-- LUALOCALS < ---------------------------------------------------------
local minetest, nodecore, pairs, vector
    = minetest, nodecore, pairs, vector
-- LUALOCALS > ---------------------------------------------------------

local function hingeaxis(pos, node)
	local fd = node and node.param2 or 0
	fd = nodecore.facedirs[fd]
	fd = vector.multiply(vector.add(fd.f, fd.r), 0.5)
	return {
		x = fd.x == 0 and 0 or pos.x + fd.x,
		y = fd.y == 0 and 0 or pos.y + fd.y,
		z = fd.z == 0 and 0 or pos.z + fd.z
	}
end

local convey = {}

local function conveytrace(okay, seg, u)
	local w = convey[u.tkey]
	if w then return w end
	if nodecore.buildable_to(u.to) then
		for x in pairs(seg) do
			okay[x] = true
		end
		return
	end
	if not u.tkey2 then return end
	u.to = u.to2
	u.tkey = u.tkey2
	w = convey[u.tkey]
	if w then return w end
	if nodecore.buildable_to(u.to) then
		for x in pairs(seg) do
			okay[x] = true
		end
	end
end

minetest.register_globalstep(function()
		local nonheads = {}
		for _, v in pairs(convey) do
			if convey[v.tkey] or nodecore.buildable_to(v.to)
			or not v.tkey2 then
				nonheads[v.tkey] = true
			else
				nonheads[v.tkey2] = true
			end
		end
		local okay = {}
		for k, v in pairs(convey) do
			if not nonheads[k] then
				local seg = {}
				local u = v
				while u do
					seg[u] = true
					u = conveytrace(okay, seg, u)
				end
				for x in pairs(seg) do
					convey[x.fkey] = nil
				end
			end
		end
		for _, v in pairs(convey) do
			okay[v] = true
		end
		convey = {}

		local air = {name = "air"}
		local toset = {}
		for v in pairs(okay) do
			toset[v.fkey] = {pos = v.from, node = air}
		end
		for v in pairs(okay) do
			toset[v.tkey] = {
				pos = v.to,
				node = v.node,
				meta = minetest.get_meta(v.from):to_table()
			}
		end
		for _, v in pairs(toset) do
			minetest.set_node(v.pos, v.node)
			if v.meta then
				minetest.get_meta(v.pos):from_table(v.meta)
				nodecore.visinv_update_ents(v.pos)
			end
			nodecore.fallcheck(v.pos)
		end
	end)

local is_falling = {groups = { falling_node = true }}

local function trypush(pos, dir, dir2)
	local node = minetest.get_node(pos)
	if not nodecore.match(node, is_falling) then return end

	local data = {
		from = pos,
		fkey = minetest.pos_to_string(pos),
		to = vector.add(pos, dir),
		node = node,
	}
	data.tkey = minetest.pos_to_string(data.to)
	if dir2 then
		data.to2 = vector.add(pos, dir2)
		data.tkey2 = minetest.pos_to_string(data.to2)
	end
	convey[data.fkey] = data
end

local squelch = {}
minetest.register_globalstep(function() squelch = {} end)

local is_door = {groups = { door = true }}

function nodecore.operate_door(pos, node, dir)
	local key = minetest.pos_to_string(pos)
	if squelch[key] then return end
	node = node or minetest.get_node_or_nil(pos)
	if (not node) or (not nodecore.match(node, is_door)) then return end

	local fd = nodecore.facedirs[node.param2 or 0]
	local rotdir
	if vector.equals(dir, fd.k) or vector.equals(dir, fd.r) then
		rotdir = "r"
	elseif vector.equals(dir, fd.l) or vector.equals(dir, fd.f) then
		rotdir = "f"
	else return end

	local found = {}
	local hinge = hingeaxis(pos, node)
	if nodecore.scan_flood(pos, 128, function(p)
			local n = minetest.get_node_or_nil(p)
			if not n then return true end
			if (not nodecore.match(n, is_door))
			or (not vector.equals(hingeaxis(p, n), hinge)) then return false end
			found[minetest.pos_to_string(p)] = {pos = p, node = n}
		end
	) then return end

	local toop = {}
	for k, v in pairs(found) do
		local ffd = nodecore.facedirs[v.node.param2 or 0]
		v.dir = ffd[rotdir]
		v.dir2 = rotdir == "r" and ffd.k or ffd.l
		local to = vector.add(v.pos, v.dir)

		if (not found[minetest.pos_to_string(to)])
		and (not nodecore.buildable_to(to))
		then return end

		local str = minetest.pos_to_string(to)
		if squelch[str] then return end

		v.str = str
		v.to = to
		v.fd = ffd

		toop[k .. "l"] = {
			pos = vector.add(v.pos, ffd.l),
			dir = rotdir == "r" and ffd.k or ffd.f
		}
		toop[k .. "k"] = {
			pos = vector.add(v.pos, ffd.k),
			dir = rotdir == "r" and ffd.r or ffd.l
		}
	end

	local toset = {}
	for k, v in pairs(found) do
		toset[k] = {pos = v.pos, name = "air"}
		squelch[k] = true
		squelch[v.str] = true
	end
	for _, v in pairs(found) do
		for i, xfd in pairs(nodecore.facedirs) do
			if vector.equals(xfd.t, v.fd.t)
			and vector.equals(xfd.r, rotdir == "r" and v.fd.f or v.fd.k) then
				toset[minetest.pos_to_string(v.to)] = {
					pos = v.to,
					name = v.node.name,
					param2 = i
				}
				break
			end
		end
	end

	for _, v in pairs(toset) do
		minetest.set_node(v.pos, v)
		if v.name ~= "air" then
			local p = vector.round(vector.multiply(v.pos, 0.25))
			local k = "sfx" .. minetest.pos_to_string(p)
			if not squelch[k] then
				squelch[k] = true
				minetest.sound_play("nc_doors_operate",
					{pos = v.pos, gain = 0.5})
			end
		end
	end
	for _, v in pairs(found) do
		trypush({x = v.pos.x, y = v.pos.y + 1, z = v.pos.z}, v.dir, v.dir2)
	end
	for _, v in pairs(toop) do
		nodecore.operate_door(v.pos, nil, v.dir)
		trypush(v.pos, v.dir)
	end
end