Trading: Allow to sell compass

mods/ENTITIES/mobs_mc/villager.lua

@@ -6,6 +6,7 @@
 -- TODO: Per-player trading inventories
 -- TODO: Particles
 -- TODO: 4s Regeneration I after trade unlock
+-- FIXME: Possible to lock all trades
 
 -- intllib
 local MP = minetest.get_modpath(minetest.get_current_modname())
@@ -21,6 +22,20 @@ local player_trading_with = {}
 --###################
 
 -- LIST OF VILLAGER PROFESSIONS AND TRADES
+
+-- TECHNICAL RESTRICTIONS (FIXME):
+-- * You can't use a clock as requested item
+-- * You can't use a compass as requested item if its stack size > 1
+-- * You can't use a compass in the second requested slot
+-- This is a problem in the mcl_compass and mcl_clock mods,
+-- these items should be implemented as single items, then everything
+-- will be much easier.
+
+local COMPASS = "mcl_compass:compass"
+if minetest.registered_aliases[COMPASS] then
+	COMPASS = minetest.registered_aliases[COMPASS]
+end
+
 local E1 = { "mcl_core:emerald", 1, 1 } -- one emerald
 local professions = {
 	farmer = {
@@ -143,11 +158,10 @@ local professions = {
 			{ { "mcl_core:paper", 24, 36 }, E1 },
 			},
 
---			{
+			{
-			-- TODO: compass
+			-- subject to special checks
-			-- the difficulty lies in supporting the compass group, not the concrete item
+			{ { "mcl_compass:compass", 1, 1 }, E1 },
---			{ { "mcl_compass:compass", 1, 1 }, E1 },
+			},
---			},
 
 			{
 			-- TODO: replace with empty map
@@ -446,9 +460,47 @@ local update_offer = function(inv, player, sound)
 	if not trade then
 		return false
 	end
-	if inv:contains_item("input", inv:get_stack("wanted", 1)) and
+	local wanted1, wanted2 = inv:get_stack("wanted", 1), inv:get_stack("wanted", 2)
-			(inv:get_stack("wanted", 2):is_empty() or inv:contains_item("input", inv:get_stack("wanted", 2))) and
+	local input1, input2 = inv:get_stack("input", 1), inv:get_stack("input", 2)
-			(trade.locked == false) then
+
+	-- BEGIN OF SPECIAL HANDLING OF COMPASS
+	-- These 2 functions are a complicated check to check if the input contains a
+	-- special item which we cannot check directly against their name, like
+	-- compass.
+	-- TODO: Remove these check functions when compass and clock are implemented
+	-- as single items.
+	local check_special = function(special_item, group, wanted1, wanted2, input1, input2)
+		if minetest.registered_aliases[special_item] then
+			special_item = minetest.registered_aliases[special_item]
+		end
+		if wanted1:get_name() == special_item then
+			local check_input = function(input, wanted, group)
+				return minetest.get_item_group(input:get_name(), group) ~= 0 and input:get_count() >= wanted:get_count()
+			end
+			if check_input(input1, wanted1, group) then
+				return true
+			elseif check_input(input2, wanted1, group) then
+				return true
+			else
+				return false
+			end
+		end
+		return false
+	end
+	-- Apply above function to all items which we consider special.
+	-- This function succeeds if ANY item check succeeds.
+	local check_specials = function(wanted1, wanted2, input1, input2)
+		return check_special(COMPASS, "compass", wanted1, wanted2, input1, input2)
+	end
+	-- END OF SPECIAL HANDLING OF COMPASS
+
+	if (
+			((inv:contains_item("input", wanted1) and
+			(wanted2:is_empty() or inv:contains_item("input", wanted2))) or
+			-- BEGIN OF SPECIAL HANDLING OF COMPASS
+			check_specials(wanted1, wanted2, input1, input2)) and
+			-- END OF SPECIAL HANDLING OF COMPASS
+			(trade.locked == false)) then
 		inv:set_stack("output", 1, inv:get_stack("offered", 1))
 		if sound then
 			minetest.sound_play("mobs_mc_villager_accept", {to_player = name})
@@ -558,10 +610,30 @@ mobs:register_mob("mobs_mc:villager", {
 							-- enough items in input after the trade
 							local wanted1 = inv:get_stack("wanted", 1)
 							local wanted2 = inv:get_stack("wanted", 2)
+							local input1 = inv:get_stack("input", 1)
+							local input2 = inv:get_stack("input", 2)
 							wanted1:set_count(wanted1:get_count()*2)
 							wanted2:set_count(wanted2:get_count()*2)
-							if inv:contains_item("input", wanted1) and
+							-- BEGIN OF SPECIAL HANDLING FOR COMPASS
-								(wanted2:is_empty() or inv:contains_item("input", wanted2)) then
+							local special_checks = function(wanted1, input1, input2)
+								if wanted1:get_name() == COMPASS then
+									local compasses = 0
+									if (minetest.get_item_group(input1:get_name(), "compass") ~= 0) then
+										compasses = compasses + input1:get_count()
+									end
+									if (minetest.get_item_group(input2:get_name(), "compass") ~= 0) then
+										compasses = compasses + input2:get_count()
+									end
+									return compasses >= wanted1:get_count()
+								end
+								return false
+							end
+							-- END OF SPECIAL HANDLING FOR COMPASS
+							if (inv:contains_item("input", wanted1) and
+								(wanted2:is_empty() or inv:contains_item("input", wanted2)))
+								-- BEGIN OF SPECIAL HANDLING FOR COMPASS
+								or special_checks(wanted1, input1, input2) then
+								-- END OF SPECIAL HANDLING FOR COMPASS
 								return -1
 							else
 								-- If less than double the wanted items,
@@ -612,11 +684,24 @@ mobs:register_mob("mobs_mc:villager", {
 					local accept
 					local name = player:get_player_name()
 					if listname == "output" then
-						inv:remove_item("input", inv:get_stack("wanted", 1))
+						local wanted1 = inv:get_stack("wanted", 1)
+						inv:remove_item("input", wanted1)
 						local wanted2 = inv:get_stack("wanted", 2)
 						if not wanted2:is_empty() then
 							inv:remove_item("input", inv:get_stack("wanted", 2))
 						end
+						-- BEGIN OF SPECIAL HANDLING FOR COMPASS
+						if wanted1:get_name() == COMPASS then
+							for n=1, 2 do
+								local input = inv:get_stack("input", n)
+								if minetest.get_item_group(input:get_name(), "compass") ~= 0 then
+									input:set_count(input:get_count() - wanted1:get_count())
+									inv:set_stack("input", n, input)
+									break
+								end
+							end
+						end
+						-- END OF SPECIAL HANDLING FOR COMPASS
 						local trader = player_trading_with[name]
 						local tradenum = player_tradenum[name]
 						local trades
@@ -649,7 +734,7 @@ mobs:register_mob("mobs_mc:villager", {
 							if trade.trade_counter >= 12 then
 								trade.locked = true
 							elseif trade.trade_counter >= 2 then
-								local r = math.random(1, math.random(1, 9))
+								local r = math.random(1, math.random(4, 10))
 								if r == 1 then
 									trade.locked = true
 								end