-- xPanes mod by xyz

local directions = {
	{x = 1, y = 0, z = 0},
	{x = 0, y = 0, z = 1},
	{x = -1, y = 0, z = 0},
	{x = 0, y = 0, z = -1},
}

local function update_pane(pos)
	if minetest.get_node(pos).name:find("xpanes:pane") == nil then
		return
	end
	local sum = 0
	for i = 1, 4 do
		local node = minetest.get_node({x = pos.x + directions[i].x, y = pos.y + directions[i].y, z = pos.z + directions[i].z})
		if minetest.registered_nodes[node.name].walkable ~= false then
			sum = sum + 2 ^ (i - 1)
		end
	end
	if sum == 0 then
		sum = 15
	end
	minetest.add_node(pos, {name = "xpanes:pane_"..sum})
end

local function update_nearby(pos)
	for i = 1,4 do
		update_pane({x = pos.x + directions[i].x, y = pos.y + directions[i].y, z = pos.z + directions[i].z})
	end
end

local half_blocks = {
	{0, -0.5, -0.06, 0.5, 0.5, 0.06},
	{-0.06, -0.5, 0, 0.06, 0.5, 0.5},
	{-0.5, -0.5, -0.06, 0, 0.5, 0.06},
	{-0.06, -0.5, -0.5, 0.06, 0.5, 0}
}

local full_blocks = {
	{-0.5, -0.5, -0.06, 0.5, 0.5, 0.06},
	{-0.06, -0.5, -0.5, 0.06, 0.5, 0.5}
}

for i = 1, 15 do
	local need = {}
	local cnt = 0
	for j = 1, 4 do
		if rshift(i, j - 1) % 2 == 1 then
			need[j] = true
			cnt = cnt + 1
		end
	end
	local take = {}
	if need[1] == true and need[3] == true then
		need[1] = nil
		need[3] = nil
		table.insert(take, full_blocks[1])
	end
	if need[2] == true and need[4] == true then
		need[2] = nil
		need[4] = nil
		table.insert(take, full_blocks[2])
	end
	for k in pairs(need) do
		table.insert(take, half_blocks[k])
	end
	local texture = "xpanes_pane.png"
	if cnt == 1 then
		texture = "xpanes_pane_half.png"
	end
	minetest.register_node("xpanes:pane_"..i, {
		drawtype = "nodebox",
		tiles = {"xpanes_white.png", "xpanes_white.png", texture},
		paramtype = "light",
		groups = {snappy=2,cracky=3,oddly_breakable_by_hand=3,drop_on_dig=1},
		drop = "xpanes:pane",
		node_box = {
			type = "fixed",
			fixed = take
		},
		selection_box = {
			type = "fixed",
			fixed = take
		},
		sounds = default.node_sound_glass_defaults(),
	})
end

minetest.register_node("xpanes:pane", {
	description = "Glass Pane",
	tiles = {"xpanes_space.png"},
	inventory_image = "xpanes_pane.png",
	wield_image = "xpanes_pane.png",
	node_placement_prediction = "",
	on_construct = update_pane
})

minetest.register_on_placenode(update_nearby)
minetest.register_on_dignode(update_nearby)

minetest.register_craft({
	output = 'xpanes:pane 16',
	recipe = {
		{'default:glass', 'default:glass', 'default:glass'},
		{'default:glass', 'default:glass', 'default:glass'}
	}
})