-- Descended from a name_restrictions mod originally by ShadowNinja
-- License: WTFPL

----------------------------
-- Restriction exemptions --
----------------------------
-- For legitimate player names that are caught by the filters.

local exemptions = {}
local temp = minetest.setting_get("name_exemptions")
temp = temp and temp:split() or {}
for _, allowed_name in pairs(temp) do
    exemptions[allowed_name] = true
end
temp = nil

-- Exempt server owner
exemptions[minetest.setting_get("name")] = true
exemptions["singleplayer"] = true

-- Exempt others
exemptions["betterthanyou710"] = true
exemptions["CaptainAmerica"]   = true

---------------------
-- Simple matching --
---------------------

local msg_not_allowed = "This name is not allowed"

local disallowed = {

[ "[Ff][Uu][Cc][Kk]"  ] = msg_not_allowed ,
[ "[Cc][Uu][Nn][Tt]"  ] = msg_not_allowed ,
[ "[Ss][Hh][Ii][Tt]"  ] = msg_not_allowed ,
[ "[Pp][Oo][Oo][Pp]"  ] = msg_not_allowed ,
[ "hot.*girl"         ] = msg_not_allowed ,

[ "[^a-zA-Z0-9_%-]"   ] = "Name contains characters not allowed" ,
[ "^-"                ] = "Dash is not allowed at start of name" ,
[ "^[xX][xX]"         ] = "Fewer X's please"                     ,
[ "[xX][xX]$"         ] = "Fewer X's please"                     ,
[ "^guest[0-9]*"      ] = "Guest accounts are not allowed"       ,
[ "adm[1il]n"         ] = "Misleading nickname"                  ,
[ "[0o]wn[e3]r"       ] = "Misleading nickname"                  ,
[ "^[0-9]+$"          ] = "All-number names are not allowed"     ,
[ "^..............."  ] = "Name is too long"                     ,
[ "%d%d%d%d%d"        ] = "Name has too many numbers"            ,
[ "[a-z]%d%d%d%d"     ] = "Please remove some digits"            ,
[ "^[Ss]adie%d%d"     ] = "Please explain all the Sadies"        ,

[ "[A-Z][a-z][A-Z][a-z][A-Z][a-z]" ] =
    "Name is too complicated" ,
}

-- ===================================================================

minetest.register_on_prejoinplayer(function(name, ip)
    if exemptions[name] then return end

-- Check for names prohibited by "disallowed" patterns

    local lname = name:lower()
    for re, reason in pairs(disallowed) do
        if lname:find(re) then
            return reason
        end
    end

end)

-----------------
-- Name length --
-----------------

local min_name_len = tonumber(minetest.setting_get("name_restrictions.minimum_name_length")) or  4
local max_name_len = tonumber(minetest.setting_get("name_restrictions.maximum_name_length")) or 17

minetest.register_on_prejoinplayer (function (name, ip)
    if exemptions[name] then return end

    if #name < min_name_len then
        return "Your player name is too short"
        .. " (" .. #name .. " characters, must be " .. min_name_len .. " characters at least)."
        .. " Please try a longer name."
    end

    if #name > max_name_len then
        return "Your player name is too long"
        .. " (" .. #name .. " characters, must be " .. max_name_len .. " characters at most)."
        .. " Please try a shorter name."
    end
end)

----------------------
-- Pronounceability --
----------------------

-- Original implementation (in Python) by sfan5
--
local function pronounceable (pronounceability, text)
    local pronounceable    = 0
    local nonpronounceable = 0
    local cn = 0
    local lastc = ""
    for c in text:lower():gmatch(".") do
        if c:find("[aeiou0-9_-]") then
            if not c:find("[0-9]") then
                if cn > 2 then
                    nonpronounceable = nonpronounceable + 1
                else
                    pronounceable = pronounceable + 1
                end
            end
            cn = 0
        else
            if cn == 1 and lastc == c and lastc ~= 's' then
                nonpronounceable = nonpronounceable + 1
                cn = 0
            end
            if cn > 2 then
                nonpronounceable = nonpronounceable + 1
                cn = 0
            end
            if lastc:find("[aeiou]") then
                pronounceable = pronounceable + 1
                cn = 0
            end
            if not (c == "r" and lastc:find("[aipfom]")) and
                    not (lastc == "c" and c == "h") then
                cn = cn + 1
            end
        end
        lastc = c
    end
    if cn > 0 then
        nonpronounceable = nonpronounceable + 1
    end
    return pronounceable * pronounceability >= nonpronounceable
end

-- Pronounceability factor:
--   nil = Checking disabled.
--   0   = Everything's unpronounceable.
--   0.5 = Strict checking.
--   1   = Normal checking.
--   2   = Relaxed checking.

local pronounceability = tonumber(minetest.setting_get("name_restrictions.pronounceability"))
if    pronounceability then
    minetest.register_on_prejoinplayer(function(name, ip)
        if exemptions[name] then return end

        if not pronounceable(pronounceability, name) then
            return "Your player name does not seem to be pronounceable."
                .."  Please choose a more pronounceable name."
        end
    end)
end