--lua locals
local S = minetest.get_translator("mcl_mobs")
local math, vector, minetest, mcl_mobs = math, vector, minetest, mcl_mobs
local mob_class = mcl_mobs.mob_class

local gamerule_doMobSpawning = vl_tuning.setting("gamerule:doMobSpawning", "bool", {
	description = S("Whether mobs should spawn naturally, or via global spawning logic, such as for cats, phantoms, patrols, wandering traders, or zombie sieges. Does not affect special spawning attempts, like monster spawners, raids, or iron golems."), default = true
})

local modern_lighting = minetest.settings:get_bool("mcl_mobs_modern_lighting", true)
local nether_threshold = tonumber(minetest.settings:get("mcl_mobs_nether_threshold")) or 11
local end_threshold = tonumber(minetest.settings:get("mcl_mobs_end_threshold")) or 0
local overworld_threshold = tonumber(minetest.settings:get("mcl_mobs_overworld_threshold")) or 0
local overworld_sky_threshold = tonumber(minetest.settings:get("mcl_mobs_overworld_sky_threshold")) or 7
local overworld_passive_threshold = tonumber(minetest.settings:get("mcl_mobs_overworld_passive_threshold")) or 7

local get_node                     = minetest.get_node
local get_node_light               = minetest.get_node_light
local find_nodes_in_area_under_air = minetest.find_nodes_in_area_under_air
local mt_get_biome_name            = minetest.get_biome_name
local get_objects_inside_radius    = minetest.get_objects_inside_radius
local get_connected_players        = minetest.get_connected_players
local registered_nodes             = minetest.registered_nodes

local math_min       = math.min
local math_max       = math.max
local math_random    = math.random
local math_floor     = math.floor
local math_ceil      = math.ceil
local math_cos       = math.cos
local math_sin       = math.sin
local math_sqrt      = math.sqrt
local math_abs       = math.abs

local vector_distance = vector.distance
local vector_new      = vector.new
local vector_floor    = vector.floor

local table_copy     = table.copy
local table_remove   = table.remove
local pairs = pairs

local logging = minetest.settings:get_bool("mcl_logging_mobs_spawn", false)
local function mcl_log(message, property)
	if property then message = message .. ": " .. dump(property) end
	mcl_util.mcl_log(message, "[Mobs spawn]", true)
end
if not logging then mcl_log = function() end end

local dbg_spawn_attempts = 0
local dbg_spawn_succ = 0

local remove_far = true

local WAIT_FOR_SPAWN_ATTEMPT = 10
local FIND_SPAWN_POS_RETRIES = 16
local FIND_SPAWN_POS_RETRIES_SUCCESS_RESPIN = 8

local MOB_SPAWN_ZONE_INNER = 24
local MOB_SPAWN_ZONE_INNER_SQ = MOB_SPAWN_ZONE_INNER^2 -- squared
local MOB_SPAWN_ZONE_MIDDLE = 32
local MOB_SPAWN_ZONE_OUTER = 128
local MOB_SPAWN_ZONE_OUTER_SQ = MOB_SPAWN_ZONE_OUTER^2 -- squared

-- range for mob count
local MOB_CAP_INNER_RADIUS = 32
local aoc_range = 136

local MISSING_CAP_DEFAULT = 15
local MOBS_CAP_CLOSE = 10

local SPAWN_MAPGEN_LIMIT  = mcl_vars.mapgen_limit - 150

local mob_cap = {
	hostile = tonumber(minetest.settings:get("mcl_mob_cap_monster")) or 70,
	passive = tonumber(minetest.settings:get("mcl_mob_cap_animal")) or 10,
	ambient = tonumber(minetest.settings:get("mcl_mob_cap_ambient")) or 15,
	water = tonumber(minetest.settings:get("mcl_mob_cap_water")) or 8,
	water_ambient = tonumber(minetest.settings:get("mcl_mob_cap_water_ambient")) or 20,
	water_underground = tonumber(minetest.settings:get("mcl_mob_cap_water_underground")) or 5,
	axolotl = tonumber(minetest.settings:get("mcl_mob_cap_axolotl")) or 2, -- TODO should be 5 when lush caves added
	player = tonumber(minetest.settings:get("mcl_mob_cap_player")) or 75,
	global_hostile = tonumber(minetest.settings:get("mcl_mob_cap_hostile")) or 300,
	global_non_hostile = tonumber(minetest.settings:get("mcl_mob_cap_non_hostile")) or 300,
	total = tonumber(minetest.settings:get("mcl_mob_cap_total")) or 500,
}

local peaceful_percentage_spawned = tonumber(minetest.settings:get("mcl_mob_peaceful_percentage_spawned")) or 30
local peaceful_group_percentage_spawned = tonumber(minetest.settings:get("mcl_mob_peaceful_group_percentage_spawned")) or 15
local hostile_group_percentage_spawned = tonumber(minetest.settings:get("mcl_mob_hostile_group_percentage_spawned")) or 20

mcl_log("Mob cap hostile: " .. mob_cap.hostile)
mcl_log("Mob cap water: " .. mob_cap.water)
mcl_log("Mob cap passive: " .. mob_cap.passive)

mcl_log("Percentage of peacefuls spawned: " .. peaceful_percentage_spawned)
mcl_log("Percentage of peaceful spawns are group: " .. peaceful_group_percentage_spawned)
mcl_log("Percentage of hostile spawns are group: " .. hostile_group_percentage_spawned)

--do mobs spawn?
local mobs_spawn = minetest.settings:get_bool("mobs_spawn", true) ~= false
local spawn_protected = minetest.settings:get_bool("mobs_spawn_protected") ~= false

-- count how many mobs are in an area
local function count_mobs(pos,r,mob_type)
	local num = 0
	for _,l in pairs(minetest.luaentities) do
		if l and l.is_mob and (mob_type == nil or l.type == mob_type) then
			local p = l.object:get_pos()
			if p and vector_distance(p,pos) < r then
				num = num + 1
			end
		end
	end
	return num
end

local function count_mobs_total(mob_type)
	local num = 0
	for _,l in pairs(minetest.luaentities) do
		if l.is_mob then
			if mob_type == nil or l.type == mob_type then
				num = num + 1
			end
		end
	end
	return num
end

local function count_mobs_add_entry (mobs_list, mob_cat)
	mobs_list[mob_cat] = (mobs_list[mob_cat] or 0) + 1
end

--categorise_by can be name or type or spawn_class
local function count_mobs_all(categorise_by, pos)
	local mobs_found_wide = {}
	local mobs_found_close = {}

	local num = 0
	for _,entity in pairs(minetest.luaentities) do
		if entity and entity.is_mob then

			local add_entry = false
			--local mob_type = entity.type -- animal / monster / npc
			local mob_cat = entity[categorise_by]

			if pos then
				local mob_pos = entity.object:get_pos()
				if mob_pos then
					local distance = vector.distance(pos, mob_pos)
					--mcl_log("distance: ".. distance)
					if distance <= MOB_SPAWN_ZONE_MIDDLE then
						--mcl_log("distance is close")
						count_mobs_add_entry (mobs_found_close, mob_cat)
						count_mobs_add_entry (mobs_found_wide, mob_cat)
						add_entry = true
					elseif distance <= MOB_SPAWN_ZONE_OUTER then
						--mcl_log("distance is wide")
						count_mobs_add_entry (mobs_found_wide, mob_cat)
						add_entry = true
					else
						--mcl_log("mob_pos: " .. minetest.pos_to_string(mob_pos))
					end
				end
			else
				count_mobs_add_entry (mobs_found_wide, mob_cat)
				add_entry = true
			end


			if add_entry then
				num = num + 1
			end
		end
	end
	--mcl_log("num: ".. num)
	return mobs_found_close, mobs_found_wide, num
end

local function count_mobs_total_cap(mob_type)
	local total = 0
	local num = 0
	local hostile = 0
	local non_hostile = 0
	for _,l in pairs(minetest.luaentities) do
		if l.is_mob then
			total = total + 1
			local nametagged = l.nametag and l.nametag ~= ""
			if ( mob_type == nil or l.type == mob_type ) and not nametagged then
				if l.spawn_class == "hostile" then
					hostile = hostile + 1
				else
					non_hostile = non_hostile + 1
				end
				num = num + 1
			else
				mcl_log("l.name", l.name)
				mcl_log("l.nametag", l.nametag)

			end
		end
	end
	mcl_log("Total mobs", total)
	mcl_log("hostile", hostile)
	mcl_log("non_hostile", non_hostile)
	return num, non_hostile, hostile
end

local function output_mob_stats(mob_counts, total_mobs, chat_display)
	if (total_mobs) then
		local total_output = "Total mobs found: " .. total_mobs
		if chat_display then
			minetest.log(total_output)
		else
			minetest.log("action", total_output)
		end

	end
	local detailed = ""
	if mob_counts then
		for k, v1 in pairs(mob_counts) do
			detailed = detailed .. tostring(k) ..  ": " .. tostring(v1) ..  "; "
		end
	end
	if detailed and detailed ~= "" then
		if chat_display then
			minetest.log(detailed)
		else
			minetest.log("action", detailed)
		end
	end
end


-- global functions

function mcl_mobs:spawn_abm_check(pos, node, name)
	-- global function to add additional spawn checks
	-- return true to stop spawning mob
end


--[[
	Custom elements changed:

name:
the mobs name

dimension:
"overworld"
"nether"
"end"

types of spawning:
"water"
"ground"
"lava"

biomes: tells the spawner to allow certain mobs to spawn in certain biomes
{"this", "that", "grasslands", "whatever"}


what is aoc??? objects in area

WARNING: BIOME INTEGRATION NEEDED -> How to get biome through lua??
]]--


--this is where all of the spawning information is kept
local spawn_dictionary = {}
--this is where all of the spawning information  is kept for mobs that don't naturally spawn
local non_spawn_dictionary = {}

function mcl_mobs:spawn_setup(def)
	if not mobs_spawn then return end

	if not def then
		minetest.log("warning", "Empty mob spawn setup definition")
		return
	end

	local name = def.name
	if not name then
		minetest.log("warning", "Missing mob name")
		return
	end

	local dimension        = def.dimension or "overworld"
	local type_of_spawning = def.type_of_spawning or "ground"
	local biomes           = def.biomes or nil
	local min_light        = def.min_light or 0
	local max_light        = def.max_light or (minetest.LIGHT_MAX + 1)
	local chance           = def.chance or 1000
	local aoc              = def.aoc or aoc_range
	local min_height       = def.min_height or mcl_mapgen.overworld.min
	local max_height       = def.max_height or mcl_mapgen.overworld.max
	local day_toggle       = def.day_toggle
	local on_spawn         = def.on_spawn
	local check_position   = def.check_position

	-- chance/spawn number override in minetest.conf for registered mob
	local numbers = minetest.settings:get(name)
	if numbers then
		numbers = numbers:split(",")
		chance = tonumber(numbers[1]) or chance
		aoc = tonumber(numbers[2]) or aoc
		if chance == 0 then
			minetest.log("warning", string.format("[mcl_mobs] %s has spawning disabled", name))
			return
		end
		minetest.log("action", string.format("[mcl_mobs] Chance setting for %s changed to %s (total: %s)", name, chance, aoc))
	end

	if chance < 1 then
		chance = 1
		minetest.log("warning", "Chance shouldn't be less than 1 (mob name: " .. name ..")")
	end

	spawn_dictionary[#spawn_dictionary + 1] = {
		name             = name,
		dimension        = dimension,
		type_of_spawning = type_of_spawning,
		biomes           = biomes,
		min_light        = min_light,
		max_light        = max_light,
		chance           = chance,
		aoc              = aoc,
		min_height       = min_height,
		max_height       = max_height,
		day_toggle       = day_toggle,
		check_position   = check_position,
		on_spawn         = on_spawn,
	}
end

function mcl_mobs:mob_light_lvl(mob_name, dimension)
	local spawn_dictionary_consolidated = {}

	if non_spawn_dictionary[mob_name] then
		local mob_dimension = non_spawn_dictionary[mob_name][dimension]
		if mob_dimension then
			--minetest.log("Found in non spawn dictionary for dimension")
			return mob_dimension.min_light, mob_dimension.max_light
		else
			--minetest.log("Found in non spawn dictionary but not for dimension")
			local overworld_non_spawn_def = non_spawn_dictionary[mob_name]["overworld"]
			if overworld_non_spawn_def then
				return overworld_non_spawn_def.min_light, overworld_non_spawn_def.max_light
			end
		end
	else
		--minetest.log("must be in spawning dictionary")
		for i,v in pairs(spawn_dictionary) do
			local current_mob_name = spawn_dictionary[i].name
			local current_mob_dim = spawn_dictionary[i].dimension
			if mob_name == current_mob_name then
				if not spawn_dictionary_consolidated[current_mob_name] then
					spawn_dictionary_consolidated[current_mob_name] = {}
				end
				spawn_dictionary_consolidated[current_mob_name][current_mob_dim] = {
					["min_light"] = spawn_dictionary[i].min_light,
					["max_light"] = spawn_dictionary[i].max_light
				}
			end
		end

		if spawn_dictionary_consolidated[mob_name] then
			--minetest.log("is in consolidated")
			local mob_dimension = spawn_dictionary_consolidated[mob_name][dimension]
			if mob_dimension then
				--minetest.log("found for dimension")
				return mob_dimension.min_light, mob_dimension.max_light
			else
				--minetest.log("not found for dimension, use overworld def")
				local mob_dimension_default = spawn_dictionary_consolidated[mob_name]["overworld"]
				if mob_dimension_default then
					return mob_dimension_default.min_light, mob_dimension_default.max_light
				end
			end
		else
			--minetest.log("not in consolidated")
		end
	end

	minetest.log("action", "There are no light levels for mob (" .. tostring(mob_name) .. ") in dimension (" .. tostring(dimension) .. "). Return defaults")
	return 0, minetest.LIGHT_MAX+1
end

function mcl_mobs:non_spawn_specific(mob_name,dimension,min_light,max_light)
	table.insert(non_spawn_dictionary, mob_name)
	non_spawn_dictionary[mob_name] = {
		[dimension] = {
			min_light = min_light , max_light = max_light
		}
	}
end

function mcl_mobs:spawn_specific(name, dimension, type_of_spawning, biomes, min_light, max_light, interval, chance, aoc, min_height, max_height, day_toggle, on_spawn, check_position)

	-- Do mobs spawn at all?
	if not mobs_spawn then
		return
	end

	assert(min_height)
	assert(max_height)

	-- chance/spawn number override in minetest.conf for registered mob
	local numbers = minetest.settings:get(name)

	if numbers then
		numbers = numbers:split(",")
		chance = tonumber(numbers[1]) or chance
		aoc = tonumber(numbers[2]) or aoc

		if chance == 0 then
			minetest.log("warning", string.format("[mcl_mobs] %s has spawning disabled", name))
			return
		end

		minetest.log("action", string.format("[mcl_mobs] Chance setting for %s changed to %s (total: %s)", name, chance, aoc))
	end

	--load information into the spawn dictionary
	local key = #spawn_dictionary + 1
	spawn_dictionary[key]               = {}
	spawn_dictionary[key]["name"]       = name
	spawn_dictionary[key]["dimension"]  = dimension
	spawn_dictionary[key]["type_of_spawning"] = type_of_spawning
	spawn_dictionary[key]["biomes"]     = biomes
	spawn_dictionary[key]["min_light"]  = min_light
	spawn_dictionary[key]["max_light"]  = max_light
	spawn_dictionary[key]["chance"]     = chance
	spawn_dictionary[key]["aoc"]        = aoc
	spawn_dictionary[key]["min_height"] = min_height
	spawn_dictionary[key]["max_height"] = max_height
	spawn_dictionary[key]["day_toggle"] = day_toggle
	spawn_dictionary[key]["check_position"] = check_position
end

local function get_next_mob_spawn_pos(pos)
	-- Select a distance such that distances closer to the player are selected much more often than
	-- those further away from the player. This does produce a concentration at INNER (24 blocks)
	local distance = math_random()^2 * (MOB_SPAWN_ZONE_OUTER - MOB_SPAWN_ZONE_INNER) + MOB_SPAWN_ZONE_INNER
	--print("Using spawn distance of "..tostring(distance).."  fx="..tostring(fx)..",x="..tostring(x))

	-- Choose a random direction. Rejection sampling is simple and fast (1-2 tries usually)
	local xoff, yoff, zoff, dd
	repeat
		xoff, yoff, zoff = math_random() * 2 - 1, math_random() * 2 - 1, math_random() * 2 - 1
		dd = xoff*xoff + yoff*yoff + zoff*zoff
	until (dd <= 1 and dd >= 1e-6) -- outside of uniform ball, retry
	dd = distance / math_sqrt(dd) -- distance scaling factor
	xoff, yoff, zoff = xoff * dd, yoff * dd, zoff * dd
	local goal_pos = vector.offset(pos, xoff, yoff, zoff)

	if not (math_abs(goal_pos.x) <= SPAWN_MAPGEN_LIMIT and math_abs(goal_pos.y) <= SPAWN_MAPGEN_LIMIT and math_abs(goal_pos.z) <= SPAWN_MAPGEN_LIMIT) then
		mcl_log("Pos outside mapgen limits: " .. minetest.pos_to_string(goal_pos))
		return nil
	end

	-- Calculate upper/lower y limits
	local d2 = xoff*xoff + zoff*zoff -- squared distance in x,z plane only
	local y1 = math_sqrt(MOB_SPAWN_ZONE_OUTER_SQ - d2) -- absolue value of distance to outer sphere

	local y_min, y_max
	if d2 >= MOB_SPAWN_ZONE_INNER_SQ then
		-- Outer region, y range has both ends on the outer sphere
		y_min = pos.y - y1
		y_max = pos.y + y1
	else
		-- Inner region, y range spans between inner and outer spheres
		local y2 = math_sqrt(MOB_SPAWN_ZONE_INNER_SQ - d2)
		if goal_pos.y > pos.y then
			-- Upper hemisphere
			y_min = pos.y + y2
			y_max = pos.y + y1
		else
			-- Lower hemisphere
			y_min = pos.y - y1
			y_max = pos.y - y2
		end
	end
	-- Limit total range of check to 32 nodes (maximum of 3 map blocks)
	y_min = math_max(math_floor(y_min), goal_pos.y - 16)
	y_max = math_min(math_ceil(y_max), goal_pos.y + 16)

	-- Ask engine for valid spawn locations
	local spawning_position_list = find_nodes_in_area_under_air(
			{x = goal_pos.x, y = y_min, z = goal_pos.z},
			{x = goal_pos.x, y = y_max, z = goal_pos.z},
			{"group:solid", "group:water", "group:lava"}
	) or {}

	-- Select only the locations at a valid distance
	local valid_positions = {}
	for _,check_pos in ipairs(spawning_position_list) do
		local dist = vector.distance(pos, check_pos)
		if dist >= MOB_SPAWN_ZONE_INNER and dist <= MOB_SPAWN_ZONE_OUTER then
			valid_positions[#valid_positions + 1] = check_pos
		end
	end
	spawning_position_list = valid_positions

	-- No valid locations, failed to find a position
	if #spawning_position_list == 0 then
		mcl_log("Spawning position isn't good. Do not spawn: " .. minetest.pos_to_string(goal_pos))
		return nil
	end

	-- Pick a random valid location
	mcl_log("Spawning positions available: " .. minetest.pos_to_string(goal_pos))
	return spawning_position_list[math_random(1, #spawning_position_list)]
end

--a simple helper function for mob_spawn
local function biome_check(biome_list, biome_goal)
	if not biome_goal then return false end
	for _, data in pairs(biome_list) do
		if data == biome_goal then
			return true
		end
	end
	return false
end

local function is_farm_animal(n)
	return n == "mobs_mc:pig" or n == "mobs_mc:cow" or n == "mobs_mc:sheep" or n == "mobs_mc:chicken" or n == "mobs_mc:horse" or n == "mobs_mc:donkey"
end

local function get_water_spawn(p)
		local nn = minetest.find_nodes_in_area(vector.offset(p,-2,-1,-2),vector.offset(p,2,-15,2),{"group:water"})
		if nn and #nn > 0 then
			return nn[math.random(#nn)]
		end
end

local function has_room(self, pos)
	local cb = self.spawnbox or self.collisionbox
	local nodes = {}
	if self.fly_in then
		local t = type(self.fly_in)
		if t == "table" then
			nodes = table.copy(self.fly_in)
		elseif t == "string" then
			table.insert(nodes,self.fly_in)
		end
	end
	table.insert(nodes,"air")

	-- Calculate area to check for room
	local cb_height = cb[5] - cb[2]
	local p1 = vector.new(
		math.round(pos.x + cb[1]),
		math.floor(pos.y),
		math.round(pos.z + cb[3]))
	local p2 = vector.new(
		math.round(pos.x + cb[4]),
		math.ceil(p1.y + cb_height) - 1,
		math.round(pos.z + cb[6]))

	-- Check if the entire spawn volume is free
	local dx = p2.x - p1.x + 1
	local dy = p2.y - p1.y + 1
	local dz = p2.z - p1.z + 1
	local found_nodes = minetest.find_nodes_in_area(p1,p2,nodes) or 0
	local n = #found_nodes
	if n == dx * dy * dz then
		return true
	end

	-- If we don't have an implementation of get_node_boxes, we can't check for sub-node space
	if not minetest.get_node_boxes then return false end

	-- Check if it's possible for a sub-node space check to succeed
	local needed_in_bottom_section = dx * ( dy - 1) * dz
	if n < needed_in_bottom_section then return false end

	-- Make sure the entire volume except for the top level is free before checking the top layer
	if dy > 1 then
		-- Remove nodes in the top layer from the count
		for i = 1,#found_nodes do
			if found_nodes[i].y == p2.y then
				n = n - 1
			end
		end

		-- If the entire volume except the top layer isn't air (or nodes) then we can't spawn this mob here
		if n < needed_in_bottom_section then return false end
	end

	-- Check the top layer to see if we have enough space to spawn in
	local top_layer_height = 1
	local processed = {}
	for x = p1.x,p2.x do
		for z = p1.z,p2.z do
			local test_pos = vector.new(x,p2.y,z)
			local node = minetest.get_node(test_pos) or { name = "ignore" }
			local cache_name = string.format("%s-%d", node.name, node.param2)
			if not processed[cache_name] then
				-- Calculate node bounding box and select the lowest y value
				local boxes = minetest.get_node_boxes("collision_box", test_pos, node)
				for i = 1,#boxes do
					local box = boxes[i]
					local y_test = box[2] + 0.5
					if y_test < top_layer_height then top_layer_height = y_test end

					local y_test = box[5] + 0.5
					if y_test < top_layer_height then top_layer_height = y_test end
				end
			end
		end
	end
	if top_layer_height + dy - 1 >= cb_height then return true end

	-- We don't have room
	return false
end

mcl_mobs.custom_biomecheck = nil

function mcl_mobs.register_custom_biomecheck(custom_biomecheck)
	mcl_mobs.custom_biomecheck = custom_biomecheck
end

local function get_biome_name(pos)
	if mcl_mobs.custom_biomecheck then return mcl_mobs.custom_biomecheck(pos) end
	local gotten_biome = minetest.get_biome_data(pos)
	return gotten_biome and mt_get_biome_name(gotten_biome.biome)
end

local function spawn_check(pos, spawn_def)
	if not spawn_def or not pos then return end
	dbg_spawn_attempts = dbg_spawn_attempts + 1

	local dimension = mcl_worlds.pos_to_dimension(pos)
	if spawn_def.dimension ~= dimension then return end -- wrong dimension
	-- find ground node below spawn position
	local node_name = get_node(pos).name
	local node_def = registered_nodes[node_name]
	if node_def and not node_def.groups.solid then -- try node one below instead
		pos.y = pos.y - 1
		node_name = get_node(pos).name
		node_def = registered_nodes[node_name]
	end
	if not node_def or not node_def.groups then return end
	-- do not spawn on bedrock
	if node_name == "mcl_core:bedrock" then return end
	pos.y = pos.y + 1
	-- check spawn height
	if pos.y < spawn_def.min_height or pos.y > spawn_def.max_height then return end
	mcl_log("spawn_check#1 position checks passed")

	-- do not spawn ground mobs on leaves
	if spawn_def.type_of_spawning == "ground" and (not node_def.groups.solid or node_def.groups.leaves) then return end
	-- water mobs only on water
	if spawn_def.type_of_spawning == "water" and not node_def.groups.water then return end
	-- lava mobs only on lava
	if spawn_def.type_of_spawning == "lava" and not node_def.groups.lava then return end
	-- farm animals on grass only
	if is_farm_animal(spawn_def.name) and not node_def.groups.grass_block then return end

	---- More expensive calls:
	-- check the biome
	if spawn_def.biomes and not biome_check(spawn_def.biomes, get_biome_name(pos)) then return end
	-- check if there is enough room
	local mob_def = minetest.registered_entities[spawn_def.name]
	if not has_room(mob_def,pos) then return end
	-- additional checks (slime etc.)
	if spawn_def.check_position and not spawn_def.check_position(pos) then return end
	if spawn_protected and minetest.is_protected(pos, "") then return end
	mcl_log("spawn_check#2 advanced checks passed")

	-- check light thresholds
	local gotten_light = get_node_light(pos)
	-- old lighting
	if not modern_lighting then return gotten_light >= spawn_def.min_light and gotten_light <= spawn_def.max_light end

	local sky_light = minetest.get_natural_light(pos)
	local art_light = minetest.get_artificial_light(get_node(pos).param1)
	if mob_def.spawn_check then
		return mob_def.spawn_check(pos, gotten_light, art_light, sky_light)
	end
	if mob_def.type == "monster" then
		if dimension == "nether" then
			if art_light <= nether_threshold then
				return true
			end
		elseif dimension == "end" then
			if art_light <= end_threshold then
				return true
			end
		elseif dimension == "overworld" then
			if art_light <= overworld_threshold and sky_light <= overworld_sky_threshold then
				return true
			end
		end
		return false
	end
	-- passive threshold is apparently the same in all dimensions ...
	return gotten_light > overworld_passive_threshold
end

function mcl_mobs.spawn(pos,id)
	if not pos or not id then return false end
	local def = minetest.registered_entities[id] or minetest.registered_entities["mobs_mc:"..id] or minetest.registered_entities["extra_mobs:"..id]
	if not def or not def.is_mob or (def.can_spawn and not def.can_spawn(pos)) then return false end
	if not has_room(def, pos) then return false end
	return minetest.add_entity(pos, def.name)
end

local function spawn_group(p,mob,spawn_on,amount_to_spawn)
	local nn= minetest.find_nodes_in_area_under_air(vector.offset(p,-5,-3,-5),vector.offset(p,5,3,5),spawn_on)
	local o
	table.shuffle(nn)
	if not nn or #nn < 1 then
		nn = {}
		table.insert(nn,p)
	end

	for i = 1, amount_to_spawn do
		local sp = vector.offset(nn[math.random(#nn)],0,1,0)
		if spawn_check(nn[math.random(#nn)],mob) then
			if mob.type_of_spawning == "water" then
				sp = get_water_spawn(sp)
			end
			o =  mcl_mobs.spawn(sp,mob.name)
			if o then dbg_spawn_succ = dbg_spawn_succ + 1 end
		end
	end
	return o
end

mcl_mobs.spawn_group = spawn_group

minetest.register_chatcommand("spawn_mob",{
	privs = { debug = true },
	description=S("spawn_mob is a chatcommand that allows you to type in the name of a mob without 'typing mobs_mc:' all the time like so; 'spawn_mob spider'. however, there is more you can do with this special command, currently you can edit any number, boolean, and string variable you choose with this format: spawn_mob 'any_mob:var<mobs_variable=variable_value>:'. any_mob being your mob of choice, mobs_variable being the variable, and variable value being the value of the chosen variable. and example of this format: \n spawn_mob skeleton:var<passive=true>:\n this would spawn a skeleton that wouldn't attack you. REMEMBER-THIS> when changing a number value always prefix it with 'NUM', example: \n spawn_mob skeleton:var<jump_height=NUM10>:\n this setting the skelly's jump height to 10. if you want to make multiple changes to a mob, you can, example: \n spawn_mob skeleton:var<passive=true>::var<jump_height=NUM10>::var<fly_in=air>::var<fly=true>:\n etc."),
	func = function(n,param)
		local pos = minetest.get_player_by_name(n):get_pos()

		local modifiers = {}
		for capture in string.gmatch(param, "%:(.-)%:") do
			table.insert(modifiers, ":"..capture)
		end

		local mod1 = string.find(param, ":")



		local mobname = param
		if mod1 then
			mobname = string.sub(param, 1, mod1-1)
		end

		local mob = mcl_mobs.spawn(pos,mobname)

		if mob then
			for c=1, #modifiers do
				modifs = modifiers[c]

				local mod1 = string.find(modifs, ":")
				local mod_start = string.find(modifs, "<")
				local mod_vals = string.find(modifs, "=")
				local mod_end = string.find(modifs, ">")
				local mob_entity = mob:get_luaentity()
				if string.sub(modifs, mod1+1, mod1+3) == "var" then
					if mod1 and mod_start and mod_vals and mod_end then
						local variable = string.sub(modifs, mod_start+1, mod_vals-1)
						local value = string.sub(modifs, mod_vals+1, mod_end-1)

						number_tag = string.find(value, "NUM")
						if number_tag then
							value = tonumber(string.sub(value, 4, -1))
						end

						if value == "true" then
							value = true
						elseif value == "false" then
							value = false
						end

						if not mob_entity[variable] then
							minetest.log("warning", n.." mob variable "..variable.." previously unset")
						end

						mob_entity[variable] = value

					else
						minetest.log("warning", n.." couldn't modify "..mobname.." at "..minetest.pos_to_string(pos).. ", missing paramaters")
					end
				else
					minetest.log("warning", n.." couldn't modify "..mobname.." at "..minetest.pos_to_string(pos).. ", missing modification type")
				end
			end

			minetest.log("action", n.." spawned "..mobname.." at "..minetest.pos_to_string(pos))
			return true, mobname.." spawned at "..minetest.pos_to_string(pos)
		else
			return false, "Couldn't spawn "..mobname
		end
	end
})

if mobs_spawn then

	-- Get pos to spawn, x and z are randomised, y is range


	local function mob_cap_space (pos, mob_type, mob_counts_close, mob_counts_wide, cap_space_hostile, cap_space_non_hostile)

		-- Some mob examples
		--type = "monster", spawn_class = "hostile",
		--type = "animal", spawn_class = "passive",
		--local cod = { type = "animal", spawn_class = "water",

		local type_cap = mob_cap[mob_type] or MISSING_CAP_DEFAULT
		local close_zone_cap = MOBS_CAP_CLOSE

		local mob_total_wide = mob_counts_wide[mob_type]
		if not mob_total_wide then
			--mcl_log("none of type found. set as 0")
			mob_total_wide = 0
		end

		local cap_space_wide = math_max(type_cap - mob_total_wide, 0)

		mcl_log("mob_type", mob_type)
		mcl_log("cap_space_wide", cap_space_wide)

		local cap_space_available = 0
		if mob_type == "hostile" then
			mcl_log("cap_space_global", cap_space_hostile)
			cap_space_available = math_min(cap_space_hostile, cap_space_wide)
		else
			mcl_log("cap_space_global", cap_space_non_hostile)
			cap_space_available = math_min(cap_space_non_hostile, cap_space_wide)
		end

		local mob_total_close = mob_counts_close[mob_type]
		if not mob_total_close then
			--mcl_log("none of type found. set as 0")
			mob_total_close = 0
		end

		local cap_space_close = math_max(close_zone_cap - mob_total_close, 0)
		cap_space_available = math_min(cap_space_available, cap_space_close)

		mcl_log("cap_space_close", cap_space_close)
		mcl_log("cap_space_available", cap_space_available)

		if false and mob_type == "water" then
			mcl_log("mob_type: " .. mob_type .. " and pos: " .. minetest.pos_to_string(pos))
			mcl_log("wide: " .. mob_total_wide .. "/" .. type_cap)
			mcl_log("cap_space_wide: " .. cap_space_wide)
			mcl_log("close: " .. mob_total_close .. "/" .. close_zone_cap)
			mcl_log("cap_space_close: " .. cap_space_close)
		end

		return cap_space_available
	end

	local function find_spawning_position(pos, max_times)
		local spawning_position
		local max_loops = max_times or 1

		--mcl_log("mapgen_limit: " .. SPAWN_MAPGEN_LIMIT)
		while max_loops > 0 do
			local spawning_position = get_next_mob_spawn_pos(pos)
			if spawning_position then return spawning_position end
			max_loops = max_loops - 1

		end
		return nil
	end

	local cumulative_chance = nil
	local mob_library_worker_table = nil
	local function initialize_spawn_data()
		if not mob_library_worker_table then
			mob_library_worker_table = table_copy(spawn_dictionary)
		end
		if not cumulative_chance then
			cumulative_chance = 0
			for k, v in pairs(mob_library_worker_table) do
				cumulative_chance = cumulative_chance + v.chance
			end
		end
	end

	local function spawn_a_mob(pos, cap_space_hostile, cap_space_non_hostile)

		local spawning_position = find_spawning_position(pos, FIND_SPAWN_POS_RETRIES)
		if not spawning_position then
			minetest.log("action", "[Mobs spawn] Cannot find a valid spawn position after retries: " .. FIND_SPAWN_POS_RETRIES)
			return
		end

		local mob_counts_close, mob_counts_wide, total_mobs = count_mobs_all("spawn_class", spawning_position)
		--output_mob_stats(mob_counts_close, total_mobs)
		--output_mob_stats(mob_counts_wide)

		--grab mob that fits into the spawning location
		--use random weighted choice with replacement to grab a mob, don't exclude any possibilities
		--shuffle table once every loop to provide equal inclusion probability to all mobs
		--repeat grabbing a mob to maintain existing spawn rates
		local spawn_loop_counter = #mob_library_worker_table

		while spawn_loop_counter > 0 do
			table.shuffle(mob_library_worker_table)
			local mob_chance_offset = math_random(1, cumulative_chance)
			local mob_index = 1
			local mob_chance = mob_library_worker_table[mob_index].chance
			local step_chance = mob_chance
			while step_chance < mob_chance_offset do
				mob_index = mob_index + 1
				if mob_index <= #mob_library_worker_table then
					mob_chance = mob_library_worker_table[mob_index].chance
					step_chance = step_chance + mob_chance
				else
					break
				end
			end
			--minetest.log(mob_def.name.." "..step_chance.. " "..mob_chance)

			local mob_def = mob_library_worker_table[mob_index]
			if mob_def and mob_def.name and minetest.registered_entities[mob_def.name] then

				local mob_def_ent = minetest.registered_entities[mob_def.name]
				local mob_spawn_class = mob_def_ent.spawn_class

				local cap_space_available = mob_cap_space (spawning_position, mob_spawn_class, mob_counts_close, mob_counts_wide, cap_space_hostile, cap_space_non_hostile)

				if cap_space_available > 0 then
					--mcl_log("Cap space available")

					-- Spawn caps for animals and water creatures fill up rapidly. Need to throttle this somewhat
					-- for performance and for early game challenge. We don't want to reduce hostiles though.
					local spawn_hostile = (mob_spawn_class == "hostile")
					local spawn_passive = (mob_spawn_class ~= "hostile") and math.random(100) < peaceful_percentage_spawned

					--mcl_log("Spawn_passive: " .. tostring(spawn_passive))
					--mcl_log("Spawn_hostile: " .. tostring(spawn_hostile))

					if (spawn_hostile or spawn_passive) and spawn_check(spawning_position,mob_def) then
						if mob_def.type_of_spawning == "water" then
							spawning_position = get_water_spawn(spawning_position)
							if not spawning_position then
								minetest.log("warning","[mcl_mobs] no water spawn for mob "..mob_def.name.." found at "..minetest.pos_to_string(vector.round(pos)))
								return
							end
						end
						if mob_def_ent.can_spawn and not mob_def_ent.can_spawn(spawning_position) then
							minetest.log("warning","[mcl_mobs] mob "..mob_def.name.." refused to spawn at "..minetest.pos_to_string(vector.round(spawning_position)))
							return
						end

						--everything is correct, spawn mob
						local spawn_in_group = mob_def_ent.spawn_in_group or 4

						local spawn_group_hostile = (mob_spawn_class == "hostile") and (math.random(100) < hostile_group_percentage_spawned)
						local spawn_group_passive = (mob_spawn_class ~= "hostile") and (math.random(100) < peaceful_group_percentage_spawned)

						mcl_log("spawn_group_hostile: " .. tostring(spawn_group_hostile))
						mcl_log("spawn_group_passive: " .. tostring(spawn_group_passive))

						local spawned
						if spawn_in_group and (spawn_group_hostile or spawn_group_passive) then
							local group_min = mob_def_ent.spawn_in_group_min or 1
							if not group_min then group_min = 1 end

							local amount_to_spawn = math.random(group_min, spawn_in_group)
							mcl_log("Spawning quantity: " .. amount_to_spawn)
							amount_to_spawn = math_min(amount_to_spawn, cap_space_available)
							mcl_log("throttled spawning quantity: " .. amount_to_spawn)

							if logging then
								minetest.log("action", "[mcl_mobs] A group of " ..amount_to_spawn .. " " .. mob_def.name .. " mob spawns on " ..minetest.get_node(vector.offset(spawning_position,0,-1,0)).name .." at " .. minetest.pos_to_string(spawning_position, 1))
							end
							spawned = spawn_group(spawning_position,mob_def,{minetest.get_node(vector.offset(spawning_position,0,-1,0)).name}, amount_to_spawn)
						else
							if logging then
								minetest.log("action", "[mcl_mobs] Mob " .. mob_def.name .. " spawns on " ..minetest.get_node(vector.offset(spawning_position,0,-1,0)).name .." at ".. minetest.pos_to_string(spawning_position, 1))
							end
							spawned = mcl_mobs.spawn(spawning_position, mob_def.name)
						end

						if spawned then
							--mcl_log("We have spawned")
							mob_counts_close, mob_counts_wide, total_mobs = count_mobs_all("spawn_class", pos)
							local new_spawning_position = find_spawning_position(pos, FIND_SPAWN_POS_RETRIES_SUCCESS_RESPIN)
							if new_spawning_position then
								mcl_log("Setting new spawning position")
								spawning_position = new_spawning_position
							else
								mcl_log("Cannot set new spawning position")
							end
						end
					else
						--mcl_log("Spawn check failed")
					end
				else
					--mcl_log("Cap space full")
				end

			end
			spawn_loop_counter = spawn_loop_counter - 1
		end
	end


	--MAIN LOOP

	local timer = 0
	minetest.register_globalstep(function(dtime)
		if not gamerule_doMobSpawning[1] then return end

		timer = timer + dtime
		if timer < WAIT_FOR_SPAWN_ATTEMPT then return end
		initialize_spawn_data()
		timer = 0

		local players = get_connected_players()
		local total_mobs, total_non_hostile, total_hostile = count_mobs_total_cap()

		local cap_space_hostile = math_max(mob_cap.global_hostile - total_hostile, 0)
		local cap_space_non_hostile =  math_max(mob_cap.global_non_hostile - total_non_hostile, 0)
		mcl_log("global cap_space_hostile", cap_space_hostile)
		mcl_log("global cap_space_non_hostile", cap_space_non_hostile)

		if total_mobs > mob_cap.total or total_mobs > #players * mob_cap.player then
			minetest.log("action","[mcl_mobs] global mob cap reached. no cycle spawning.")
			return
		end --mob cap per player

		for _, player in pairs(players) do
			local pos = player:get_pos()
			local dimension = mcl_worlds.pos_to_dimension(pos)
			-- ignore void and unloaded area
			if dimension ~= "void" and dimension ~= "default" then
				spawn_a_mob(pos, cap_space_hostile, cap_space_non_hostile)
			end
		end
	end)
end

local function despawn_allowed(self)
	local nametag = self.nametag and self.nametag ~= ""
	local not_busy = self.state ~= "attack" and self.following == nil
	if self.can_despawn == true then
		if not nametag and not_busy and not self.tamed == true and not self.persistent == true then
			return true
		end
	end
	return false
end

function mob_class:despawn_allowed()
	despawn_allowed(self)
end


assert(despawn_allowed({can_despawn=false}) == false, "despawn_allowed - can_despawn false failed")
assert(despawn_allowed({can_despawn=true}) == true, "despawn_allowed - can_despawn true failed")

assert(despawn_allowed({can_despawn=true, nametag=""}) == true, "despawn_allowed - blank nametag failed")
assert(despawn_allowed({can_despawn=true, nametag=nil}) == true, "despawn_allowed - nil nametag failed")
assert(despawn_allowed({can_despawn=true, nametag="bob"}) == false, "despawn_allowed - nametag failed")

assert(despawn_allowed({can_despawn=true, state="attack"}) == false, "despawn_allowed - attack state failed")
assert(despawn_allowed({can_despawn=true, following="blah"}) == false, "despawn_allowed - following state failed")

assert(despawn_allowed({can_despawn=true, tamed=false}) == true, "despawn_allowed - not tamed")
assert(despawn_allowed({can_despawn=true, tamed=true}) == false, "despawn_allowed - tamed")

assert(despawn_allowed({can_despawn=true, persistent=true}) == false, "despawn_allowed - persistent")
assert(despawn_allowed({can_despawn=true, persistent=false}) == true, "despawn_allowed - not persistent")

function mob_class:check_despawn(pos, dtime)
	self.lifetimer = self.lifetimer - dtime

	-- Despawning: when lifetimer expires, remove mob
	if remove_far and despawn_allowed(self) then
		if self.despawn_immediately or self.lifetimer <= 0 then
			if logging then
				minetest.log("action", "[mcl_mobs] Mob "..self.name.." despawns at "..minetest.pos_to_string(pos, 1) .. " lifetimer ran out")
			end
			mcl_burning.extinguish(self.object)
			self.object:remove()
			return true
		elseif self.lifetimer <= 10 then
			if math.random(10) < 4 then
				self.despawn_immediately = true
			else
				self.lifetimer = 20
			end
		end
	end
end

minetest.register_chatcommand("mobstats",{
	privs = { debug = true },
	func = function(n,param)
		local pos = minetest.get_player_by_name(n):get_pos()
		minetest.chat_send_player(n,"mobs: within 32 radius of player/total loaded :"..count_mobs(pos,MOB_CAP_INNER_RADIUS) .. "/" .. count_mobs_total())
		minetest.chat_send_player(n,"spawning attempts since server start:" .. dbg_spawn_succ .. "/" .. dbg_spawn_attempts)

		local mob_counts_close, mob_counts_wide, total_mobs = count_mobs_all("name") -- Can use "type"
		output_mob_stats(mob_counts_wide, total_mobs, true)
	end
})