Cat petting and purring

TODO

@@ -1,3 +1,6 @@
 Cat lifecycle:
-- Cats can be petted
+- Petting cats after long enough around another cat may eject a prill
-- Petting cats after long enough around another cat may eject a prill
+- Cat behaviors
+  - Push item stacks off nearby ledges?
+  - Sometimes randomly give you some junk as a present?
+  - Dig up nearby plants?

init.lua

@@ -11,3 +11,4 @@ include("node")
 include("item")
 include("ore")
 include("craft")
+include("pet")

node.lua

@@ -53,8 +53,8 @@ reg(7, "#c0a080", "#806020") -- light brown
 nodecore.register_ambiance({
 		label = modname .. " ambiance",
 		nodenames = {"group:" .. modname .. "_cat"},
-		interval = 1,
+		interval = 5,
-		chance = 10,
+		chance = 5,
 		sound_name = modname .. "_mew",
 		sound_gain = 0.5
 	})

pet.lua

@@ -0,0 +1,71 @@
+-- LUALOCALS < ---------------------------------------------------------
+local math, minetest, nodecore, pairs, vector
+    = math, minetest, nodecore, pairs, vector
+local math_random
+    = math.random
+-- LUALOCALS > ---------------------------------------------------------
+
+local modname = minetest.get_current_modname()
+
+local purrtimes = {
+	1.676,
+	1.617,
+	1.642,
+	1.655
+}
+
+local hashpos = minetest.hash_node_position
+local purring = {}
+
+local purrgain = 0.15
+
+local function purr(pos)
+	purring[hashpos(pos)] = true
+	local id = math_random(1, #purrtimes)
+	local fade = math_random(1, 10) == 1
+	if not fade then
+		local nearby
+		for _, player in pairs(minetest.get_connected_players()) do
+			if not nearby then
+				local ppos = player:get_pos()
+				local diff = vector.subtract(pos, ppos)
+				local dsqr = vector.dot(diff, diff)
+				nearby = nearby or dsqr < 25
+			end
+		end
+		fade = not nearby
+	end
+	local sh = nodecore.sound_play("nc_cats_purr_" .. id, {
+			pos = pos,
+			gain = purrgain,
+			not_ephemeral = fade
+		})
+	if fade then
+		minetest.sound_fade(sh, -purrgain / purrtimes[id], 0)
+		return minetest.after(purrtimes[id], function()
+				purring[hashpos(pos)] = nil
+			end)
+	else
+		nodecore.dnt_set(pos, modname .. ":purr", purrtimes[id])
+	end
+end
+
+nodecore.register_dnt({
+		name = modname .. ":purr",
+		nodenames = {"group:" .. modname .. "_cat"},
+		action = purr
+	})
+
+nodecore.register_craft({
+		label = "pet cat",
+		action = "pummel",
+		toolgroups = {thumpy = 1},
+		indexkeys = {"group:" .. modname .. "_cat"},
+		check = function(pos)
+			return not purring[hashpos(pos)]
+		end,
+		nodes = {
+			{match = {groups = {[modname .. "_cat"] = true}}}
+		},
+		after = purr
+	})