local base64 = {}

base64.encode = function(data)
    local letters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
    return ((data:gsub('.', function(x) 
        local r,b='',x:byte()
        for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
        return r;
    end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
        if (#x < 6) then return '' end
        local c=0
        for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
        return letters:sub(c+1,c+1)
    end)..({ '', '==', '=' })[#data%3+1])
end
base64.decode = function(data)
    local b = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
    data = string.gsub(data, '[^'..b..'=]', '')
    return (data:gsub('.', function(x)
        if x == '=' then return '' end
        local r, f = '', (b:find(x) - 1)
        for i = 6, 1, -1 do
            r = r .. (f % 2^i - f % 2^(i - 1) > 0 and '1' or '0')
        end
        return r;
    end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
        if #x ~= 8 then return '' end
        local c = 0
        for i = 1, 8 do
            c = c + (x:sub(i, i) == '1' and 2^(8 - i) or 0)
        end
        return string.char(c)
    end))
end

return base64;