--code copied from Pilzadam's nether mod and edited

-- kills the player if he uses PilzAdam portal
local portal_target = nether.buildings+1
local nether_prisons = minetest.settings:get_bool("enable_damage")
local obsidian_portal_kills = nether_prisons and true
local mclike_portal = false

local abm_allowed
minetest.after(5, function()
	abm_allowed = true
end)

table.icontains = table.icontains or function(t, v)
	for _,i in ipairs(t) do
		if i == v then
			return true
		end
	end
	return false
end

local players_in_nether = {}
-- only get info from file if nether prisons
if nether_prisons then
	local file = io.open(minetest.get_worldpath()..'/nether_players', "r")
	if file then
		local contents = file:read('*all')
		io.close(file)
		if contents then
			players_in_nether = string.split(contents, " ")
		end
	end
end

local function save_nether_players()
	local output = ''
	for _,name in ipairs(players_in_nether) do
		output = output..name..' '
	end
	local f = io.open(minetest.get_worldpath()..'/nether_players', "w")
	f:write(output)
	io.close(f)
end

local update_background
if nether_prisons then
	function update_background(player, down)
		if down then
			player:set_sky({r=15, g=0, b=0}, "plain")
		else
			player:set_sky(nil, "regular")
		end
	end
else
	function update_background()end
end

-- returns nodename if area is generated, else calls generation function
local function generated_or_generate(pos)
	local name = minetest.get_node(pos).name
	if name ~= "ignore" then
		return name
	end
	minetest.get_voxel_manip():read_from_map(pos, pos)
	name = minetest.get_node_or_nil(pos)
	if not name then
		minetest.emerge_area(vector.subtract(pos, 80), vector.add(pos, 80))
		return false
	end
	return name.name
end

-- where the player appears after dying
local function get_player_died_target(player)
	local target = vector.add(player:getpos(), {x=math.random(-100,100), y=0, z=math.random(-100,100)})
	target.y = portal_target + math.random(4)
	return target
end

-- used for obsidian portal
local function obsidian_teleport(player, pname)
	minetest.chat_send_player(pname, "For any reason you arrived here. Type /nether_help to find out things like craft recipes.")
	if obsidian_portal_kills then
		player:set_hp(0)
		return true
	end
	if not mclike_portal then
		local target = vector.round(get_player_died_target(player))
		if generated_or_generate(target) then
			player:moveto(target)
			return true
		end
	end
	return false
end

-- teleports players to nether or helps it
local function player_to_nether(player, safe)
	local pname = player:get_player_name()
	if table.icontains(players_in_nether, pname) then
		return
	end
	players_in_nether[#players_in_nether+1] = pname
	save_nether_players()
	if not safe then
		minetest.chat_send_player(pname, "For any reason you arrived here. Type /nether_help to find out things like craft recipes.")
		player:set_hp(0)
		if not nether_prisons then
			player:moveto(get_player_died_target(player))
		end
	end
	update_background(player, true)
end

local function player_from_nether(player)
	local pname = player:get_player_name()
	local changes
	for n,i in ipairs(players_in_nether) do
		if i == pname then
			table.remove(players_in_nether, n)
			changes = true
		end
	end
	if changes then
		save_nether_players()
	end
	update_background(player)
end


local function player_exists(name)
	for _,player in pairs(minetest.get_connected_players()) do
		if player:get_player_name() == name then
			return true
		end
	end
	return false
end

-- Chatcommands (edited) written by sss
minetest.register_chatcommand("to_hell", {
	params = "[<player_name>]",
	description = "Send someone to hell",
	func = function(name, pname)
		if not minetest.check_player_privs(name, {nether=true}) then
			return false, "You need the nether priv to execute this chatcommand."
		end
		if not player_exists(pname) then
			pname = name
		end
		local player = minetest.get_player_by_name(pname)
		if not player then
			return false, "Something went wrong."
		end
		minetest.chat_send_player(pname, "Go to hell !!!")
		player_to_nether(player)
		return true, pname.." is now in the nether."
	end
})

minetest.register_chatcommand("from_hell", {
	params = "[<player_name>]",
	description = "Extract from hell",
	func = function(name, pname)
		if not minetest.check_player_privs(name, {nether=true}) then
			return false, "You need the nether priv to execute this chatcommand."
		end
		if not player_exists(pname) then
			pname = name
		end
		local player = minetest.get_player_by_name(pname)
		if not player then
			return false, "Something went wrong."
		end
		minetest.chat_send_player(pname, "You are free now")
		player_from_nether(player)
		local pos = player:getpos()
		player:moveto({x=pos.x, y=100, z=pos.z})
		return true, pname.." is now out of the nether."
	end
})


if nether_prisons then
	-- randomly set player position when he/she dies in nether
	minetest.register_on_respawnplayer(function(player)
		local pname = player:get_player_name()
		if not table.icontains(players_in_nether, pname) then
			return
		end
		local target = get_player_died_target(player)
		player:moveto(target)
		minetest.after(0, function(pname, target)
			-- fixes respawn bug
			local player = minetest.get_player_by_name(pname)
			if player then
				player:moveto(target)
			end
		end, pname, target)
		return true
	end)

	-- function for teleporting players where they belong to
	local function update_players()
		for _,player in pairs(minetest.get_connected_players()) do
			local pname = player:get_player_name()
			local ppos = player:getpos()
			if table.icontains(players_in_nether, pname) then
				if ppos.y > nether.start then
					player:moveto({x=ppos.x, y=portal_target, z=ppos.z})
					update_background(player, true)
					--[[minetest.kick_player(pname, "\n1. Maybe you were not allowed to teleport out of the nether."..
						"\n2. Maybe the server lagged."..
						"\n3. please rejoin")]]
				end
			elseif ppos.y < nether.start then
				update_background(player)
				player:moveto({x=ppos.x, y=20, z=ppos.z})
				--[[minetest.kick_player(pname, "\n1. Maybe you were not allowed to teleport to the nether."..
					"\n2. Maybe the server lagged."..
					"\n3. please rejoin")]]
			end
		end
	end

	-- the function delayer mod works similar to a scheduler
	local delay_function = minetest.delay_function or minetest.after
	local function tick()
		update_players()
		minetest.after(0.5, function() delay_function(1.5, tick) end)
	end
	tick()

	-- set background when player joins
	minetest.register_on_joinplayer(function(player)
		minetest.after(0, function(player)
			if player
			and player:getpos().y < nether.start then
				update_background(player, true)
			end
		end, player)
	end)
else
	-- test if player is in nether when he/she joins
	minetest.register_on_joinplayer(function(player)
		minetest.after(0, function(player)
			if player:getpos().y < nether.start then
				if not table.icontains(players_in_nether, pname) then
					players_in_nether[#players_in_nether+1] = pname
				end
				return
			end
			for i,name in pairs(players_in_nether) do
				if name == pname then
					players_in_nether[i] = nil
					return
				end
			end
		end, player)
	end)
end

-- removes the violet stuff from the obsidian portal
local function remove_portal_essence(pos)
	for z = -1,1 do
		for y = -2,2 do
			for x = -1,1 do
				local p = {x=pos.x+x, y=pos.y+y, z=pos.z+z}
				if minetest.get_node(p).name == "nether:portal" then
					minetest.remove_node(p)
				end
			end
		end
	end
end

-- change parts of the particledefinition instead of recreating it every time
local particledef = {
	amount = 32,
	time = 4,
	minvel = {x=0, y=1, z=0},
	maxvel = {x=0, y=2, z=0},
	minacc = {x=-0.5,y=-3,z=-0.3},
	maxacc = {x=0.5,y=-0.4,z=0.3},
	minexptime = 1,
	maxexptime = 1,
	minsize = 0.4,
	maxsize = 3,
	collisiondetection = true,
}

-- teleports player to neter (obsidian portal)
local function obsi_teleport_player(player, pos, target)
	local pname = player:get_player_name()
	if table.icontains(players_in_nether, pname) then
		return
	end

	local objpos = player:getpos()
	objpos.y = objpos.y+0.1 -- Fix some glitches at -8000
	if minetest.get_node(vector.round(objpos)).name ~= "nether:portal" then
		return
	end

	if not obsidian_teleport(player, pname) then
		-- e.g. ungenerated area
		return
	end

	players_in_nether[#players_in_nether+1] = pname
	save_nether_players()
	update_background(player, true)

	remove_portal_essence(pos)

	minetest.sound_play("nether_portal_usual", {to_player=pname, gain=1})
	--obj:setpos(target)
end

-- abm for particles of the obsidian portal essence and for teleporting
minetest.register_abm({
	nodenames = {"nether:portal"},
	interval = 1,
	chance = 2,
	catch_up = false,
	action = function(pos, node)
		if not abm_allowed then
			return
		end
		particledef.minpos = {x=pos.x-0.25, y=pos.y-0.5, z=pos.z-0.25}
		particledef.maxpos = {x=pos.x+0.25, y=pos.y+0.34, z=pos.z+0.25}
		particledef.texture = "nether_portal_particle.png^[transform"..math.random(0,7)
		minetest.add_particlespawner(particledef)
		for _,obj in pairs(minetest.get_objects_inside_radius(pos, 1)) do
			if obj:is_player() then
				local meta = minetest.get_meta(pos)
				local target = minetest.string_to_pos(meta:get_string("target"))
				if target then
					minetest.after(3, obsi_teleport_player, obj, pos, target)
				end
			end
		end
	end,
})

local function move_check(p1, max, dir)
	local p = {x=p1.x, y=p1.y, z=p1.z}
	local d = math.abs(max-p1[dir]) / (max-p1[dir])
	while p[dir] ~= max do
		p[dir] = p[dir] + d
		if minetest.get_node(p).name ~= "default:obsidian" then
			return false
		end
	end
	return true
end

local function check_portal(p1, p2)
	if p1.x ~= p2.x then
		if not move_check(p1, p2.x, "x") then
			return false
		end
		if not move_check(p2, p1.x, "x") then
			return false
		end
	elseif p1.z ~= p2.z then
		if not move_check(p1, p2.z, "z") then
			return false
		end
		if not move_check(p2, p1.z, "z") then
			return false
		end
	else
		return false
	end

	if not move_check(p1, p2.y, "y") then
		return false
	end
	if not move_check(p2, p1.y, "y") then
		return false
	end

	return true
end

-- tests if it's an obsidian portal
local function is_portal(pos)
	for d=-3,3 do
		for y=-4,4 do
			local px = {x=pos.x+d, y=pos.y+y, z=pos.z}
			local pz = {x=pos.x, y=pos.y+y, z=pos.z+d}
			if check_portal(px, {x=px.x+3, y=px.y+4, z=px.z}) then
				return px, {x=px.x+3, y=px.y+4, z=px.z}
			end
			if check_portal(pz, {x=pz.x, y=pz.y+4, z=pz.z+3}) then
				return pz, {x=pz.x, y=pz.y+4, z=pz.z+3}
			end
		end
	end
end

-- put here the function for creating a second portal
local create_second_portal
if mclike_portal then
	function create_second_portal(target)
		-- change target here
	end
end

-- adds the violet portal essence
local function make_portal(pos)
	local p1, p2 = is_portal(pos)
	if not p1
	or not p2 then
		print("[nether] something failed.")
		return false
	end

	local in_nether = p1.y < nether.start

	if in_nether
	and not mclike_portal then
		print("[nether] aborted, obsidian portals can't be used to get out")
		return
	end

	for d=1,2 do
	for y=p1.y+1,p2.y-1 do
		local p
		if p1.z == p2.z then
			p = {x=p1.x+d, y=y, z=p1.z}
		else
			p = {x=p1.x, y=y, z=p1.z+d}
		end
		if minetest.get_node(p).name ~= "air" then
			return false
		end
	end
	end

	local param2
	if p1.z == p2.z then
		param2 = 0
	else
		param2 = 1
	end

	local target = {x=p1.x, y=p1.y, z=p1.z}
	target.x = target.x + 1
	if in_nether then
		target.y = 0
		create_second_portal(target)
	else
		target.y = portal_target + math.random(4)
	end

	if not generated_or_generate(target)
	and mclike_portal then
		return false
	end

	for d=0,3 do
	for y=p1.y,p2.y do
		local p = {}
		if param2 == 0 then
			p = {x=p1.x+d, y=y, z=p1.z}
		else
			p = {x=p1.x, y=y, z=p1.z+d}
		end
		if minetest.get_node(p).name == "air" then
			minetest.set_node(p, {name="nether:portal", param2=param2})
		end
		local meta = minetest.get_meta(p)
		meta:set_string("p1", minetest.pos_to_string(p1))
		meta:set_string("p2", minetest.pos_to_string(p2))
		meta:set_string("target", minetest.pos_to_string(target))
	end
	end
	print("[nether] construction accepted.")
	return true
end

-- destroy the portal when destroying obsidian
minetest.override_item("default:obsidian", {
	on_destruct = function(pos)
		local meta = minetest.get_meta(pos)
		local p1 = minetest.string_to_pos(meta:get_string("p1"))
		local p2 = minetest.string_to_pos(meta:get_string("p2"))
		local target = minetest.string_to_pos(meta:get_string("target"))
		if not p1 or not p2 then
			return
		end
		for x=p1.x,p2.x do
		for y=p1.y,p2.y do
		for z=p1.z,p2.z do
			local nn = minetest.get_node({x=x,y=y,z=z}).name
			if nn == "default:obsidian" or nn == "nether:portal" then
				if nn == "nether:portal" then
					minetest.remove_node({x=x,y=y,z=z})
				end
				local m = minetest.get_meta({x=x,y=y,z=z})
				m:set_string("p1", "")
				m:set_string("p2", "")
				m:set_string("target", "")
			end
		end
		end
		end
		meta = minetest.get_meta(target)
		if not meta then
			return
		end
		p1 = minetest.string_to_pos(meta:get_string("p1"))
		p2 = minetest.string_to_pos(meta:get_string("p2"))
		if not p1 or not p2 then
			return
		end
		for x=p1.x,p2.x do
		for y=p1.y,p2.y do
		for z=p1.z,p2.z do
			local nn = minetest.get_node({x=x,y=y,z=z}).name
			if nn == "default:obsidian" or nn == "nether:portal" then
				if nn == "nether:portal" then
					minetest.remove_node({x=x,y=y,z=z})
				end
				local m = minetest.get_meta({x=x,y=y,z=z})
				m:set_string("p1", "")
				m:set_string("p2", "")
				m:set_string("target", "")
			end
		end
		end
		end
	end
})

-- override mese crystal fragment for making an obsidian portal
minetest.after(0.1, function()
	minetest.override_item("default:mese_crystal_fragment", {
		on_place = function(stack, player, pt)
			if pt.under
			and minetest.get_node(pt.under).name == "default:obsidian" then
				--print("[nether] tries to enable a portal")
				local done = make_portal(pt.under)
				if done then
					minetest.chat_send_player(
						player:get_player_name(),
						"Warning: If you are in the nether you may not be able to find the way out!"
					)
					if not minetest.settings:get_bool("creative_mode") then
						stack:take_item()
					end
				end
			end
			return stack
		end
	})
end)


-- a not filled square
vector.square = vector.square or
function(r)
	local tab, n = {}, 1
	for i = -r+1, r do
		for j = -1, 1, 2 do
			local a, b = r*j, i*j
			tab[n] = {a, b}
			tab[n+1] = {b, a}
			n=n+2
		end
	end
	return tab
end

-- detects if it's a portal
local function netherport(pos)
	local x, y, z = pos.x, pos.y, pos.z
	for _,i in pairs({-1, 3}) do
		if minetest.get_node({x=x, y=y+i, z=z}).name ~= "nether:white" then
			return
		end
	end
	for _,sn in pairs(vector.square(1)) do
		if minetest.get_node({x=x+sn[1], y=y-1, z=z+sn[2]}).name ~= "nether:netherrack"
		or minetest.get_node({x=x+sn[1], y=y+3, z=z+sn[2]}).name ~= "nether:blood_cooked" then
			return
		end
	end
	for _,sn in pairs(vector.square(2)) do
		if minetest.get_node({x=x+sn[1], y=y-1, z=z+sn[2]}).name ~= "nether:netherrack_black"
		or minetest.get_node({x=x+sn[1], y=y+3, z=z+sn[2]}).name ~= "nether:wood_empty" then
			return
		end
	end
	for i = -1,1,2 do
		for j = -1,1,2 do
			if minetest.get_node({x=x+i, y=y+2, z=z+j}).name ~= "nether:apple" then
				return
			end
		end
	end
	for i = -2,2,4 do
		for j = 0,2 do
			for k = -2,2,4 do
				if minetest.get_node({x=x+i, y=y+j, z=z+k}).name ~= "nether:netherrack_brick_blue" then
					return
				end
			end
		end
	end
	for i = -1,1 do
		for j = -1,1 do
			if minetest.get_node({x=x+i, y=y+4, z=z+j}).name ~= "nether:wood_empty" then
				return
			end
		end
	end
	return true
end

-- cache known portals
local known_portals_d = {}
local known_portals_u = {}
local function get_portal(t, z,x)
	return t[z] and t[z][x]
end
local function set_portal(t, z,x, y)
	t[z] = t[z] or {}
	t[z][x] = y
end

-- used when a player eats that fruit in a portal
function nether_port(player, pos)
	if not player
	or not pos
	or not pos.x then
		minetest.log("error", "[nether] nether_port: something failed.")
		return
	end
	if not netherport(pos) then
		return
	end
	minetest.sound_play("nether_teleporter", {pos=pos})
	local meta = minetest.get_meta({x=pos.x, y=pos.y-1, z=pos.z})
	if pos.y < nether.start then
		set_portal(known_portals_d, pos.z,pos.x, pos.y)
		player_from_nether(player)

		local my = tonumber(meta:get_string("y"))
		local y = get_portal(known_portals_u, pos.z,pos.x)
		if y then
			if y ~= my then
				meta:set_string("y", y)
			end
		else
			y = my or 100
		end
		pos.y = y

		player:moveto(pos)
	else
		set_portal(known_portals_u, pos.z,pos.x, pos.y)

		local my = tonumber(meta:get_string("y"))
		local y = get_portal(known_portals_d, pos.z,pos.x)
		if y then
			if y ~= my then
				meta:set_string("y", y)
			end
		else
			y = my or portal_target+math.random(4)
		end
		pos.y = y

		player:moveto(pos)
		player_to_nether(player, true)
	end
	minetest.sound_play("nether_teleporter", {pos=pos})
	return true
end