--A simple remote Lua shell. Displays command prompt, supports "=" prefix
--and has initial support for print/io.stdout redirection to the network
--connection. For convenience, I recommend you to install rlwrap and connect
--to the host like this:
--
--  rlwrap ncat somehost
--
--This will give you convenient line editing and history, just like in the
--real interpreter.

--Couldn't simply edit metatable of io.stdout - there's no Lua-side interface
--for that.
old_stdout = io.stdout
io.stdout = {
  write = function (self, data)
    if lastconn ~= old_stdout then
      lastconn.super:send(data)
    else
      old_stdout:write(data)
    end
  end,
}

function print (...)
  for k, v in pairs {
    ...,
  } do
    io.stdout:write(tostring(v) .. "\t")
  end
  io.stdout:write "\n"
end

function eval (line)
  if line:sub(1, 1) == "=" then
    line = "return " .. line:sub(2)
  end

  local results = {
    pcall(load(line)),
  }

  local tosend = ""
  for _, v in pairs {
    table.unpack(results, 2, results.n),
  } do
    tosend = tosend .. (tostring(v)) .. "\t"
  end
  if tosend == "" then
    tosend = "nil"
  else
    tosend = tosend:sub(1, -2)
  end
  tosend = tosend .. "\n> "
  return tosend
end

showed_prompt = false

return {

  connect = function (self, host, port)
    local ret = self.super:connect(host, port)
    if not showed_prompt then
      old_stdout:write "> "
      old_stdout:flush()
      showed_prompt = true
    end
    self.super:send "> "
    return ret
  end,

  recv = function (self)
    local line, err = self.super:recv()
    if line == nil then
      return line, err
    end

    lastconn = self
    local tosend = eval(line)
    self.super:send(tosend)

    return ""
  end,

  send = function (self, str)
    if last_sent == str then
      return ""
    else
      last_sent = str
    end
    lastconn = old_stdout
    old_stdout:write(eval(str))
    old_stdout:flush()
    return ""
  end,
}