allow transferring ownership of petz

README.md

@@ -139,3 +139,11 @@ callback = function(player, shop, i)
     -- called when the shop sells out of something
 end
 ```
+* `smartshop.api.register_transaction_transform(callback)`
+```lua
+callback = function(player, shop, i, shop_removed, player_removed)
+    -- sometimes, it is necessary to alter the items in an exchange
+    -- e.g. changing the owner of a petz "pet"
+    return shop_removed, player_removed
+end
+```

api/purchase_mechanics.lua

@@ -10,6 +10,7 @@ api.registered_purchase_mechanics = {}
 api.registered_on_purchases = {}
 api.registered_on_shop_fulls = {}
 api.registered_on_shop_emptys = {}
+api.registered_transaction_transforms = {}
 
 --[[
 	TODO: mechanic definition isn't set in stone currently, see below
@@ -49,6 +50,17 @@ function api.on_shop_empty(player, shop, i)
 	end
 end
 
+function api.register_transaction_transform(callback)
+	table.insert(api.registered_transaction_transforms, callback)
+end
+
+function api.do_transaction_transforms(player, shop, i, shop_removed, player_removed)
+	for _, callback in ipairs(api.registered_transaction_transforms) do
+		shop_removed, player_removed = callback(player, shop, i, shop_removed, player_removed)
+	end
+	return shop_removed, player_removed
+end
+
 function api.try_purchase(player, shop, i)
 	for _, def in ipairs(api.registered_purchase_mechanics) do
 		if def.allow_purchase(player, shop, i) then
@@ -126,6 +138,9 @@ api.register_purchase_mechanic({
 
 		local shop_removed = shop:remove_item(give_stack, "give")
 		local player_removed = player_inv:remove_item(pay_stack)
+
+		shop_removed, player_removed = api.do_transaction_transforms(player, shop, i, shop_removed, player_removed)
+
 		local player_remaining = player_inv:add_item(shop_removed)
 		local shop_remaining = shop:add_item(player_removed, "pay")
 

compat/currency.lua

@@ -341,6 +341,8 @@ api.register_purchase_mechanic({
 			shop_removed = shop:remove_item(give_stack, "give")
 		end
 
+		shop_removed, player_removed = api.do_transaction_transforms(shop_removed, player_removed)
+
 		if is_currency(pay_stack) then
 			shop_remaining = currency.add_item(shop, player_removed, "pay")
 		else

compat/init.lua

@@ -14,6 +14,10 @@ if smartshop.has.mesecons_mvps then
 	smartshop.dofile("compat", "mesecons_mvps")
 end
 
+if smartshop.has.petz then
+	smartshop.dofile("compat", "petz")
+end
+
 if smartshop.has.pipeworks then
 	smartshop.dofile("compat", "pipeworks")
 end

compat/petz.lua

@@ -0,0 +1,35 @@
+-- petz has its own mechanism for "selling" petz; this allows transferring ownership of animals put in shops
+
+local function set_owner(petstack, new_owner_name)
+	local meta = petstack:get_meta()
+	local serialized_data = meta:get("staticdata")
+	if not serialized_data then
+		return
+	end
+
+	local data = minetest.deserialize(serialized_data)
+
+	if not (data and data.memory) then
+		return
+	end
+
+	if (data.memory.owner or "") ~= "" then
+		data.memory.owner = new_owner_name
+		meta:set_string("staticdata", minetest.serialize(data))
+	end
+end
+
+local function is_petz(itemstack)
+	local name = itemstack:get_name()
+	return name:match("^petz:.*_set$")
+end
+
+smartshop.api.register_transaction_transform(function(player, shop, i, shop_removed, player_removed)
+	if is_petz(shop_removed) then
+		set_owner(shop_removed, player:get_player_name())
+	end
+	if is_petz(player_removed) then
+		set_owner(player_removed, shop:get_owner())
+	end
+	return shop_removed, player_removed
+end)

init.lua

@@ -33,6 +33,7 @@ smartshop = {
 		default = minetest.get_modpath("default"),
 		mesecons = minetest.get_modpath("mesecons"),
 		mesecons_mvps = minetest.get_modpath("mesecons_mvps"),
+		petz = minetest.get_modpath("petz"),
 		pipeworks = minetest.get_modpath("pipeworks"),
 		tubelib = minetest.get_modpath("tubelib"),
 	},

mod.conf

@@ -1,3 +1,3 @@
 name = smartshop
 description = A smarter and easier shop
-optional_depends = currency, default, mesecons, mesecons_mvps, pipeworks, tubelib
+optional_depends = currency, default, mesecons, mesecons_mvps, petz, pipeworks, tubelib