local ecs = require 'honey.ecs.ecs'

local module = {}
setmetatable(module, {__index=_G})
setfenv(1, module)

--===== transform cascading =====--

local function recursiveTransform(db, id, node)
	if node._visited then
		return node._matrix
	end

	if not node.parent then
		node._matrix = node.matrix
	else
		local parentNode = db:getComponent(node.parent, "node")
		local parentMatrix = recursiveTransform(db, node.parent, parentNode)
		node._matrix = parentMatrix * node.matrix
		if node.name then
			if not parentNode._child then parentNode._child = {} end
			parentNode._child[node.name] = ecs.Accessor(db, id)
		end
	end
	node._visited = true
	return node._matrix
end



system = {ecs.System("node", function(db, dt, params)
	local nodes = db:queryComponent("node")

	-- prepare nodes
	for id, node in pairs(nodes) do
		node._visited = false
		node._child = nil
	end

	-- compute nodes
	for id, node in pairs(nodes) do
		recursiveTransform(db, id, node)
	end
end)}


return module