debug.lua

local debug_enabled_players = {}
local hud_data = {}

minetest.register_chatcommand("cityblock_debug", {
	func = function(name, param)
		local player = minetest.get_player_by_name(name)
		if not player then
			return false, "player not found"
		end

        if param == "on" then
            debug_enabled_players[name] = true
            return true, "Debug enabled"
        else
            debug_enabled_players[name] = false
            return true, "Debug disabled"
        end
	end
})

local function setup_hud(player, name)
    local data = {}
    hud_data[name] = data
    data.debug_txt = player:hud_add({
        hud_elem_type = "text",
        position = { x=0.5, y=0.5 },
        text = "Initializing..."
    })
end

local function remove_hud(player, name)
    local data = hud_data[name]
    if data then
        player:hud_remove(data.debug_txt)
    end
    hud_data[name] = nil
end

local function update_hud(player, data)
    local pos = player:get_pos()

    local mapblock_pos = mapblock_lib.get_mapblock(pos)
    local cityblock_data = citygen.get_cityblock_mapblock(mapblock_pos)

    player:hud_change(data.debug_txt, "text", dump(cityblock_data))
end

local function debug_worker()
    for _, player in ipairs(minetest.get_connected_players()) do
        local name = player:get_player_name()

        if debug_enabled_players[name] and not hud_data[name] then
            setup_hud(player, name)
        elseif debug_enabled_players[name] and hud_data[name] then
            update_hud(player, hud_data[name])
        elseif not debug_enabled_players[name] and hud_data[name] then
            remove_hud(player, name)
        end
    end

    minetest.after(1, debug_worker)
end

minetest.register_on_leaveplayer(remove_hud)
minetest.after(1, debug_worker)