Update the API documentation

api.md

@@ -1,17 +1,13 @@
 
-Hopper API
+# Hopper API
-----------
 
-This API is kept simple by adding a single command which allows mods to add
+This API provides two functions for adding containers such as chests and furnaces that will interact with hoppers.
-containers like chests and furnaces to the hopper check list.
 
+## hopper:add_container
 
-Command Usage
+```lua
--------------
+hopper:add_container({ {"where_from", "node_name", "inventory_name"}, })
-
+```
-Make sure any mods using this function has 'hopper' in the depends.txt file.
-
-hopper:add_container({ {"where_from", "node_name", "inventory_name"} })
 
   'where_from' is a string telling the api that items are coming from either
                the 'top' node into a hopper below, going into the 'bottom' node
@@ -24,29 +20,35 @@ hopper:add_container({ {"where_from", "node_name", "inventory_name"} })
 
 e.g.
 
+```lua
 hopper:add_container({
 	{"top", "default:furnace", "dst"}, -- take cooked items from above into hopper below
 	{"bottom", "default:furnace", "src"}, -- insert items below to be cooked from hopper above
 	{"side", "default:furnace", "fuel"}, -- replenish furnace fuel from hopper at side
 })
+```
 
 You can also register hopper interaction targets by group, or by a group and a specific group
 value. For example:
 
+```lua
 hopper:add_container({
 	{"top", "group:loot_chest", "loot"},
 	{"bottom", "group:loot_chest", "loot"},
 	{"side", "group:loot_chest", "loot"},
 })
+```
 
 Would cause hoppers to interact with the "loot" inventory of all nodes belonging to the group
 "loot_chest", and
 
+```lua
 hopper:add_container({
 	{"top", "group:protected_container=1", "main"},
 	{"bottom", "group:protected_container=1", "main"},
 	{"side", "group:protected_container=1", "main"},
 })
+```
 
 Would cause hoppers to interact with the "main" inventory of nodes belonging to the group
 "protected_container" provided they had a value of 1 in that group. Hoppers prioritize the most
@@ -59,6 +61,36 @@ will take priority. Using the above examples, if there were a node that belonged
 the groups "loot_chest" and "protected_container=1" there's no way of knowing ahead of time
 whether hoppers would interact with the "loot" or "main" inventories. Try to avoid this situation.
 
+### Optional parameter: get_inventory function
+
+```lua
+hopper:add_container({ {"where_from", "node_name", "inventory_name", get_inventory = function get_inventory(node_pos)}, })
+```
+
+This option allows you to use a different inventory instead of the inventory of this node. Unlike others, this parameter does not have to be set.
+
+## hopper:set_extra_container_info
+
+```lua
+hopper:set_extra_container_info({ {"node_name", EXTRA PARAMETERS}, })
+```
+
+The function adds additional information about the container, which does not depend on where the items arrive. Before using it, you need to add a container.
+Of course, it is not necessary to use it.
+
+### EXTRA PARAMETER: set_hopper_param2 function
+
+```lua
+hopper:set_extra_container_info({ {"node_name", set_hopper_param2 = function set_hopper_param2(hopper_pos, node_pos)}, })
+```
+
+When we place the hopper, we have the position of the node we are looking at and the position of the funnel.
+When other nodes get into the nodebox of one node, the information becomes insufficient, see [minetest 9147 issue](https://github.com/minetest/minetest/issues/9147). In particular, this feature was useful for adding [connected chests](https://github.com/HybridDog/connected_chests/pull/14) support.
+
+This function takes priority over the usual installation of the hopper.
+
+## Already supported containers
+
 The hopper mod already have support for the wine barrel inside of the Wine mod and protected
 chests inside of Protector Redo, as well as default chests, furnaces and hoppers
 themselves.