DigWorks/mods/ITEMS/mcl_mushrooms/small.lua

local on_place = function(itemstack, placer, pointed_thing)
	if pointed_thing.type ~= "node" then
		-- no interaction possible with entities
		return itemstack
	end

	-- Call on_rightclick if the pointed node defines it
	local node = minetest.get_node(pointed_thing.under)
	if placer and not placer:get_player_control().sneak then
		if minetest.registered_nodes[node.name] and minetest.registered_nodes[node.name].on_rightclick then
			return minetest.registered_nodes[node.name].on_rightclick(pointed_thing.under, node, placer, itemstack) or itemstack
		end
	end

	local a = pointed_thing.above
	local u = pointed_thing.under
	local node_above = minetest.get_node(a)
	local node_under = minetest.get_node(u)
	local def_above = minetest.registered_nodes[node_above.name]
	local def_under = minetest.registered_nodes[node_under.name]

	local place_pos, soil_node, place_node, soil_def, place_def
	if def_under.buildable_to then
		place_pos = u
		place_node = node_under
		place_def = def_under
	elseif def_above.buildable_to then
		place_pos = a
		place_node = node_above
		place_def = def_above
	else
		return itemstack
	end
	soil_node = minetest.get_node({x=place_pos.x, y=place_pos.y-1, z=place_pos.z})
	soil_def = minetest.registered_nodes[soil_node.name]

	-- Placement rules:
	-- * Always allowed on podzol or mycelimu
	-- * Otherwise, must be solid, opaque and have daylight light level <= 12
	local light = minetest.get_node_light(place_pos, 0.5)
	local light_ok = false
	if light and light <= 12 then
		light_ok = true
	end
	if (soil_node.name == "mcl_core:podzol" or soil_node.name == "mcl_core:mycelium") or
			(light_ok and (soil_def.groups and soil_def.groups.solid and soil_def.groups.opaque)) then
		local idef = itemstack:get_definition()
		local success = minetest.item_place_node(itemstack, placer, pointed_thing)

		if success then
			if idef.sounds and idef.sounds.place then
				minetest.sound_play(idef.sounds.place, {pos=above, gain=1})
			end
		end
	end

	return itemstack
end

local longdesc = [[Mushrooms are fungi which grow and spread in darkness, but are sensitive to light.

A single mushroom will slowly spread over time towards a random opaque block with a light level of 12 or lower in a 5×5×5 cube around the mushroom. A mushroom stops spreading when there are 5 or more mushrooms of the same color within an area of 9×3×9 blocks around the mushroom.
Mushrooms will eventually uproot at a light level of 12 or higher. On mycelium or podzol, they survive and spread at any light level.]]

local usagehelp = "Mushrooms can be placed on mycelium and podzol at any light level. They can also be placed on blocks which are both solid and opaque, as long as the light level at daytime is not higher than 12."

minetest.register_node("mcl_mushrooms:mushroom_brown", {
	description = "Brown Mushroom",
	_doc_items_longdesc = longdesc,
	_doc_items_usagehelp = usagehelp,
	drawtype = "plantlike",
	tiles = { "farming_mushroom_brown.png" },
	inventory_image = "farming_mushroom_brown.png",
	wield_image = "farming_mushroom_brown.png",
	sunlight_propagates = true,
	paramtype = "light",
	walkable = false,
	groups = {dig_immediate=3,mushroom=1,attached_node=1,dig_by_water=1,dig_by_piston=1,deco_block=1},
	sounds = mcl_sounds.node_sound_leaves_defaults(),
	light_source = 1,
	selection_box = {
		type = "fixed",
		fixed = { -3/16, -0.5, -3/16, 3/16, -2/16, 3/16 },
	},
	node_placement_prediction = "",
	on_place = on_place,
	_mcl_blast_resistance = 0,
})

minetest.register_node("mcl_mushrooms:mushroom_red", {
	description = "Red Mushroom",
	_doc_items_longdesc = longdesc,
	_doc_items_usagehelp = usagehelp,
	drawtype = "plantlike",
	tiles = { "farming_mushroom_red.png" },
	inventory_image = "farming_mushroom_red.png",
	wield_image = "farming_mushroom_red.png",
	sunlight_propagates = true,
	paramtype = "light",
	walkable = false,
	groups = {dig_immediate=3,mushroom=1,attached_node=1,dig_by_water=1,dig_by_piston=1,deco_block=1},
	sounds = mcl_sounds.node_sound_leaves_defaults(),
	selection_box = {
		type = "fixed",
		fixed = { -3/16, -0.5, -3/16, 3/16, -2/16, 3/16 },
	},
	node_placement_prediction = "",
	on_place = on_place,
	_mcl_blast_resistance = 0,
})

minetest.register_craftitem("mcl_mushrooms:mushroom_stew", {
	description = "Mushroom Stew",
	_doc_items_longdesc = "Mushroom stew is a healthy soup which can be consumed for 6 hunger points.",
	inventory_image = "farming_mushroom_stew.png",
	on_place = minetest.item_eat(6, "mcl_core:bowl"),
	on_secondary_use = minetest.item_eat(6, "mcl_core:bowl"),
	groups = { food = 3, eatable = 6 },
	stack_max = 1,
})

minetest.register_craft({
	type = "shapeless",
	output = "mcl_mushrooms:mushroom_stew",
	recipe = {'mcl_core:bowl', 'mcl_mushrooms:mushroom_brown', 'mcl_mushrooms:mushroom_red'}
})

--[[ Mushroom spread and death
Code based on information gathered from Minecraft Wiki
<http://minecraft.gamepedia.com/Tutorials/Mushroom_farming#Videos>
]]
minetest.register_abm({
	label = "Mushroom spread",
	nodenames = {"mcl_mushrooms:mushroom_brown", "mcl_mushrooms:mushroom_red"},
	interval = 11,
	chance = 50,
	action = function(pos, node)
		if minetest.get_node_light(pos, nil) > 12 then
			minetest.dig_node(pos)
			return
		end

		local pos0 = vector.add(pos, {x=-4, y=-1, z=-4})
		local pos1 = vector.add(pos, {x=4, y=1, z=4})

		-- Stop mushroom spread if a 9×3×9 box is too crowded
		if #minetest.find_nodes_in_area(pos0, pos1, node.name) >= 5 then
			return
		end

		local selected_pos = table.copy(pos)

		-- Do two random selections which may place the new mushroom in a 5×5×5 cube
		local random = {
			x = selected_pos.x + math.random(-1, 1),
			y = selected_pos.y + math.random(0, 1) - math.random(0, 1),
			z = selected_pos.z + math.random(-1, 1)
		}
		local random_node = minetest.get_node_or_nil(random)
		if not random_node or random_node.name ~= "air" then
			return
		end
		local node_under = minetest.get_node_or_nil({x = random.x, y = random.y - 1, z = random.z})
		if not node_under then
			return
		end

		if minetest.get_node_light(random, 0.5) > 12 or (minetest.get_item_group(node_under.name, "opaque") == 0) then
			return
		end
		local random2 = {
			x = random.x + math.random(-1, 1),
			y = random.y,
			z = random.z + math.random(-1, 1)
		}
		random_node = minetest.get_node_or_nil(random2)
		if not random_node or random_node.name ~= "air" then
			return
		end
		node_under = minetest.get_node_or_nil({x = random2.x, y = random2.y - 1, z = random2.z})
		if not node_under then
			return
		end
		if minetest.get_node_light(random2, 0.5) > 12 or (minetest.get_item_group(node_under.name, "opaque") == 0) then
			return
		end

		minetest.set_node(random2, {name = node.name})
	end
})