-- Minetest: builtin/misc.lua

--
-- Misc. API functions
--

function core.check_player_privs(name, ...)
	if core.is_player(name) then
		name = name:get_player_name()
	elseif type(name) ~= "string" then
		error("core.check_player_privs expects a player or playername as " ..
			"argument.", 2)
	end

	local requested_privs = {...}
	local player_privs = core.get_player_privs(name)
	local missing_privileges = {}

	if type(requested_privs[1]) == "table" then
		-- We were provided with a table like { privA = true, privB = true }.
		for priv, value in pairs(requested_privs[1]) do
			if value and not player_privs[priv] then
				missing_privileges[#missing_privileges + 1] = priv
			end
		end
	else
		-- Only a list, we can process it directly.
		for key, priv in pairs(requested_privs) do
			if not player_privs[priv] then
				missing_privileges[#missing_privileges + 1] = priv
			end
		end
	end

	if #missing_privileges > 0 then
		return false, missing_privileges
	end

	return true, ""
end


function core.send_join_message(player_name)
	if not core.is_singleplayer() then
		core.chat_send_all("*** " .. player_name .. " joined the game.")
	end
end


function core.send_leave_message(player_name, timed_out)
	local announcement = "*** " ..  player_name .. " left the game."
	if timed_out then
		announcement = announcement .. " (timed out)"
	end
	core.chat_send_all(announcement)
end


core.register_on_joinplayer(function(player)
	local player_name = player:get_player_name()
	if not core.is_singleplayer() then
		local status = core.get_server_status(player_name, true)
		if status and status ~= "" then
			core.chat_send_player(player_name, status)
		end
	end
	core.send_join_message(player_name)
end)


core.register_on_leaveplayer(function(player, timed_out)
	local player_name = player:get_player_name()
	core.send_leave_message(player_name, timed_out)
end)


function core.is_player(player)
	-- a table being a player is also supported because it quacks sufficiently
	-- like a player if it has the is_player function
	local t = type(player)
	return (t == "userdata" or t == "table") and
		type(player.is_player) == "function" and player:is_player()
end


function core.player_exists(name)
	return core.get_auth_handler().get_auth(name) ~= nil
end


-- Returns two position vectors representing a box of `radius` in each
-- direction centered around the player corresponding to `player_name`

function core.get_player_radius_area(player_name, radius)
	local player = core.get_player_by_name(player_name)
	if player == nil then
		return nil
	end

	local p1 = player:get_pos()
	local p2 = p1

	if radius then
		p1 = vector.subtract(p1, radius)
		p2 = vector.add(p2, radius)
	end

	return p1, p2
end


function core.hash_node_position(pos)
	return (pos.z + 32768) * 65536 * 65536
		 + (pos.y + 32768) * 65536
		 +  pos.x + 32768
end


function core.get_position_from_hash(hash)
	local pos = {}
	pos.x = (hash % 65536) - 32768
	hash  = math.floor(hash / 65536)
	pos.y = (hash % 65536) - 32768
	hash  = math.floor(hash / 65536)
	pos.z = (hash % 65536) - 32768
	return pos
end


function core.get_item_group(name, group)
	if not core.registered_items[name] or not
			core.registered_items[name].groups[group] then
		return 0
	end
	return core.registered_items[name].groups[group]
end


function core.get_node_group(name, group)
	core.log("deprecated", "Deprecated usage of get_node_group, use get_item_group instead")
	return core.get_item_group(name, group)
end


function core.setting_get_pos(name)
	local value = core.settings:get(name)
	if not value then
		return nil
	end
	return core.string_to_pos(value)
end


-- See l_env.cpp for the other functions
function core.get_artificial_light(param1)
	return math.floor(param1 / 16)
end


-- To be overriden by protection mods

function core.is_protected(pos, name)
	return false
end


function core.record_protection_violation(pos, name)
	for _, func in pairs(core.registered_on_protection_violation) do
		func(pos, name)
	end
end

-- To be overridden by Creative mods

local creative_mode_cache = core.settings:get_bool("creative_mode")
function core.is_creative_enabled(name)
	return creative_mode_cache
end

-- Checks if specified volume intersects a protected volume

function core.is_area_protected(minp, maxp, player_name, interval)
	-- 'interval' is the largest allowed interval for the 3D lattice of checks.

	-- Compute the optimal float step 'd' for each axis so that all corners and
	-- borders are checked. 'd' will be smaller or equal to 'interval'.
	-- Subtracting 1e-4 ensures that the max co-ordinate will be reached by the
	-- for loop (which might otherwise not be the case due to rounding errors).

	-- Default to 4
	interval = interval or 4
	local d = {}

	for _, c in pairs({"x", "y", "z"}) do
		if minp[c] > maxp[c] then
			-- Repair positions: 'minp' > 'maxp'
			local tmp = maxp[c]
			maxp[c] = minp[c]
			minp[c] = tmp
		end

		if maxp[c] > minp[c] then
			d[c] = (maxp[c] - minp[c]) /