Automatically collect all crafting groups

2 files changed, 21 insertions, 4 deletions

diff --git a/API.md b/API.md
index a054eb7..5470ef8 100644
--- a/API.md
+++ b/API.md
@@ -258,19 +258,18 @@ Add a list of groups you think are notable enough to be mentioned in the
 
 `groupnames` is a table of group names.
 
-By default, no groups are shown for this factoid which means this factoid
-is never displayed.
+Groups which are used for crafting are already automatically added.
 
 What is “notable” is subjective, but here's a rule of thumb you may follow:
 
 You should add groups with this function if:
 
-* This group is used for crafting purposes
 * This group is somehow important for interaction
 * This group appears in `connect_to` definitions of nodes
 
 Do not add groups if:
 
+* This group is only used for crafting purposes (this is already covered)
 * The group is only used internally
 * The group is uninteresting for the player
 * A factoid covering this group already exists
diff --git a/init.lua b/init.lua
index 89b0f10..67c8ab8 100644
--- a/init.lua
+++ b/init.lua
@@ -52,7 +52,7 @@ local groups_to_string = function(grouptable, filter)
 	local gstring = ""
 	local groups_count = 0
 	for id, value in pairs(grouptable) do
-		if groupdefs[id] ~= nil and (filter == nil or filter[id] == true) then
+		if (filter == nil or filter[id] == true) then
 			-- Readable group name
 			if groups_count > 0 then
 				-- List seperator
@@ -1064,6 +1064,24 @@ local function gather_descs()
 		end
 	end
 
+	-- ... and gather all groups which appear in crafting recipes
+	for id, def in pairs(minetest.registered_items) do
+		local crafts = minetest.get_all_craft_recipes(id)
+		if crafts ~= nil then
+			for c=1,#crafts do
+				for k,v in pairs(crafts[c].items) do
+					if string.sub(v,1,6) == "group:" then
+						local groupstring = string.sub(v,7,-1)
+						local groups = string.split(groupstring, ",")
+						for g=1, #groups do
+							miscgroups[groups[g]] = true
+						end
+					end
+				end
+			end
+		end
+	end
+
 	-- 2nd pass: Add entries
 
 	-- Set default air text