From 62e04b9c0de18684fb3cdc74e0ca8f376ff6c75c Mon Sep 17 00:00:00 2001
From: Zefram <zefram@fysh.org>
Date: Mon, 21 Jul 2014 00:22:47 +0100
Subject: [PATCH] Improved can usage

Make the use of cans more like the digging and placement of ordinary
nodes, and specifically make it much closer to the use of buckets.
The main change is that left-click with a can is now only used to take
liquid; placing liquid is now done with a right-click.  This makes the use
of cans a lot less error-prone, compared to the old scheme of determining
the operation based on the type of node pointed to.  Other changes are
that liquid placement is now permitted to replace any buildable_to node,
and the cans obey node protection.
---
 technic/tools/cans.lua | 74 +++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 34 deletions(-)

diff --git a/technic/tools/cans.lua b/technic/tools/cans.lua
index f46a401..f12ec93 100644
--- a/technic/tools/cans.lua
+++ b/technic/tools/cans.lua
@@ -12,6 +12,14 @@ local function set_can_wear(itemstack, level, max_level)
 	itemstack:set_wear(temp)
 end
 
+local function get_can_level(itemstack)
+	if itemstack:get_metadata() == "" then
+		return 0
+	else
+		return tonumber(itemstack:get_metadata())
+	end
+end
+
 function technic.register_can(d)
 	local data = {}
 	for k, v in pairs(d) do data[k] = v end
@@ -22,46 +30,44 @@ function technic.register_can(d)
 		wear_represents = "content_level",
 		liquids_pointable = true,
 		on_use = function(itemstack, user, pointed_thing)
-			if pointed_thing.type ~= "node" then
+			if pointed_thing.type ~= "node" then return end
+			local node = minetest.get_node(pointed_thing.under)
+			if node.name ~= data.liquid_source_name then return end
+			local charge = get_can_level(itemstack)
+			if charge == data.can_capacity then return end
+			if minetest.is_protected(pointed_thing.under, user:get_player_name()) then
+				minetest.log("action", user:get_player_name().." tried to take "..node.name.." at protected position "..minetest.pos_to_string(pointed_thing.under).." with a "..data.can_name)
 				return
 			end
-			node = minetest.get_node(pointed_thing.under)
-
-			local charge = nil
-			if itemstack:get_metadata() == "" then
-				charge = 0
-			else
-				charge = tonumber(itemstack:get_metadata())
+			minetest.remove_node(pointed_thing.under)
+			charge = charge + 1
+			itemstack:set_metadata(tostring(charge))
+			set_can_wear(itemstack, charge, data.can_capacity)
+			return itemstack
+		end,
+		on_place = function(itemstack, user, pointed_thing)
+			if pointed_thing.type ~= "node" then return end
+			local pos = pointed_thing.under
+			local def = minetest.registered_nodes[minetest.get_node(pos).name] or {}
+			if def.on_rightclick and user and not user:get_player_control().sneak then
+				return def.on_rightclick(pos, minetest.get_node(pos), user, itemstack, pointed_thing)
 			end
-			if node.name == data.liquid_source_name then
-				if charge < data.can_capacity then
-					minetest.remove_node(pointed_thing.under)
-					charge = charge + 1
-					itemstack:set_metadata(tostring(charge))
-					set_can_wear(itemstack, charge, data.can_capacity)
-				end
-				return itemstack
+			if not def.buildable_to then
+				pos = pointed_thing.above
+				def = minetest.registered_nodes[minetest.get_node(pos).name] or {}
+				if not def.buildable_to then return end
 			end
-			if charge == 0 then
+			local charge = get_can_level(itemstack)
+			if charge == 0 then return end
+			if minetest.is_protected(pos, user:get_player_name()) then
+				minetest.log("action", user:get_player_name().." tried to place "..data.liquid_source_name.." at protected position "..minetest.pos_to_string(pos).." with a "..data.can_name)
 				return
 			end
-
-			if node.name == data.liquid_flowing_name then
-				minetest.set_node(pointed_thing.under, {name=data.liquid_source_name})
-				charge = charge - 1
-				itemstack:set_metadata(tostring(charge))
-				set_can_wear(itemstack, charge, data.can_capacity)
-				return itemstack
-			end
-
-			node = minetest.get_node(pointed_thing.above)
-			if node.name == "air" then
-				minetest.set_node(pointed_thing.above, {name=data.liquid_source_name})
-				charge = charge - 1
-				itemstack:set_metadata(tostring(charge))
-				set_can_wear(itemstack, charge, data.can_capacity)
-				return itemstack
-			end		
+			minetest.set_node(pos, {name=data.liquid_source_name})
+			charge = charge - 1
+			itemstack:set_metadata(tostring(charge))
+			set_can_wear(itemstack, charge, data.can_capacity)
+			return itemstack
 		end,
 		on_refill = function(stack)
 			stack:set_metadata(tostring(data.can_capacity))