Add hopper mod support

init.lua

@@ -649,3 +649,59 @@ minetest.register_alias("connected_chests:chest_left_locked", "default:chest_loc
 minetest.register_alias("connected_chests:chest_right_locked", "default:chest_locked_connected_right")
 minetest.register_alias("connected_chests:chest_locked_left", "default:chest_locked_connected_left")
 minetest.register_alias("connected_chests:chest_locked_right", "default:chest_locked_connected_right")
+
+if minetest.get_modpath("hopper") then
+	local function get_inventory(chest_right_pos)
+		local node_right = minetest.get_node(chest_right_pos)
+		if node_right.param2 > 3 then
+			-- The right connected chest node has an invalid param2 value
+			-- Cannot determine the inventory
+			return
+		end
+		local x, z = unpack(param_tab2[node_right.param2])
+		local chest_left_pos = {x=chest_right_pos.x+x, y=chest_right_pos.y, z=chest_right_pos.z+z}
+		local node_left = minetest.get_node(chest_left_pos)
+		if node_left.name ~= "default:chest_connected_left" and node_left.name ~= "default:chest_connected_left_open" then
+			minetest.log("error","The left chest is not a chest: " .. node_left.name .. " at " .. vector.to_string(chest_left_pos))
+			return
+		end
+		if node_left.param2 ~= node_right.param2 then
+			minetest.log("error","The chests are pointing in different directions: node_left.param2:"
+				.. node_left.param2 .. ", node_right.param2:" .. node_right.param2)
+			return
+		end
+		return minetest.get_meta(chest_left_pos):get_inventory()
+	end
+	hopper:add_container({
+		{"top", "default:chest_connected_left", "main"},
+		{"bottom", "default:chest_connected_left", "main"},
+		{"side", "default:chest_connected_left", "main"},
+		{"top", "default:chest_connected_right", "main", get_inventory = get_inventory},
+		{"bottom", "default:chest_connected_right", "main", get_inventory = get_inventory},
+		{"side", "default:chest_connected_right", "main", get_inventory = get_inventory},
+		{"top", "default:chest_connected_left_open", "main"},
+		{"bottom", "default:chest_connected_left_open", "main"},
+		{"side", "default:chest_connected_left_open", "main"},
+		{"top", "default:chest_connected_right_open", "main", get_inventory = get_inventory},
+		{"bottom", "default:chest_connected_right_open", "main", get_inventory = get_inventory},
+		{"side", "default:chest_connected_right_open", "main", get_inventory = get_inventory},
+	})
+	local function set_hopper_param2(hopper_pos, chest_left_pos)
+		local param2_by_offset = {
+			[vector.new(-1, 0, 0):to_string()] = 0,
+			[vector.new( 0, 0, 1):to_string()] = 1,
+			[vector.new( 1, 0, 0):to_string()] = 2,
+			[vector.new( 0, 0,-1):to_string()] = 3,
+		}
+		local hopper_param2 = param2_by_offset[(chest_left_pos - hopper_pos):to_string()]
+		if hopper_param2 then
+			return hopper_param2
+		end
+		local x, z = unpack(param_tab2[minetest.get_node(chest_left_pos).param2])
+		local chest_right_pos = {x=chest_left_pos.x-x, y=chest_left_pos.y, z=chest_left_pos.z-z}
+		return param2_by_offset[(chest_right_pos - hopper_pos):to_string()]
+	end
+	hopper:set_extra_container_info({
+		{"default:chest_connected_left", set_hopper_param2 = set_hopper_param2},
+	})
+end

mod.conf

@@ -1,3 +1,3 @@
 name = connected_chests
 depends = default
-optional_depends = pipeworks,technic
+optional_depends = pipeworks,technic,hopper