local mtver = minetest.get_version()
local maxslots = (string.sub(mtver.string, 1, 4) ~= "0.4.") and 32 or 23

local function validate_size(s)
    local size = s and tonumber(s) or 16
    if (size == 8 or size == 10 or size == 16 or size == 23 or size == 24 or size == 32)
      and size <= maxslots then
        return size
    else
        return 16
    end
end

local hotbar_size_default = validate_size(minetest.settings:get("hotbar_size"))

local player_hotbar_settings = {}

local function load_hotbar_settings()
    local f = io.open(minetest.get_worldpath()..DIR_DELIM.."hotbar_settings","r")
    if not f then return end
    local d = f:read("*all")
    f:close()
    player_hotbar_settings = minetest.deserialize(d)
end

local function save_hotbar_settings()
    local f = io.open(minetest.get_worldpath()..DIR_DELIM.."hotbar_settings","w")
    if not f then
        minetest.log("error","Failed to save hotbar settings")
        return
    end
    local d = minetest.serialize(player_hotbar_settings)
    f:write(d)
    f:close()
end

local function get_hotbar_setting(name)
    return tonumber(player_hotbar_settings[name]) or hotbar_size_default
end

load_hotbar_settings()

minetest.register_on_joinplayer(function(player)
    local hotbar_size = validate_size(get_hotbar_setting(player:get_player_name()))
    player:hud_set_hotbar_itemcount(hotbar_size)
    minetest.after(0.5,function(hotbar_size)
        player:hud_set_hotbar_selected_image("gui_hotbar_selected.png")
        player:hud_set_hotbar_image("gui_hb_bg_"..hotbar_size..".png")
    end,hotbar_size)
end)

minetest.register_chatcommand("hotbar", {
    params = "[size]",
    description = "Sets the size of your hotbar",
    func = function(name, slots)
        local hotbar_size = validate_size(tonumber(slots))
        player_hotbar_settings[name] = hotbar_size
        local player = minetest.get_player_by_name(name)
        player:hud_set_hotbar_itemcount(hotbar_size)
        minetest.chat_send_player(name, "[_] Hotbar size set to " ..hotbar_size.. ".")
        player:hud_set_hotbar_image("gui_hb_bg_"..hotbar_size..".png")
        save_hotbar_settings()
    end,
})