Lua SteamID Converter

do -- player.util
    util = {}

    local universes64 = {
        [ "45036" ] = "0",
        [ "76561" ] = "1",
        [ "14861" ] = "2",
        [ "22067" ] = "3",
        [ "29273" ] = "4",
        [ "36479" ] = "5"
    }
    local bases64 = {
        [ "0" ] = "450360",
        [ "1" ] = "76561",
        [ "2" ] = "14861",
        [ "3" ] = "22067",
        [ "4" ] = "29273",
        [ "5" ] = "36479"
    }
    local offsets64 = {
        [ "0" ] = 3922337792,
        [ "1" ] = 197960265728,
        [ "2" ] = 8791998193664,
        [ "3" ] = 6386036121600,
        [ "4" ] = 3980074049536,
        [ "5" ] = 1574111977472
    }

    function util.IsSteamID64( sParam )
        if type( sParam ) ~= "string" then return end
        return universes64[ string.sub( sParam, 1, 5 ) ]
    end

    function util.IsSteamID32( sParam )
        if type( sParam ) ~= "string" then return end
        return string.match( sParam, "STEAM_([012345]):([01]):(%d+)" )
    end

    function util.ChangeSteamID( sSteamID, sNewUniverse, bTo64 )
        sNewUniverse = tostring( sNewUniverse or 1 )
        if not offsets64[ sNewUniverse ] then return end
        local sUniverse64 = util.IsSteamID64( sSteamID )
        if sUniverse64 then
            if sUniverse64 == sNewUniverse and bTo64 ~= false then return sSteamID end
            local iAccount = tonumber( string.sub( sSteamID, 6 ) ) - offsets64[ sUniverse64 ]
            if bTo64 ~= false then
                return string.format( "%s%s", bases64[ sNewUniverse ], tostring( iAccount + offsets64[ sNewUniverse ] ) )
            else
                local sLow, sHigh = tostring( iAccount % 2 ), tostring( math.floor( iAccount / 2 ) )
                return string.format( "STEAM_%s:%s:%s", sNewUniverse, sLow, sHigh )
            end
        else
            local sUniverse32, sLow, sHigh = util.IsSteamID32( sSteamID )
            if sUniverse32 == sNewUniverse and not bTo64 then return sSteamID end
            if not bTo64 then
                return string.format( "STEAM_%s:%s:%s", sNewUniverse, sLow, sHigh )
            else
                local iAccount = tonumber( sLow ) + tonumber( sHigh ) * 2
                return string.format( "%s%s", bases64[ sNewUniverse ], tostring( iAccount + offsets64[ sNewUniverse ] ) )
            end
        end
    end
end