local base = _G
local ltn12 = require("ltn12")
local mime = require("mime.core")
local string = require("string")
local _M = mime
local encodet, decodet, wrapt = {}, {}, {}
_M.encodet = encodet
_M.decodet = decodet
_M.wrapt = wrapt
local choose = function(table)
  return function(name, opt1, opt2)
    if base.type(name) ~= "string" then
      name, opt1, opt2 = "default", name, opt1
    end
    local f = table[name or "nil"]
    if not f then
      base.error("unknown key (" .. base.tostring(name) .. ")", 3)
    else
      return f(opt1, opt2)
    end
  end
end

function encodet.base64()
  return ltn12.filter.cycle(_M.b64, "")
end

encodet["quoted-printable"] = function(mode)
  return ltn12.filter.cycle(_M.qp, "", mode == "binary" and "=0D=0A" or "\r\n")
end

function decodet.base64()
  return ltn12.filter.cycle(_M.unb64, "")
end

decodet["quoted-printable"] = function()
  return ltn12.filter.cycle(_M.unqp, "")
end
local format = function(chunk)
  if chunk then
    if chunk == "" then
      return "''"
    else
      return string.len(chunk)
    end
  else
    return "nil"
  end
end

function wrapt.text(length)
  length = length or 76
  return ltn12.filter.cycle(_M.wrp, length, length)
end

wrapt.base64 = wrapt.text
wrapt.default = wrapt.text
wrapt["quoted-printable"] = function()
  return ltn12.filter.cycle(_M.qpwrp, 76, 76)
end
_M.encode = choose(encodet)
_M.decode = choose(decodet)
_M.wrap = choose(wrapt)

function _M.normalize(marker)
  return ltn12.filter.cycle(_M.eol, 0, marker)
end

function _M.stuff()
  return ltn12.filter.cycle(_M.dot, 2)
end

return _M
