techage/basic_machines/forceload.lua

--[[

	TechAge
	=======

	Copyright (C) 2019 Joachim Stolberg

	GPL v3
	See LICENSE.txt for more information

	Forceload  block
	
]]--

-- for lazy programmers
local M = minetest.get_meta
local P2S = function(pos) if pos then return minetest.pos_to_string(pos) end end
local S = techage.S

local function calc_area(pos)
	local xpos = (math.floor(pos.x / 16) * 16)
	local ypos = (math.floor(pos.y / 16) * 16)
	local zpos = (math.floor(pos.z / 16) * 16)
	local pos1 = {x=xpos, y=ypos, z=zpos}
	local pos2 = {x=xpos+15, y=ypos+15, z=zpos+15}
	return pos1, pos2
end

local function in_list(list, x)
	local pos1 = calc_area(x)
	for _,v in ipairs(list) do
		local pos2 = calc_area(v)
		if vector.equals(pos1, pos2) then return true end
	end
	return false
end

local function remove_list_elem(list, x)
	local n = nil
	for idx, v in ipairs(list) do
		if vector.equals(v, x) then 
			n = idx
			break
		end
	end
	if n then
		table.remove(list, n)
	end
	return list
end

local function chat(player, text)
	minetest.chat_send_player(player:get_player_name(), "[Techage] "..text)
end

local function add_pos(pos, player)
	local lPos = minetest.deserialize(player:get_attribute("techage_forceload_blocks")) or {}
	if not in_list(lPos, pos) and (#lPos < techage.max_num_forceload_blocks or
				creative and creative.is_enabled_for and 
				creative.is_enabled_for(player:get_player_name())) then
		lPos[#lPos+1] = pos
		player:set_attribute("techage_forceload_blocks", minetest.serialize(lPos))
		return true
	end
	return false
end
	
local function del_pos(pos, player)
	local lPos = minetest.deserialize(player:get_attribute("techage_forceload_blocks")) or {}
	lPos = remove_list_elem(lPos, pos)
	player:set_attribute("techage_forceload_blocks", minetest.serialize(lPos))
end

local function get_pos_list(player)
	return minetest.deserialize(player:get_attribute("techage_forceload_blocks")) or {}
end

local function set_pos_list(player, lPos)
	player:set_attribute("techage_forceload_blocks", minetest.serialize(lPos))
end

local function get_data(pos, player)
	local pos1, pos2 = calc_area(pos)
	local num = #minetest.deserialize(player:get_attribute("techage_forceload_blocks")) or 0
	local max = techage.max_num_forceload_blocks
	return pos1, pos2, num, max
end

local function formspec(player)
	local lPos = get_pos_list(player)
	local tRes = {}
	for idx,pos in ipairs(lPos) do
		local pos1, pos2 = calc_area(pos)
		local ypos = 0.2 + idx * 0.4
		tRes[#tRes+1] = idx
		tRes[#tRes+1] = minetest.formspec_escape(P2S(pos1))
		tRes[#tRes+1] = "to"
		tRes[#tRes+1] = minetest.formspec_escape(P2S(pos2))
	end
	return "size[7,9]"..
		default.gui_bg..
		default.gui_bg_img..
		default.gui_slots..
		"label[0,0;List of your Forceload Blocks:]"..
		"tablecolumns[text,width=1.2;text,width=12;text,width=1.6;text,width=12]"..
		"table[0,0.6;6.8,8.4;output;"..table.concat(tRes, ",")..";1]"
end


minetest.register_node("techage:forceload", {
	description = "Techage Forceload Block",
	tiles = {
		-- up, down, right, left, back, front
		'techage_filling_ta2.png^techage_frame_ta2_top.png',
		'techage_filling_ta2.png^techage_frame_ta2_top.png',
		{
			image = "techage_filling_ta2.png^techage_frame_ta2_top.png^techage_appl_forceload.png",
			backface_culling = false,
			animation = {
				type = "vertical_frames",
				aspect_w = 32,
				aspect_h = 32,
				length = 0.5,
			},
		},
	},

	after_place_node = function(pos, placer, itemstack)
		if add_pos(pos, placer) then
			minetest.forceload_block(pos, true)
			local pos1, pos2, num, max = get_data(pos, placer)
			M(pos):set_string("infotext", "Area "..P2S(pos1).." to "..P2S(pos2).." loaded!\n"..
				"Punch the block to make the area visible.")
			chat(placer, "Area ("..num.."/"..max..") "..P2S(pos1).." to "..P2S(pos2).." loaded!")
			techage.mark_region(placer:get_player_name(), pos1, pos2)
			M(pos):set_string("owner", placer:get_player_name())
		else
			chat(placer, "Area already loaded or max. number of Forceload Blocks reached!")
			minetest.remove_node(pos)
			return itemstack
		end
	end,

	after_dig_node = function(pos, oldnode, oldmetadata, digger)
		local player = minetest.get_player_by_name(oldmetadata.fields.owner)
		if player then
			del_pos(pos, player)
		end
		minetest.forceload_free_block(pos, true)
		techage.unmark_region(oldmetadata.fields.owner)
	end,
	
	on_rightclick = function(pos, node, clicker, itemstack, pointed_thing)
		if M(pos):get_string("owner") == clicker:get_player_name() or
				minetest.check_player_privs(clicker:get_player_name(), "server") then
			local s = formspec(clicker)
			minetest.show_formspec(clicker:get_player_name(), "techage:forceload", s)
		end
	end,
	
	on_punch = function(pos, node, puncher, pointed_thing)
		local pos1, pos2 = calc_area(pos)
		techage.switch_region(puncher:get_player_name(), pos1, pos2)
	end,

	paramtype = "light",
	sunlight_propagates = true,
	groups = {choppy=2, cracky=2, crumbly=2, 
		not_in_creative_inventory = techage.max_num_forceload_blocks == 0 and 1 or 0},
	is_ground_content = false,
	sounds = default.node_sound_wood_defaults(),
})


if techage.max_num_forceload_blocks > 0 then
	minetest.register_craft({
		output = "techage:forceload",
		recipe = {
			{"group:wood", "", "group:wood"},
			{"default:mese_crystal_fragment", "techage:usmium_nuggets", "default:mese_crystal_fragment"},
			{"group:wood", "techage:iron_ingot", "group:wood"},
		},
	})
end

minetest.register_on_joinplayer(function(player)
	local lPos = {}
	for _,pos in ipairs(get_pos_list(player)) do
		local node = techage.get_node_lvm(pos)
		if node.name == "techage:forceload" then
			minetest.forceload_block(pos, true)
			lPos[#lPos+1] = pos
		end
	end
	set_pos_list(player, lPos)
end)

minetest.register_on_leaveplayer(function(player)
	for _,pos in ipairs(get_pos_list(player)) do
		minetest.forceload_free_block(pos, true)
	end
end)