local ffi = require('ffi')
local crypto = ffi.load("crypto.so.1.1", true)
local ffi_string = ffi.string

ffi.cdef[[
  char *MD5(const char *d, size_t n, char *md);
  int EVP_DecodeBlock(unsigned char *t, const unsigned char *f, int n);
  int EVP_EncodeBlock(unsigned char *t, const unsigned char *f, int n);
]]

local _M = { version = 0.2 }

function string.tohex(str)
  return (str:gsub('.', function (c)
    return string.format('%02X', string.byte(c))
  end))
end

function _M.md5(data)
  local buf = ffi.new("char[16]")
  crypto.MD5(data, #data, buf)
  return ffi_string(buf):tohex()
end

function _M.decode_base64(data)
  local len = #data - #data/4
  local buf = ffi.new("unsigned char["..len.."]")
  len = crypto.EVP_DecodeBlock(buf, data, #data)
  return ffi_string(buf, len - 1)
end

function _M.encode_base64(data)
  local len = #data + #data/4
  local buf = ffi.new("unsigned char["..len.."]")
  len = crypto.EVP_EncodeBlock(buf, data, #data)
  return ffi_string(buf, len - 1)
end

return _M