-- No guests mod.
-- By VanessaE, sfan5, and kaeza.

local disallowed = {
	["guest"] = "Guest accounts are disallowed on this server.  "..
							"Please choose a proper username and try again.",
	["[4a]dm[1il]n"] = "That is a clearly false, misleading, or otherwise disallowed username. "..
 										 "Please choose a unique username and try again.",
	["^[0-9]+$"] = "All-numeric usernames are disallowed on this server. "..
								 "Please choose a proper username and try again.",
	["[0-9].-[0-9].-[0-9].-[0-9].-[0-9]"] = "Too many numbers in your username. "..
												"Please try again with less than five digits in your username.",
	["^[A-Za-z]+[0-9][0-9]+$"] = "Please choice your own username. Usernames with letters then 2 or more digits are not allowed"
}

-- Original implementation (in Python) by sfan5
local function judge(msg)
	local numspeakable = 0
	local numnotspeakable = 0
	local cn = 0
	local lastc = '____'
	for c in msg:gmatch(".") do
		c = c:lower()
		if c:find("[aeiou0-9_-]") then
			if cn > 2 and not c:find("[0-9]") then
				numnotspeakable = numnotspeakable + 1
			elseif not c:find("[0-9]") then
				numspeakable = numspeakable + 1
			end
			cn = 0
		else
			if (cn == 1) and (lastc == c) and (lastc ~= 's') then
				numnotspeakable = numnotspeakable + 1
				cn = 0
			end
			if cn > 2 then
				numnotspeakable = numnotspeakable + 1
				cn = 0
			end
			if lastc:find("[aeiou]") then
				numspeakable = numspeakable + 1
				cn = 0
			end
			if not ((lastc:find("[aipfom]") and c == "r") or (lastc == "c" and c == "h")) then
				cn = cn + 1
			end
		end
		lastc = c
	end
	if cn > 0 then
		numnotspeakable = numnotspeakable + 1
	end
	return (numspeakable >= numnotspeakable)
end

minetest.register_on_prejoinplayer(function(name, ip)
	if not minetest.player_exists(name) then
		local lname = name:lower()
		for re, reason in pairs(disallowed) do
			if lname:find(re) then
				return reason
			end
		end

		if #name < 2 then
			return "Too short of a username. "..
					"Please pick a name with at least two letters and try again."
		end

		if not judge(name) and #name > 5 then
			return "Your username just plain looks like gibberish. "..
					"Please pick something readable and try again."
		end
	end
end)