local p = {}



function p._isIpV6(s)

	local dcolon, groups

	if type(s) ~= "string"

		or s:len() == 0

		or s:find("[^:%x]") -- only colon and hex digits are legal chars

		or s:find("^:[^:]") -- can begin or end with :: but not with single :

		or s:find("[^:]:$")

		or s:find(":::")

	then

		return false

	end

	s, dcolon = s:gsub("::", ":")

	if dcolon > 1 then return false end -- at most one ::

	s = s:gsub("^:?", ":") -- prepend : if needed, upper

	s, groups = s:gsub(":%x%x?%x?%x?", "") -- remove valid groups, and count them

	return ( (dcolon == 1 and groups < 8) or (dcolon == 0 and groups == 8) )

		and ( s:len() == 0 or (dcolon == 1 and s == ":") ) -- might be one dangling : if original ended with ::

end



function p._isIpV4(s)

	local function legal(n) return (tonumber(n) or 256) < 256  and not n:match("^0%d") end

	if type(s) ~= "string" then return false end

	local p1, p2, p3, p4 = s:match("^(%d+)%.(%d+)%.(%d+)%.(%d+)$")

	return legal(p1) and legal(p2) and legal(p3) and legal(p4)

end



function p._isIp(s)

	return p._isIpV4(s) and "4" or p._isIpV6(s) and "6"

end



function p._isIpV4Range(s)

	return p._isIpV4(s:gsub("/%d+$", "")) and (p._isIpOrRange(s) == 'range')

end



function p._isIpV6Range(s)

	return p._isIpV6(s:gsub("/%d+$", "")) and (p._isIpOrRange(s) == 'range')

end



function p._isIpOrRange(s)

	local modip = require('Module:IP')

	local success, ip = pcall(modip.IPAddress.new, s)

	if success then

		return 'ip'

	end

	success, ip = pcall(modip.Subnet.new, s)

	if success then

		return 'range'

	end

	return ''

end



local function input(frame)

	-- Return input parameter after replacing any of following directional markers.

	-- LRM : LEFT-TO-RIGHT MARK (U+200E)         : hex e2 80 8e = 226 128 142

	-- LRE : LEFT-TO-RIGHT EMBEDDING (U+202A)    : hex e2 80 aa = 226 128 170

	-- PDF : POP DIRECTIONAL FORMATTING (U+202C) : hex e2 80 ac = 226 128 172

	-- This is required for MediaWiki:Blockedtext message.

	return (frame.args1 or ''):gsub('\226\128\142\170\172]', ' ')  -- replace LRM, LRE, PDF with space delimiter

end



function p.isIpV6(frame) return p._isIpV6(input(frame)) and "1" or "0" end

function p.isIpV4(frame) return p._isIpV4(input(frame)) and "1" or "0" end

function p.isIpV6Range(frame) return p._isIpV6Range(input(frame)) and "1" or "0" end 

function p.isIpV4Range(frame) return p._isIpV4Range(input(frame)) and "1" or "0" end 

function p.isIp(frame) return p._isIp(input(frame)) or "" end



function p.isIpOrRange(frame)

	-- {{#invoke:IPAddress|isIpOrRange|x}} → 'ip' (IPv4/IPv6) or 'range' (CIDR IPv4/IPv6) or '' (invalid)

	return p._isIpOrRange(input(frame))

end



return p