- Check for membership of the airlike group
	local name = minetest.get_name_from_content_id(id)
	local airlike_value = minetest.get_item_group(name, "airlike")
	if airlike_value ~= nil and airlike_value > 0 then
		return true
	end
	-- Just in case
	if worldeditadditions.string_starts(this_node_name, "wielded_light") then
		return true
	end
	-- Just in case
	return false
end

--- Determines whether the given node/content id is a liquid-ish node or not.
-- It is recommended that the result of this function be cached.
-- @param	id		number	The content/node id to check.
-- @return	bool	Whether the given node/content id is a liquid-ish node or not.
function worldeditadditions.is_liquidlike(id)
	-- print("[is_liquidlike]")
	if id == node_id_ignore then return false end
	
	local node_name = minetest.get_name_from_content_id(id)
	if node_name == nil or not minetest.registered_nodes[node_name] then return false end
	
	local liquidtype = minetest.registered_nodes[node_name].liquidtype
	-- print("[is_liquidlike]", "id", id, "liquidtype", liquidtype)
	
	if liquidtype == nil or liquidtype == "none" then return false end
	-- If it's not none, then it has to be a liquid as the only other values are source and flowing
	return true
end

--- Determines whether the given node/content id is a sapling or not.
-- Nodes with the "sapling" group are considered saplings.
-- It is recommended that the result of this function be cached.
-- @param	id		number	The content/node id to check.
-- @return	bool	Whther the given node/content id is a sapxling or not.
function worldeditadditions.is_sapling(id)
	local node_name = minetest.get_name_from_content_id(data[i])
	return minetest.get_item_group(node_name, "sapling") ~= 0
end