--lua locals
local get_node                     = minetest.get_node
local get_item_group               = minetest.get_item_group
local get_node_light               = minetest.get_node_light
local find_nodes_in_area_under_air = minetest.find_nodes_in_area_under_air
local 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 minetest_get_perlin          = minetest.get_perlin

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_round     = function(x) return (x > 0) and math_floor(x + 0.5) or math_ceil(x - 0.5) end

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

-- range for mob count
local aoc_range = 136

local mob_cap = {
	monster = 70,
	animal =10,
	ambient =15,
	water = 5, --currently unused
	water_ambient = 20, --currently unused
}

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


local noise_params = {
	offset = 0,
	scale  = 3,
	spread = {
		x = 301,
		y = 50,
		z = 304,
	},
	seed = 100,
	octaves = 3,
	persistence = 0.5,
}

-- THIS IS THE BIG LIST OF ALL BIOMES - used for programming/updating mobs
-- Also used for missing parameter
-- Please update the list when adding new biomes!

local list_of_all_biomes = {

	-- underground:

	"FlowerForest_underground",
	"JungleEdge_underground",
	"ColdTaiga_underground",
	"IcePlains_underground",
	"IcePlainsSpikes_underground",
	"MegaTaiga_underground",
	"Taiga_underground",
	"ExtremeHills+_underground",
	"JungleM_underground",
	"ExtremeHillsM_underground",
	"JungleEdgeM_underground",

	-- ocean:

	"RoofedForest_ocean",
	"JungleEdgeM_ocean",
	"BirchForestM_ocean",
	"BirchForest_ocean",
	"IcePlains_deep_ocean",
	"Jungle_deep_ocean",
	"Savanna_ocean",
	"MesaPlateauF_ocean",
	"ExtremeHillsM_deep_ocean",
	"Savanna_deep_ocean",
	"SunflowerPlains_ocean",
	"Swampland_deep_ocean",
	"Swampland_ocean",
	"MegaSpruceTaiga_deep_ocean",
	"ExtremeHillsM_ocean",
	"JungleEdgeM_deep_ocean",
	"SunflowerPlains_deep_ocean",
	"BirchForest_deep_ocean",
	"IcePlainsSpikes_ocean",
	"Mesa_ocean",
	"StoneBeach_ocean",
	"Plains_deep_ocean",
	"JungleEdge_deep_ocean",
	"SavannaM_deep_ocean",
	"Desert_deep_ocean",
	"Mesa_deep_ocean",
	"ColdTaiga_deep_ocean",
	"Plains_ocean",
	"MesaPlateauFM_ocean",
	"Forest_deep_ocean",
	"JungleM_deep_ocean",
	"FlowerForest_deep_ocean",
	"MushroomIsland_ocean",
	"MegaTaiga_ocean",
	"StoneBeach_deep_ocean",
	"IcePlainsSpikes_deep_ocean",
	"ColdTaiga_ocean",
	"SavannaM_ocean",
	"MesaPlateauF_deep_ocean",
	"MesaBryce_deep_ocean",
	"ExtremeHills+_deep_ocean",
	"ExtremeHills_ocean",
	"MushroomIsland_deep_ocean",
	"Forest_ocean",
	"MegaTaiga_deep_ocean",
	"JungleEdge_ocean",
	"MesaBryce_ocean",
	"MegaSpruceTaiga_ocean",
	"ExtremeHills+_ocean",
	"Jungle_ocean",
	"RoofedForest_deep_ocean",
	"IcePlains_ocean",
	"FlowerForest_ocean",
	"ExtremeHills_deep_ocean",
	"MesaPlateauFM_deep_ocean",
	"Desert_ocean",
	"Taiga_ocean",
	"BirchForestM_deep_ocean",
	"Taiga_deep_ocean",
	"JungleM_ocean",

	-- water or beach?

	"MesaPlateauFM_sandlevel",
	"MesaPlateauF_sandlevel",
	"MesaBryce_sandlevel",
	"Mesa_sandlevel",

	-- beach:

	"FlowerForest_beach",
	"Forest_beach",
	"StoneBeach",
	"ColdTaiga_beach_water",
	"Taiga_beach",
	"Savanna_beach",
	"Plains_beach",
	"ExtremeHills_beach",
	"ColdTaiga_beach",
	"Swampland_shore",
	"MushroomIslandShore",
	"JungleM_shore",
	"Jungle_shore",

	-- dimension biome:

	"Nether",
	"BasaltDelta",
	"CrimsonForest",
	"WarpedForest",
	"SoulsandValley",
	"End",

	-- Overworld regular:

	"Mesa",
	"FlowerForest",
	"Swampland",
	"Taiga",
	"ExtremeHills",
	"Jungle",
	"Savanna",
	"BirchForest",
	"MegaSpruceTaiga",
	"MegaTaiga",
	"ExtremeHills+",
	"Forest",
	"Plains",
	"Desert",
	"ColdTaiga",
	"MushroomIsland",
	"IcePlainsSpikes",
	"SunflowerPlains",
	"IcePlains",
	"RoofedForest",
	"ExtremeHills+_snowtop",
	"MesaPlateauFM_grasstop",
	"JungleEdgeM",
	"ExtremeHillsM",
	"JungleM",
	"BirchForestM",
	"MesaPlateauF",
	"MesaPlateauFM",
	"MesaPlateauF_grasstop",
	"MesaBryce",
	"JungleEdge",
	"SavannaM",
}

-- 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


-- 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 = {}
local summary_chance = 0

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 list_of_all_biomes
	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,
	}
	summary_chance = summary_chance + chance
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)

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

	-- 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

	summary_chance = summary_chance + chance
end

local two_pi = 2 * math.pi
local function get_next_mob_spawn_pos(pos)
	local distance = math_random(25, 32)
	local angle = math_random() * two_pi
	return {
		x = math_round(pos.x + distance * math_cos(angle)),
		y = pos.y,
		z = math_round(pos.z + distance * math_sin(angle))
	}
end

local function decypher_limits(posy)
	posy = math_floor(posy)
	return posy - 32, posy + 32
end

--a simple helper function for mob_spawn
local function biome_check(biome_list, biome_goal)
	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 dbg_spawn_attempts = 0
local dbg_spawn_succ = 0

local function spawn_group(p,mob,spawn_on,group_max,group_min)
	if not group_min then group_min = 1 end
	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
	if not nn or #nn < 1 then
		nn = {}
		table.insert(nn,p)
	end
	for i = 1, math.random(group_min,group_max) do
		local sp = vector.offset(nn[math.random(#nn)],0,1,0)
		if mob.type_of_spawning == "water" then
			sp = get_water_spawn(sp)
		end
		o = minetest.add_entity(sp,mob.name)
		if o then dbg_spawn_succ = dbg_spawn_succ + 1 end
	end
	return o
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:"..count_mobs(pos,32))
		minetest.chat_send_player(n,"total mobs:"..count_mobs_total())
		minetest.chat_send_player(n,"spawning attempts since server start:"..dbg_spawn_attempts)
		minetest.chat_send_player(n,"successful spawns since server start:"..dbg_spawn_succ)
	end
})

if mobs_spawn then

	local perlin_noise

	local function spawn_a_mob(pos, dimension, y_min, y_max)
		dbg_spawn_attempts = dbg_spawn_attempts + 1
		local dimension = dimension or mcl_worlds.pos_to_dimension(pos)
		local goal_pos = get_next_mob_spawn_pos(pos)
		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"}
		)
		if #spawning_position_list <= 0 then return end
		local spawning_position = spawning_position_list[math_random(1, #spawning_position_list)]

		local gotten_node = get_node(spawning_position).name
		local gotten_biome = minetest.get_biome_data(spawning_position)
		if not gotten_node or not gotten_biome then return end
		gotten_biome = get_biome_name(gotten_biome.biome) --makes it easier to work with

		--add this so mobs don't spawn inside nodes
		spawning_position.y = spawning_position.y + 1

		--only need to poll for node light if everything else worked
		local gotten_light = get_node_light(spawning_position)

		local is_water = get_item_group(gotten_node, "water") ~= 0
		local is_lava  = get_item_group(gotten_node, "lava") ~= 0
		local is_leaf  = get_item_group(gotten_node, "leaves") ~= 0
		local is_bedrock  = gotten_node == "mcl_core:bedrock"
		local is_ground = not (is_water or is_lava)
		local is_grass = minetest.get_item_group(gotten_node,"grass_block") ~= 0
		local has_bed = minetest.find_node_near(pos,25,{"group:bed"})

		if not is_ground then
			spawning_position.y = spawning_position.y - 1
		end

		local mob_def

		--create a disconnected clone of the spawn dictionary
		--prevents memory leak
		local mob_library_worker_table = table_copy(spawn_dictionary)

		--grab mob that fits into the spawning location
		--randomly grab a mob, don't exclude any possibilities
		perlin_noise = perlin_noise or minetest_get_perlin(noise_params)
		local noise = perlin_noise:get_3d(spawning_position)
		local current_summary_chance = summary_chance
		table.shuffle(mob_library_worker_table)
		while #mob_library_worker_table > 0 do
			local mob_chance_offset = (math_round(noise * current_summary_chance + 12345) % current_summary_chance) + 1
			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
				mob_chance = mob_library_worker_table[mob_index].chance
				step_chance = step_chance + mob_chance
			end
			local mob_def = mob_library_worker_table[mob_index]
			local mob_type = minetest.registered_entities[mob_def.name].type
			local spawn_in_group = minetest.registered_entities[mob_def.name].spawn_in_group or 4
			local mob_count_wide = count_mobs(pos,aoc_range,mob_type)
			local mob_count = count_mobs(spawning_position,32,mob_type)
			if mob_def
				and mob_count_wide < (mob_cap[mob_type] or 15)
				and mob_count < 5
				and spawning_position.y >= mob_def.min_height
				and spawning_position.y <= mob_def.max_height
				and mob_def.dimension == dimension
				and biome_check(mob_def.biomes, gotten_biome)
				and gotten_light >= mob_def.min_light
				and gotten_light <= mob_def.max_light
				and (is_ground or mob_def.type_of_spawning ~= "ground")
				and (mob_def.type_of_spawning ~= "ground" or not is_leaf)
				and (mob_def.check_position and mob_def.check_position(spawning_position) or true)
				and (not is_farm_animal(mob_def.name) or is_grass)
				and (mob_type ~= "npc" or has_bed)
				and (mob_def.type_of_spawning ~= "water" or is_water)
				and not is_bedrock
				then
					if mob_def.type_of_spawning == "water" then
						spawning_position = get_water_spawn(spawning_position)
						if not spawning_position then
							return
						end
					end
					--everything is correct, spawn mob
					local object
					if spawn_in_group then
						object = spawn_group(spawning_position,mob_def,{gotten_node},spawn_in_group,spawn_in_group_min)
					else object = minetest.add_entity(spawning_position, mob_def.name)
					end


					if object then
						return mob_def.on_spawn and mob_def.on_spawn(object, spawning_position)
					end
			end
			current_summary_chance = current_summary_chance - mob_chance
			table_remove(mob_library_worker_table, mob_index)
		end
	end


	--MAIN LOOP

	local timer = 0
	minetest.register_globalstep(function(dtime)
		timer = timer + dtime
		if timer < 10 then return end
		timer = 0
		for _, player in pairs(get_connected_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
				local y_min, y_max = decypher_limits(pos.y)
				for i = 1, math_random(1, 4) do
					spawn_a_mob(pos, dimension, y_min, y_max)
				end
			end
		end
	end)
end