local S = minetest.get_translator(minetest.get_current_modname())

local gamemode_ids = {
	survival = 1,
	creative = 2,
}

local id_to_gamemode = {}
for gamemode, id in pairs(gamemode_ids) do
	id_to_gamemode[id] = gamemode
end

local creative_mode = 'creative'

local storage = minetest.get_mod_storage()

local player_to_gamemode_id = minetest.deserialize(storage:get_string("player_to_gamemode_id") or "return {}") or {}
minetest.register_on_shutdown(function()
	storage:set_string("player_to_gamemode_id", minetest.serialize(player_to_gamemode_id))
end)

local core_is_creative_enabled = minetest.is_creative_enabled

minetest.is_creative_enabled = function(name)
	local id = player_to_gamemode_id[name]
	if id then
		local gamemode = id_to_gamemode[id]
		if gamemode then
			return gamemode == creative_mode
		end
	end
	return core_is_creative_enabled(name)
end

local function handle_gamemode_command(player_name, new_gamemode)
	player_to_gamemode_id[player_name] = gamemode_ids[new_gamemode]
	return true
end

if minetest.registered_chatcommands["gamemode"] then
	minetest.unregister_chatcommand("gamemode")
end

local function get_gamemode_param()
	local param
	local i = 0
	for gamemode, _ in pairs(gamemode_ids) do
		if i == 0 then
			param = "("
		else
			param = param .. " | "
		end
		i = i + 1
		param = param .. gamemode
	end
	if i > 0 then
		param = param .. ") "
	end
	return param
end

minetest.register_chatcommand("gamemode", {
	params = S("@1[<name>]", get_gamemode_param()),
	description = S("Set game mode for player or yourself"),
	privs = {server=true},
	func = function(name, param)
		if (param == "") then
			return false, S("Error: No game mode specified.")
		end
		if (gamemode_ids[param]) then
			handle_gamemode_command(name, param)
		else
			local new_gamemode, player_name = string.match(param, "^([%a]+) ([%a%d_-]+)$")
			if not new_gamemode or not gamemode_ids[new_gamemode] or not player_name then
				return false, S("Invalid usage, see /help @1", "gamemode")
			end
			handle_gamemode_command(player_name, new_gamemode)
		end
	end
})