From 627d103b20508a53b7fe69893bfa9d48f6c15c07 Mon Sep 17 00:00:00 2001
From: Wuzzy <almikes@aol.com>
Date: Thu, 3 Aug 2017 01:01:44 +0200
Subject: [PATCH] Don't drop when node dug by too weak tool

---
 mods/ENTITIES/mcl_item_entity/init.lua | 58 ++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/mods/ENTITIES/mcl_item_entity/init.lua b/mods/ENTITIES/mcl_item_entity/init.lua
index 871c7fd04..8e8cdf47c 100644
--- a/mods/ENTITIES/mcl_item_entity/init.lua
+++ b/mods/ENTITIES/mcl_item_entity/init.lua
@@ -154,11 +154,69 @@ minetest.register_globalstep(function(dtime)
 	end
 end)
 
+local minigroups = { "shearsy", "swordy", "shearsy_wool", "swordy_cobweb" }
+local basegroups = { "pickaxey", "axey", "shovely" }
+local materials = { "wood", "gold", "stone", "iron", "diamond" }
+
+-- Checks if the given node would drop its useful drop if dug by a tool
+-- with the given tool capabilities. Returns true if it will yield its useful
+-- drop, false otherwise.
+local check_can_drop = function(node_name, tool_capabilities)
+	local handy = minetest.get_item_group(node_name, "handy")
+	local dig_immediate = minetest.get_item_group(node_name, "dig_immediate")
+	if handy == 1 or dig_immediate == 2 or dig_immediate == 3 then
+		return true
+	else
+		local toolgroupcaps
+		if tool_capabilities then
+			toolgroupcaps = tool_capabilities.groupcaps
+		else
+			return false
+		end
+
+		-- Compare node groups with tool capabilities
+		for m=1, #minigroups do
+			local minigroup = minigroups[m]
+			local g = minetest.get_item_group(node_name, minigroup)
+			if g ~= 0 then
+				local plus = minigroup .. "_dig"
+				if toolgroupcaps[plus] then
+					return true
+				end
+			end
+		end
+		for b=1, #basegroups do
+			local basegroup = basegroups[b]
+			local g = minetest.get_item_group(node_name, basegroup)
+			if g ~= 0 then
+				for m=g, #materials do
+					local plus = basegroup .. "_dig_"..materials[m]
+					if toolgroupcaps[plus] then
+						return true
+					end
+				end
+			end
+		end
+
+		return false
+	end
+end
+
 function minetest.handle_node_drops(pos, drops, digger)
 	local doTileDrops = minetest.setting_getbool("mcl_doTileDrops") or true
 	if minetest.setting_getbool("creative_mode") or doTileDrops == false then
 		return
 	end
+
+	-- Check if node will yield its useful drop by the digger's tool
+	local dug_node = minetest.get_node(pos)
+	local tool = digger:get_wielded_item()
+	local toolcaps = tool:get_tool_capabilities()
+
+	if not check_can_drop(dug_node.name, toolcaps) then
+		return
+	end
+
 	for _,item in ipairs(drops) do
 		local count, name
 		if type(item) == "string" then